Can Personalized Diets Help Control Blood Sugar?

April 30, 2024 by Dr. Steve Chaney

What Does This Study Mean For You?

Author: Dr. Stephen Chaney

Personalized diets are highly advertised. We are told to forget the old “one size fits all” diets of the past. We are told we are all different, so diets should be individualized to us.

We are promised that by collecting DNA samples from our tissue or bacteria in our gut, blood samples, and personal medical history, a personalized diet can be created that “fits us like a glove”.

But are those promises true, or are they hype? Diets to control blood sugar spikes should be a perfect topic for testing those claims. Millions of Americans have trouble controlling their blood sugar levels. Specifically:

1 million adults (14.7% of US adults) have diabetes, mostly type 2 diabetes.

6 million adults (38.0% of US adults) have prediabetes.

- That amounts to 52% of the US population who have trouble controlling blood sugar levels.

Previous studies have shown that prediabetes and type 2 diabetes are largely reversible with diet and lifestyle change.

Recent studies have shown tremendous inter-person variability in the blood sugar response to any given food.

Previous studies have shown that our gut bacteria influence our blood sugar response to foods.

In theory, blood sugar control should be the perfect candidate for personalized diets. With that in mind, the authors of this study have created an algorithm called PNP (Personal Nutrition Program) that combines continuous blood glucose monitoring, HbA1c measurement (a measure of blood sugar control), personal characteristics (physical activities, sleep times, stress, and hunger), and a DNA analysis of stool samples to identify the species of gut bacteria. They also created a PNP app to allow participants to monitor and modify the foods they ate on a continuous basis.

In this study (AY Kharmats et al, The American Journal of Clinical Nutrition, 118: 443-451, 2023) the authors compared the effectiveness of their Personalized Nutrition Program algorithm with a standard, one-size-fits-all, low fat diet for improving blood sugar control in patients with prediabetes and type 2 diabetes.

Note: They used a low fat diet because, despite what you may have heard, low fat diets are better than low carb diets for diabetics. Of course, the low fat diet they used was created by dietitians. The carbohydrates came from whole foods rather than added sugars.

How Was The Study Done?

The investigators recruited 156 participants from the NYU Langone Health Center between January 2018 and March 2021. The participants selected were overweight with prediabetes or moderately controlled type 2 diabetes. For participants with type 2 diabetes, it was managed with lifestyle alone or lifestyle plus metformin. Other characteristic of the study participants were:

Gender: 33.5% male, 66.5% female.
Race & Ethnicity: 55.7% white, 24.1% black, 16.5% Hispanic.
Education: 69.5% with a college degree.
Baseline BMI: 33 (Obese).
Baseline HbA1c: 5.8% (prediabetic range) with 12% of participants ≥6.5% (diabetic range).

The participants were randomly divided into two groups that were matched with respect to weight and blood sugar control. One group was put on a diet based on the investigator’s PNP algorithm. The other group was put on a standardized low fat (< 25% of calories from fat) diet that is often used with diabetic patients.

Upon admission to the study, blood samples were drawn for HbA1c, a detailed questionnaire was filled out, and stool samples were obtained for DNA analysis to identify the species of bacteria in their gut.

Each participant was given a continuous glucose monitoring device to wear during the study. This allowed the investigators to monitor the participants blood sugar control throughout the study.

All this information was used to provide individual diet recommendations for the personalized diet group using the PNP algorithm developed by the investigators.

The study lasted 6 months and measured improvements in blood sugar control as assessed by a decrease in blood sugar spikes and a reduction in HbA1c.

Both Groups were put on a registered dietitian-led behavioral intervention program targeting 7% weight loss and a calorie deficit goal of 500 calories per day. The 1-hour sessions were conducted by Webex weekly for 4 weeks and then every other week for the remaining 5 months. The sessions included:

Education (e.g., obesity risks, benefits of weight loss, strategies for restricting calories, protocols for aerobic exercise and strength training, and dealing with weight loss plateaus)

Behavioral change (e.g., importance of behavioral change, goal setting, self-reward, and problem-solving around common barriers to weight loss success)

The participants were advised to gradually build up to 150 min/week of moderate intensity exercise.

Each participant was given access to the PNP mobile app designed by the investigators. The app provided real-time feedback regarding their dietary intake relative to the target specific to their group (low fat diet or personalized diet). Participants were asked to use the app to:

Enter their dietary intake and self-monitor their meals (If the meal did not match the target specific to their group, the participants were trained how to substitute other foods, so their meal better matched their target.)

For the Standardized Low Fat Group, the PNP app provided real-time feedback regarding calorie intake and macronutrient distribution for meals and snacks logged in by the participants.

For the Personalized Group the PNP app scored meals as excellent, very good, good, bad, or very bad based on the PNP algorithm developed by the investigators.

Can Personalized Diets Help Control Blood Sugar?

The results were clear-cut:

Weight loss was identical on both diets. This is no surprise. The study design included an exceptionally well-designed weight loss protocol for both groups.

The decrease in HbA1c was identical on both diets.

The improvement in blood sugar control was identical on both diets.

The investigators concluded, “[The] personalized diet did not result in an increased reduction in GV [blood sugar control] or HbA1c in patients with prediabetes or moderately controlled type 2 diabetes compared to a standardized diet.”

Since the investigators had designed the algorithm used to create personalized diets for this study, this was probably not the result they wanted.

So, they added, “Additional subgroup analyses may help to identify patients who are more likely to benefit from this personalized intervention.”

What Does This Study Mean For You?

This first takeaway from this study was obvious:

The personally designed diet did not perform any better than a standard, one size fits all, diet at improving blood sugar control.

Of course, this was not any standard diet. It was a diet that has been used successfully with diabetics for years. However, a lot of research had gone into developing the personalized diet. One might have expected it to perform better.

This is not the first study in which a personalized diet has performed no better than a standard diet. It doesn’t mean that the concept behind personalized diets is faulty. It just means we don’t yet know enough to design a personalized diet that really works.

The second takeaway from this study might be less obvious:

Weight loss is the most important factor for improving blood sugar control. Any diet that reduces weight will improve blood sugar control. This is also true for many other health issues such as high cholesterol, high blood pressure, high triglycerides, and osteoarthritis.

However, this should not come as a surprise either.

- Vegan and keto diets are polar opposites. Yet both give similar short-term weight loss and provide similar short-term health benefits.

- Studies have shown that intermittent fasting gives no better weight loss and health benefits than any diet that cuts calories to a similar extent.

- In other words, the diet you choose or the way you choose to restrict calories doesn’t matter. It is weight loss that provides the health benefits.

However, diet does appear to matter in the long term. If you look at studies ranging from 10 to 30 years, primarily plant-based diets provide better health benefits than primarily meat-based diets. And diets consisting primarily of whole, unprocessed foods provide better health benefits than diets high in processed foods.

Finally, there is an important corollary to this study showing that a personalized diet performed no better than a standardized diet at controlling blood sugar.

Some companies are trying to sell you expensive personalized diets with extravagant claims about the health benefits of their diet. Be wary of those diets. The science supporting their diets is premature. Their claims may be misleading.

And if the companies claim their diet is supported by published clinical studies, you should evaluate those studies carefully. The study I reviewed in this article was an exceptionally well-designed study. Any study that does not control for weight loss is likely to provide misleading results.

The Bottom Line

A recent study compared the effectiveness of a personalized diet and a standardized diet in improving blood sugar control for patients with prediabetes or type 2 diabetes. The results were clear-cut:

Weight loss was identical on both diets. This is no surprise. The study design included an exceptionally well-designed weight loss protocol for both groups.

The decrease in HbA1c was identical on both diets.

The improvement in blood sugar control was identical on both diets.

This doesn’t mean that the concept behind personalized diets is faulty. It just means we don’t yet know enough to design a personalized diet that really works.

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.

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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

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About The Author

Dr. Chaney has a BS in Chemistry from Duke University and a PhD in Biochemistry from UCLA. He is Professor Emeritus from the University of North Carolina where he taught biochemistry and nutrition to medical and dental students for 40 years. Dr. Chaney won numerous teaching awards at UNC, including the Academy of Educators “Excellence in Teaching Lifetime Achievement Award”.

Dr Chaney also ran an active cancer research program at UNC and published over 100 scientific articles and reviews in peer-reviewed scientific journals. In addition, he authored two chapters on nutrition in one of the leading biochemistry text books for medical students.

Since retiring from the University of North Carolina, he has been writing a weekly health blog called “Health Tips From the Professor”. He has also written two best-selling books, “Slaying the Food Myths” and “Slaying the Supplement Myths”. And most recently he has created an online lifestyle change course, “Create Your Personal Health Zone”. For more information visit https://chaneyhealth.com.

For the past 45 years Dr. Chaney and his wife Suzanne have been helping people improve their health holistically through a combination of good diet, exercise, weight control and appropriate supplementation.

What Is The Truth About Low Carb Diets?

August 30, 2022 by Dr. Steve Chaney

Why Is The Cochrane Collaboration The Gold Standard?

Author: Dr. Stephen Chaney

Atkins, South Beach, Whole30, Low Carb, high Fat, Low Carb Paleo, and Keto. Low carb diets come in many forms. But they have these general characteristics:

They restrict carbohydrate intake to <40% of calories.

They restrict grains, cereals, legumes, and other carbohydrate foods such as dairy, fruits, and some vegetables.

They replace these foods with foods higher in fat and protein such as meats, eggs, cheese, butter, cream, and oils.

When recommended for weight loss, they generally restrict calories.

What about the science? Dr. Strangelove and his friends tell you that low carb diets are better for weight loss, blood sugar control, and are more heart healthy than other diets. But these claims are controversial.

Why is that? I have discussed this in previous issues of “Health Tips From The Professor”. Here is the short version.

Most studies on the benefits of low carb diets compare them with the typical American diet.

- The typical American diet is high in fat, sugar and refined flour, and highly processed foods. Anything is better than the typical American diet.

Most low carb diets are whole food diets.

- Any time you replace sodas and highly processed foods with whole foods you will lose weight and improve your health.

Most low carb diets are highly structured. There are rules for which foods to avoid, which foods to eat, and often additional rules to follow.

- Any highly structured diet causes you to focus on what you eat. When you do that, you lose weight. When you lose weight, your health parameters improve.

- As I have noted before, short term weight loss and improvement in health parameters are virtually identical for the very low carb keto diet and the very low-fat vegan diet.

With all this uncertainty you are probably wondering, “What is the truth about low carb diets?”

A recent study by the Cochrane Collaboration (CE Naude et al, Cochrane Database of Systematic Reviews, 28 January 2022) was designed to answer this question.

The Cochrane Collaboration is considered the gold standard of evidence-based medicine. To help you understand why this is, I will repeat a summary of how the Cochrane Collaboration approaches clinical studies that I shared two weeks ago.

Why Is The Cochrane Collaboration The Gold Standard?

Who you gonna call? It’s not Ghostbusters. It’s not Dr. Strangelove’s health blog. It’s a group called the Cochrane Collaboration.

The Cochrane Collaboration consists of 30,000 volunteer scientific experts from across the globe whose sole mission is to analyze the scientific literature and publish reviews of health claims so that health professionals, patients, and policy makers can make evidence-based choices about health interventions.

In one sense, Cochrane reviews are what is called a “meta-analysis”, in which data from numerous studies are grouped together so that a statistically significant conclusion can be reached. However, Cochrane Collaboration reviews differ from most meta-analyses found in the scientific literature in a very significant way.

Many published meta-analyses simply report “statistically significant” conclusions. However, statistics can be misleading. As Mark Twain said: “There are lies. There are damn lies. And then there are statistics”.

The Cochrane Collaboration also reports statistically significant conclusions from their meta-analyses. However, they carefully consider the quality of each individual study in their analysis. They look at possible sources of bias. They look at the design and size of the studies. Finally, they ask whether the conclusions are consistent from one study to the next. They clearly define the quality of evidence that backs up each of their conclusions as follows:

High-quality evidence. Further research is unlikely to change their conclusion. This is generally reserved for conclusions backed by multiple high-quality studies that have all come to the same conclusion. These are the recommendations that are most often adopted into medical practice.

Moderate-quality evidence. This conclusion is very likely to be true, but further research could have an impact on it.

Low-quality evidence. Further research is needed and could alter the conclusion. They are not judging whether the conclusion is true or false. They are simply saying more research is needed to reach a definite conclusion.

This is why their reviews are considered the gold standard of evidence-based medicine. If you are of a certain age, you may remember that TV commercial “When EF Hutton talks, people listen.” It is the same with the Cochrane Collaboration. When they talk, health professionals listen.

How Was The Study Done?

The authors of this Cochrane Collaboration Report included 61 published clinical trials that randomized participants into two groups.

The first group was put on a low carbohydrate diet (carbohydrates = <40% of calories).

The second group was put on a “normal carbohydrate” diet (carbohydrates = 45-65% of calories, as recommended by the USDA and most health authorities).

- The normal carbohydrate diet was matched with the low carbohydrate diet in terms of caloric restriction.

- Both diets were designed by dietitians and were generally whole food diets.

The participants in these studies:

Were middle-aged.
Were overweight or obese.
Did not have diagnosed heart disease or cancer.
May have diagnosed type-2 diabetes. Some studies selected participants that had diagnosed type 2 diabetes. Other studies excluded those patients.

The studies were of 3 types:

Short-term: Participants in these studies followed their assigned diets for 3 to <12 months.

Long-term: Participants in these studies followed their assigned diets for >12 to 24 months.

Short-term with maintenance: Participants in these studies followed their assigned diets for 3 months followed by a 9-month maintenance phase.

What Is The Truth About Low Carb Diets?

All the studies included in the Cochrane Collaboration’s meta-analysis randomly assigned overweight participants to a low carbohydrate diet (carbohydrates = <40% of calories) or to a “normal carbohydrate” diet (carbohydrates = 45-65% of calories) with the same degree of caloric restriction.

If low carb diets have any benefit in terms of weight loss, improving blood sugar control, or reducing heart disease risk, these are the kind of studies that are required to validate that claim.

This is what the Cochrane Collaboration’s meta-analysis showed.

When they analyzed studies done with overweight participants without type 2 diabetes:

Weight loss was not significantly different between low carb and normal carb diets in short-term studies (3 to <12 months), long-term studies (>12 to 24 months), and short-term studies followed by a 9-month maintenance period.

There was also no significant difference in the effect of low carb and normal carb diets on the reduction in diastolic blood pressure and LDL cholesterol.

Since diabetics have trouble controlling blood sugar, you might expect that type 2 diabetics would respond better to low carb diets. However, when they analyzed studies done with overweight participants who had type 2 diabetes:

Weight loss was also not significantly different on low carb and normal carb diets.

There was no significant difference in the effect of low carb and normal carb diets on the reduction in diastolic blood pressure, LDL cholesterol, and hemoglobin A1c, a measure of blood sugar control.

Of course, the reason Cochrane Collaboration analyses are so valuable is they also analyze the strength of the studies that were included in their analysis.

You may remember in my article two weeks ago, I reported on the Cochrane Collaboration’s report supporting the claim that omega-3 supplementation reduces pre-term births. In that report they said that the studies included in their analysis were high quality. Therefore, they said their report was definitive and no more studies were needed.

This analysis was different. The authors of this Cochrane Collaboration report said that the published studies on this topic were of moderate quality. This means their conclusion is very likely to be true, but further research could have an impact on it.

What Does This Study Mean For You?

If you are a bit confused by the preceding section, I understand. That was a lot of information to take in. Let me give you the Cliff Notes version.

In short, this Cochrane Collaboration Report concluded:

Low carb diets (<40% of calories from carbohydrates) are no better than diets with normal carbohydrate content (45-65% of calories from carbohydrates) with respect to weight loss, reduction in heart disease risk factors, and blood sugar control. Dr. Strangelove has been misleading you again.

This finding is equally true for people with and without type 2 diabetes. This calls into question the claim that people with type 2 diabetes will do better on a low carb diet.

The published studies on this topic were of moderate quality. This means their conclusion is very likely to be true, but further research could have an impact on it.

If you are thinking this study can’t be true because low carb diets work for you, that is because you are comparing low carb diets to your customary diet, probably the typical American diet.

Remember that any whole food diet that eliminates sodas and processed foods and restricts the foods you eat will cause you to lose weight. Whole food keto and vegan diets work equally well short-term compared to the typical American diet.

And any diet that allows you to lose weight improves heart health parameters and blood sugar control.

If you are thinking about the blogs, books, and videos you have seen extolling the virtues of low carb diets, remember that the Dr. Strangeloves of the world only select studies comparing low carb diets to the typical American diet to support their claims.

The studies included in this Cochrane Collaboration report randomly assigned participants to the low carb and normal carb diets and followed them for 3 to 24 months.

- Both diets were whole food diets designed by dietitians.

- Both diets reduced caloric intake to the same extent.

What about the claims that low carb diets are better for your long-term health? There are very few studies on that topic. Here are two:

At the 6.4-year mark a recent study reported that the group with the lowest carbohydrate intake had an increased risk of premature death – 32% for overall mortality, 50% for cardiovascular mortality, 51% for cerebrovascular mortality, and 36% for cancer mortality. I will analyze this study in a future issue of “Health Tips From The Professor”.

At the 20-year mark a series of studies reported that:

- Women consuming a meat-based low carb diet for 20 years gained just as much weight and had just as high risk of heart disease and diabetes as women consuming a high carbohydrate, low fat diet.

- However, women consuming a plant-based low carb diet for 20 years gained less weight and had reduced risk of developing heart disease and diabetes as women consuming a high carbohydrate, low fat diet.

My recommendation is to avoid low-carb diets. They have no short-term benefits when compared to a healthy diet that does not eliminate food groups. And they may be bad for you in the long run. Your best bet is a whole food diet that includes all food groups but eliminates sodas, sweets, and processed foods.

However, if you are committed to a low carb diet, my recommendation is to choose the low-carb version of the Mediterranean diet. It is likely to be healthy long term.

The Bottom Line

The Cochrane Collaboration, the gold standard of evidence-based medicine, recently issued a report that evaluated the claims made for low carb diets.

All the studies analyzed in the Cochrane Collaboration’s report randomly assigned overweight participants to a low carbohydrate diet (carbohydrates = <40% of calories) or to a “normal carbohydrate” diet (carbohydrates = 45-65% of calories) with the same degree of caloric restriction.

If low carb diets have any benefit in terms of weight loss, improving blood sugar control, or reducing heart disease risk, these are the kind of studies that are required to validate that claim.

The Cochrane Collaboration Report concluded:

Low carb diets (<40% of calories from carbohydrates) are no better than diets with normal carbohydrate content (45-65% of calories from carbohydrates) with respect to weight loss, reduction in heart disease risk factors, and blood sugar control.

This is equally true for people with and without type 2 diabetes.

The published studies on this topic were of moderate quality. This means their conclusion is very likely to be true, but further research could have an impact on it.

My recommendation is to avoid low carb diets. They have no short-term benefits when compared to a healthy diet that does not eliminate food groups. And they may be bad for you in the long run. Your best bet is a whole food diet that includes all food groups but eliminates sodas, sweets, and processed foods.

However, if you are committed to a low carb diet, my recommendation is to choose the low carb version of the Mediterranean diet. It is likely to be healthy long term.

For more details on the 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.

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.

Does Resveratrol Improve Blood Sugar Control?

May 27, 2014 by Dr. Steve Chaney

Is The Promise of Resveratrol True?

Author: Dr. Stephen Chaney

It was just a few years ago that resveratrol was the latest “miracle nutrient”. It was featured on Dr. Oz and on 60 Minutes. It was hot! Today you see dueling headlines. The headlines one week proclaim the benefits of resveratrol. Next week’s headlines say that it’s all hype. What’s a person to believe?

Let me take you behind the headlines to look at the actual studies and answer some important questions.

1) What do we actually know about the benefits of resveratrol?

2) Is the evidence for beneficial effects of resveratrol where it should be considering the number of clinical studies that have been published?

3) What additional studies need to be done before we can be sure that resveratrol is beneficial?

4) Should you wait until we are absolutely certain resveratrol is beneficial, before you start using it? This is perhaps the most important question of all.

To answer those questions, let’s examine the study behind one of the latest headlines, namely: “Resveratrol Improves Blood Sugar Control in Diabetics”. One of the promises of resveratrol has been that it might help diabetics and pre-diabetics who struggle with blood sugar control. However, this promise was based on animal studies. The study that generated the headlines in question was a meta-analysis of recently published human clinical trials in this area (Liu et al, Am. J. Clin. Nut., 2014, doi: 10.3945/ajcn.113.082024).

Does Resveratrol Improve Blood Sugar Control?

The meta-analysis included 11 published placebo controlled double blind clinical studies looking at the effects of resveratrol supplementation on fasting blood sugar levels, insulin levels, hemoglobin A1c (a measure of blood sugar control) and insulin resistance (a measure closely associated with type 2 diabetes).

A strength of this meta-analysis is the fact that it included 11 clinical studies. However, a weakness of this analysis is that these studies utilized a wide variety of resveratrol doses (10 mg/day to 1 gram/day), a wide variety of end points and both diabetic and non-diabetic patients. That means that there were only a few studies with common population groups, resveratrol doses, and end points.

The conclusions of the study (and the headlines you may have seen) were that:

• Resveratrol appeared to improve blood sugar control (based on improvements in fasting blood sugar levels, insulin levels, hemoglobin A1c and insulin resistance) in diabetics.

• No consistent effect of resveratrol on blood sugar control was seen in non-diabetics.

How Good Are These Studies?

While these studies are very promising, they are bot definitive. There were only 3 published clinical studies in diabetics. While all 3 of the studies showed a positive effect of resveratrol supplementation:

• The doses used were different in each study (ranging from 10 mg/day to 1 gram/day)

• Each study measured different end points (one measured blood glucose, insulin levels, hemoglobin A1c and insulin resistance, one measured blood glucose and hemoglobin A1c and the third measured insulin resistance).

As a research scientist I would like to see more studies done at comparable doses and measuring the same end points – we scientists always want more studies.

Similarly, there was not enough consistency in the studies with non-diabetics to draw a firm conclusion. (3 were with obese patients, 3 were with patients with cardiovascular disease, 1 was with patients with metabolic syndrome and 1 was with perfectly healthy subjects.)

If you really wanted to see if something like resveratrol helps non-diabetics with blood sugar control, you would want to start with people who are already experiencing some difficulties with blood sugar control (pre-diabetics or patients with metabolic syndrome) and follow them for a couple of years to see if resveratrol reduces the number of them who become diabetic.

Are The Headlines Just Hype?

Does that mean that the blood sugar benefits of resveratrol are just hype? The answer is no. There is a difference between “very promising, but not yet definitive” and “hype”. We shouldn’t be surprised that human studies on the health benefits of resveratrol are not yet definitive. Science moves slowly. It often takes decades of scientific research before promising concepts are widely accepted by the scientific community.

When a research area is as young as this one, we sometimes need to go beyond the clinical studies and look at the totality of evidence. In this case:

• In mice resveratrol exerts its beneficial effects by turning on a specific anti-aging gene called SIRT1 (Cell Metabolism, 15: 675-690, 2012). In humans, resveratrol appears to activate the same genetic pathways as in mice (Journal of Clinical Endocrinology & Metabolism, 96: 1409-1414, 2011).

• In obese mice resveratrol improves markers of blood sugar control (Nature, 444: 337-342, 2006). Published clinical studies in diabetic humans also show improvements in blood sugar control (Journal of Clinical Nutrition, 2014, doi: 10.3945/ajcn.113.082024).

So while more and better clinical studies are needed to be absolutely certain that resveratrol helps improve blood sugar control, the evidence supporting that effect is substantial.

What Should You Do?

The ONLY important question for each of you is probably: “Should I wait a decade or two until we are absolutely sure about the health benefits of resveratrol before I take a resveratrol supplement?” That question is ultimately yours to answer. It’s all about benefits and risk.

Benefits – In animal studies resveratrol clearly improves blood sugar control. The human clinical studies published to date are consistent with the animal studies.

Risk – Current data suggest that resveratrol appears to be safe, even at high doses. For example, one recent study indicated that up to 5 gm/day is safe (Cancer Epidemiology BioMarkers & Prevention, volume 16:1246-1262, 2007), but I wouldn’t personally recommend exceeding 100-200 mg/day.

The Bottom Line:

1) Don’t get too excited about the headlines suggesting that resveratrol might help improve blood sugar control in diabetics. The few human clinical studies that have been published to date are consistent with previous animal studies. That is very promising, but more studies are needed before we can be absolutely confident that resveratrol supplementation is beneficial for diabetics.

2) Similarly, don’t be discouraged by the headlines suggesting that resveratrol does not help with blood sugar control in non-diabetics. Those results are preliminary as well.

3) That doesn’t mean that the headlines are just hype. It takes decades to accumulate definitive proof that any kind of food or nutrient offers proven benefits, and the bulk of human clinical research on reveratrol has occurred in the last couple of years. We are exactly where we should expect to be at this point in time.

4) With something as promising as resveratrol, the real question becomes whether you can afford to wait a decade or two until you know whether the potential benefits have been definitely proven. That question is up to you. On the plus side, current data suggest that resveratrol is highly promising for blood sugar control. In addition, resveratrol appears to be safe, even at high doses, but I wouldn’t personally recommend exceeding 100-200 mg/day.

5) We already know that weight control, exercise and a healthy diet improve blood sugar control. You should think of resveratrol as something you may wish to add to a healthy lifestyle, not as a substitute for a healthy lifestyle.

6) If you are diabetic and decide to try a resveratrol supplement, be sure to work with your physician so they can modify your dose of insulin or blood sugar medication as necessary.

7) Finally, you may be asking whether resveratrol supplements are even necessary. Can’t you just get all the resveratrol you need from a glass or two of red wine? Stay tuned. I’ll have the answer to that question in a couple of weeks.

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.