Can You Believe The “Experts”?
Author: Dr. Stephen Chaney
Your 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).
The 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?
This 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?
You 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.)
- 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?
The 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.