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What Role Should DNA Testing Play In Nutritional Recommendations?

May 2, 2023 by Dr. Steve Chaney

The Promise And Problems Of Nutrigenomics

Author: Dr. Stephen Chaney

When the human genome was sequenced in 2003, many of us in the scientific community thought we were on the verge of a revolution in human health and longevity. We would soon be able to tell individuals their risk of developing various diseases.

Even better, we would be able to tell them the kind of diet and supplementation they needed to avoid those diseases. We would be able to personalize our nutritional recommendation for every individual based on their genome – something called nutrigenomics.

How naive we were! It has turned out to be much more complicated to design personalized nutrition recommendations based on someone’s genome than we ever imagined.

What Is Nutrigenomics?

As a Professor at the University of North Carolina I specialized in cancer drug development for over 30 years. Over the last decade of my career a ﬁeld called pharmacogenomics became widely accepted in the ﬁeld of cancer drug development. In simple terms, pharmacogenomics looks at how an individual’s genes influence the effectiveness and side effects of drugs.

Because of pharmacogenomics, drugs today are being approved to target cancers for people whose cancer cells have a particular genetic makeup. These drugs would not have been approved a decades ago because if you test them on cancer in the general population, they have little or no eﬀectiveness. They only work on a subset of people who have a form of cancer with a specific genetic makeup.

In principle, nutrigenomics is the same principle. You’ve heard for years that we all have unique nutritional needs. Now we are starting to learn why. It’s because we all have unique variations in our genetic makeup. These genetic mutations increase our risk of certain diseases, and they increase our needs for certain nutrients.

For example, mutations in the MTHFR gene increase the risk of certain birth defects, and supplementation with folic acid is particularly important for reducing birth defects in that population group.

Similarly, mutations in the vitamin D receptor, the VDR gene, interfere with vitamin D absorption from foods and are associated with a condition known as “vitamin D-resistant rickets”. Babies born with this genetic defect require mega doses of vitamin D for normal bone formation.

These are the best-established examples of gene mutations that affect nutritional needs. Many more gene-nutrient interactions have been proposed, but they have not been validated by follow-up experiments.

The situation is similar when we look at gene mutations associated with metabolic responses such as fat and carbohydrate metabolism, obesity, insulin resistance and type 2 diabetes. There are a few gene mutations that have strong associations with obesity and diabetes. Many more gene-metabolism interactions have been proposed, but the data are weak and inconsistent.

The Promise And Problems Of Nutrigenomics

The Promise Of Nutrigenomics.

Now that you understand what nutrigenomics is and have some background information about it, let’s look at the promise of nutrigenomics. One promise of nutrigenomics is personalized supplement programs.

We all have different nutritional needs. Wouldn’t it be wonderful if someone could analyze your genome and provide you with a personalized supplement program that precisely fits your genetically determined nutritional requirements?

There are companies that offer such personalized supplement programs. Are they providing you with something of value or is their testing bogus? Are their supplements worthless?

Another promise of nutrigenomics is personalized diet advice. Some people seem to do better on low-fat diets. Other people do better on low-carb diets. Saturated fats and red meats may be more problematic for some individuals than for others. Wouldn’t it be wonderful if someone could analyze your genome and provide you with a personalized diet program – one that allows you to lose weight easily and gain vibrant health.

There are companies that will analyze your genome and tell you whether you are more likely to lose weight and be healthier on a low-fat or low-carbohydrate diet. Is their testing accurate or is it bogus? Are they providing you with useful information, or is their diet advice worthless?

The Problem With Nutrigenomics

The short answer to the questions I posed in the previous section is that personalized supplement and diet programs are on the horizon, but we are not there yet. Companies promising you personalized nutrition programs based only on DNA tests are misleading you. They quote a few studies supporting the tests they run and ignore the many studies showing their tests are worthless.

In case you think that is just my opinion, let me quote from some recent reviews on the current status of nutrigenomics.

For example, a review (C Murgia and MM Adamski, Nutrients, 366, 2017) published in 2017 concluded: “The potential applications to nutrition of this invaluable tool were apparent since the genome was mapped. The first articles discussing nutrigenomics and nutrigenetics were published less than a year after the first draft of the human DNA sequence was made available…However, fifteen years and hundreds of publications later, the gap between the experimental and epidemiologic evidence and health practice is not yet closed.”

“The [complexity] of the genotype information is not the only factor that complicates this translation into practice. The discovery of other levels of control, including epigenetics [modifications of DNA that affect gene expression] and the intestinal microbiome, are other complicating factors. While the science of nutritional genomics continues to demonstrate potential individual responses to nutrition, the complex nature of gene, nutrition and health interactions continues to provide a challenge for healthcare professionals to analyze, interpret and apply to patient recommendations.”

Another review (M Gaussch-Ferre et al, Advances in Nutrition, 9: 128-135, 2018) published in 2018 concluded: “Overall, the scientific evidence supporting the dissemination of genomic information for nutrigenomic purposes remains sparse. Therefore, additional knowledge needs to be generated…”

In short, the experts are saying we still don’t know enough to predict the best diets, or the best supplements based on genetic information alone. Why is that? Why is it so complicated? In part, it can be explained by a term called penetrance. Penetrance simply means that the same gene mutation can have different effects in different people. In some people, its effects may be barely noticeable. In other people its effects may be debilitating.

The Truth About DNA Testing And Personalized Nutrition

Penetrance is just a word. It’s a concept. The important question is, “What causes differences in genetic penetrance?” Here are the most likely explanations.

1) Human genetics is very complex. There are some gene mutations, such as those causing cystic fibrosis and sickle cell anemia, that can cause a disease by themselves. Most gene mutations, however, simply predispose to a disease or metabolic disturbance and are highly influenced by the activity of other genes. That’s because the products of gene expression form intricate regulatory and metabolic networks. When a single gene is mutated, it interacts with many other genes in the network. And, that network is different for each of us.

2) Many common diseases are polygenic. That includes diseases like heart disease, diabetes, and most cancers. Simply put, that means that they are not caused by a single gene mutation. They are caused by the cumulative effect of many mutations, each of which has a small effect on disease risk. The same appears to be true for mutations that influence carbohydrate and fat metabolism and affect nutrient requirements.

3) The outcome of gene mutations is strongly influenced by our diet, lifestyle, and environment. For example, a common mutation in a gene called FTO predisposes to obesity. However, the effect of this mutation on obesity is strongest when it is coupled with inactivity and foods of high caloric density (translation: junk foods and fast foods instead of fresh fruits and vegetables). Simply put, that means most of us are genetically predisposed to obesity if we follow the American lifestyle, but obesity is not inevitable.

4) Epigenetics has an important influence on gene expression. When I was a graduate student, we believed our genetic destiny was solely determined by our DNA sequence. That was still the prevailing viewpoint when the human genome project was initiated. We thought that once we had our complete DNA sequence, we would know everything we needed to know about our genetic destiny.

How short sighted we were! It turns out that our DNA can be modified in multiple ways. These modifications do not change the DNA sequence, but they can have major effects on gene expression. They can turn genes on or turn them off. More importantly, we have come to learn that these DNA modifications can be influenced by our diet, lifestyle, and exposure to environmental pollutants.

This is the science we call epigenetics. We have gone from believing we have a genome (DNA sequence) that is invariant and controls our genetic destiny to understanding that we also have an “epigenome” (modifications to our DNA) that is strongly influenced by our diet, lifestyle, and environment and can change day-to-day.

5) Our microbiome has an important influence on our health and nutritional status. Simply put, the term microbiome refers to our intestinal microbes. Our intestinal bacteria are incredibly diverse. Each of us has about 1,000 distinct species of bacteria in our intestines.

Current evidence suggests these intestinal bacteria influence our immune system, inflammation and auto-immune diseases, brain function and mood, and our predisposition to weight gain – and this may just be the tip of the iceberg.

More importantly, our microbiome is influenced by our diet. For example, vegetarians and meat eaters have entirely different microbiomes. Furthermore, the effect of diet on our microbiome is transitory. If you change your diet, the species of bacteria in your microbiome will completely change in a few weeks.

Finally, our microbiome also influences our nutritional requirements. For example, some species of intestinal bacteria are the major source of biotin and vitamin K2 for all of us and the major source of vitamin B12 for vegans. Intestinal bacteria may also contribute to our supply of folic acid and thiamine. Other intestinal bacteria inactivate and/or remove some vitamins from the intestine for their own use. Thus, the species of bacteria that populate our intestines can influence our nutritional requirements.

Now that you know the complexity of gene interactions you understand why we are not ready to rely on DNA tests yet. We don’t yet know enough to design a simple DNA test to predict our unique nutritional needs. That science is at least 10-20 years in the future. Companies that tell you otherwise are lying to you.

What Role Should DNA Testing Play In Nutritional Recommendations?

The algorithms that are most successful in creating personalized diet and/or supplement recommendations:

1) Start with an analysis of your diet and lifestyle. They powerfully affect both gene expression and your microbiome.

2) Add in health parameters such as blood pressure, LDL cholesterol, HDL cholesterol, triglycerides, and hemoglobin A1c (a measure of blood sugar control). For example, a DNA analysis may suggest you are at risk for having elevated cholesterol, but whether you do or not is influenced by many other factors. A simple blood test indicates whether that risk is real for you.

3) Consider your personal health goals. If nutritional recommendations are to be personalized to you, they should emphasize the health goals you value most.

4) Include any diseases you have and recommendations of your doctor. If your doctor has recommended you lower your blood pressure, your cholesterol, or blood sugar levels, that is valuable information to include in the mix.

5) Now you are ready to include DNA testing in the mix. It can provide some valuable insights, but those insights need to be filtered through the lens of all the critical information collected in the first four steps. Genetics gives you possibilities. The information collected in the first four steps represents your realities.

The Bottom Line

Nutrigenomics is defined as the interaction between our genetic makeup and our diet. How far have we advanced in the science of nutrigenomics? Can a simple DNA test provide us with useful information?

For example, we all have different nutritional needs. Wouldn’t it be wonderful if someone could analyze your genome and provide you with a personalized supplement program that precisely fits your genetically determined nutritional requirements?

There are companies that will analyze your genome and offer personalized supplement programs. Are they providing you with something of value or is their testing bogus? Are their supplements worthless?

Two recent reviews have surveyed the nutrigenomic literature (all published clinical studies) and have concluded that we still don’t know enough to predict the best diets, or the best supplements based on genetic information alone. Why is that? It is because:

1) Human genetics is very complex.

2) Many common diseases are polygenic (caused by the cumulative effect of many mutations).

3) The effect of gene mutations on our health and wellbeing is strongly influenced by our diet, lifestyle, and environment.

4) Epigenetics has an important influence on gene expression.

5) Our microbiome has an important influence on our health and nutritional status.

For more details on these studies and the kind of testing that best determines the right diet and/or supplement program for you, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

Can Lifestyle Overcome Bad Genes?

January 31, 2023 by Dr. Steve Chaney

Lifestyle, Genetics, And Dementia Risk

Author: Dr. Stephen Chaney

Alzheimer’s disease and other forms of dementia are among the most feared diseases of aging. What use is it to have a healthy body, a loving family, and a successful career if you can’t remember any of it? You should be able to enjoy your Golden years, not see them slip through your fingers.

If you have a family history of dementia or have sent your DNA off for testing and learned you are genetically predisposed to dementia, you are probably worried.

Perhaps the scariest thing about Alzheimer’s is that the medical community has no answers. There are no drugs to prevent or cure Alzheimer’s and brain transplants are out of the question. Some medical professionals will tell you nothing can be done, but is that true?

Before I answer that question let me share a fictional story because it provides a clue. In 1997, when I was still a relatively young scientist, I saw a film called GAATACA. [If you are looking for an entertaining film to watch, it is still available on some streaming services.]

This film envisioned a future society in which parents had their sperm and eggs sequenced so that their children would be genetically perfect. In that society the term “love child” had been redefined as a child who had been conceived without prior DNA sequencing.

The hero of this film was, of course, a love child. He was born with a genetic predisposition for heart disease. He was considered inferior, a second-class citizen of this future world.

Without giving away the plot of the film (I don’t want to spoil the enjoyment for you if you are thinking of watching it), he overcame his genetic inferiority. With a strict regimen of diet and physical fitness he became stronger and healthier than many of his genetically perfect peers.

This is when I first began to realize that our genes do not have to determine our destiny. We have the power to overcome bad genetics. We also have the power to undermine good genetics.

With that in mind, let’s return to Alzheimer’s. Studies have suggested that a healthy lifestyle can help reduce your risk of developing Alzheimer’s and other forms of dementia. But what about genetics? Will a healthy lifestyle only reduce your risk of dementia if your genetic risk is low, or will it be equally effective when your genetic risk is high? Can lifestyle overcome genetics?

The current study (A Tin et al, Neurology, 99: e154-e163, 2022) was designed to answer these questions.

How Was This Study Done?

This study included 11,561 participants from the Atherosclerosis Risk In Communities (ARIC) study. The ARIC study recruited middle-aged adults (average age of 54) from both urban and rural areas of the United States and followed them for 26 years. The participants were 57% female and 53% white.

Simply put, the study was designed to look at the effect of a healthy lifestyle on the genetic risk of developing dementia.

A healthy lifestyle was defined based on something called “Life’s Simple 7” (LS7) score.

The LS7 score was developed by the American Heart Association to define the effect of lifestyle on the risk of developing heart disease. However, it works equally well for defining the effect of lifestyle on risk of developing dementia.

The LS7 score consists of 7 modifiable health factors.

- The factors are diet, physical activity, BMI (a measure of obesity), smoking, total cholesterol, blood pressure, and fasting blood glucose.

The data for deriving the LS7 scores were derived from data gathered from each participant when they enrolled in the ARIC study.

- Diet was assessed by a 66-item food frequency questionnaire.

- Physical activity and smoking were assessed in separate questionnaires.

- BMI, blood pressure, total cholesterol, and fasting blood glucose were measured during a visit to a designated clinic at the beginning of the study.

Each modifiable health factor was separated into 3 categories (ideal, intermediate, and poor) and the highest score was assigned to the ideal category. The LS7 score was the sum of the scores from all 7 modifiable health factors.

Genetic risk of developing dementia was defined based on something called “The Genetic Risk Score” (GRS).

We have known for years that individuals of European descent who have the APOE ɛ4 gene variant have a 2 to 5-fold increased lifetime risk of developing dementia.

In recent years scientists have discovered several additional gene variants that increase the risk of dementia.

These have been combined with APOE ɛ4 to create a Genetic Risk Score for dementia.

The Genetic Risk Score for each participant was determined by DNA sequencing at the beginning of the study, with the highest score indicating the greatest risk for developing dementia.

The onset and severity of dementia were determined based on 7 clinic visits during the study.

Questionnaires were administered at each visit to assess self-reported dementia symptoms.

Cognitive tests were administered at visits 2 and 4.

Detailed cognitive and functional assessments were conducted at visits 5, 6, and 7.

The data were reviewed by an expert committee of physicians and neuropsychologists to determine dementia status.

Lifestyle, Genetics, And Dementia Risk

At the end of the 26-year study:

When participants with the highest Genetic Risk Scores were compared to those with the lowest Genetic Risk Scores:

- European American participants were 2.7-fold more likely to develop dementia.

- African American participants were 1.55-fold more likely to develop dementia.

When participants with the highest LS7 (healthy lifestyle) scores were compared to those with the lowest LS7 scores:

- European American participants were 40% less likely to develop dementia.

- African American participants were 17% less likely to develop dementia.

- A healthy lifestyle decreased the risk of developing dementia to a comparable extent at all levels of genetic risk for dementia.

The authors concluded, “Higher LS7 scores [a measure of a healthy lifestyle] are largely associated with a lower risk of incident dementia across strata of genetic risk [at all levels of genetic risk], supporting the use of LS7 [a healthy lifestyle] for maintaining brain health and offsetting genetic risk. More studies with larger study populations are needed…”

I should briefly comment on why African Americans were less responsive to both genetic risk and a healthy lifestyle than European Americans. The reasons for these discrepancies are not known, but:

There are socioeconomic factors and health disparities that increase the risk of dementia that are not included in the LS7 score.
A recent study has identified genetic risk factors for dementia that are unique to African Americans that are not included in the genetic risk score used in this study.

Can Lifestyle Overcome Bad Genes?

Dr. James Watson, who was co-discoverer of the DNA double helix and was heavily involved in the sequencing of the human genome, asked that he not be told about his risk of developing Alzheimer’s when his own DNA was sequenced in the early 2000’s. His reasoning was, “Why know the risk if you can’t change it?”

If the study I discussed today is true, you can modify the risk. Your genes don’t have to be your destiny. But is it true?

There is good reason to believe it might be true. Multiple studies have shown that each of the health factors included in LS7 score reduce the risk of developing dementia. However, most of those studies have not looked at the interaction between a healthy lifestyle and genetic risk.

Fortunately, there is another recent study that looked at the interaction between a healthy lifestyle and genetic risk of developing dementia.

This study used a different database (The UK Biobank study which enrolled 500,000 participants) and different criteria for defining a healthy lifestyle (diet, physical activity, smoking, and alcohol use).

However, the conclusions of this study were very similar:

People at high genetic risk were almost twice as likely to develop dementia as those at low genetic risk.

A healthy lifestyle decreased the risk of developing dementia by about 40% for both people at high genetic risk and for people at low genetic risk.

But this study went one step further than the study I discussed in this article. The British study reported that:

People at low genetic risk and an unhealthy lifestyle (the typical American) were just as likely to develop dementia as people at high genetic risk and a healthy lifestyle.

In other words, bad genetics does not doom you to Alzheimer’s and dementia. A healthy lifestyle can cut your risk almost in half. Conversely, good genetics is not a “Get Out of Jail Free” card. You can squander the advantage of good genetics with an unhealthy lifestyle.

And, just like the hero of the movie I discuss at the beginning of this article, a healthy lifestyle may be able to overcome bad genes and make you just as healthy (with respect to the risk of developing dementia) as people with good genes and an unhealthy lifestyle – which includes most Americans.

The Bottom Line

If you have a family history of dementia or have sent your DNA off for testing and learned you are genetically predisposed to dementia, you are probably worried.

Studies have suggested that a healthy lifestyle can help reduce your risk of developing Alzheimer’s and other forms of dementia. But what about genetics? Will a healthy lifestyle only reduce your risk of dementia if your genetic risk is low, or will it be equally effective when your genetic risk is high? Can lifestyle overcome genetics?

A recent study was designed to answer these questions. It found:

When participants with the highest Genetic Risk Scores were compared to those with the lowest Genetic Risk Scores:

- They were 1.5 to 2.7-fold more likely to develop dementia.

When participants with the highest LS7 (healthy lifestyle) scores were compared to those with the lowest LS7 scores:

- They were 17% to 40% less likely to develop dementia.

A healthy lifestyle decreased the risk of developing dementia to a comparable extent at all levels of genetic risk for dementia.

This, and other studies discussed in this issue of “Health Tips For The Professor” suggest that your genes don’t have to determine your destiny. You can overcome bad genes with a healthy lifestyle.

For more details on this study, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease.

Who Benefits Most From Supplementation?

February 8, 2022 by Dr. Steve Chaney

Supplements Are Part of a Holistic Lifestyle

Author: Dr. Stephen Chaney

The headlines about supplementation are so confusing. Are they useful, or are they a waste of money? Will they cure you, or will they kill you? I feel your pain.

I have covered these questions in depth in my book, “Slaying The Supplement Myths”, but let me give you a quick overview today. I call it: “Who Benefits Most From Supplementation?” I created the graphic on the left to illustrate why I feel responsible supplementation is an important part of a holistic lifestyle for most Americans. Let me give you specific examples for each of these categories.

Examples of Poor Diet

You have heard the saying that supplementation fills in the nutritional gaps in our diets, so what are the nutritional gaps? According to the USDA’s 2020-2025 Dietary Guidelines for Americans, many Americans are consuming too much fast and convenience foods. Consequently, we are getting inadequate amounts of calcium, magnesium, and vitamins A, D, E and C. Iron is considered a nutrient of concern for young children and pregnant women. In addition, folic acid, vitamin B6, and iodine are nutrients of concern for adolescent girls and pregnant women.

According to a recent study, regular use of a multivitamin is sufficient to eliminate all these deficiencies except for calcium, magnesium and vitamin D (J.B. Blumberg et al, Nutrients, 9(8): doi: 10.3390/nu9080849, 2017). A well-designed calcium, magnesium and vitamin D supplement may be needed to eliminate those deficiencies.

In addition, intake of omega-3 fatty acids from foods appears to be inadequate in this country. Recent studies have found that American’s blood levels of omega-3s are among the lowest in the world and only half of the recommended level for reducing the risk of heart disease (K.D. Stark et al, Progress In Lipid Research, 63: 132-152, 2016; S.V. Thuppal et al, Nutrients, 9, 930, 2017; M Thompson et al, Nutrients, 11: 177, 2019). Therefore, omega-3 supplementation is often a good idea.

In previous editions of “Health Tips From the Professor” I have talked about our “mighty microbiome”, the bacteria and other microorganisms in our intestine. These intestinal bacteria can affect our tendency to gain weight, our immune system, inflammatory diseases, chronic diseases such as diabetes, cancer, and heart diseases, our mood—the list goes on and on. This is an emerging science. We are learning more every day, but for now it appears our best chances for creating a health-enhancing microbiome are to consume a primarily plant-based diet and take a probiotic supplement.

Finally, diets that eliminate whole food groups create nutritional deficiencies. For example, vegan diets increase the risk of deficiencies in vitamin B12, vitamin D, calcium, iron, zinc and long chain omega-3 fatty acids. A recent study reported that the Paleo diet increased the risk of calcium, magnesium, iodine, thiamin, riboflavin, folate and vitamin D deficiency (A. Genomi et al, Nutrients, 8, 314, 2016). The Keto diet is even more restrictive and is likely to create additional deficiencies.

Examples of Increased Need

We have known for years that pregnancy and lactation increase nutritional requirements. In addition, seniors have increased needs for protein, calcium, vitamin D and vitamin B12. In previous issues of “Health Tips From the Professor” I have also shared recent studies showing that protein requirements are increased with exercise.

Common medications also increase our need for specific nutrients. For example, seizure medications can increase your need for vitamin D and calcium. Drugs to treat diabetes and acid reflux can increase your need for vitamin B12. Other drugs increase your need for vitamin B6, folic acid, and vitamin K. Excess alcohol consumption increases your need for thiamin, folic acid, and vitamin B6. These are just a few examples.

Vitamin D is a special case. Many people with apparently adequate intake of vitamin D have low blood levels of 25-hydroxy vitamin D. It is a good idea to have your blood 25-hydroxy vitamin D levels measured on an annual basis and supplement with vitamin D if they are low.

More worrisome is the fact that we live in an increasing polluted world and some of these pollutants may increase our needs for certain nutrients. For example, in a recent edition of “Health Tips From the Professor” I shared a study reporting that exposure to pesticides during pregnancy increases the risk of giving birth to children who will develop autism, and that supplementation with folic acid during pregnancy reduces the effect of pesticides on autism risk. I do wish to acknowledge that this is a developing area of research. This and similar studies require confirmation. It is, however, a reminder that there may be factors beyond our control that have the potential to increase our nutritional needs.

Examples of Genetics Influencing Nutritional Needs

The effect of genetic variation on nutritional needs is known as nutrigenomics. One of the best-known examples of nutrigenomics is genetic variation in the methylenetetrahydrofolate reductase (MTHFR) gene. MTHFR gene mutations increase the risk of certain birth defects, such as neural tube defects. MTHFR mutations also slightly increase the requirement for folic acid. A combination of food fortification and supplementation with folic acid have substantially decreased the prevalence of neural tube defects in the US population. This is one of the great success stories of nutrigenomics. Parenthetically, there is no evidence that methylfolate is needed to decrease the risk of neural tube defects in women with MTHFR mutations.

Let me give you a couple of additional examples:

One of them has to do with vitamin E and heart disease (A.P. Levy et al, Diabetes Care, 27: 2767, 2004). Like a lot of other studies there was no significant effect of vitamin E on cardiovascular risk in the general population. But there is a genetic variation in the haptoglobin gene that influences cardiovascular risk. The haptoglobin 2-2 genotype increases oxidative damage to the arterial wall, which significantly increases the risk of cardiovascular disease. When the authors of this study looked at the effect of vitamin E in people with this genotype, they found that it significantly decreased heart attacks and cardiovascular deaths.

This has been confirmed by a second study specifically designed to look at vitamin E supplementation in that population group (F. Micheletta et al, Arteriosclerosis, Thrombosis and Vascular Biology, 24: 136, 2008). This is an example of a high-risk group benefiting from supplementation, but in this case the high risk is based on genetic variation.

Let’s look at soy and heart disease as a final example. There was a study called the ISOHEART study (W.L. Hall et al, American Journal of Clinical Nutrition, 82: 1260-1268, 2005 (http://ajcn.nutrition.org/content/82/6/1260.abstract); W.L. Hall et al, American Journal of Clinical Nutrition, 83: 592-600, 2006) that looked at a genetic variation in the estrogen receptor which increases inflammation and decreases levels of HDL. As you might expect, this genotype significantly increases cardiovascular risk.

Soy isoflavones significantly decrease inflammation and increase HDL levels in this population group. But they have no effect on inflammation or HDL levels in people with other genotypes affecting the estrogen reception. So, it turns out that soy has beneficial effects, but only in the population that’s at greatest risk of cardiovascular disease, and that increased risk is based on genetic variation.

These examples are just the “tip of the iceberg”. Nutrigenomics is an emerging science. New examples of genetic variations that affect the need for specific nutrients are being reported on a regular basis. We are not ready to start genotyping people yet. We don’t yet know enough to design a simple genetic test to predict our unique nutritional needs. That science is 10-20 years in the future, but this is something that’s coming down the road.

What the current studies tell us is that some people are high-risk because of their genetic makeup, and these are people for whom supplementation is going to make a significant difference. However, because genetic testing is not yet routine, most people are completely unaware that they might be at increased risk of disease or have increased nutritional requirements because of their genetic makeup.

Examples of Disease Influencing Nutritional Needs

Finally, let’s consider the effect of disease on our nutritional needs. If you look at the popular literature, much has been written about the effect of stress on our nutritional needs. In most case, the authors are referring to psychological stress. In fact, psychological stress has relatively minor effect on our nutritional needs.

Metabolic stress, on the other hand, has major effects on our nutritional needs. Metabolic stress occurs when our body is struggling to overcome disease, recover from surgery, or recover from trauma. When your body is under metabolic stress, it is important to make sure your nutritional status is optimal.

The effects of surgery and trauma on nutritional needs are well documented. In my book, “Slaying The Supplement Myths”, I discussed the effects of disease on nutritional needs in some detail. Let me give you a brief overview here. It is very difficult to show beneficial effects of supplementation in a healthy population (primary prevention). However, when you look at populations that already have a disease, or are at high risk for disease, (secondary prevention), the benefits of supplementation are often evident.

For example, studies suggest that vitamin E, B vitamins, and omega-3s each may reduce heart disease risk, but only in high-risk populations. Similarly, B vitamins (folic acid, B6 and B12) appear to reduce breast cancer risk in high risk populations.

Who Benefits Most From Supplementation?

With this information in mind, let’s return to the question: “Who benefits most from supplementation? Here is my perspective.

1) The need for supplementation is greatest when these circles overlap, as they do for most Americans.

2) The problem is that while most of us are aware that our diets are not what they should be, we are unaware of our increased needs and/or genetic predisposition. We are also often unaware that we are at high risk of disease. For too many Americans the first indication they have heart disease is sudden death, the first indication of high blood pressure is a stroke, or the first indication of cancer is a diagnosis of stage 3 or 4 cancer.

So, let’s step back and view the whole picture. The overlapping circles are drawn that way to make a point. A poor diet doesn’t necessarily mean you have to supplement. However, when a poor diet overlaps with increased need, genetic predisposition, disease, or metabolic stress, supplementation is likely to be beneficial. The more overlapping circles you have, the greater the likely benefit you will derive from supplementation.

That is why I feel supplementation should be included along with diet, exercise, and weight control as part of a holistic approach to better health.

The Bottom Line

In this article I provide a perspective on who benefits most from supplementation and why. There are four reasons to supplement.

Fill Nutritional gaps in our diet

2) Meet increased nutritional needs due to pregnancy, lactation, age, exercise, many common medications, and environmental pollutants.

3) Compensate for genetic variations that affect nutritional needs.

4) Overcome needs imposed by metabolic stress due to trauma, surgery, or disease.

With this information in mind, let’s return to the question: “Who benefits most from supplementation? Here is my perspective.

A poor diet alone doesn’t necessarily mean you have to supplement. However, when a poor diet overlaps with increased need, genetic predisposition, or metabolic stress, supplementation is likely to be beneficial. The more overlap you have, the greater the likely benefit you will derive from supplementation.

For more details, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

Is DNA Testing Valuable?

October 5, 2021 by Dr. Steve Chaney

What Is The True Value Of DNA Tests?

Author: Dr. Stephen Chaney

DNA testing is hot! DNA testing companies claim they can tell you your disease risk and personalize your diet and supplement program – all based on the sequence of your DNA.

On the other hand, most reputable medical sources say these DNA testing companies overpromise and underdeliver. They tell you that diet, lifestyle, and supplement recommendations based only on your DNA sequence are often inaccurate.

So, what should you believe? At this point you are probably wondering:

Is DNA testing valuable or is it a waste of money?

Is there a way to make DNA testing more accurate?

What is the true value of DNA testing to you, the consumer?

I will consider these 3 questions in my article below. But first let me share two stories about DNA testing, one true and the other fictional.

Perspectives on DNA Testing

When the human genome was first sequenced in 2003, it took 13 years and cost millions of dollars. That was an exciting time. Many of us in the scientific community thought we were on the verge of a revolution in human health and longevity. We would soon be able to tell individuals their risk of developing various diseases.

How naive we were! It has turned out to be much more complicated to design personalized nutrition recommendations based on someone’s genome than we ever imagined.

Today an analysis of your genome requires hours and costs less than $200. That represents a tremendous advance in technology. However, we are no closer to being able to make personal nutrition recommendations based on our DNA sequence today than we were 18 years ago.

Why is that? Let me share a fictional story because it provides a clue. In 1997, when I was still a relatively young scientist, I saw a film called GAATACA. [If you are looking for an entertaining film to watch, it is still available on some streaming services.]

The hero of this film was, of course, a love child. He was born with a genetic predisposition for heart disease. He was considered inferior, a second-class citizen of this future world.

This is when I first began to realize that our DNA does not have to be our destiny. We have the power to overcome bad genetics. We also have the power to undermine good genetics.

You might be wondering, “How can this be? Why doesn’t our DNA determine our destiny” I will answer that question in two parts.

First, I will share what experts say about the value of DNA testing.

Then I will put on my professor hat and discuss “Genetics 101 – What we didn’t know in 2003” (When the genome was first sequenced).

Is DNA Testing Valuable?

As I said above, most scientists are skeptical about the ability of DNA testing to predict our ideal diet and supplementation regimens. For example, here are two recent reviews on the current status of DNA testing. [Note: These scientists are using “science speak”. Don’t worry if you don’t understand all the terms. I will explain their message in simpler terms in the next section.]

One review (C Murgia and MM Adamski, Nutrients, 366, 2017) published in 2017 concluded: “The potential applications to nutrition of this invaluable tool [DNA sequencing] were apparent since the genome was mapped…However, fifteen years and hundreds of publications later, the gap between genome mapping and health practice is not yet closed.”

“The discovery of other levels of control, including epigenetics [modifications of DNA that affect gene expression] and the intestinal microbiome complicate the interpretation of genetic data. While the science of nutritional genomics remains promising, the complex nature of gene, nutrition and health interactions provides a challenge for healthcare professionals to analyze, interpret and apply to patient recommendations.”

Another review (M Gaussch-Ferre et al, Advances in Nutrition, 9: 128-135, 2018) published in 2018 concluded: “Overall, the scientific evidence supporting the dissemination of genomic information for nutrigenomic purposes [predicting ideal diet and supplement regimens] remains sparse. Therefore, additional knowledge needs to be generated…”

In short, the experts are saying we still don’t know enough to predict the best diet or the best supplements based on genetic information alone.

Genetics 101 – What We Didn’t Know In 2003

In simple terms the experts who published those reviews are both saying that the linkage between our DNA sequence and either diet or supplementation is much more complex than we thought in 2003 when the genome was first sequenced.

That is because our understanding of genetics has been transformed by two new areas of research, epigenetics and our microbiome. Let me explain.

Epigenetics has an important influence on gene expression. When I was a graduate student, we believed our genetic destiny was solely determined by our DNA sequence. That was still the prevailing viewpoint when the human genome project was initiated. As I said above, we thought that once we had our complete DNA sequence, we would know everything we needed to know about our genetic destiny.

It turns out that our DNA can be modified in multiple ways. These modifications do not change the DNA sequence, but they can have major effects on gene expression. They can turn genes on or turn them off. More importantly, we have come to learn that these DNA modifications can be influenced by our diet and lifestyle.

2) Our microbiome also has an important influence on our health and nutritional status. Simply put, the term microbiome refers to our intestinal microbes. Our intestinal bacteria are incredibly diverse. Each of us has about 1,000 distinct species of bacteria in our intestines.

Current evidence suggests these intestinal bacteria influence our immune system, inflammation and auto-immune diseases, brain function and mood, and our predisposition to gain weight – and this may just be the tip of the iceberg.

More importantly, our microbiome is also influenced by our diet and lifestyle, and environment. For example, vegetarians and meat eaters have entirely different microbiomes.

Furthermore, the effect of diet and lifestyle on our microbiome also changes day to day. If you change your diet, the species of bacteria in your microbiome will completely change in a few days.

If you are wondering how that could be, let me [over]simplify it for you:

- What we call fiber, our gut bacteria call food.

- Different gut bacteria thrive on different kinds of fiber.

- Different plant foods provide different kinds of fiber.

- Whenever we change the amount or type of fiber in our diet, some gut bacteria will thrive, and others will starve.

- Bacteria grow and die very rapidly. Thus, the species of bacteria that thrive on a particular diet quickly become the predominant species in our gut.

- And when we change our diet, those gut bacteria will die off and other species will predominate.

Finally, our microbiome also influences our nutritional requirements. For example, some species of intestinal bacteria are the major source of biotin and vitamin K2 for all of us and the major source of vitamin B12 for vegans. Other intestinal bacteria inactivate and/or remove some vitamins from the intestine for their own use. Thus, the species of bacteria that populate our intestines can influence our nutritional requirements.

Now that you know the complexity of gene interactions you understand why we are not ready to rely on DNA tests alone. That science is at least 10-20 years in the future. Companies that tell you otherwise are lying to you.

What Is The True Value Of DNA Tests?

By now you are probably thinking that my message is that DNA tests are worthless. Actually, my message is a bit different. What I, and most experts, are saying is that DNA tests are of little value by themselves.

To understand the true value of DNA tests, let me start with defining a couple of terms you may vaguely remember from high school biology – genotype and phenotype.

Genotype is your genes.

Phenotype is you – your health, your weight, and your nutritional needs. Your phenotype is determined by your genes plus your diet and your lifestyle.

With that in mind, let’s review the take-home messages from earlier sections of this article.

The take-home message from the two stories in “Perspectives on DNA Testing” is that our DNA does not have to be our destiny. We have the power to overcome bad genetics. We also have the power to undermine good genetics.

The take-home message from “Genetics 101” is that while the genes we inherit do not change, the expression of those genes is controlled in part by:

- Epigenetic modifications to the DNA. And those epigenetic modifications are controlled by our diet and our lifestyle.

- Our microbiome (gut bacteria). And our microbiome is controlled by our diet and our lifestyle.

Now we are ready to answer the question, “What is the true value of DNA testing?” There are actually two answers to this question. You have probably guessed the first answer by now, but you will be surprised by the second.

DNA testing can only indicate the potential for obesity, the potential for nutritional deficiencies, and the potential for disease. But whether that potential is realized depends on our diet and lifestyle. Therefore, the true value of DNA testing comes from adding a comprehensive analysis of diet and lifestyle to the DNA test results. That includes:

- Questionnaires that assess diet, lifestyle, health goals, and health concerns.

For example, your genetics may indicate an increased need for vitamin D. This is a concern if your vitamin D intake is marginal but may not be a concern if you are getting plenty of vitamin D from your diet, supplementation, and sun exposure.

- Direct measurements of obesity such as height and weight (from which BMI can be calculated) and waist circumference (belly fat is more dangerous to our health than fat stored elsewhere in our body).

For example, most Americans have a genetic predisposition to obesity, but not everyone is obese. If you are overweight or obese, your nutrition and lifestyle recommendations should include approaches to reduce your weight. If not, these recommendations are not needed, even if you have a genetic predisposition to obesity.

- Blood pressure and blood markers of disease risk (cholesterol, triglycerides, and blood sugar).

For example, you may have genetic predisposition to high blood pressure or high cholesterol. If either of these are high, your recommendations should include nutrition and lifestyle approaches to lower them. However, if you are already keeping them under control through diet and lifestyle, no further changes may be necessary.

2) While the scientific community now knows the limitations of DNA testing, this information has not filtered down to the general public. This brings me to the second value of DNA testing. Several recent studies have shown that people are much more likely to follow recommendations based on DNA testing than recommendations based on dietary questionnaires, blood markers of disease, or even recommendations from their physician.

The Bottom Line

DNA testing is hot! DNA testing companies claim they can tell you your disease risk and personalize your diet and supplement program – all based on the sequence of your DNA.

So, what is the true value of DNA testing? To answer that question, we need to know two things:

1) Our DNA is not our destiny. We have the power to overcome bad genetics. We also have the power to undermine good genetics.

2) While the genes we inherit do not change, the expression of these genes is controlled in part by:

- Epigenetic modifications to the DNA. And those epigenetic modifications are controlled by our diet and our lifestyle.

- Our microbiome (gut bacteria). And our microbiome is controlled by our diet and our lifestyle.

With this information in mind, we are ready to answer the question, “What is the true value of DNA testing?” The true value of DNA testing is tw0-fold:

1) It comes from adding a comprehensive analysis of diet and lifestyle to the DNA test results. This includes:

- Questionnaires that assess diet, lifestyle, health goals, and health concerns.

- Direct measurements of obesity such as height and weight (from which BMI can be calculated) and waist circumference (belly fat is more dangerous to our health than fat stored elsewhere in our body).

- Blood pressure and blood markers of disease risk (cholesterol, triglycerides, and blood sugar).

2) In addition, several recent studies have shown that people are much more likely to follow recommendations based on DNA testing than recommendations based on dietary questionnaires, blood markers of disease, or even recommendations from their physician.

For more details and explanations of the statements in “The Bottom Line”, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease.

Can DNA Testing Help You Lose Weight?

June 30, 2020 by Dr. Steve Chaney

How Does DNA Testing Work Best?

Genomics (DNA testing) is hot. You are being told that if you just knew your genes, you could lose weight successfully, be healthier, be happier, leap tall buildings in a single bound (Actually, I haven’t heard the last claim, but it’s about the only claim that genomics marketers haven’t made). Which of these claims are true, and which are just hot air?

The experts agree that the benefits of DNA testing have been greatly oversold. As I said in a recent article on DNA testing, the idea that genes control our destiny is no longer considered valid. There are 3 reasons for this. I will start with the scientific term for each and then give you the non-scientific explanation.

Penetrance simply means that the severity of most gene mutations is influenced by our genetic background. Simply put, the same mutation can have a significant effect in one individual and a trivial effect in another individual.

Epigenetics refers to modifications of the DNA that influence gene expression. These DNA modifications are, in turn, influenced by diet and lifestyle.

Microbiome refers our gut bacteria. In many cases, our microbiome has just as much influence on our health as our genes. And our microbiome is influenced by diet and lifestyle.

Now you know the complexity of DNA testing, it is easy to see why experts feel that it is premature to use DNA testing to predict the best diet for either weight loss or health.

As an example, one recent study used DNA testing to predict whether study participants were more likely to lose weight on a low-carb or low-fat diet. The participants were then randomly assigned to low-carb and low-fat diets. At the end of 12 months:

There was no significant difference in weight loss for those on low-fat and low-carb diets. This has been reported in multiple previous studies but is an inconvenient truth that most low-carb enthusiasts tend to ignore.

DNA testing offered no predictive value as to whether a low-carb or low-fat diet was more effective for weight loss.

However, DNA testing may have one benefit that is overlooked by many experts. What if the DNA test results motivated people to do better? After all, most diet advice is generic. People feel it may or may not apply to them. Does personalized diet advice based on their genetic makeup motivate people to stick with the diet better?

Some studies have suggested that people may follow personalized diet plans based on their DNA more faithfully. However, most of those studies have been short-term.

That is why I have chosen today’s study (J Horne et al, BMJ Nutrition, Prevention & Health, 2020) to discuss. It is a very well-designed study and it lasted for a full year.

How Was The Study Done?

This was an extremely well-designed study. In fact, it was so well designed that it probably needs the “Results are not typical” designation the FDA requires when some diet companies make claims about weight loss success. Here are the details:

The study participants were highly motivated, college educated, middle-aged (average age = 55), obese (average weight = 216 pounds) Caucasian women who had a positive attitude about their ability to change what they ate. In case you weren’t counting, there were four characteristics of this group that might be considered atypical for the average American.

The participants volunteered for a highly structured weight loss program called the “Group Lifestyle Balance”, or GLB, program.

- Participants were given a detailed calorie-controlled nutrition plan at the beginning of the program.

- They were asked to track their daily food and beverage intake for the first 2-3 months of the program.

- In the second week of the program participants were educated on how to count and track calories and nutrients such as total fat or saturated fat.

- There were weekly meetings with dietitians the first 3 months and monthly meetings for the remainder of the 12-week program to provide the guidance and support needed to stick with their nutrition plan.

The plan also incorporated a behavior change program called Theory of Planned Behavior (TPB) that evaluates and influences attitudes, subjective norms, and behavioral control that are key to behavior change. During the regular meetings:

- The participants were informed about of the health benefits associated with a healthy lifestyle.

- They were educated on positive mindsets and mindfulness.

- They were taken through a stepwise, goal setting approach designed to positively impact behavioral change.

In short, this is a gold standard diet program that provided the nutritional support needed to stick with the diet program and the psychological support needed to change eating behavior. Unfortunately, this is also atypical. Very few diet programs provide this level of support.

Everyone in the study participated in this program. However, the participants were divided into two groups.

Both groups were advised to follow a standard calorie-controlled, moderately low-fat (25% of total calories) nutrition plan.

In addition, the second group was put on a plan that was either high protein or low saturated fat (<10% of total calories) based on their DNA test results.

The nutritional support was identical except that the second group was told that their nutrition plan was specific for them, based on their DNA analysis.

The dietary intake of both groups was assessed with a 3-day dietary recall (2 week days and 1 weekend day) at baseline (before the program began) and at 3, 6, and 12 months to assess the participants adherence to their diet plan.

Can DNA Testing Help You Lose Weight?

I hate to disappoint you, but the short answer to this question, is no. Both groups lost the same amount of weight, which is not surprising considering the comprehensive nature of the diet program that both groups were enrolled in.

However, the group given advice based on their DNA test were more motivated to stick with their personalized nutrition goals. Specifically:

Long-term adherence to reductions in saturated fat intake was significantly greater in the group that was told their diet plan was personalized based on their DNA analysis.

- The control group reduced their saturated fat intake by 12% at 3 months, but only by 4% at 6 months, and 2.5% at 12 months.

- The group with the personalized diet plan reduced their saturated fat intake by 14% at 3 months, 18% at 6 months, and 22% at 12 months.

Long-term adherence to reductions in total fat intake was also significantly greater in the group that was told their diet plan was personalized based on their DNA analysis.

- The control group reduced their total fat intake by 18% at 3 months, but only by 4% at 6 and 12 months.

- The group with the personalized diet plan reduced their total fat intake by 11% at 3 months, 13% at 6 months, and 16% at 12 months.

- It is important to remember that both groups had been advised to reduce their total fat intake to 25% of calories and had received nutritional and psychological support to achieve that goal. The only difference was that the second group had been told that advice was based on their DNA test.

The authors of the study concluded: “Weight management interventions guided by nutrigenomics can motivate long-term improvements in dietary fat intake above and beyond gold-standard population-based interventions.”

How Does DNA Testing Work Best?

There remain significant concerns about the validity of personalized weight loss advice based on DNA testing. However, this and other studies suggest that DNA testing may provide one valuable asset for weight loss programs. It appears that people are more likely to stick with a program they believe has been personalized for them.

There are, however, several caveats to this conclusion.

Participants in this study received nutritional and psychological support throughout the 12-month program. We don’t know how well participants would have stuck with the program if they had not been continually reminded that the program had been personalized for them.

Participants in this study were well-educated, highly motivated, Caucasian women. We don’t know whether these results apply to men and to other ethnic and socioeconomic groups.

This study only looked at personalized diet advice based on DNA testing. Some studies suggest that other methods of diet personalization may also improve adherence.

Personalization can be misused to recommend unhealthy dietary changes. It is not enough to follow personalized diet advice. You also need to ask whether it is healthy dietary advice.

For example, DNA test results consistent with reduced carbohydrate intake are sometimes used to recommend unhealthy diets that eliminate one or more food groups rather than low-carb versions of healthy diets like the Mediterranean diet.

The Bottom Line

There remain significant concerns about the validity of personalized weight loss advice based on DNA testing. However, DNA testing may provide one valuable asset for weight loss programs. Some studies have suggested that people are more likely to stick with a program they believe has been personalized for them.

However, most of these studies have been short term. A recent study asked whether the improvement in motivation lasted for 12 months.

Two matched groups of well-educated, highly motivated women were enrolled in a “gold-standard” weight loss program that provided both nutritional and psychological support for 12 months.

Both groups were given a diet plan that restricted total calorie intake and advised reducing fat intake to 25% of total calories. However, based on their DNA test results one group was given a personalized diet plan that also advised them to reduce their saturated fat intake to less than 10% of total calories.

The group receiving personalized diet advice did a better job of reducing both saturated and total fat intake and maintaining that change for 12 months compared to the group that just received a set diet plan.

These results suggest that personalization of diet advice may improve long-term adherence to healthy dietary changes.

There are, however, several caveats to this conclusion.

Participants in this study received both nutritional and psychological support throughout the 12-month program. We don’t know how well participants would have stuck with the program if they had not been continually reminded that the program had been personalized for them.

Participants in this study were well-educated, highly motivated, Caucasian women. We don’t know whether these results apply to men and to other ethnic and socioeconomic groups.

This study only looked at personalized diet advice based on DNA testing. Some studies suggest that other methods of diet personalization may also improve adherence.

Personalization can be misused to recommend unhealthy dietary changes. It is not enough to follow personalized diet advice. You also need to ask whether it is healthy dietary advice.

For more details read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease.