carbohydrates Archives - Health Tips From The Professor

Are All Carbs Bad?

August 1, 2023 by Dr. Steve Chaney

Are Low Carb Enthusiasts Right About The Dangers Of Carbohydrates?

Author: Dr. Stephen Chaney

Low carb enthusiasts have been on the warpath against carbohydrates for years.

Almost everyone agrees that sugar-sweetened sodas and highly processed, refined foods with added sugar are bad for us. But low carb enthusiasts claim that we should also avoid fruits, grains, and starchy vegetables. Have they gone too far?

Several recent studies suggest they have. For example, both association studies and randomized controlled studies suggest that total carbohydrate intake is neither harmful nor beneficial for heart health.

In addition, recent studies suggest that free sugar intake is associated with both elevated triglyceride levels and an increase in heart disease risk.

But those studies have mostly looked at free sugar intake from sugar-sweetened sodas. The authors of this study (RK Kelley et al, BMC Medicine, 21:34, 2023) decided to look more carefully at the effect of all free sugars and other types of carbohydrates on triglyceride levels and heart disease risk.

How Was This Study Done?

The 110,497 people chosen for this study were a subgroup of participants in the UK Biobank Study, a large, long-term study looking at the contributions of genetic predisposition and environmental exposure (including diet) to the development of disease in England, Scotland, and Wales.

The participants in this study were aged between 37 and 73 (average age = 56) on enrollment and were followed for an average of 9.4 years. None of them had a history of heart disease or diabetes or were taking diabetic medications at the time of enrollment.

During the 9.4-year follow-up, five 24-hour dietary recalls were performed, so that usual dietary intake could be measured rather than dietary intake at a single time point. The people in this study participated in an average of 2.9 diet surveys, and none of them had less than two diet surveys.

The averaged data from the dietary recalls were analyzed for the amount and kinds of carbohydrate in the diet. With respect to the types of carbohydrate, the following definitions would be useful.

The term free sugars includes all monosaccharides and disaccharides added to foods by the manufacturer, cook, or consumer, plus sugars naturally present in honey, syrups, and unsweetened fruit juices.

The term non-free sugars includes all sugars not in the free sugar category, mostly sugars naturally occurring in fruits, vegetables, and dairy products.

The term refined grains includes white bread, white pasta, white rice, most crackers and cereals, pizza, and grain dishes with added fat.

The term whole grains includes wholegrain bread, wholegrain pasta, brown rice, bran cereal, wholegrain cereals, oat cereal, and muesli.

Finally, the study looked at the association of total carbohydrate and each class of carbohydrate defined above with all heart disease, heart attacks, stroke, and triglyceride levels.

Are All Carbs Bad?

The study looked at total carbohydrate intake, free sugar intake, and fiber intake. In each case, the study divided the participants into quartiles and compared those in the highest quartile with those in the lowest quartile.

Using this criterion:

Total carbohydrate intake was not associated with any cardiovascular outcome measured (total heart disease risk, heart attack risk, and stroke risk).

Free sugar intake was positively associated with all cardiovascular outcomes measured. Each 5% increase in caloric intake from free sugars was associated with a:

- 7% increase in total heart disease risk.

- 6% increase in heart attack risk.

- 10% increase in stroke risk.

- 3% increase in triglyceride levels.

Fiber intake was inversely associated with total heart disease risk. Specifically, each 5 gram/day increase in fiber was associated with a:

- 4% decrease in total heart disease risk.

The investigators also looked at the effect of replacing less healthy carbohydrates with healthier carbohydrates. They found that:

Replacing 5% of caloric intake from refined grains with whole grains reduced both total heart disease risk and stroke risk by 6%.

Replacing 5% of caloric intake from free sugars (mostly sugar-sweetened beverages, fruit juices, and processed foods with added sugar) with non-free sugars (mostly fruits, vegetables, and dairy products) reduced total heart disease risk by 5% and stroke risk by 9%.

Are Low Carb Enthusiasts Right About The Dangers Of Carbohydrates?

With these data in mind let’s look at the claims of the low-carb enthusiasts.

Claim #1: Carbohydrates raise triglyceride levels. This study shows:

This claim is false with respect to total carbohydrate intake and high fiber carbohydrate intake (fruits, vegetables, and whole grains. This study did not measure intake of beans, nuts, and seeds, but they would likely be in the same category).

However, this claim is true with respect to foods high in free sugars (sugar-sweetened beverages, fruit juices, and processed foods with added sugar).

Claim #2: Carbohydrates increase heart disease risk. This study shows:

That claim is false with respect to total carbohydrate intake and high fiber carbohydrate intake.

However, this claim is true with respect to foods high in free sugars.

Claim #3: Carbohydrates cause weight gain [Note: Low carb enthusiasts usually word it differently. Their claim is that eliminating carbohydrates will help you lose weight. But that claim doesn’t make sense unless you believed eating carbohydrates caused you to gain weight.] This study shows:

This claim is false with respect to total carbohydrate intake and high fiber carbohydrate intake.

Once again, this claim is true with respect to foods high in free sugars.

The data with high fiber carbohydrates was particularly interesting. When the authors compared the group with the highest fiber intake to the group with the lowest fiber intake, the high-fiber group:

Consumed 33% more calories per day.

But had lower BMI and waste circumference (measures of obesity) than the low-carbohydrate group.

This suggests that you don’t need to starve yourself to lose weight. You just need to eat healthier foods.

And, in case you were wondering, the high fiber group ate:

5 more servings of fruits and vegetables and…

2 more servings of whole grain foods than the low fiber group.

This is consistent with several previous studies showing that diets containing a lot of fruits, vegetables, and whole grains are associated with a healthier weight.

The authors concluded, “Higher free sugar intake was associated with higher cardiovascular disease incidence and higher triglyceride concentrations…Higher fiber intake and replacement of refined grain starch and free sugars with wholegrain starch and non-free sugars, respectively, may be protective for incident heart disease.”

In short, with respect to heart disease, the type, not the amount of dietary carbohydrate is the important risk factor.

What Does This Mean For You?

Forget the low carb “mumbo jumbo”.

Carbohydrates aren’t the problem. The wrong kind of carbohydrates are the problem. Fruit juice, sugar-sweetened sodas, and processed foods with added sugar:

- Increase triglyceride levels.

- Are associated with weight gain.

- Increase the risk for heart disease.

In other words, they are the villains. They are responsible for the bad effects that low carb enthusiasts ascribe to all carbohydrates.

Don’t fear whole fruits, vegetables, dairy, and whole grain foods. They are the good guys.

- They have minimal effect on triglyceride levels.

- They are associated with healthier weight.

- They are associated with a lower risk of heart disease and diabetes.

So, the bottom line for you is simple. Not all carbs are created equal.

Your mother was right. Eat your fruits, vegetables, and whole grains.

Avoid fruit juice, sodas and other sugar-sweetened beverages, and processed foods with added sugar. [Note: Artificially sweetened beverages are no better than sugar-sweetened beverages, but that’s another story for another day.]

And, if you were wondering why low carb diets appear to work for weight loss, it’s because any restrictive diet works short term. As I have noted previously, keto and vegan diets work equally well for short-term weight loss.

The Bottom Line

Low carb enthusiasts have been telling us for years to avoid all carbohydrates (including fruits, starchy vegetables, and whole grains) because carbohydrates:

Increase triglyceride levels.

Cause weight gain.

Increase our risk for heart disease.

A recent study has shown that these claims are only true for some carbohydrates, namely fruit juices, sodas and other sugar-sweetened beverages, and processed foods with added sugar.

Whole fruits, vegetables, and whole grain foods have the opposite effect. They:

Have a minimal effect on triglyceride levels.

Are associated with a healthier weight.

Are associated with a lower risk of heart disease and diabetes.

So, forget the low carb “mumbo jumbo” and be sure to eat your fruits, vegetables, and whole grains.

For more information on 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.

___________________________________________________________________________

My posts and “Health Tips From the Professor” articles carefully avoid claims about any brand of supplement or manufacturer of supplements. However, I am often asked by representatives of supplement companies if they can share them with their customers.

My answer is, “Yes, as long as you share only the article without any additions or alterations. In particular, you should avoid adding any mention of your company or your company’s products. If you were to do that, you could be making what the FTC and FDA consider a “misleading health claim” that could result in legal action against you and the company you represent.

For more detail about FTC regulations for health claims, see this link.

https://www.ftc.gov/business-guidance/resources/health-products-compliance-guidance

Does An Apple A Day Keep Diabetes Away?

August 3, 2021 by Dr. Steve Chaney

A Holistic Approach To Preventing Diabetes

Author: Dr. Stephen Chaney

Low carb enthusiasts will tell you that carbohydrates are the villain. They tell you that cutting carbohydrates out of your diet will reduce your risk of obesity, diabetes, heart disease, and cancer.

If they limited their list of villainous foods to foods with white flour and/or added sugars, many nutrition experts would agree with them. There is widespread agreement in the nutrition community that we eat far too much of these foods.

However, I don’t have to tell you that many low carb diets also eliminate fruits, whole grains, and beans from their diets based solely on the carbohydrate content of these foods. Is this good advice? Is there any data to back up this claim?

The short answer is no. In fact, most studies suggest the opposite is true. I have covered these studies in previous issues of “Health Tips From The Professor”. For example:

In one issue I covered studies showing the people consuming primarily plant-based diets weigh less, have less inflammation, and have a lower risk of diabetes, heart disease, and high blood pressure than people consuming the typical American diet.

In another issue I shared studies showing that women consuming a plant-based low carb diet weigh less, and have reduced risk of diabetes and heart disease than women consuming a meat-based low carb diet.

However, these studies looked at the effect of the whole diet, not individual components of the diet.

This week I will review a study (NP Bondonno et al, The Journal of Clinical Endocrinology & Metabolism, 2021, doi:10.1210/clinem/dgab335) looking at the effect of fruit consumption on the risk of developing type 2 diabetes.

Next week I will review a study looking at the effect of whole grain consumption on the risk of developing type 2 diabetes.

How Was This Study Done?

This study made use of data from the Australian Diabetes Obesity And Lifestyle Study. This study recruited 7675 Australians 25 years or older from 7 states and territories in Australia in 1999 and 2000 and followed them for 5 years. The characteristics of the study population were:

Gender = 45% male, 55% female
Average age = 54 years
Average BMI = 26.8 (slightly overweight)
Did not have diabetes at time of entry into the study.

The participants filled out a food frequency questionnaire at the time of entry into the study. This questionnaire was used to analyze:

the amount of fruit consumed.

the amounts of vegetables, red meat, and processed meat consumed.

how many calories were consumed.

At the time of entry into the study several measurements were taken that assessed whether the participants had an increased risk of developing diabetes (otherwise known as pre-diabetes). These included:

Fasting plasma glucose and insulin levels.

A 2-hour glucose tolerance test. The results of this test were used to calculate insulin resistance and insulin sensitivity.

The study also recorded any participants who were diagnose with diabetes over the next 5 years.

Does An Apple A Day Keep Diabetes Away?

The data from this study were statistically adjusted for confounding variables (Other variables that might affect the risk of diabetes). Many confounding variables were included in the adjustment, but the ones of interest to us are age, sex, physical activity, obesity, caloric intake, and intakes of alcohol, vegetables, red meat, and processed meat.

After adjustment for all these variables the results were:

At the beginning of the study:

Fruit intake was inversely associated with insulin levels and insulin resistance.

Fruit intake was directly associated with insulin sensitivity.

In other words, the more fruit people ate, the less likely they were to have prediabetes at the time they entered the study.

At 5 years:

Fruit intake was inversely associated with diabetes.

Fruit juice had no effect on diabetes risk.

In other words, the more fruit people ate, the less likely they were to develop diabetes 5 years later. Fruit juice, on the other hand, had no beneficial effect on diabetes risk.

The benefit of fruit intake plateaued at 2-3 servings a day.

In other words, you don’t need to become a fruitarian. A modest intake of fruit (2-3 servings a day) is all you need.

In case you haven’t noticed, 2-3 servings of fruit a day matches USDA recommendations – and the recommendations of almost every other governmental and medical organization. What do they know that you didn’t know?

The most commonly eaten fruits in this study were apples (23%), bananas (20%), and oranges and other citrus fruits (18%). Enough people ate these three fruits that their effects on the risk of developing diabetes could be analyzed separately.

The beneficial effect of each of these fruits plateaued at about one serving a day.

In other words, an apple a day does keep diabetes away. However, apples can’t do it alone. You need a variety of fruits for optimal benefit.

The authors concluded, “A healthy diet including whole fruits, but not fruit juice, may play a role in mitigating type 2 diabetes risk.”

A Holistic Approach To Preventing Diabetes

This study explodes the myth that you should avoid fruits if you want to prevent diabetes. Yes, fruits do contain sugar, but:

They also contain fiber, which slows the absorption of that sugar.

The sugar is trapped in a cellular matrix, which must be digested before that sugar can be released. That also slows the absorption of sugar.

This is why fruit consumption reduces the risk of diabetes while fruit juice consumption does not.

However, I don’t want to give you the impression that you can reduce your risk of diabetes just by consuming more fruit. You need a holistic approach. Here are diabetes prevention tips from the American Diabetes Association.

Get more physical activity.

- The greatest benefit comes from a fitness program that includes both aerobic exercise and resistance training.

2) Get plenty of fiber.

- Include fruits, vegetables, whole grains, beans, and nuts in your diet.

3) Lose extra weight.

- One recent study showed that losing as little as 7% of your body weight and exercising regularly could reduce your risk of developing diabetes by almost 60%.

4) Skip fad diets and simply make healthier food choices.

- “Low-carb diets, the glycemic index diet, and other fad diets may help you lose weight initially. But their effectiveness at preventing diabetes and their long-term effects aren’t known. And by excluding or strictly limiting a particular food group, you may be giving up essential nutrients.”

5) See your doctor on a regular basis and have your blood sugar tested, especially if you are overweight, have a family history of diabetes, or are over 45.

The Bottom Line

Low carb enthusiasts tell you to eliminate fruits from your diet if you want to reduce your risk of developing diabetes. Is this true? Is it good advice?

A recent study put this advice to the test. The study recruited 7675 Australians 25 years or older and followed them for 5 years. It correlated fruit intake with measures of prediabetes at the beginning of the study and correlated fruit intake with the onset of diabetes over the next 5 years. Here is what the study found.

The more fruit people ate, the less likely they were to have prediabetes at the time they entered the study.

The more fruit people ate, the less likely they were to develop diabetes 5 years later.

The benefit of fruit intake plateaued at 2-3 servings a day. In other words, you don’t need to become a fruitarian. A modest intake of fruit (2-3 servings a day) is all you need.

The beneficial effect of each of these fruits plateaued at about one serving a day.

In other words, an apple a day keeps diabetes away. However, apples can’t do it alone. You need a variety of fruits for optimal benefit.

The authors concluded, “A healthy diet including whole fruits, but not fruit juice, may play a role in mitigating type 2 diabetes risk.”

For more details about this study and a holistic approach to reducing your risk of diabetes recommended by the American Diabetes Association, 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 The Paleo Diet Based On A Myth?

June 8, 2021 by Dr. Steve Chaney

Are Starchy Foods Bad For Us?

Author: Dr. Stephen Chaney

The Paleo Diet is still very popular. And it does have its good points. It is a whole food diet. It eliminates sodas, junk foods, and highly processed foods. Any diet that does that can’t be all bad.

But is it unnecessarily restrictive? It eliminates starchy foods like grains, beans, peas, and corn. It is true that widespread consumption of these foods did not occur until after the agricultural revolution some 12,000 years ago. Our paleolithic ancestors probably did not consume significant quantities of these foods.

But did they consume other starchy foods? Our ideas about this have come primarily from comparing the diets of modern man with the diets of the few primitive hunter-gatherer populations that currently exist in our world. Based on that comparison, some Paleo advocates have concluded that the paleolithic diet contained few, if any, starchy foods.

More importantly, some Paleo advocates have gone a step further to assert that our bodies are not designed to eat starchy foods. They claim that foods like grains, legumes, corn, and potatoes are bad for us. They should be avoided.

How can we test whether these claims are true? After all, we don’t have any way of directly determining whether our paleolithic ancestors ate starchy foods or not. Or do we? That question is the topic of a new study (JA Fellows et al, PNAS, 118 No. 20 e2021655118 I will share with you today.

But first I need to acquaint you with what starch is and how we digest it. Once again, it is time for Biochemistry 101.

Biochemistry 101

Starch is simply a long polymer of glucose molecules. Digestion of starch starts in our mouth. Our saliva contains an enzyme called alpha-amylase that breaks the bond between adjacent glucose molecules. Alpha-amylase breaks starch down sequentially, first to maltodextrin (a shorter polymer of glucose molecules), then to maltose (two glucose molecules), and finally to glucose.

[Note: The nutrition gurus that tell you to read labels and avoid foods with maltodextrin are ignoring the fact that we produce maltodextrin naturally whenever we digest starch in the foods we eat.]

All humans contain the alpha-amylase gene. Simply put, that means that all humans have the potential to digest starchy foods.

However, not all humans have the same number of copies of the alpha-amylase gene. When we habitually consume a diet containing starchy foods, our bodies duplicate the alpha-amylase gene until our saliva contains enough alpha-amylase to easily digest the amount of starchy foods we are consuming. Simply put, that means our bodies are designed to easily adapt to the amount of starchy foods in our diet.

Most modern human populations have between six and 30 copies of the alpha-amylase gene. Our saliva contains a lot of alpha-amylase. However, the few primitive hunter-gatherer societies that still exist in our world have only two or three copies of the alpha-amylase gene. Their saliva contains very little alpha-amylase.

It is this difference that has led to the hypothesis that our paleolithic ancestors did not possess salivary alpha-amylase, which implies they didn’t eat starchy foods. This hypothesis also assumes that humans only began producing significant quantities of salivary alpha-amylase after the agricultural revolution when starchy foods like grains, rice, and beans became widely available.

This hypothesis is one of the central tenets of the Paleo diet. But we need to remember that it is just a hypothesis. It has not been directly tested because we thought there was no way to determine the starch content of the paleolithic diet – until now. However, before we get to the study that explodes this hypothesis, I want to revisit the Paleo Diet myths I described in an earlier issue of “Health Tips From The Professor”. I call this next section “Unicorns And The Paleo Diet”.

Unicorns And the Paleo Diet

I titled this section “Unicorns and the Paleo Diet” because both are myths. In fact, the Paleo Diet is based on several myths.

Myth #1: Our ancestors all had the same diet. What we currently know as the Paleo diet is based on the diets of a few primitive hunter-gatherer societies that still exist in some regions of the world. However, when you look at the data more carefully, you discover that the diet of primitive societies varies with their local ecosystems.

The “Paleo diet” is typical of ecosystems in which game is plentiful and fruits and vegetables are less abundant or are seasonal. In ecosystems where fruits and vegetables are abundant, primitive societies tend to be more gatherers than hunters. They eat more fruits and vegetables and less meat.

The assumption that starchy foods were absent in the paleolithic diet is also a myth. For some primitive societies, starchy fruits or starchy roots are a big part of their diet. In short, our paleolithic ancestors ate whatever nature provided.

Myth #2: Our genetic makeup is hardwired around the “paleolithic diet”. In fact, humans are very adaptable. We are omnivores, which means we can eat whatever nature provides. We are designed to thrive in a wide variety of ecosystems. It is this adaptability that has allowed us to expand to every nook and cranny of the world.

For example, the enzymes needed to digest grains are all inducible, which means the body can turn them on when needed. Our paleolithic ancestors may not have eaten much grain, but we can very quickly adapt to the introduction of grains into our diet. As I described above, for alpha-amylase this adaptation occurs through gene duplication.

Myth #3: Our paleolithic ancestors were healthier than modern man: It some respects, the paleolithic diet is healthy, as I mentioned above. However, we need to remember that our paleolithic ancestors rarely lived past 30 or 40. They simply did not live long enough to experience degenerative diseases like heart disease and cancer. We have no idea whether a diet that served our paleolithic ancestors well will keep us healthy into our 70s, 80s and beyond.

How Was This Study Done?

This is a fascinating study, and one that would have been impossible just a few years ago. As I have described in previous issues of “Health Tips From the Professor”, studies on our microbiome, the bacteria that inhabit our bodies, is a rapidly evolving area of research.

When we talk about our microbiome, we generally think about our gut bacteria. However, the term “microbiome” includes all the bacteria that reside in our body, including those that reside in our oral mouth.

And, like our gut bacteria, the species of bacteria that reside in our mouth are heavily dependent on the foods we eat. Specifically, there are three species of oral bacteria that thrive on starch. They possess an “amylase binding protein” that allows them to capture salivary alpha-amylase and use it to break down dietary starch so they can use it as an energy source.

Consequently, the abundance of these three bacterial species in the oral microbiome is a precise marker for the amount of starch in a person’s diet. More importantly, high throughput DNA sequencing and supercomputers have made it simple to sequence all the bacteria in the oral microbiome and quantify the relative abundance of these three bacterial species.

You are probably thinking, “That’s fine, but how could you possibly determine the abundance of those bacteria in the mouth of a paleolithic human?” Here is where it gets really interesting!

The bacteria in our mouth form biofilms on our teeth, something we refer to as plaque. If the plaque remains on our teeth long enough, it calcifies, forming what is referred to as dental calculus (tooth tartar).

In the modern world we remove dental biofilms by brushing after every meal. We remove dental plaque and tartar by semi-annual visits to the dentist. But these are recent developments. They are not something our ancestors did.

Our ancestors simply accumulated dental calculus during their lifetime. More importantly, the dental calculus excluded air and water, so it preserved the DNA of the bacteria in their oral microbiome. That was the basis of the current study.

The study was a collaboration of 50 scientists over a 7-year period. The scientists sequenced 124 oral microbiomes from humanoid species in Africa, including Neanderthals (430,000 to 40,000 years ago), Late Pleistocene (129,000 to 11,700 years ago) humans, and modern-day humans.

Bacterial DNA from modern-day humans was obtained from dental calculus obtained during routine dental cleaning procedures by practicing dentists. The older DNA samples were obtained from dental calculus in the teeth of skeletal remains. The oldest DNA sample was obtained from a Neanderthal that lived around 100,000 years ago.

For comparison they also obtained bacterial DNA from the dental calculus of chimpanzees and gorillas, man’s closest primate relatives.

The species of bacteria in the oral microbiome from all these samples were determined by high throughput sequences and computerized analysis using high speed supercomputers.

Is The Paleo Diet Based On A Myth?

There were three important findings from this analysis:

The species of bacteria in the oral microbiome of Neanderthals and Late Pleistocene humans was much more diverse than for modern humans. This suggests that their diets were more diverse (perhaps depending on what foods were available in their environment), while modern diets have become more standardized.

2) The species of bacteria that thrive on starchy foods were remarkably constant in the oral microbiome of all human species from Neanderthals to Late Pleistocene humans to modern-day humans.

3) The species of bacteria that thrive on starchy foods were virtually absent from the oral microbiomes of our most closely related primates – chimpanzees and gorillas.

The authors concluded, “This … supports an early importance of starch-rich foods in Homo evolution.”

In other words, our paleolithic ancestors likely did eat starchy foods. Their diet may not have contained grains, rice, or beans in significant quantities. However, they consumed whatever starchy roots, fruits, and vegetables they could find.

So, is the Paleo diet based on a myth? It depends on how you phrase the question.

If we ask whether our paleolithic ancestors consumed grains, rice, or beans, the answer is probably, “No”. The introduction of these foods in significant quantities probably depended on the agricultural revolution that occurred thousands of years later.

If we ask whether our paleolithic ancestors consumed starchy foods, the answer is probably, “Yes”. The foundation of the Paleo diet was based on a myth. Their oral microbiome contained bacterial species that thrived on starchy foods. In fact, starchy foods may have been an important staple in their diet because they are more calorie dense than other fruits and vegetables.

If we ask whether our paleolithic ancestors were capable of thriving on a diet that included grains, rice, and beans, the answer is also probably, “Yes”. The oral bacterial species that thrive on starchy foods do so by utilizing the alpha-amylase in human saliva. This means our paleolithic ancestors likely had enough alpha-amylase in their saliva to digest and to thrive on starchy foods like grains, rice, and beans.

Are Starchy Foods Bad For Us?

It is not just the Paleo diet. Many popular diets have villainized starchy foods. Are starchy foods as bad for us as some “experts” would have you believe?

Let’s start by identifying starchy foods. If we think in terms of whole foods, they are:

Root vegetables (for example, potatoes, sweet potatoes, beets, carrots, and parsnips).

Legumes (for example, beans, peas, and lentils).

Grains (for example, wheat, rye, barley, oats, and rice).

Winter squash (for example, acorn squash, butternut squash, hubbard squash, and pumpkin).

Corn

These foods are good sources of nutrients and phytonutrients. Many of them are also excellent sources of fiber, including a special type of fiber called resistant starch. (I have described the benefits of resistant starch in a previous issue of “Health Tips From the Professor”.) These are foods that definitely deserve to be part of a healthy diet.

The only drawback of starchy vegetables is that they tend to be more calorie dense than other vegetables. While this was a “plus” for our paleolithic ancestors, it is not quite as advantageous in our modern world. If you are trying to watch your calories, my advice is to incorporate these foods into your diet sparingly.

However, there is another class of starchy foods you want to avoid. Of course, I am talking about highly processed foods made from grains, legumes, and corn. They retain all the calories but lose most of the nutrients, phytonutrients, and fiber of the foods they came from.

In short, starchy whole foods are a valuable part of a healthy diet. It is the starchy processed foods made from these whole foods you want to avoid. Of course, I am talking about bread, pasta, and pastries made from refined grains and sugar.

So, how do you know which starchy foods to avoid? My advice is not to become an expert label reader. Just eat foods without labels.

The Bottom Line

One of the founding principles on which the Paleo diet is based is that our paleolithic ancestors ate very few starchy foods, and the human body really isn’t designed to handle these foods. Accordingly, the Paleo diet recommends we should avoid starchy foods like grains and legumes. This has the unfortunate effect of creating an unbalanced diet that overemphasizes meat and animal fats.

But is this founding principle correct, or is it just a myth? When you look beneath the surface, you discover that it is a hypothesis based on the diets of the few primitive hunter-gatherer populations that still exist in our world.

It has been assumed that was as good an estimate of the paleolithic diet as we could get. After all there was no way to directly determine the starch content of the paleolithic diet – until now.

In this issue of “Health Tips From the Professor” I describe a novel approach that allowed scientists to determine the species of bacteria residing in the mouth of our humanoid ancestors based on the DNA extracted from the plaque coating their teeth. (For details on how this was done, read the article above.)

What the scientists found was that all human species, including a Neanderthal who died 100,000 years ago, harbored bacteria in their mouths that thrive on starchy foods.

The scientists concluded, “This … supports an early importance of starch-rich foods in Homo evolution.” In other words, our paleolithic ancestors likely did eat starchy foods. Restricting whole grains and legumes from the Paleo diet is based on a myth. They are an important part of a healthy diet.

For more details about the study and which starchy foods are bad 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.

Why Do Diet Sodas Make You Fat?

March 10, 2020 by Dr. Steve Chaney

Is Mixing Diet Sodas With Carbs Bad For You?

Many people, and many doctors, believe that diet sodas and artificially sweetened foods are a healthy choice. After all:

Cutting calories by drinking diet sodas and eating artificially sweetened foods should help you lose weight.

If sugar is the problem for diabetics, diet sodas and artificially sweetened foods should be a healthier choice.

On the surface, these ideas appear to be self-evident. They seem to be “no-brainers”. The truth, however, is more complicated.

When studies are tightly controlled by dietitians so that the people consuming diet sodas don’t add any extra calories to their diet, the results are exactly as expected. People consuming diet sodas lose weight compared to people drinking regular sodas.

However, as I have described in an earlier issue of “Health Tips From the Professor”, the results are different in the real world where you don’t have a dietitian looking over your shoulder. In those studies, diet sodas are just as likely to cause weight gain as regular sodas.

As Barry Popkin, a colleague at the University of North Carolina, put it” “The problem is that we [Americans] are using diet sodas to wash down our Big Macs and fries.” In short, people drinking diet sodas tend to increase their caloric intake by adding other foods to their diet. Even worse, the added foods aren’t usually fruits and vegetables. They are highly processed junk foods.

Why is that? The short answer is that nobody knows (more about that later). However, a recent study (JR Dalenberg et al, Cell Metabolism, 31: 493-502, 2020) suggests an unexpected mechanism for the weight gain associated with diet soda consumption. Let’s look at that study.

How Was The Study Done?

The study recruited 45 healthy young adults (ages 20-45) who habitually consumed less than 3 diet sodas a month. They were randomly assigned to three groups. The participants in each group came into the testing facility seven times over a span of 2 weeks. Each time they were given 12 ounces of one of three equally sweet tasting beverages in a randomized, double-blind fashion.

Group 1 received a sucralose-sweetened drink contained 0.06 grams of sucralose (equivalent to two packets of Splenda).

Group 2 received a sugar-sweetened drink contained 7 teaspoons of sucrose (table sugar).

Group 3 received a combo drink contained 0.06 grams of sucralose plus 7 teaspoons of maltodextrin. Maltodextrin is a water-soluble carbohydrate that does not have a sweet taste.

o Maltodextrin was used because Splenda and most other commercial sucralose products contain it along with sucralose. You need something to fill up those little sucralose-containing packets.

o This drink was included as a control. The expectation was that it would give the same results as the sucralose-sweetened drink.

Three measurements were performed prior to and following the 2-week testing period:

An oral glucose tolerance test in which participants drink a beverage containing a fixed amount of glucose. Then their blood sugar and blood insulin levels are measured over the next two hours.

o This is a measure of how well they were able to control their blood sugar levels.

A test in which they were given samples that had either a sweet, sour, salty, or savory taste. Then:

o They were asked to identify each taste and report how strong the taste was.

o MRI scans of their brains were performed to determine how strongly their brains responded to each of the tastes.

Is Mixing Diet Soda With Carbs Bad For You?

The results were surprising. The first surprise came when the investigators unblinded the results of the oral glucose tolerance test:

Blood sugar and blood insulin responses were unaffected by the 2-week exposure to sugar-sweetened drinks.

o This was expected.

Blood sugar and blood insulin were relatively unaffected by the 2-week exposure to sucralose-sweetened drinks. If anything, the control of blood sugar levels was slightly improved at the end of two weeks.

o This was a disappointment for the investigators. One of the prevailing theories is that artificially sweetened beverages alter the blood sugar response. The investigators found no evidence for that idea.

Following the 2-week exposure to the combo drinks (sucralose plus maltodextrin), blood sugar levels were unaffected, but blood insulin levels were increased. This implies that more insulin was required to control blood sugar levels. In other words, these participants had developed insulin resistance.

o This result was unexpected. Remember the investigators had included this drink as a control.

o The investigators pointed out that the insulin resistance associated with the sucralose-maltodextrin combo could increase the risk of type 2 diabetes and obesity.

Because of this unexpected result, the investigators did a follow-up study in which participants were given a maltodextrin-only drink using the same study protocol. The oral glucose tolerance test was unchanged by the 2-week exposure to maltodextrin-only drinks.

When the investigators conducted taste tests, the ability of participants to taste all four flavors was unchanged by a 2-week exposure to any of the drinks.

However, when the investigators did MRI scans to measure the brain’s response to these flavors:

A two-week exposure to the sucralose plus maltodextrin drinks reduced the brain’s response to sweet but not to any of the other flavors.

o In other words, the subjects could still taste sweet flavors, but their brains were not responding to the sweet taste. Since sweetness activates pleasure centers in the brain this could lead to an increased appetite for sweet-tasting foods.

o This might explain the weight gain that has been observed in many previous studies of diet sodas.

Two-week exposures to the other drinks had no effect on the brain’s response to any of the flavors. Once again, this effect was only seen in the sucralose-maltodextrin combination.

The investigators concluded:

“Consumption of sucralose combined with carbohydrates impairs insulin sensitivity…and…neural responses to sugar.

Insulin sensitivity is not altered by sucralose or carbohydrate consumption alone.

The results suggest that consumption of sucralose in the presence of a carbohydrate dysregulates gut-brain regulation of glucose metabolism.”

The investigators pointed out that this could have several adverse consequences. Again, in the words of the authors:

“Similar exposure combinations (artificial sweeteners plus carbohydrates) almost certainly occur in free-living humans, especially if one considers the consumption of a diet drink along with a meal. This raises the possibility that the combination effect may be a major contributor to the rise in incidence of type 2 diabetes and obesity. If so, addition of artificial sweeteners to increase the sweetness of carbohydrate-containing food and beverages should be discouraged and consumption of diet drinks with meals should be counseled against.”

Why Do Diet Sodas Make You Fat?

As I mentioned at the start of this article, there are a lot of hypotheses as to why diet sodas make us fat. These hypotheses break down into two classifications: psychological and physiological.

The psychological hypothesis is easiest to explain. Essentially, it goes like this: We feel virtuous for choosing a zero-calorie sweetener, so we allow ourselves to eat more of our favorite foods. It is unlikely that this hypothesis holds for all diet soda drinkers. However, it is also hard to exclude it as at least part of the explanation for the food overconsumption associated with diet soda use.

There are multiple physiological hypotheses. Most of them are complicated, but here are simplified explanations of the three most popular hypotheses:

The sweet taste of artificial sweeteners tricks the brain into triggering insulin release by the pancreas. This causes blood sugar levels to plummet, which increases appetite.

The sweet taste of artificial sweeteners is not appropriately recognized by the brain. This diminishes release of hormones that suppress appetite.

Artificial sweeteners interfere with insulin signaling pathways, which leads to insulin resistance.

There is some evidence for and against each of these hypotheses.

However, this study introduces a new physiological hypothesis – namely that it is the combination of artificial sweeteners and carbohydrates that results in a dysregulation of the normal mechanisms controlling appetite and blood sugar.

What Does This Study Mean For You?

Let’s start with the obvious. This is just a hypothesis.

This was a very small study. Until it is confirmed by other, larger studies, we don’t know whether it is true.

This study only tested sucralose. We don’t know whether this applies to other artificial sweeteners.

The study only tested maltodextrin in combination with sucralose. We don’t know whether it applies to other carbohydrates.

Therefore, in discussing how this study applies to you, let’s consider two possibilities – if it is true, and if it is false.

If this hypothesis is true, it is concerning because:

We often consume diet sodas with meals. If, for example, we take the earlier example of a diet soda with a Big Mac and fries, both the hamburger bun and the fries are high carbohydrate foods.

Sucralose and other artificial sweeteners are used in low calorie versions of many carbohydrate rich processed foods.

If this hypothesis is false, it does not change the underlying association of diet soda consumption with weight gain and type 2 diabetes. It is merely an attempt to explain that association. We should still try to eliminate diet sodas and reduce our consumption of artificially sweetened, low calorie foods.

My recommendation is to substitute water and other unsweetened beverages for the diet drinks or sugar sweetened beverages you are currently consuming. If you crave the fizz of sodas, drink carbonated water. If you need more taste, try herbal teas or infuse water with slices of lemon, lime, or your favorite fruit. If you buy commercial brands of flavored water, check the labels carefully. They may contain sugars or artificial sweeteners. Those you want to avoid.

The Bottom Line

Many studies have called into question the assumption that diet sodas and diet foods help us lose weight. In fact, most of these studies show that diet soda consumption is associated with weight gain rather than weight loss.

There are many hypotheses to explain this association, but none of them have been proven at present.

This study introduces a new hypothesis – namely that the combination of artificial sweeteners and carbohydrates results in a dysregulation of the normal mechanisms controlling appetite and blood sugar. In particular, this study suggested that combining sucralose with carbohydrates caused insulin resistance and reduce the ability of the brain to respond appropriately to sweet tastes.

The authors concluded: “Similar exposure combinations (artificial sweeteners plus carbohydrates) almost certainly occur in free-living humans, especially if one considers the consumption of a diet drink along with a meal. This raises the possibility that the combination effect may be a major contributor to the rise in incidence of type 2 diabetes and obesity. If so, addition of artificial sweeteners to increase the sweetness of carbohydrate-containing food and beverages should be discouraged and consumption of diet drinks with meals should be counseled against.”

If this hypothesis is true, it is concerning because:

We often consume diet sodas with meals. If, for example, we take the example of a diet soda with a Big Mac and fries, both the hamburger bun and the fries are high carbohydrate foods.

Artificial sweeteners are used in low calorie versions of many carbohydrate rich processed foods.

If this hypothesis is false, it does not change the underlying association of diet soda consumption with weight gain and type 2 diabetes. It is merely an attempt to explain that association. We should still try to eliminate diet sodas and reduce our consumption of artificially sweetened, low calorie foods.

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.

How Much Carbohydrates Should We Eat?

September 11, 2018 by Dr. Steve Chaney

The “Goldilocks Effect”

Author: Dr. Stephen Chaney

How much carbohydrates should we eat?

The low-carb wars rage on. Low-carb enthusiasts claim that low-carb diets are healthy. Many health experts warn about the dangers of low-carb diets. Several studies have reported that low-carb diets increase risk of mortality (shorten lifespan).

However, two recent studies have come to the opposite conclusion. Those studies reported that high carbohydrate intake increased mortality, and low carbohydrate intake was associated with the lowest mortality.

One of those studies, called the Prospective Urban Rural Epidemiology (PURE) study was published just last year. It included data from 135,335 participants from 18 countries across 5 continents. That’s a very large study, and normally we expect very large studies to be accurate. The results from the PURE study had low-carb enthusiasts doing a victory lap and claiming it was time to rewrite nutritional guidelines to favor low-carb diets.

Whenever controversies like this arise, reputable scientists are motivated to take another look at the question. They understand that all studies have their weaknesses and biases. So, they look at previous studies very carefully and try to design a study that eliminates the weaknesses and biases of those studies. Their goal is to design a stronger study that reconciles the differences between the previous studies.

Such a study has just been published (SB Seidelmann et al, The Lancet, doi.org/10.1016/S2468-2667(18)30135-X ). This study resolves the conflicting data and finally answers the question: “How much carbohydrates should we be eating if we desire a long and healthy life?” The answer is “Enough.”

I call this “The Goldilocks Effect” You may remember “Goldilocks And The Three Bears.” One bed was too hard. One bed was too soft. But, one bed was “just right.” One bowl of porridge was too hot. One was two cold. But, one was “just right.” According to this study, the same is true for carbohydrate intake. High carbohydrate intake is unhealthy. Low carbohydrate intake is unhealthy. But, moderate carbohydrate intake is “just right.”

How Was The Study Done?

This study was performed in two parts. This first part drew on data from the Atherosclerosis Risk in Communities (ARIC) study. That study enrolled 15,428 men and women, aged 45-64, from four US communities between 1987 and 1989. This group was followed for an average of 25 years, during which time 6283 people died. Carbohydrate intake was calculated based on food frequency questionnaires administered when participants enrolled in the study and again 6 years later. The study evaluated the association between carbohydrate intake and mortality.

The second part was a meta-analysis that combined the data from the ARIC study with all major clinical studies since 2007 that measured carbohydrate intake and mortality and lasted 5 years or more. The total number of participants included in this meta-analysis was 432,179, and it included data from both studies that claimed low-carbohydrate intake was associated with decreased mortality.

How Much Carbohydrates Should We Eat?

The results from the ARIC study were:

The relationship between mortality and carbohydrate intake was a U-shaped curve.
The lowest risk of death was observed with a moderate carbohydrate intake (50-55%). This is the intake recommended by current nutrition guidelines.
The highest risk of death was observed with a low carbohydrate intake (<40%).
The risk of death also increased with very high carbohydrate intake (>70%).
When the investigators used the mortality data to estimate life expectancy, they predicted a 50-year old participant would have a projected life expectancy of:
1 years if they had a moderate intake of carbohydrates.
Their life expectancy was 4 years less if they had a low carbohydrate intake.
Their life expectancy was 1.1 year less if they had a very high carbohydrate intake.
The risk associated with low carbohydrate intake was affected by what the carbohydrate was replaced with.
When carbohydrate was replaced with animal protein and animal fat there was an increased risk of mortality on a low-carb diet. The animal-based low-carb diet contained more beef, pork, lamb, chicken and fish. It was also higher in saturated fat.
When carbohydrate was replaced with plant protein and plant fats, there was a decreased risk of mortality on a low-carb diet. The plant-based low-carb diet contained more nuts, peanut butter, dark or whole grain breads, chocolate, and white bread. It was also higher in polyunsaturated fats.
The effect of carbohydrate intake on mortality was virtually the same for all-cause mortality, cardiovascular mortality, and non-cardiovascular mortality.
There was no significant affect of carbohydrate intake on long-term weight gain (another myth busted).

The results from the meta-analysis were very similar. When the data from all studies were combined:

Both low carbohydrate diets and very high carbohydrate diets were associated with increased mortality.
Meat-based low-carb diets increased mortality, and plant-based low-carb diets decreased mortality.
Once again, the results were the same for total mortality, cardiovascular mortality, and non-cardiovascular mortality.

The authors concluded: “Our findings suggest a negative long-term association between life-expectancy on both low carbohydrate and high carbohydrate diets…These data also provide further evidence that animal-based low carbohydrate diets should be discouraged. Alternatively, when restricting carbohydrate intake, replacement of carbohydrates with predominantly plant-based fats and proteins could be considered as a long-term approach to healthy aging.”

Why Were Some Previous Studies Misleading?

This study also resolved the discrepancies between previous studies. The authors pointed out that the average carbohydrate intake is very different in Europe and the US than in Asian countries and low-income countries. In the US and Europe, mean carbohydrate intake is about 50% of calories and it ranges from 25% to 70% of calories. With that range of carbohydrate intake, it is possible to observe the increase in mortality associated with both low and high carbohydrate intakes.

White rice is a staple in Asian countries, and protein is a garnish rather than a main course. Consequently, overall carbohydrate intake is greater in Asian countries and very few Asians eat a low carbohydrate diet. High protein foods tend to be more expensive than high carbohydrate foods. Thus, very few people in developing countries can afford to follow a low carbohydrate diet, and overall carbohydrate intake also tends to be higher.

Therefore, in Asian and developing countries the average carbohydrate intake is greater (~61%) than in the US and Europe, and the range of carbohydrate intake is from 45% to 80% of calories. With that range of intake, it is only possible to see the increase in mortality associated with high carbohydrate intake.

Both the studies that low-carb enthusiast quote to support their claim that low-carb diets are healthy relied heavily on data from Asian and developing countries. In fact, when the authors of the current study overlaid the data from the PURE study with their ARIC data, there was an almost perfect fit. The only difference was that their ARIC data covered both low and high carbohydrate intake while the PURE study touted by low-carb enthusiasts only covered moderate to high carbohydrate intake. [I have given you my rendition of the graph on the left. If you would like to see the data yourself, look at the paper .]

Basically, low-carb advocates are telling you that diets with carbohydrate intakes of 30% or less are healthy based on studies that did not include carbohydrate intakes below 40%. That is misleading. The studies they quote are incapable of detecting the risks of low carbohydrate diets.

What Does This Mean For You?

There are several important take-home lessons from this study:

All major studies agree that very high carbohydrate intake is unhealthy. In part, that reflects the fact that diets with high carbohydrate intake are likely to be high in sodas and sugary junk foods. It may also reflect the fact that diets which are high in carbohydrate are inevitably low in protein or healthy fats or both.
All studies that cover the full range of carbohydrate intake agree that low carbohydrate intake is also unhealthy. It shortens life expectancy of a 50-year old by about 4 years.
The studies quoted by low carb enthusiasts to support their claim that low-carb diets are healthy don’t include carbohydrate intakes below 40%. That means their claims are misleading. The studies they quote are incapable of detecting the risks of low carbohydrate diets.
Meat-based low-carb diets decrease life expectancy while plant-based low carb diets increase life expectancy. This is consistent with previous studies. For more details on those studies, see my article “Are Any Low-Carb Diets Healthy?” in “Health Tips From The Professor” or my book, “Slaying The Food Myths.”

The health risks of meat-based low-carb diets may be due to the saturated fat content or the heavy reliance on red meat. However, the risks are just as likely to be due to the foods these diets leave out – typically fruits, whole grains, legumes, and some vegetables. Proponents of low-carb diets assume that you can make up for the missing nutrients by just taking a multivitamin. However, each food group also provides a unique combination of phytonutrients and fibers. The fibers, in turn, influence your microbiome. Simply put, whenever you leave out whole food groups, you put your health at risk.

Limitations Of This Study

My main concern with this study and all previous studies is that they lump all carbohydrates together, as if they were equally healthy or unhealthy. We should really be focusing on healthy carbohydrates versus unhealthy carbohydrates, healthy proteins versus unhealthy proteins, and healthy fats versus unhealthy fats. We should be focusing on foods.

For example, the plant-based low carbohydrate diets in this study probably had a higher percentage of healthy carbohydrates because those diets feature whole, plant-based foods. The very high carbohydrate diets in this study probably had a higher percentage of unhealthy carbohydrates. However, we have no idea whether the diets with moderate carbohydrate intake featured healthy carbohydrates or unhealthy carbohydrates. That is critical because moderate carbohydrate intake was the baseline to which all other diets were compared.

An important unanswered question is: “What is the relationship between carbohydrate intake and lifespan when most of the carbohydrates come from whole, plant-based foods?” Is low carbohydrate intake healthier or less healthy than moderate carbohydrate intake? Is high carbohydrate intake still less healthy? We have no idea. No studies have analyzed the data in that way.

Similarly, we know from multiple studies that meat-based, low-carb diets increase mortality and plant-based, low-carb diets decrease mortality when compared to moderate carbohydrate intake with no differentiation of protein source. But, what if the moderate carbohydrate group had also been subdivided into meat eaters and plant eaters? Would meat-based, low-carb diets still be less healthy than meat-based, moderate-carbohydrate diets? Would plant-based, low-carb diets still be healthier than plant-based, moderate-carb diets? We have no idea.

The Bottom Line

The low-carb wars are raging. Several studies have reported that low-carb diets increase risk of mortality (shorten lifespan). However, two recent studies have come to the opposite conclusion. Those studies have low-carb enthusiasts doing a victory lap and claiming it is time to rewrite nutritional guidelines to favor low-carb diets.

However, a study just published a couple of weeks ago resolves the conflicting data and finally answers the question: “How much carbohydrate should we be eating if we desire a long and healthy life?” The answer is “Enough.”

I call this “The Goldilocks Effect.” According to this study, high carbohydrate intake is unhealthy. Low carbohydrate intake is unhealthy. But, moderate carbohydrate intake is “just right.”

Specifically, this study reported:

Moderate carbohydrate intake (50-55%) is healthiest. This is also the carbohydrate intake recommended by current nutritional guidelines.
All major studies agree that very high carbohydrate intake (60-70%) is unhealthy. It shortens life expectancy of a 50-year old by about a year.
All studies that cover the full range of carbohydrate intake agree that low carbohydrate intake (<40%) is also unhealthy. It shortens life expectancy of a 50-year old by about 4 years.
The studies quoted by low carb enthusiasts to support their claim that low-carb diets are healthy don’t include carbohydrate intakes below 40%. That means their claims are misleading. The studies they quote are incapable of detecting the risks of low carbohydrate diets.
Meat-based, low-carb diets decrease life expectancy while plant-based, low carb diets increase life expectancy. This is consistent with the results of previous studies.

The authors concluded: “Our findings suggest a negative long-term association between life-expectancy and both low carbohydrate and high carbohydrate diets…These data also provide further evidence that animal-based low carbohydrate diets should be discouraged. Alternatively, when restricting carbohydrate intake, replacement of carbohydrates with predominantly plant-based fats and proteins could be considered as a long-term approach to healthy aging.”

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.