Which Foods Lower Blood Sugar?

Written by Dr. Steve Chaney on . Posted in Blood Sugar

Can You Believe The “Experts”?

Author: Dr. Stephen Chaney

which foods lower blood sugarYour blood sugar levels have been creeping up. Your doctor has been bugging you to do something about it – even threatening to put you on medications if you don’t get your blood sugar under control. So, which foods lower blood sugar?

Now it’s the first of the year, and you’ve vowed to do something about it. You have vowed to make better food choices. That should be easy. There is lots of great advice about foods that lower blood sugar on the internet. For example, in a recent search, I found articles proclaiming “9 foods that lower blood sugar”, “7 foods that control blood sugar”, and “12 power foods to beat diabetes”.

But, are those foods the right ones for you? What if we are remarkably different in our blood sugar responses to the same food? This is just what a recent study suggests.

How Was The Study Designed?

A group of scientists in Isreal set out to test the hypothesis that people eating identical meals might have a high variability in their post-meal blood glucose response (Zeevi et al, Cell, 163, 1079-1094, 2015).

measure glucoseThe investigators enrolled 800 subjects ages 18-70 into their study. None of the individuals had diabetes. However, 54% of them were overweight (BMI ≥ 25 kg/m2) and 22% of them were obese (BMI ≥ 30 kg/m2). Thus, their subject population was typical of the adult population of almost every Western, industrialized country.

All 800 subjects were followed for one week during which time:

  • They were connected to a continuous glucose monitor, which measured their blood glucose levels every 5 seconds.
  • They were given a Smartphone app and instructed to log their food intake, exercise, and sleep in real time.
  • They were told to follow their normal daily routine and dietary habits except for the first meal of every day, which consisted of five different types of standardized “meals” (glucose, fructose, bread, bread with butter, bread with chocolate), all providing 50 gm of available carbohydrate.

The glucose monitor recorded blood sugar responses for 2 hours following each meal. From that information, the investigators calculated a PPGR (post-prandial glycemic response), which I will mercifully refer to as “blood sugar response”, for every meal eaten by every subject throughout the week.

The standardized “meals” eaten at the beginning of the day were used to validate the study. For example:

  • Two of the standardized meals were given to each subject twice during the study separated by at least one day.
    • There was very little variability in blood sugar response when the same standardized meal was given to the same subject on different days.
    • However, there was a significant amount of variability in blood sugar response when the same standardized meal was given to different subjects.
  • The average blood sugar response to each of the standardized meals was very similar to literature values from previous studies (Most previous studies have reported only average blood sugar responses, not individual variability).

In short, the results from the standardized “meals” validated both the reliability and reproducibility of the data.

Finally, to eliminate as many confounding variables as possible, the investigators compared blood sugar response only for those meals in which a single food was the major component of the meal and that food provided 20-40 gm of carbohydrate.

Here is where things got really interesting!

Which Foods Lower Blood Sugar?

breadThis study showed that there is tremendous individual variability in the blood sugar response to any given food. For example, individual blood sugar responses varied by:

  • 4-fold for sugar-sweetened soft drinks, grapes and apples.
  • 5-fold for rice.
  • 6-fold for bread and potatoes.
  • 7-fold for ice cream and dates.

Put another way:

  • Some people had almost no blood sugar response to cookies, but a very high blood sugar response to a banana.
  • Other people had almost no blood sugar response to bananas, but a very high blood sugar response to cookies.

That is a pretty striking result. Which foods lower blood sugar? This study suggests that some people trying to control their blood sugar can eat bananas, while others should avoid them. It might even mean that some people trying to control blood sugar can eat cookies. I know that is what many people would like to hear, but I’m not ready to make that recommendation.

Why Is There So Much Individuality in Blood Sugar Response?

good food choicesYou are probably wondering why there is such variability in blood sugar response to the same foods. There are several factors that influence individual blood sugar response. For example,

  • Overweight and obesity (Both tend to increase blood sugar response).
  • Dietary habits (Meats, particularly fatty meats, processed grains, and simple sugars tend to increase blood sugar response to a given amount of carbohydrate. Unprocessed grains, fresh fruits & vegetables tend to decrease blood sugar response to a given amount of carbohydrate).
  • What we eat with a given meal (Protein, fiber, and fat in a meal can decrease blood sugar response to the carbohydrate in that meal).
  • Physical activity (Increased muscle mass decreases blood sugar response to a given amount of carbohydrate).
  • The bacteria in our intestine (This may be a chicken-and egg thing. The bacteria in our intestine are influenced by our dietary habits.)
  • Genetics.
  • Things we don’t yet know about.

The good news is that we can actually control some of these variables. The ones over which we have the most control are weight, dietary habits, what we eat along with the carbohydrates in our meals, and physical activity.

What Does This Mean For You?

blood sugarThe authors concluded that “universal dietary recommendations [for lowering blood sugar levels] may have limited utility.”  That is because dietary recommendations are based on average responses and none of us are average. As the saying goes “We are all wonderfully [and differently] made”.

So, when you read about diets and foods that will help you keep your blood sugar levels under control, take those recommendations with a grain of…sugar. They are a good starting place, but you need to listen to your body, and eat the foods that work best for you.  So, which foods lower blood sugar?  It is different for different people, but there are some variables you can control.

Don’t get carried away, however. I’m pretty sure Twinkies washed down with a soft drink are bad for just about everyone.

More importantly, control the variables you can – weight, dietary habits, foods you eat along with carbohydrates, and physical activity. If you control those four variables, you will be well on your way to ideal blood sugar control.

 

The Bottom Line

 

  • A recent study has shown that there is tremendous variability in blood sugar response to identical meals from one individual to the next.
  • The authors of the study concluded that “universal dietary recommendations [for lowering blood sugar levels] may have limited utility.” That is because dietary recommendations are based on average responses, and none of us are average.
  • So, when you read about diets and foods that will help you keep your blood sugar levels under control, take those recommendations with a grain of…sugar. They are a good starting place, but you need to listen to your body, and eat the foods that work best for you.
  • There are variables influencing our blood sugar response that we cannot control, such as genetics. However, there are some very important variables that we can control. For example, we can improve our blood sugar response by:
    • Attaining and maintaining ideal weight. Losing as little as 5-10 pounds can result in a significant improvement.

 

    • Eating a diet that emphasizes fresh fruits & vegetables, nuts, and whole grains and minimizes meats, especially fatty meats, processed grains, and simple sugars. This may act by influencing the bacteria that populate our intestine.

 

    • Consuming carbohydrates along with protein, fiber-rich foods, and even some fat in the same meal.

 

    • Increasing physical activity, especially activity that increases lean muscle mass.

 

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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Latest Article

Can Plant-based Diets Be Unhealthy?

Posted September 10, 2019 by Dr. Steve Chaney

Do Plant-Based Diets Reduce Heart Disease Deaths?

Author: Dr. Stephen Chaney

 

plant-based diets vegetablesPlant-based diets have become the “Golden Boys” of the diet world. They are the diets most often recommended by knowledgeable health and nutrition professionals. I’m not talking about all the “Dr. Strangeloves” who pitch weird diets in books and the internet. I am talking legitimate experts who have spent their life studying the impact of nutrition on our health.

Certainly, there is an overwhelming body of evidence supporting the claim that plant-based diets are healthy. Going on a plant-based diet can help you lower blood pressure, inflammation, cholesterol and triglycerides. People who consume a plant-based diet for a lifetime weigh less and have decreased risk of heart disease, diabetes, and cancer.

But, can a plant-based diet be unhealthy? Some people consider a plant-based diet to simply be the absence of meat and other animal foods. Is just replacing animal foods with plant-based foods enough to make a diet healthy?

Maybe not. After all, sugar and white flour are plant-based food ingredients. Fake meats of all kinds abound in our grocery stores. Some are very wholesome, but others are little more than vegetarian junk food. If you replace animal foods with plant-based sweets, desserts, and junk food, is your diet really healthier?

While the answer to that question seems obvious, very few studies have asked that question. Most studies on the benefits of plant-based diets have compared population groups that eat a strictly plant-based diet (Seventh-Day Adventists, vegans, or vegetarians) with the general public. They have not looked at variations in plant food consumption within the general public. Nor have they compared people who consume healthy and unhealthy plant foods.

This study (H Kim et al, Journal of the American Heart Association, 8:e012865, 2019) was designed to fill that void.

 

How Was The Study Done?

plant-based diets studyThis study used data collected from 12,168 middle aged adults in the ARIC (Atherosclerosis Risk in Communities) study between 1987 and 2016.

The participant’s usual intake of foods and beverages was assessed by trained interviewers using a food frequency questionnaire at the time of entry into the study and again 6 years later.

Participants were asked to indicate the frequency with which they consumed 66 foods and beverages of a defined serving size in the previous year. Visual guides were provided to help participants estimate portion sizes.

The participant’s adherence to a plant-based diet was assessed using four different well-established plant-based diet scores. For the sake of simplicity, I will include 3 of them in this review.

  • The PDI (Plant-Based Diet Index) categorizes foods as either plant foods or animal foods. A high PDI score means that the participant’s diet contains more plant foods than animal foods. A low PDI score means the participant’s diet contains more animal foods than plant foods.
  • The hPDI (healthy plant-based diet index) is based on the PDI but emphasizes “healthy” plant foods. A high hPDI score means that the participant’s diet is high in healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, coffee and tea) and low in animal foods.
  • The uPDI (unhealthy plant-based diet index) is based on the PDI but emphasizes “unhealthy” plant foods. A high uPDI score means that the participant’s diet is high in unhealthy plant foods (refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts) and low in animal foods.

For statistical analysis the scores from the various plant-based diet indices were divided into 5 equal groups. In each case, the group with the highest score consumed the most plant foods and least animal foods. The group with the lowest score consumed the least plant foods and the most animal foods.

The health outcomes measured in this study were heart disease events, heart disease deaths, and all-cause deaths. Again, for the sake of simplicity, I will only include 2 of these outcomes (heart disease deaths and all-cause deaths) in this review. The data on deaths were obtained from state death records and the National Death Index. (Yes, your personal information is available on the web even after you die.)

 

Do Plant-Based Diets Reduce Heart Disease Deaths?

plant-based diets reduce heart deathsThe participants in this study were followed for an average of 25 years.

The investigators looked at heart disease deaths over the 25 years and compared people with the highest intake of plant foods to people with the highest intake of red meat and other animal foods. The results were:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, coffee and tea) had a 19-32% lower risk of dying from heart disease than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods (refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts) had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

When the investigators looked at all-cause deaths over the 25 years:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods had an 11-25% lower risk of dying from any cause than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

What Else Did The Study Show?

The investigators made a couple of other interesting observations:

  • The association of the overall diet with heart disease and all-cause deaths was stronger than the association of individual food components. This underscores the importance of looking at the effect of the whole diet on health outcomes rather than the “magic” foods you hear about on Dr. Strangelove’s Health Blog.
  • Diets with the highest amount of healthy plant foods were associated with higher intake of carbohydrates, plant protein, fiber, and micronutrients, including potassium, magnesium, iron, vitamin A, vitamin C, folate, and lower intake of saturated fat and cholesterol.
  • Diets with the highest amount of unhealthy plant foods were associated with higher intake of calories and carbohydrates and lower intake of fiber and micronutrients.

The last two observations may help explain some of the health benefits of plant-based diets.

 

Can Plant-Based Diets Be Unhealthy?

plant-based diets unhealthy cookiesNow, let’s return to the question I asked at the beginning of this article: “Can plant-based diets be unhealthy?” Although some previous studies have suggested that unhealthy plant-based diets might increase the risk of heart disease, this study did not show that.

What this study did show was that an unhealthy plant-based diet was no better for you than a diet containing lots of red meat and other animal foods.

If this were the only conclusion from this study, it might be considered a neutral result. However, this result clearly contrasts with the data from this study and many others showing that both plant-based diets in general and healthy plant-based diets reduce the risk of heart disease deaths and all-cause deaths compared to animal-based diets.

The main message from this study is clear.

  • Replacing red meat and other animal foods with plant foods can be a healthier choice, but only if they are whole, minimally processed plant foods like whole grains, fruits, vegetables, nuts, legumes, coffee and tea.
  • If the plant foods are refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts, all bets are off. You may be just as unhealthy as if you kept eating a diet high in red meat and other animal foods.

There is one other subtle message from this study. This study did not compare vegans with the general public. Everyone in the study was the general public. Nobody in the study was consuming a 100% plant-based diet.

For example:

  • The group with the highest intake of plant foods consumed 9 servings per day of plant foods and 3.6 servings per day of animal foods.
  • The group with the lowest intake of plant foods consumed 5.4 servings per day of plant foods and 5.6 servings per day of animal foods.

In other words, you don’t need to be a vegan purist to experience health benefits from adding more whole, minimally processed plant foods to your diet.

 

The Bottom Line

A recent study analyzed the effect of consuming plant foods on heart disease deaths and all-cause deaths over a 25-year period.

When the investigators looked at heart disease deaths over the 25 years:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods had a 19-32% lower risk of dying from heart disease than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

When the investigators looked at all-cause deaths over the 25 years:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods had an 11-25% lower risk of dying from any cause than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

The main message from this study is clear.

  • Replacing red meat and other animal foods with plant foods can be a healthier choice, but only if they are whole, minimally processed plant foods like whole grains, fruits, vegetables, nuts, legumes, coffee and tea.
  • If the plant foods are refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts, all bets are off. You may be just as unhealthy as if you kept eating a diet high in red meat and other animal foods.

A more subtle message from the study is that you don’t need to be a vegan purist to experience health benefits from adding more whole, minimally processed plant foods to your diet. The people in this study were not following some special diet. The only difference was that some of the people in this study ate more plant foods and others more animal foods.

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

 

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

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