Is Fructose Good For You Or Bad For You?

Is It The Fructose Or Is It The Food?

Author: Dr. Stephen Chaney

VillainFructose is the villain of the day. It is #1 on everyone’s “No-No” list. Almost every website, blog, and diet book demonize it. Even authors I highly respect say we should absolutely avoid it.

We are told it causes obesity, diabetes, heart disease, and non-alcoholic fatty liver disease – a disease that was unheard of only a few decades ago. We are told to read labels and avoid any foods with fructose or high-fructose corn syrup listed on their label.

But wait. Isn’t fructose a natural sugar? The answer is, “Yes”. It is the main sugar in fruit and many other naturally sweet whole foods. In fact, there is the same amount of fructose in an 8-ounce soda and a medium apple.

Does that mean that fruits are also bad for us? What is the truth?

Is It The Fructose Or Is It The Food?

AppleLet me put this into perspective for you. I have covered this in detail in a previous issue of Health Tips From The Professor. Here is a brief summary.

  • There are no sugar villains. There are no sugar heroes. Most of your favorite “natural” sugars are chemically and biologically indistinguishable from high-fructose corn syrup. Other natural sugars, like agave sugar, contain more fructose than high-fructose corn syrup.
  • All the studies showing the bad effects of fructose have been done with sodas and/or highly processed foods with added sugar. Let’s be clear. Those foods are bad for you.
  • Fruits, on the other hand, are good for you. You’ve heard the old adage, “An apple a day keeps the doctor away”. A recent study showed that isn’t just an “old wives’ tale”. It is true.

Why is that? Why is fructose in sodas and junk foods bad for us and fructose in fruits good for us?

Part of the answer is that fruits are high in fiber, which slows the release of fructose into the intestine as fruits are digested. In addition, the fructose in fruits is trapped in a cellular matrix, which also slows the release of fructose during digestion.

Sodas and highly processed foods, on the other hand, have nothing to slow the release of fructose. It is immediately available as soon as the food reaches the intestine.

A recent study sheds light on why the rate of fructose release in our intestine may be important. The study showed:

  • When fructose is released slowly our bodies know exactly what to do with it.
    • Most of it is metabolized by the cells that line our intestine, and the rest is metabolized by the liver.
    • In both cases fructose is converted to glucose and slowly released into the bloodstream.
    • This stabilizes blood sugar levels.
  • When fructose is released quickly our bodies are overwhelmed and bad things happen.
    • The intestine passes the excess on to the liver, and the liver converts it to fat rather than glucose.
    • The fat is stored in the liver.
    • This leads to insulin resistance, diabetes, heart disease, and fatty liver disease.

But could the fiber in fruits have other beneficial effects such as supporting populations of beneficial gut bacteria? The study ( J Beisner et al, Nutrients, 12: 3444, 2020) I will focus on today suggests the answer is yes.

How Was The Study Done?

Clinical StudyInvestigators from the University of Hohenheim, Germany recruited 12 healthy female volunteers, ages 20 – 40 (average age = 28).

Each of the subjects was given a series of diets to follow for one week each.

  • Week one was a low fructose diet (10 g of fructose/day). For this diet phase subjects had to avoid sweets, highly processed foods, sodas, and fruits and vegetables containing more than 1 g of fructose per serving.
  • Week two was a high fructose fruit diet (100 g of fructose/day). This diet phase emphasized fructose-rich fruits and vegetables. Sweets, highly processed foods, and sodas had to be avoided.
  • Week three was a repeat of the low fructose diet (10 g of fructose/day).
  • Week four was a high-fructose corn syrup diet (100 g of fructose/day). For this diet phase subjects had to sweeten the food they were eating with a measured amount of high-fructose corn syrup. They also had to avoid fructose-rich fruits and vegetables.

The diets were designed to have around 2,000 calories/day and to have the same amounts of fat (30% of calories), protein (15% of calories), and carbohydrate (55% of calories). However, the fiber content of the diets was very different (around 17 g/day on the low fructose and high-fructose corn syrup diets and around 38 g/day on the high fructose fruit diet).

The subjects were given detailed instructions and training before starting on the 4-week program. They also kept a daily dietary record of everything they ate and drank so the investigators would know how closely they stuck to their dietary instructions.

This experimental design was based on previous studies showing that populations of gut bacteria change within 24-48 hours when you go on a new diet. Stool samples were collected at the end of each week and analyzed for gut bacteria.

Is Fructose Good For You Or Bad For You?

MicrobiomeThe study showed:

  • Consumption of a high-fructose, fruit-rich diet resulted in:
    • An increase in beneficial butyrate-producing bacteria (more about that below).
    • A decrease in bacteria associated with elevated total and LDL cholesterol.
    • Decreased blood levels of total and LDL cholesterol.
  • Consumption of a high-fructose corn syrup diet had the opposite effect. It resulted in:
    • A decrease in beneficial butyrate-producing bacteria.
    • An increase in bacteria associated with elevated total and LDL cholesterol.
    • Increased blood levels of total and LDL cholesterol.

The authors concluded: “We provide evidence that the high-fructose corn syrup diet induces an imbalanced microbiota [gut bacteria] profile characterized by a significantly reduced abundance of beneficial butyrate-producing bacteria and of bacteria known for anti-obesity effects…Despite the high fructose content, the fruit-rich diet shifts the intestinal microbiota composition in a protective manner…”

The authors said that there were probably two mechanisms for the different effects of fructose in high-fructose corn syrup and in fruits.

  • The fiber found in fruit supports the growth of beneficial bacteria in our intestine.
  • When high-fructose corn syrup is present in foods with low fiber content, it is released rapidly in the intestine. As I noted above, the cells that line our intestine become overwhelmed and pass some of that excess fructose on to our liver. However, the authors cited previous studies showing that some of that excess fructose remains in our intestine and supports the growth of unhealthy bacteria.

What Does Butyrate Do?

Question MarkYou are probably wondering what is special about butyrate-producing bacteria. Here is a brief synopsis.

  • Butyrate is a short chain fatty acid. As you might expect from its name, it was originally identified as a constituent of butter.
  • Some species of gut bacteria convert the fats in our diet to butyrate.
    • It is used as a preferred energy source for the cells that line our intestine. Consequently, butyrate production in our intestines has been linked to:
      • Reduced inflammation of the cells lining our intestine, which reduces the risk for diseases like inflammatory bowel disease (IBS) and Crohn’s Disease.
      • Reduced risk of “leaky gut syndrome”.
      • Reduced risk of colon cancer.
    • It is also absorbed into the bloodstream and appears to affect several metabolic pathways. For example, butyrate production in the intestine is associated with:
      • Decreased cholesterol levels.
      • Improved blood sugar control.
      • A healthy body weight.

What Does This Mean For You?

Questioning ManThis was a small study. As the authors noted, larger studies of longer duration are needed to confirm that the effects of fructose on our gut bacteria depend on the food the fructose is in. However, several other studies have come to similar conclusions.

More importantly, this study merely shows that the effect of fructose-containing foods on our gut bacteria is a potential mechanism for explaining why the effect of fructose depends on the food it is in.

There is already overwhelming evidence that fructose in fruits is good for us, while high-fructose corn syrup in sodas and highly processed foods is bad for us.

Does that mean high-fructose corn syrup is villainous? Should we read labels and avoid any food containing high-fructose corn syrup?

I would remind you that the amount of fructose and the relative abundance of fructose and glucose are virtually identical in fruits and high-fructose corn syrup. It is not high-fructose corn syrup that is the problem, it is the foods it is found in.

We don’t need to become compulsive label readers. We just need to eat more foods without labels.

The Bottom Line 

High-fructose corn syrup has been vilified in recent years. However, there is increasing evidence that it is not fructose that is the problem. It is the foods it is found in.

A recent study was designed to test that hypothesis. The investigators fed subjects high fructose diets in which the fructose came either from fruits or high-fructose corn syrup. The amount of fructose was identical in the two diets. The investigators then asked what effect the two diets had on gut bacteria. In short:

  • Consumption of the high-fruit diet increased healthy levels of beneficial gut bacteria and suppressed levels of unhealthy gut bacteria.
  • Consumption of the high-fructose corn syrup diet had the opposite effect. It increased unhealthy bacteria and suppressed beneficial bacteria.

The authors concluded: “We provide evidence that the high-fructose corn syrup diet induces an imbalanced microbiota [gut bacteria] profile characterized by a significantly reduced abundance of beneficial…bacteria and of bacteria known for anti-obesity effects…Despite the high fructose content, the fruit-rich diet shifts the intestinal microbiota composition in a protective manner…”

My take is as follows: This study shows that the effect of fructose-containing foods on our gut bacteria is a potential mechanism for explaining why the effect of fructose depends on the food it is in.

There is already overwhelming evidence that fructose in fruits is good for us, and high-fructose corn syrup in sodas and highly processed foods is bad for us.

Does that mean that high-fructose corn syrup is villainous? Should we read labels and avoid any food containing high-fructose corn syrup?

I would remind you that the amount of fructose and the relative abundance of fructose and glucose is virtually identical in fruits and high-fructose corn syrup. It is not high-fructose corn syrup that is the problem, it is the foods it is found in.

We don’t need to become compulsive label readers. We just need to eat more foods without labels.

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.

Reversing Fatty Liver Disease

Are Sodas Damaging Your Child’s Liver?

 Author: Dr. Stephen Chaney

 

reversing fatty liver diseaseIs reversing fatty liver disease possible?

Years ago, fatty liver disease was unheard of in children. Chronic liver disease in children was almost always caused by rare gene mutations. That was before the obesity epidemic. Obesity and overweight have increased two- to three-fold in our children and adolescents over the last two decades, and the incidence of non-alcoholic fatty liver disease has skyrocketed along with it.

Non-alcoholic fatty liver disease is now the leading cause of chronic liver disease in children and adolescents in the United States. It was found in 9.6% of all our children, 17.3% of our adolescents ages 15-19, and 38% of our children who are overweight or obese (JB Schwimmer et al, Pediatrics, 118: 1388-1393, 2006).

This is alarming because fatty liver disease increases the risk of developing type-2 diabetes, heart disease, cirrhosis of the liver, end stage liver disease, and liver cancer. If this epidemic of fatty liver disease in our adolescents is not reversed, we are condemning them to a lifetime of poor health.

Consumption of sodas and sugary processed foods is strongly associated with both obesity and fatty liver disease. That has led many experts to recommend we eliminate sodas, fruit juices, and sugary desserts and processed foods from our diet. However, associations do not prove cause and effect. Food manufacturers have claimed there was no proof these foods cause obesity and fatty liver disease.

That’s where a recent study performed at Emory University and the University of California at San Diego, (JB Schwimmer et al, JAMA, 321: 256-265, 2019) comes in. This study was a randomized clinical trial that asked whether elimination of soft drinks, fruit juices, and foods with added sugars from the diet of adolescents with fatty liver disease could reverse the disease.

This study has two important implications. If it showed that elimination of these foods can reverse fatty liver disease:

  • It provides a strategy for treatment of children and adults with fatty liver disease.
  • It strengthens the evidence that these foods cause fatty liver disease.

How Was The Study Done?

reversing fatty liver disease studyThe study started with 40 adolescent boys, ages 11-16, who already had fatty liver disease. They averaged 21-25% liver fat, which is more than four times the normal limit.

  • The study only included boys, because the incidence of fatty liver disease is higher in males than in females. All the subjects were severely overweight or obese (average BMI was >30).
  • The subjects were primarily (90%) Hispanic, because the incidence of fatty liver disease is slightly higher for Hispanics than for other ethnic groups.

The study design was as follows:

  • Twenty of the subjects were randomly assigned to an 8-week intervention diet designed to decrease free sugars (defined as added sugars found in sodas and processed foods and naturally occurring sugars found in fruit juices) from 10% of calories to <3% of calories.
  • Use of artificial sweeteners was prohibited because studies suggest they are also highly correlated with obesity and insulin resistance, both of which increase the risk of fatty liver disease.
  • The whole family followed the intervention diet during the 8-week study. By including the whole family in the study, the adherence of the adolescent to the diet was significantly improved.
  • Prior to starting on the intervention diet, study staff inventoried all food items in the household. Sodas, fruit juices, and processed foods containing added sugar were removed and replaced with low or no-added-sugar food items.
  • A registered dietitian prepared weekly diet plans tailored to family food preferences and the habitual diet of the child without restricting calorie intake. In short, this was not designed as a weight loss diet. In fact, the children consumed on average an additional 291 calories per day on the intervention diet.
  • The diets were neither low carb nor low fat. They did not restrict any food groups. They did not restrict sugars found naturally in fruits, vegetables, grains, and legumes. They were simply healthier versions of the diets the families were already eating without fruit juices and the added sugars found in sodas and processed foods.
  • Participants were instructed to avoid sugar-containing processed foods and drinks including fruit juice when not eating at home.
  • Food sufficient for the entire family was delivered to each participant’s home twice a week. Participants and their families were instructed not to purchase any food and to consume only the food provided by the study staff.
  • If the parents preferred to prepare their own meals, the ingredients for the meals were provided to ensure they met the free-sugar goal.
  • To increase dietary adherence, the study staff made twice-weekly calls to assess food satisfaction, cravings, and assist with special family events and holiday alternatives.
  • Each participant’s diet was evaluated based on 24-hour food recalls on 2 weekdays and 1 weekend at the beginning of the study and between weeks 3 and 8.
  • The other twenty subjects were told to continue with their present diet.
  • Participants in the control group were provided with a weekly food stipend to be used at the food stores of their choice.
  • Participants were told not to make any major changes to their physical activity for the duration of the study.

In short, this was a very well-designed study.

 

Reversing Fatty Liver Disease is Possible?

 

reversing fatty liver disease possibleThe results of the study were dramatic. For the intervention group:

  • Adherence to the diet was excellent. 18 of the 20 participants reduced free sugar intake to <3%. In fact, the average free sugar intake at week 8 was <1% of total calories.
  • The amount of fat in their livers was reduced from 25% to 17% in just 8 weeks.
  • Three markers of liver damage (ALT, aspartate aminotransferase, and γ-glutamyl transpeptidase) were also significantly reduced.
  • Participants lost an average of 3 pounds even though they were consuming an extra 291 calories per day. Forget calorie counting, low carb, and low fat. The best way to lose weight may be to cut out sodas and sugary junk foods. That’s everyone’s dream diet. Eat more and lose weight.

In the control group:

  • Free sugar intake decreased slightly to 10% of calories.
  • There was no significant change in the amount of fat in their livers.
  • ALT and aspartate aminotransferase decreased slightly.
  • Participants gained an average of 1.3 pounds during the 8-week study.

The authors concluded: “In this study of adolescent boys with non-alcoholic fatty liver disease, 8 weeks of provision of a diet low in free sugar compared with the usual diet resulted in significant improvement of hepatic steatosis [fat in the liver]…further research is required to assess long-term and clinical outcomes.”

In short, this is a preliminary study, but it suggests that elimination of sodas, sugary processed foods and fruit juice is enough to substantially reverse fatty liver disease.

 

Are Sodas Damaging Your Child’s Liver?

 

soda and reversing fatty liver diseaseThis study also strengthens the argument that sodas, sugary processed foods, and fruit juices play a significant role in the origin of fatty liver disease.

Why are sodas and the other foods such a problem? To answer that question, we first need to eliminate the myths.

  • Sugar isn’t the problem. This study did not eliminate naturally occurring sugars from fruits, vegetables, grains, and legumes. They aren’t the problem.
  • High fructose corn syrup isn’t the problem. High fructose corn syrup is a mixture of fructose and glucose and is chemically indistinguishable from sucrose (table sugar), honey, coconut sugar, and the fruit sugars used to sweeten “natural” processed foods. More to the point, an 8 oz soda contains the same amount and same kind of sugars as a medium apple. Apples are good for you, but sodas can give you fatty liver disease.
  • Fructose isn’t the problem. The name fructose is derived from fruit. It is the major sugar found in most fruits. Fruits are nutritional powerhouses and are an indispensable part of a healthy diet.
  • It’s sodas, sugary processed foods, and fruit juices that are the problem. That’s because our body was designed to handle the sugars found in fruits, vegetables, grains and legumes in a healthy manner. These sugars are packed into foods with lots of fiber and a cellular matrix that meters sugar into our bloodstream gradually.

When that happens, liver and muscle cells remove sugar from the bloodstream and store it as glycogen. Blood glucose and insulin levels never get very high. The liver converts fructose to glucose and releases it into the bloodstream slowly. Our metabolism is perfectly designed to handle foods in their natural form.

In contrast, sodas, sugary processed foods and fruit juices contain lots of sugar and very little fiber. The sugar rushes into our bloodstream and overwhelms our normal metabolic pathways. The excess glucose causes high blood sugar and insulin levels which increase inflammation and the risk of multiple diseases. The excess fructose is converted to fat in the liver. Some of that fat is released into the bloodstream as triglycerides, but much of it remains in the liver, where it can lead to fatty liver disease. For more details, read my book, Slaying The Food Myths.

In short, our body can metabolize naturally occurring sugars found in whole foods quite well. Those same sugars in sodas, sugary processed foods and fruit juices can destroy our health.

What Does This Study Mean For You?

reversing fatty liver disease questionsThe greatest strength of this study is also its greatest weakness.

  • The whole family went on the same diet. This was not just a diet for the children in the household.
  • The study staff inventoried all food items in the household. Sodas, sugary processed foods, and fruit juices were removed and replaced with healthier foods with low or no-added-sugar.
  • A dietitian designed the diets and families were provided with all the food they needed for the 8-week program.

Its weakness is obvious. If you think of this as a public health intervention, it would be impossible to implement it on a significant scale.

However, as a parent this is very doable. If you care about the health of your children, make a healthier change for the whole family.

  • Throw out the sodas, fruit juices, and processed foods with added sugars.
  • Replace them with whole unprocessed foods from all 5 food groups.
  • If you buy any processed foods, choose those with little or no added sugar.
  • Don’t replace them with artificially sweetened foods. Most recent studies suggest artificial sweeteners are just as bad for you as the sugars they replace. For more details, read my book, Slaying The Food Myths.

 

The Bottom Line

 

Fatty liver disease is increasing at an alarming rate in our children, especially our teenagers.

This is alarming because fatty liver disease increases the risk of developing type-2 diabetes, heart disease, cirrhosis of the liver, end stage liver disease, and liver cancer. If this epidemic of fatty liver disease in our adolescents is not reversed, we are condemning them to a lifetime of poor health.

Sodas, fruit juices, and processed foods with added sugars have been implicated in obesity and fatty liver disease. It has been difficult, however, to prove cause and effect.

A recent clinical study showed that eliminating sodas, fruit juices, and processed foods with added sugar from the diet of obese, adolescent boys with fatty liver disease for just 8-weeks:

  • Significantly reversed fat accumulation in the liver (fatty liver disease) and markers of liver damage. This may be a promising approach for reversing fatty liver disease. It also strengthens the argument that sodas and processed foods with added sugar play an important role in causing fatty liver disease.
  • The boys lost an average of 3 pounds even though they were consuming an extra 291 calories per day. Forget calorie counting, low carb, and low fat. The best way to lose weight may be to cut out sodas and sugary junk foods. That’s everyone’s dream diet. Eat more and lose weight.

This was a very well controlled study.

  • The whole family followed the intervention diet during the 8-week study. By including the whole family in the study, the adherence of the adolescent to the diet was significantly improved.
  • Prior to starting on the intervention diet, study staff inventoried all food items in the household. Sodas, fruit juices, and processed foods containing added sugar were removed and replaced with low or no-added-sugar food items.
  • A registered dietitian prepared weekly diet plans tailored to family food preferences and the habitual diet of the child without restricting calorie intake. In short, this was not designed as a weight loss diet. In fact, the children consumed on average an additional 291 calories per day on the intervention diet.
  • The diets were neither low carb nor low fat. They did not restrict any food groups. They did not restrict sugars found naturally in fruits, vegetables, grains, and legumes. They were simply healthier versions of the diets the families were already eating without fruit juices and the added sugars found in sodas and processed foods.
  • Food sufficient for the entire family was delivered to each participant’s home twice a week.
  • Adherence to the diet was strictly monitored.

If you think of this as a public health intervention, it would be impossible to implement it on a significant scale.

However, as a parent this is very doable. If you care about the health of your children, make a healthier change for the whole family.

  • Throw out the sodas, fruit juices, and processed foods with added sugars.
  • Replace them with whole unprocessed foods from all 5 food groups.
  • If you buy any processed foods, choose those with little or no added sugar.
  • Don’t replace them with artificially sweetened foods. Most recent studies suggest artificial sweeteners are just as bad for you as the sugars they replace.

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.

Health Tips From The Professor