How Does Red Meat Cause Colon Cancer?

How Can You Decrease Your Risk Of Colon Cancer? 

Author: Dr. Stephen Chaney

Grilled HamburgersBoth red meat and processed meat consumption are associated with increased risk of colon cancer. But the strength of that association differs between the two.

Processed meat has been classified as a carcinogen by the IARC*, indicating the evidence that processed meat causes colon cancer is definitive. Red meat, on the other hand, has been classified as a probable carcinogen by the IARC*. That means the evidence that red meat causes colon cancer is strong, but not definitive.

*[In case you were wondering, the IARC (International Agency for Research on Cancer) is an international agency charged by the WHO to, among other things, determine the risk of cancer from various foods, industrial chemicals, and environmental pollutants.]

As I said above, red meat consumption is associated with increased risk of colon cancer. But…

  • Not all studies agree (more about that later), and…
  • Association doesn’t prove cause and effect. It could be some other characteristic of red meat eaters that increases their risk of colon cancer.
  • Until recently we had no clear idea of how red meat might cause colon cancer.

Several mechanisms have been proposed. I will discuss each mechanism and ways to reduce the risk of colon cancer by that mechanism:

#1: When fat and juices from the meat drip onto an open flame, carcinogenic polyaromatic hydrocarbons (PAHs) Barbecue Gatheringare formed that stick to the surface of the meat. PAHs can be metabolized to cancer causing chemicals in our body.

  • PAH formation can be reduced by marinating the meat prior to cooking or by using cooking techniques that don’t involve an open flame.
  • PAH formation can be reduced, but not eliminated, by lower fat meat choices, such as grass-fed beef.
  • High fiber diets reduce exposure to PAHs by binding to them and flushing them through the intestine.
  • Cruciferous vegetables block the conversion of PAHs to cancer causing chemicals in our body.

#2: When red meats are cooked at high temperatures, amino acids in the meat combine with creatine, which is found in all red meats, to form heterocyclic amines (HCAs). HCAs can also be metabolized to cancer causing chemicals in our body.

  • HCA formation can be reduced by cooking the meat at lower temperatures.
  • Grass-fed beef does not reduce HCA formation because this mechanism is not dependent on the fat content of the meat.
  • High fiber diets and cruciferous vegetables reduce the danger of HCAs by the same mechanisms as for PAHs.

#3: The nitrates and nitrites used as preservatives in many processed meats react with amino acids from the meat to form carcinogenic N-nitrosamines in our intestines.

  • Antioxidant-rich fruits and vegetables can divert nitrates and nitrites into an alternative pathway that coverts them into nitric oxide, which is beneficial to our bodies. I have discussed this in a previous issue of “Health Tips From the Professor”.

#4: Heme, which is found in all red meats, combines with amino acids in the meat to form carcinogenic N-nitrosamines and similar N-nitroso compounds in our intestines.

  • This mechanism is inherent in all red meats and cannot be eliminated by choosing grass-fed beef or cooking at lower temperatures.
  • The formation of N-nitroso compounds from red meat appears to be carried out by gut bacteria. We know that meat eaters and vegetarians have very different populations of gut bacteria, but we don’t know whether this influences N-nitroso formation.

Mechanism #4 (formation of N-nitroso compounds from heme-containing red meat in our intestines) is the one I will be discussing in this article. But first, it’s time for Metabolism 101.

Metabolism 101: Why Should We Fear N-Nitroso Compounds?

ProfessorSimply put, N-nitroso compounds react with our DNA. They transfer methyl and ethyl groups to the nucleotides that make up our DNA sequence. The general term for these reactions is alkylation of the DNA.

  • In some cases, this causes the alkylated nucleotides to miscode during DNA replication. This can lead to cancer causing mutations.
  • In other cases, this causes genes to be permanently turned on or off.

To understand why this is a problem, you need to know a bit about cancer cell biology.

  • We have certain genes called “oncogenes”. These are genes that turn on processes like cell division. Normally these genes are tightly regulated so that cell division only occurs when it is needed. When these genes are permanently turned on, unregulated, continuous cell division occurs. In short, the cell becomes a cancer cell.
  • We have other genes called “tumor suppressor genes”. These are genes that do things like shutting down cell division when it is not needed. When these genes are permanently turned off, unregulated cell division can occur.

With this in mind, let us review what we know about red meat and colon cancer:

  • Red meat consumption is associated with increased risk of colon cancer.
  • Red meat consumption is also associated with increased concentrations of N-nitroso compounds in the colon. Studies also show:
  • The formation of N-nitroso compounds correlates with the heme content of the meat.
  • The formation of N-nitroso compounds in the colon is dependent on certain strains of gut bacteria.
  • The formation of N-nitroso compounds is reduced by diets high in fiber. It is likely this is because high fiber diets influence the types of bacteria in the colon, but that has not been proven yet.

What is missing is evidence that colon cancer cells contain the kind of DNA modifications (DNA alkylation) caused by N-nitroso compounds. That is what the current study (C Gurjao et al, Cancer Discovery, published online June 17, 2021) was designed to test.

How Was This Study Done?

Clinical StudyOne reason previous studies had not been able to demonstrate a clear correlation between red meat consumption and DNA modifications was that the studies were too small to obtain statistically significant results.

So, the authors of this study combined data from women in the Nurses’ Health Study, the Nurses’ Health Study II, and men in the Health Professionals Follow-Up Study. There were over 238,130 women and 51,529 men in these three studies.

None of the participants had cancer at the time they entered the studies. The participants were followed for at least 27 years. During that time 4855 participants developed colon cancer.

At the beginning of each study and every 4 years later the participants were asked to fill out a food frequency questionnaire to collect information about their usual diet over the past year. Validation studies showed that the diets of the participants changed little over the interval of the studies.

The participants in these studies were sent follow-up questionnaires every two years to collect information on lifestyle and newly diagnosed diseases like colon cancer.

For those who developed colon cancer, their medical records were reviewed to collect data on tumor size, tumor location, and disease stage.

The diagnoses of colon cancer often involves removing tissue from the cancer and from surrounding normal tissue and putting it in formalin-fixed paraffin-embedded tissue blocks. These were collected, and the DNA was extracted and sequenced to determine the extent and genetic location of alkylated DNA sequences.

How Does Red Meat Cause Colon Cancer?

colon cancerThis study measured the effect of red meat consumption on the extent and location of what the authors called “alkylation signatures”, which refers to the kinds of DNA modifications caused by N-nitroso compounds. Here is what they found:

  • Red meat consumption was positively associated with an increase in alkylation signatures caused by N-nitroso compounds in tumor tissue from patients with colon cancer.
    • This was true for both processed and unprocessed red meat.
    • There was no difference between men and women after adjusting for differences in red meat intake.
    • White meat (chicken and fish) did not cause an increase in alkylation damage in colon cells.
  • More importantly, there was an inverse association between alkylation damage in the tumor tissue and patient survival. Simply put, high levels of alkylation damage were associated with short survival times.

Previous studies have shown that processed red meat consumption was associated with increased levels of N-nitroso compounds and an increased risk of colon cancer in the distal colon.

  • This study showed colon cancer patients who had been consuming processed red meats had higher alkylation damage in tumors in the distal colon.

Previous studies have shown that certain oncogenes (genes that drive the conversion of normal cells to cancer cells) are activated in colon cancer cells and this activation is associated with alkylation damage to their DNA.

  • This study showed that tumors with activated oncogenes were enriched with the alkylation signature characteristic of N-nitroso compounds.

I realize this study is highly technical. It is not easy to understand, so let me simplify it.

  • Previous studies have shown that red meat consumption is associated with an increased risk of colon cancer.
  • Previous studies have also shown that red meat consumption is associated with an increased concentration of carcinogenic N-nitroso compounds in the colon.
  • This study shows that red meat consumption is associated with the kind of DNA damage caused by N-nitroso compounds in colon tumor cells. More importantly, this is the kind of damage that can lead to cancer-causing mutations. In addition:
    • The DNA damage occurs in the exact location of the colon predicted from earlier studies.
    • The DNA damage occurs in genes known to drive the conversion of normal colon cells to cancer cells.

In short, this study provides a plausible mechanism for the effect of red meat consumption on increased risk of colon cancer. It shows how red meat can cause colon cancer.

“In the words of the authors, “Our study has leveraged a comprehensive dataset with repeated dietary measures over years…and [DNA sequencing] on a large collection of colorectal tumors. It provides unique evidence supporting the direct impact of dietary behaviors on colorectal carcinogenesis…”

How Can You Decrease Your Risk Of Colon Cancer?

Steak SaladWhen this study is combined with previous studies, it provides a clear explanation of how red and processed meats can cause colon cancer. And, unfortunately, grass-fed beef is not a “Get Out Of Jail Free” card. This mechanism is equally applicable to grass-fed beef and conventionally raised beef.

Does this mean you need to become a vegan? While I have nothing against veganism, the answer appears to be no. As I discussed above whole, unprocessed plant foods are the antidote to the carcinogenic compounds formed from red meat. This is due to:

  • Their fiber, which sweeps some carcinogens out of the intestine before they can be absorbed.
  • Their antioxidants, which prevent some carcinogens from being formed.
  • Their phytonutrients, which block the activation of some carcinogens.
  • The friendly gut bacteria they support, which displace the bad bacteria that form some carcinogen precursors in the intestine.

The good news is that some red meat may be OK in the context of a primarily plant-based diet. For example, 3 ounces of red meat in a green salad or stir fry is less likely to increase your risk of colon cancer than an 8-ounce steak and fries.

The bad news is this is why not all studies have shown an association of red meat consumption and increased risk of colon cancer. Unfortunately, far too many of these studies have ignored other components of the diet.

The Bottom Line

A recent study looked at the effect of red meat consumption on DNA modifications in colon cells that are associated with the conversion of normal cells to cancer cells. It is a highly technical study, but the simplified version is:

  • Previous studies have shown that red meat consumption is associated with an increased risk of colon cancer.
  • Studies have also shown that red meat consumption is associated with an increased concentration of carcinogenic N-nitroso compounds in the colon.
  • This study shows that red meat consumption is associated with the kind of DNA damage caused by N-nitroso compounds in colon tumor cells – the kind of damage that can lead to cancer-causing mutations. In addition:
    • The DNA damage occurs in the exact location of the colon predicted from earlier studies.
    • The DNA damage occurs in genes known to drive the conversion of normal colon cells to cancer cells.

In short, this study provides a plausible mechanism for the effect of red meat consumption on increased risk of colon cancer. It shows how red meat can cause colon cancer.

“In the words of the authors, “Our study has leveraged a comprehensive dataset with repeated dietary measures over years…and [DNA sequencing] on a large collection of colorectal tumors. It provides unique evidence supporting the direct impact of dietary behaviors on colorectal carcinogenesis…”

For more details about this study and how you can eat red meat and still reduce your risk of colon cancer, 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.

How Diet And Gut Bacteria Affect Our Health

Why Is Your Microbiome Important? 

Author: Dr. Stephen Chaney

Vegan FoodsWe have known for years that primarily plant-based diets are healthy. As I have shared in my book, “Slaying The Food Myths”, people who consume primarily plant-based diets have lower risk of heart disease, diabetes, and some cancers and live longer than people who consume the typical American diet.

But why is that?

  • Is it the nutrients, phytonutrients, and fiber plant foods provide?
  • Is it because plant foods are lower in saturated fats and are good sources of healthier monounsaturated and polyunsaturated fats?
  • Or is it because plant foods have a low caloric density, which makes it easier to maintain a healthy weight?

The answer, of course, is that all the above are important. But is there something else? Is there a “missing link” we don’t talk about much? Many experts think our microbiome (our gut bacteria) is that missing link.

You have heard the saying, “We are what we eat”. You might be scratching your head and saying, “I could eat cabbages all day long, but I am never going to become a cabbage.” It seems like a crazy saying.

But for our microbiome that saying is true. What we call fiber, our gut bacteria call food. Consequently, microbiomevegetarians and meat eaters have very different populations of gut bacteria in their microbiome. The question, of course, is whether these differences influence our health. This central question has spurred multiple research studies on our microbiome in recent years.

Two central themes have emerged from these studies:

  • There are certain populations of gut bacteria that are associated with healthy outcomes (lower risk of obesity, diabetes, heart disease, and some cancers). We can think of these as “good bacteria”.
    • There are certain populations of gut bacteria that are associated with unhealthy outcomes (increased risk of obesity, diabetes, heart disease, and some cancers). We can think of these as “bad bacteria”.
  • People consuming primarily plant-based diets tend to have more of the “good bacteria” and less of the “bad bacteria” in their gut microbiome.

However, most of these studies have been small and have looked at individual foods rather than the effect of the overall diet.

The study (KK Koponen et al, American Journal Of Clinical Nutrition, 2021; doi.org/10.1093/ajcn/nqab077 I will describe today was designed to overcome those limitations.

Metabolism 101: What Are Short Chain Fatty Acids And Why Are They Important?

professor owlTo fully understand the findings of this study, you need to understand what short chain fatty acids are and why they are important. Simply put, short chain fatty acids are the end products of fiber digestion by some species of gut bacteria in our intestines. The major short chain fatty acids in our intestines are acetate (2 carbons), propionate (3 carbons), and butyrate (4 carbons).

There are the key facts about short chain fatty acids you should know:

  1. They are formed by anaerobic fermentation of dietary fiber by our gut bacteria. However:
    • Not all gut bacteria can produce short chain fatty acids.
    • The amount and type(s) of dietary fiber determine whether the gut bacteria that can produce short chain fatty acids are present.

2) Acetate is readily absorbed into the bloodstream and is utilized for fat production and other biosynthetic pathways.

3) Short chain fatty acids, especially butyrate, are the primary energy source for cells lining the colon. Because of this, they have several important health benefits.

    • They support the immune cells that line our intestine. This helps strengthen our immune system.
    • They help maintain the integrity of the intestinal wall. This helps protect against leaky gut syndrome.
    • They reduce inflammation. This reduces the risk of inflammatory bowel diseases like ulcerative colitis and Crohn’s disease.
    • They reduce the risk of colon cancer.

4) In addition, small amounts of propionate and butyrate can be absorbed into the bloodstream. Butyrate is of particular interest because it has the potential to regulate gene expression.

    • There is some evidence that short chain fatty acid production in the intestine is correlated with reduced risk of inflammatory diseases, obesity, type 2 diabetes, and heart disease, but these studies remain controversial.

How Was This Study Done?

Clinical StudyThis study made use of data from the FINRISK Study. This study was conducted by the Finnish Institute of Health and Welfare every 5 years between 1972 and 2012 to assess risk factors for noncommunicable diseases, health behavior, and their changes in adult Finns.

This study included 4930 individuals from the 2002 FINRISK assessment. The characteristics of the group were:

  • 53% female, 47% male.
  • Average age = 48.
  • Average BMI = 26.9 (slightly overweight).

Upon entry into the study, the participants were asked to fill out a food frequency questionnaire.

  • The data from this questionnaire were used to calculate a Healthy Food Choices (HFC) score based on the Nordic Nutrition Dietary Guidelines for a healthy diet.
    • The HFC score ranged from 9-745 and was based on the consumption of fiber-rich breads; vegetables (including beans and lentils); fruits; berries; fresh, non- sweetened berry and fruit juices; fish; poultry; low-fat cheeses; salad dressings and oils; nuts; and seeds.
    • In the words of the authors, “A high HFC score effectively acts as an indicator of a healthy omnivorous Nordic diet rich in plants, fiber, and polyunsaturated fatty acids.”
  • The data were also used to calculate a total dietary fiber score.

The participants were also asked to provide a stool sample. DNA was extracted from the stool sample and sequenced to determine the number and types of bacteria in their gut microbiome. These data were analyzed for:

  • Bacterial diversity (greater bacterial diversity is associated with better health outcomes).
  • Species of gut bacteria known to be associated with better health outcomes.
  • Species of bacteria known to produce short chain fatty acids.

How Diet And Gut Bacteria Affect Our Health

MicrobiomeMicrobiome research is complex. But here is a description of the results in simple terms.

Both the Healthy Food Choice (HFC) and fiber scores correlated positively with:

  • Bacterial diversity (greater bacterial diversity is associated with better health outcomes).
  • Species of gut bacteria known to be associated with better health outcomes.
  • Species of bacteria known to produce short chain fatty acids that are associated with better health outcomes.

Simply put, a healthy, primarily plant-based Nordic diet produces the kind of gut microbiome that is associated with better health outcomes.

When the authors analyzed the contribution of individual components of the diet to a healthy microbiome:

  • Vegetables; berries; fruits; fiber-rich breads; salad dressings and oils; low-fat cheeses; poultry; fresh, unsweetened juices; and fish were all positively associated with a healthy microbiome.
    • Each of these foods supported the growth of different gut bacteria that contributed to the healthy microbiome.
    • Simply put, none of these foods was sufficient by itself. It was a healthy diet with all these foods that resulted in a healthy microbiome.
  • Nuts and seeds did not affect the microbiome. This may have been because there was too little of them in the diet to have a significant effect.
  • Red and processed meats were negatively associated with a healthy microbiome.

The authors concluded, “Our results from a large, population-based survey confirm and extend the findings of other, smaller-scale studies that plant- and fiber-rich dietary choices are associated with a more diverse and compositionally distinct microbiome with a greater potential to produce short chain fatty acids.”

The authors also said, “The associated between red and processed meat products and the gut microbiome cannot be ignored either…[Our data] indicate that increased usage of red and processed meat is associated with the microbiome composition in an opposite manner to that of a healthy diet.”

Why Is Your Microbiome Important?

happy gut bacteriaThe most important message from this and previous studies is that your gut microbiome is the “missing link” between a healthy diet and a healthy body.

Simply put,    healthy diet →→→healthy microbiome→→→healthy body

However, I also need to acknowledge microbiome research is in its infancy. That is because our microbiome is very complex:

  • We have around 38 trillion microorganisms (give or take a few trillion) in our intestine. That means we have slightly more microorganisms than we do cells in our body.
  • Each of us have more than 1,000 different species of bacteria in our intestine.
  • Collectively, these bacteria have around 750,000 genes. That is 30 times more than the number of genes in our DNA.
  • Finally, we all have different species of bacteria in our intestines. We are all unique.

The only simplifying principle is that these bacteria exist in communities that generally group together. Unraveling the complexities and identifying the communities of bacteria in our intestines requires high throughput DNA sequencing and supercomputers to analyze the data.

Studies like this one can identify the associations between diet and distinct communities of bacteria. They can even identify which foods in the diet support the growth of these bacterial communities. Other studies can identify the association between distinct communities of bacteria and healthy outcomes.

The strength of this study is that it identifies the kind of diet and the kinds of food that support the communities of bacteria associated with healthy outcomes. However, these are just associations. They don’t tell us why these associations occur. Specifically:

  • We don’t know why certain diets are associated with different communities of gut bacteria. However, we do know several things.
    • High fiber diets are a major driving force in creating a healthy gut microbiome. This is because what we call fiber, our gut bacteria call food.High Fiber Foods
    • The diet should contain a variety of high fiber foods. This is because different kinds of fiber support the growth of different kinds of gut bacteria, and the diversity of our gut microbiome is associated with healthy outcomes. As I have said before, “We have 5 food groups for a reason”.
    • However, the type of fat and the type of protein in the diet also influence the type of bacteria that thrive in our intestines. We know less about why that is.
  • We also don’t know why certain communities of gut bacteria are associated with healthy outcomes.
    • The exception is communities of bacteria that produce short chain fatty acids. We do have a good idea why short chain fatty acids are associated with gut health.

However, the fact we don’t know why these associations occur, doesn’t detract from the strength of these associations.

  • The associations between a healthy, primarily plant-based diet and a healthy microbiome are not based on this study alone. The same associations have been seen in multiple studies.
  • The associations between a healthy microbiome and better health outcomes have also been seen in multiple studies.

The evidence for these associations is too strong to ignore.

What Does This Study Mean For You?

Questioning WomanThis study shows that a healthy Nordic diet is associated with a healthy microbiome. “But what is a healthy Nordic diet?”, you might ask. Simply put, it is a whole food, omnivorous, primarily plant-based diet with Scandinavian food preferences.

And, if pickled herring, potato pancakes, and meatballs aren’t your favorite foods, never fear. You have lots of other options:

  • The Mediterranean diet is essentially the same diet with Mediterranean food preferences.
  • The DASH diet is essentially the same diet with American food preferences.
  • You can start with a semi-vegetarian diet and tailor it to your food preferences. Of course, some common sense is required here. You will need to primarily include whole, unprocessed food preferences in your diet.

Let me close with some simple advice I have shared before:

  • We are what we eat. Our microbiome (gut bacteria) reflects what we eat.
  • What we call fiber, our gut bacteria call food. A primarily plant-based diet is best because our friendly gut bacteria thrive on the fiber it provides.
  • We have 5 food groups for a reason. Each plant food group provides different kinds of fiber and feeds different families of friendly gut bacteria. We eliminate plant food groups at our peril.
  • We should think of red meat as a condiment, not a main course. Plants contain antidotes to many of the harmful ingredients in red meat. Two to three ounces of steak as part of a green salad or stir fry is much healthier than an 8-ounce steak and fries.

The Bottom Line

Most previous studies on the effect of diet on our microbiome have been small and have looked at individual foods rather than the effect of the overall diet. In this week’s “Health Tips From the Professor” I report on a large, well-designed study that examined the effect of a healthy Nordic diet on our microbiome.

In case you were wondering, the investigators defined a healthy Nordic diet as a whole food diet that:

  • Includes lots of fruits, vegetables, and whole grains and is, therefore, high in fiber.
  • Uses fish, poultry, and low-fat cheeses as its primary protein source.
  • Minimizes red and processed meats.
  • Has more polyunsaturated oils than saturated fats.
  • Reflects Scandinavian food preferences.

This study found that a healthy Nordic diet correlated positively with:

  • Bacterial diversity (greater bacterial diversity is associated with better health outcomes).
  • Species of gut bacteria known to be associated with better health outcomes.
  • Species of bacteria known to produce short chain fatty acids that are associated with better gut health outcomes.

Simply put, a healthy, primarily plant-based Nordic diet produces the kind of gut microbiome that is associated with better health outcomes. To put this into perspective, a healthy Nordic diet is similar to a healthy Mediterranean diet or a healthy DASH diet except that the Mediterranean diet reflects Mediterranean food preferences, and the Dash diet reflects American food preferences.

The most important message from this and previous studies is that your gut microbiome is the “missing link” between a healthy diet and a healthy body.

Simply put,    healthy diet →→→healthy microbiome→→→healthy body

I summed up the article with some simple advice I have shared before:

  • We are what we eat. Our microbiome (gut bacteria) reflects what we eat.
  • What we call fiber, our gut bacteria call food. A primarily plant-based diet is best because our friendly gut bacteria thrive on the fiber it provides.
  • We have 5 food groups for a reason. Each plant food group provides different kinds of fiber and feeds different families of friendly gut bacteria. We eliminate plant food groups at our peril.
  • We should think of red meat as a condiment, not a main course. Plants contain antidotes to many of the harmful ingredients in red meat. Two to three ounces of steak as part of a green salad or stir fry is much healthier than an 8-ounce steak and fries.

For more details about this study and what it means 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.

 

Diet And Cancer Risk

What Can You Do To Reduce Your Risk Of Cancer?

Magic WandIt seems like everyone has a magic pill, essential oil, food, or diet that prevents cancer. It doesn’t take a genius to figure out that all the claims can’t be true. No wonder you are confused. You want to know:

  • Which of these claims are true?
  • What can you do to reduce your risk of cancer?

These aren’t trivial questions.

  • Cancer is the second leading cause of death in this country, and some experts predict it will surpass heart disease as the leading cause of death in the near future.
  • While cancer treatments have become much more effective in the past few decades, these treatment successes are often associated with severe side-effects, enormous expense, or both.

That is why I was intrigued by a recent study (FF Zhang et al, JNCI Cancer Spectrum (2019) 3(2): pkz034) on diet and cancer that came from the prestigious Friedman School of Nutrition and Public Policy at Tufts University. This study asked two important questions:

  • How many newly diagnosed cancer cases could have been prevented by changes in the American diet? This is something the authors referred to as the “preventable cancer burden associated with poor diet”.
  • Which foods increased or decreased the risk of cancer? This, of course, is the most useful information for you and me.

Diet And Cancer Risk

Diet And CancerThis study estimated that 80,110 new cancer cases among US adults 20 and older could be primarily attributed to poor diet. While poor diet contributes to many more cancers, the authors of this study felt 80,110 represented the number of cancer cases that were clearly preventable by some simple dietary changes.

While all cancers were affected by diet to some degree, the cancers most affected by poor diet were:

  • Colon cancer (65% of cases)
  • Mouth and throat cancer (18% of cases)
  • Endometrial cancer (4.0% of cases)
  • Breast cancer (3.8% of cases)

When the diet was broken down into individual food groups:

  • Low intake of whole grains was associated with the largest number of preventable cancer cases (35% of cases). This was followed by.
  • Low intake of dairy foods (22% of cases).
  • High intake of processed meats (18% of cases).
  • Low intake of vegetables (16% of cases).
  • Low intake of fruits (10% of cases).
  • High intake of red meat (7.1% of cases).
  • High intake of sugar sweetened beverages (4.0% of cases).

Of the diet-associated cancer cases, the scientists who lead the study estimated that 84% of them represented a direct effect of diet on cancer risk. The dietary factors most likely to directly increase the risk of cancer were:

  • Low intake of whole grains.
  • Low intake of dairy foods.
  • High intake of processed meats.

The scientists estimated that 16% of diet-associated cancer cases were “mediated by obesity”. In layman’s terms, this means that diet increased the risk of obesity and obesity increased the risk of cancer. The dietary factors most likely to increase the risk of obesity-mediated cancers were:

  • High intake of sugar sweetened beverages.
  • Low intake of fruits.

The authors concluded: “More than 80,000 new cancer cases [per year] are estimated to be associated with suboptimal diet among US adults…Our findings underscore the need for reducing cancer burden in the United States by improving the intake of key food groups and nutrients of Americans.”

What Does This Mean For You?

Questioning ManThese findings aren’t novel. Many previous studies have come to the same conclusions. However, many people find these recommendations to be confusing. Should they increase their intake of certain foods? Should they follow some sort of magic diet?

Perhaps we need to get away from the magic food concept. We need to understand that every time we increase one food in our diet, we exclude other foods. We need to step back and look at the overall diet.

Let me break down the recommendations from this study into three categories: foods we should eliminate from our diet, foods we should include in our diet, and foods we should balance in our diet.

Foods we should eliminate from our diet:

  • Sugar Sweetened Beverages. They provide no nutritional benefit, and the sugar in most beverages rushes into our bloodstream and overwhelms our body’s ability to utilize it in a healthy way. This leads to obesity, diabetes, and a host of other health issues.
    • Public enemy number one is sodas. However, this category also includes fruit juices, sweetened teas and energy drinks, and sugary processed foods.
    • This category also includes diet sodas. For reasons we don’t completely understand, diet sodas appear to be just as likely to lead to obesity, diabetes, and heart disease as sugar sweetened sodas. I have discussed the proposed explanations of this phenomenon in a recent issue of “Health Tips From the Professor”.
    • Sugar, however, is not the enemy. Sugar found naturally in fruits and other whole foods enters the bloodstream slowly and is metabolized in healthy ways by the body. I have discussed this in another issue  of “Health Tips From the Professor”. This is what I mean by restoring balance in our diet. Decreasing the sugar intake from sugar sweetened beverages and increasing sugar intake from fruits is associated with a decreased risk of obesity and obesity-related cancers.
  • Processed Meats. The evidence is overwhelming at this point that processed meats directly increase the risk of cancer.
    • If you have trouble completely eliminating processed meats from your diet, my advice is to minimize them and consume them only in the context of an overall healthy diet. Personally, I still consume bacon occasionally as flavoring for a healthy green salad.

Whole GrainsFoods we should include in our diet. I put these in a separate category because Dr. Strangelove and his colleagues have been telling us to eliminate them from our diet, and many Americans are following those recommendations:

  • Whole grains. We can think of whole grains as the underserving victim of the low-carb craze. The low-carb craze is on the mark when it comes to eliminating added sugars and refined grains from the diet. However, eliminating whole grains from the diet may be doing more harm than good. In fact, this and other studies suggest that whole grains are the most effective foods for reducing cancer risk. Why is that?
    • If we assume whole grains are just a good source of fiber and a few vitamins and minerals, it is hard to grasp their importance. We could easily get those nutrients elsewhere.
    • However, we are beginning to realize that whole grains play a unique role in supporting certain species of gut bacteria that are very beneficial to our health. In short, whole grains may be essential for a healthy gut.
  • Dairy Foods. This is another food that has been treated as a villain by Dr. Strangelove and his many colleagues. However, for reasons we don’t completely understand, dairy foods appear to decrease the risk of heart disease and cancer.

Foods we should balance in our diet.

  • Red Meat. Diets high in red meat are consistently associated with a slight increase in cancer risk. The World Health Organization lists red meat as a probable carcinogen, but that has proven to be controversial.
    • Much of the research has centered on why red meat causes cancer. Several mechanisms have been proposed, but none of them have been proven.
    • In contrast, very little consideration has been given to what red meat is displacing from the diet. Diets high in red meat are often low in whole grains, fruits and/or vegetables.
    • Perhaps instead of eliminating red meat from our diets we should be talking about balancing red meat in our diets by consuming less red meat and more whole grains, fruits, and vegetables.

What Can You Do To Reduce Cancer Risk?

American Cancer SocietyYou may have been thinking that 80,110 cases/year represents a small percentage of new cancer cases. That’s because diet is only one component of a holistic cancer prevention strategy. Here is what the American Cancer Society recommends for reducing cancer risk:

  • Avoid tobacco.
  • Limit sun exposure.
  • Achieve and maintain a healthy weight.
  • Eat a healthy diet, with an emphasis on plant foods (Their recommendations are in line with this study).
  • Be physically active.
  • Limit alcohol use.
  • Get vaccinated against HPV.
  • Get regular medical checkups.

Doing any of these things will reduce your cancer risk. But the more of these you can incorporate into your lifestyle, the lower your risk.

The Bottom Line

A recent study looked at diet and cancer risk. The authors reported that 80,110 new cancer cases among US adults 20 and older could be primarily attributed to poor diet.

When the diet was broken down into individual food groups:

  • Low intake of whole grains was associated with the largest number of preventable cancer cases. This was followed in descending order by.
  • Low intake of dairy foods.
  • High intake of processed meats.
  • Low intake of vegetables.
  • Low intake of fruits.
  • High intake of red meat.
  • High intake of sugar sweetened beverages.

The authors concluded: “More than 80,000 new cancer cases [per year] are estimated to be associated with suboptimal diet among US adults…Our findings underscore the need for reducing cancer burden in the United States by improving the intake of key food groups and nutrients of Americans.”

For more details, read the article above. For example, I discuss which foods we should eliminate, which foods we should eat more of, and which foods we should balance in our diet. To add a more holistic perspective, I also discuss the American Cancer Society’s recommendations for reducing cancer risk.

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.

Colon Cancer Prevention

Why Is Colon Cancer Increasing In Young Adults?

Author: Dr. Stephen Chaney

 

colon cancer intestinesA recent study on colorectal cancer reminds me of that famous Dickens quote: “It was the best of times. It was the worst of times.”

The good news (best of times) is that colorectal cancer rates in the United States have been declining for several decades for adults over 50. The decline is attributed to a healthier lifestyle and better screening.

The bad news (worst of times) is that colorectal cancer rates are increasing at an alarming rate for young adults. We have also learned recently that heart attacks are increasing for young women.

These studies are a wake-up call. We need to be asking:

  • Why are young people in our country dying from diseases that we traditionally associate with older adults?
  • What can we do about it?

How Was The Study Done?

colon cancer studyThis study (RL Siegel et al, Journal of the National Cancer Institute, 109 (8): djw322, 2017 ) was an analysis of data collected between 1974 and 2013 from a registry of cancer diagnoses called the Surveillance, Epidemiology, and End Results (SEER) Program. The data were collected from nine regions of the United States (Atlanta, Connecticut, Detroit, Hawaii, Iowa, New Mexico, Seattle-Puget Sound, San Francisco-Oakland, and Utah).

In this study 490,305 patients 20 years and older developed colorectal cancer between 1974 and 2013. This study divided those colorectal cancer cases into 11 age groups (20-29, 30-39, 40-49, 50-54, 55-59, 60-64, 65-69, 70-74, 75-79, 80-84, and 84+). The study then compared colorectal cancer rates for each age group in 8 five-year time periods (1974-1978, 1979-1983, 1984-1988, 1989-1993, 1994-1998, 1999-2003, 2004-2008, and 2009-2013).

What Did The Study Show?

colon cancer increaseWhen the investigators looked at the change in colon cancer incidence over time in different age groups, the results were quite alarming.

  • For adults age 20-29 colon cancer rates increased by 2.4% per year between the mid-1980s and 2013. While that doesn’t sound like much, 2.4% per year adds up. Colon cancer rates almost doubled between 1985 and 2013 for that age group.
  • For adults age 30-39 colon cancer rates increased by 1% per year over that same time period. That’s a 25% increase between 1985 and 2013.
  • By the mid-1990s colon cancer rates started increasing by 1.3% per year for the 40-49 age group and 0.5% per year for the 50-54 age group.
  • The only good news was that colon cancer rates continued to decrease for adults aged 55 and above.

When the investigators looked at the change in rectal cancer incidence over time in different age groups the results were even more alarming.

  • For adults age 20-29 rectal cancer rates increased by 3.2% per year between 1974 and 2013. That’s an almost 4-fold increase in rectal cancer for that age group.
  • For adults age 30-39 rectal cancer rates increased by 3.2% per year between the mid-1980s and 2013. That’s about a 3-fold increase.
  • By the 1990s rectal cancer rates started increasing by 2.3% per year for the 40-49 age group and the 50-54 age group.
  • Once again, the only good news was that rectal cancer rates continued to decrease for adults aged 55 and above.

 

Why Is Colon Cancer Increasing In Young Adults?

 

whyThis study is a clear wake-up call. If colorectal cancer rates are increasing so dramatically in young adults, it does not bode well for them once they reach their 60s, 70s and beyond. This is an impending health crisis. We need to ask:

  • Why this is happening?
  • What can we do about it?

The simple answer to the first question is that no one knows for sure why colorectal cancer incidence is increasing in young adults. However, here is what experts think might be happening:

  • Obesity is a prime suspect. The increase in colorectal cancer incidence in young adults closely parallels the obesity epidemic, and obesity is associated with an increased risk of colon cancer.
  • Many of today’s most popular diets may just make matters worse. Fad diets promise rapid weight loss, but they may also increase the risk of colorectal cancer.
  • Fad diets often restrict fruits, grains, and/or legumes. Plant based diets containing lots of fruits, vegetables, whole grains, and legumes are associated with a significantly lower risk of colorectal cancer. We have no evidence that we can leave out any component of a plant-based diet and still reduce colorectal cancer risk to the same extent.
  • Fad diets often emphasize red meat as a protein source. The World Health Organization considers red meat as a probable carcinogen. The association between red meat consumption and cancer incidence is stronger for colon cancer than for any other cancer.
  • Fad diets are often high in saturated fats, and saturated fat is associated with an increased risk of colorectal cancer.
  • Finally, fad diets are often low in fiber. Low fiber diets alter our microbiome (gut bacteria), and recent research suggests our microbiome may play an important role in preventing colon cancer.
  • The typical American diet is no better. It is high in red meat and saturated fats. It is low in fruits, vegetables, whole grains, legumes and fiber. Plus, it is high in sugar, sweets, and refined grains. With respect to colorectal cancer risk, it is the worst of all possible worlds.
  • We don’t get enough folic acid, calcium and omega-3s in our diet. Those nutrients are associated with a lower risk of colorectal cancer.
  • We don’t move enough. A sedentary lifestyle is also associated with an increased risk of colorectal cancer.
  • Cigarettes and alcohol are associated with an increased risk of colorectal cancer. However, smoking and alcohol consumption have been declining in recent years, so they do not explain the increase in colorectal cancer we are seeing in young adults.

In summary, the authors of this study concluded: “These results highlight the need for…research to elucidate causes for the…increase in disease risk in young [adults], as well as creative new strategies to curb the obesity epidemic and shift Americans towards healthier eating and more active lifestyles.”

Colon Cancer Prevention

 

colon cancer fruits and vegetablesIf you are a young adult, you are probably wondering what you can do to reduce your risk of colorectal cancer. The good news is that we have a good idea of how to reduce the risk of colon cancer, and it works at any age.

Let’s start with the American Cancer Society recommendations  for decreasing the risk of colorectal cancer. They are (with direct quotes from The American Cancer Society in quotation marks):

  • Get screened for colorectal cancer. The American Cancer Society recommends that screening start at age 45. However, you may want to consult with your doctor about earlier screening if you have a family history of early-onset colon cancer, have blood in your stool, or develop bowel changes that last more than a few weeks.
  • Eat lots of vegetables, fruits, and whole grains. According to the American Cancer Society: “Diets that include lots of vegetables, fruits, and whole grains have been linked with decreased risk of colon or rectal cancers.”
  • Eat less red meat and processed meats. They “have been linked with an increased risk of colorectal cancer.”
  • Get regular exercise. “If you are not physically active, you may have a greater chance of developing colon or rectal cancers.”
  • Watch your weight. “Being overweight increases your risk of getting and dying from colon or rectal cancer.”
  • Don’t smoke. “Long-term smokers are more likely than non-smokers to develop and die from colon or rectal cancer.”
  • Limit alcohol. “Alcohol use has been linked with a higher risk of colorectal cancer.”

 

Other experts recommend:

  • Limit saturated fats. Replace saturated fats with monounsaturated fats and polyunsaturated fats.
  • Get plenty of fiber. That should be no problem if you are consuming a primarily plant-based diet containing lots of fruits, vegetables, whole grains and legumes.
  • Make sure you are getting enough folic acid, calcium, and omega-3s. I recommend supplementation because even healthy diets often fall short of these nutrients.

I would add one final recommendation:

  • Avoid fad diets that take you away from a healthy eating pattern (described above), one that is known to reduce colorectal cancer risk.

 

The Bottom Line

 

A recent study has reported an alarming increase in colorectal cancer incidence in young adults.

  • For adults in the 20-29 age range, colon cancer incidence has increased 2-fold and rectal cancer incidence has increased 4-fold over the last few decades.
  • Colon and rectal cancer incidence have also increased significantly for adults in the 30-39 and 40-49 age groups.
  • The only good news from this study is that colon and rectal cancer incidence is continuing to decline for older adults.

This is a clear wake-up call. If this trend is not reversed, it does not bode well for these adults when they reach their 60s, 70s, 80s, and beyond.

For more details on what experts think is causing this alarming increase in colorectal cancer among young adults and what young adults can do to protect themselves from colorectal cancer, 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

Colon Cancer Prevention and Anti-Inflammatory Diets

How Can You Reduce Colon Cancer Risk?

Author: Dr. Stephen Chaney

 

colon cancer prevention colorectalColorectal cancer is third most common form of cancer in the United States. The American Cancer Society estimates that there will be 140,000 new cases and 50,000 deaths from colorectal cancer in 2018. The death rate has been decreasing due to more aggressive screening, but it is still much too high.

Thus, there is considerable interest in discovering colon cancer prevention we can control. Several studies have suggested that inflammatory diets may be one preventable cause of colon cancer. There are many reasons for suspecting that inflammation may increase colon cancer risk. For example, we know:

  • Inflammation plays an important mechanistic role in cancer development.
  • Obesity causes a chronic state of low-grade inflammation, and obesity increases colon cancer risk.
  • Inflammatory bowel disease increases the risk of colon cancer.
  • Anti-inflammatory medications such as aspirin decrease colon cancer risk.

However, it has been difficult to prove that inflammatory diets increase colon cancer risk. In part, that is because we can’t measure inflammation directly. We must rely on inflammatory markers such as C-reactive protein (CRP), interleukin-6 (IL-6) and tumor necrosis factor (TNF). Unfortunately, these markers correlate with different inflammatory processes in the body and seldom increase or decrease in unison.

The authors of the current study (FK Tabung et al, JAMA Oncology, 4: 366-373, 2018 ) used a dietary scoring system based on all three inflammatory markers to examine the correlation between an inflammatory diet and colon cancer risk.

How Was The Study Done?

colon cancer prevention inflammationThis study made use of data collected from 46,804 men enrolled in the Health Professionals Follow-up Study (conducted between 1986 and 2012) and 74,246 women enrolled in the Nurses’ Health Study (conducted between 1984 and 2012). Lifestyle, medical, and other health-related information were collected every 2 years. A comprehensive dietary questionnaire was administered every 4 years. During the 26-year follow-up period 2699 cases of colon cancer were diagnosed.

The inflammatory potential of the diet was estimated using an index called the empirical dietary inflammation pattern (EDIP) score that the authors had developed in a previous study (FK Tabung et al, Journal of Nutrition, 146: 1560-1570, 2016 ). This index was based on the effects of individual foods on all three markers of inflammation (CRP, IL-6, and TNF). Inflammatory foods had positive EDIP scores (they increased levels of one or more of the inflammatory markers). Anti-inflammatory foods had negative EDIP scores (they decreased levels of one or more inflammatory markers).

Most of the EDIP scores were consistent with previous studies on the inflammatory potential of various foods. For example:

  • Red meats, processed meats, refined grains, sugar-sweetened beverages, and diet beverages all scored as highly inflammatory.
  • One serving of beer or wine, coffee, dark yellow vegetables, and leafy green vegetables all scored as highly anti-inflammatory.

 

Colon Cancer Prevention By Avoiding Inflammatory Diets

colon cancer prevention fireThe subjects enrolled in the study were divided into five groups based on their inflammatory diet (EDIP) scores. When the investigators compared subjects who had the most inflammatory diet with subjects who had the least inflammatory diet:

  • The risk of colon cancer was increased by 44% in men and 22% in women.
  • People who refrain from alcohol consumption received even greater benefit from anti-inflammatory diets. For teetotalers an anti-inflammatory diet decreased colon cancer risk by 62% in men and 33% in women.

The authors concluded: “Findings from this large prospective [that is scientific jargon meaning the study was carried out over a period of many years] study support a role for the inflammatory potential of diet in colorectal cancer development, suggesting inflammation as a potential mechanism linking dietary patterns and colorectal cancer development.”

 

How To Prevent Colon Cancer Or At Lest Reduce The Risk?

 

colon cancer prevention american cancer societyOf course, holistic approaches are always best. Reducing colon cancer risk involves much more than simply consuming an anti-inflammatory diet. To put this study in perspective, let’s look at what the American Cancer Society recommendations about modifiable lifestyle factors that increase your risk of colon cancer. So, consider these when you think about colon cancer prevention.  I call this the 10,000-foot view because they only list the biggest contributors to colon cancer – the ones for which there is the most scientific evidence (I have put their exact comments in quotes):

#1: Being overweight or obese. “If you are overweight or obese your risk of developing and dying from colorectal cancer is higher”.

#2: Physical inactivity. “If you are not physically active, you have a greater chance of developing colon cancer.”

#3: Certain types of diets.

  • “A diet that’s high in red meats (such as beef, pork, lamb, or liver) and processed meats (like bacon, sausage, hot dogs and some luncheon meats) raises your colorectal cancer risk.” My comment: The evidence is stronger for red meats and processed meats than for any other foods. Processed meats are listed as likely carcinogens and red meats are listed as probable carcinogens by the International Agency For Research On Cancer (IARC), an agency of the WHO.
  • “Cooking meats at very high temperatures (frying, broiling, or grilling) creates chemicals that may raise your cancer risk.”

#4: Smoking. “People who have smoked for a long time are more likely than non-smokers to develop and die from colorectal cancer.”

#5: Heavy alcohol use. “Colorectal cancer has been linked to moderate to heavy alcohol use. Limiting alcohol use to no more than 2 drinks a day for men and 1 drink a day for women could have many health benefits, including a lower risk of many kinds of cancer. “

#6: Early detection. In case you have not heard, the American Cancer Society just released new guidelines recommending that screening for colon cancer begin at age 45.

If you want to take a closer look at the diet – colon cancer connection, you might be interested in the recommendations of Harvard’s Men’s Health Watch newsletter.

 

What Does This Mean For You?

colon cancer prevention inflammatory dietsIf you are confused about the conflicting information about which foods affect colon cancer risk, start with the American Cancer Society recommendations. Avoid red meats and processed meats as much as possible and don’t cook your meats at high temperatures. I realize this is not popular advice at the time of year when everyone is firing up their grills for summer cookouts, but these recommendations will go a long way towards colon cancer prevention. Don’t shoot the messenger. I’m just conveying information based on the best scientific evidence we have to date.

For best results follow the recommendations of the Harvard Men’s Health Watch newsletter to also avoid fried foods, sugary beverages and refined carbohydrates and add anti-inflammatory foods such as fresh fruits & vegetables, nuts, olive oil, and fatty fish.

With Harvard’s recommendations in mind, let me extend an olive branch to all of you red meat lovers. An ounce or two of red meat in a green salad or a stir fry with lots of fresh, colorful vegetables is much less likely to increase your risk of cancer than a steak or burger with fries. You will find more information on this topic in my book “Slaying The Food Myths.”

 

The Bottom Line:

A major study has just been published looking at the correlation between an inflammatory diet and colon cancer risk. When the investigators compared subjects who had the most inflammatory diet with subjects who had the least inflammatory diet:

  • The risk of colon cancer was increased by 44% in men and 22% in women.
  • People who refrain from alcohol consumption received even greater benefit from anti-inflammatory diets. For teetotalers an anti-inflammatory diet decreased colon cancer risk by 62% in men and 33% in women.

The authors concluded: “Findings from this large study support a role for the inflammatory potential of diet in colorectal cancer development, suggesting inflammation as a potential mechanism linking dietary patterns and colorectal cancer development.”

If you are confused about the conflicting information about which foods are inflammatory and anti-inflammatory, start with the American Cancer Society recommendations. Avoid red meats and processed meats as much as possible and don’t cook your meats at high temperatures. I realize this is not popular advice at the time of year that everyone is firing up their grills for summer cookouts, but these recommendations will go a long way towards colon cancer prevention.

For best results follow the recommendations of the Harvard Men’s Health Watch newsletter to also avoid inflammatory foods such as fried foods, sugary beverages and refined grains and add anti-inflammatory foods such as fresh fruits & vegetables, nuts, olive oil, and fatty fish.

With Harvard’s recommendations in mind, let me extend an olive branch to all of you red meat lovers. An ounce or two of red meats in a green salad or a stir fry with lots of fresh, colorful fruits and vegetables is much less likely to increase your risk of cancer than a steak or burger with fries. You will find more information on this topic in my book “Slaying The Food Myths.”

For more details on the American Cancer Society and Harvard recommendations and colon cancer prevention, 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.

Health Tips From The Professor