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Harvard Health Blog
The data are in: Eat right, reduce your risk of diabetes
- By Robert H. Shmerling, MD, Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing
Follow me on Twitter @RobShmerling
Here’s a new medical study with a conclusion that might just change your life: eat healthy.
Sure, you’ve heard it before, but this time the benefit is the prevention of diabetes. That’s a big deal, especially if, like so many other people, you are at risk for the disease. More on that in a moment.
First, let’s review the study. Researchers publishing in PLoS Medicine describe a study of more than 200,000 people in the U.S. who participated in health surveys over a 20-year period. They found that:
- People who chose diets that were predominately of plant-based foods developed type 2 diabetes 20% less often than the rest of the study subjects.
- For those with the very healthiest plant-based diets (including fruits, vegetables, nuts, beans, and whole grains), the reduction in type 2 diabetes was 34%.
- On the other hand, those who made less healthy choices (such as sugar-sweetened beverages and refined grains) developed type 2 diabetes 16% more often than the rest.
It’s worth emphasizing that this was not a study of the effect of being a vegan or of following an expensive, pre-packaged diet plan that might be hard to maintain over time. This was a study of “normal” dietary choices across a spectrum, from largely animal-based to largely plant-based with all variations in between. That makes it more applicable to the average person.
While this type of study cannot prove that the reduction in diabetes was strictly due to the difference in diet, the “dose response” (the higher degree of protection with the very healthiest diets) is strongly suggestive of real effect due to diet.
The USDA’s current dietary guidelines (called “MyPlate”) urge everyone to choose healthy foods. For example:
- Half of each meal should consist of whole fruits and vegetables.
- About a quarter of each meal should be made up of protein, and another quarter grains (especially whole grains).
- Low-fat dairy products such as low-fat milk and yogurt are preferred over higher fat options.
- Moderate total calorie intake (depending on your age, gender, size, and physical activity).
- Reduce the intake of saturated fat, sodium, and added sugar. Read nutrition labels so you know what you’re eating.
According to the USDA’s website, the MyPlate diet “can help you avoid overweight and obesity and reduce your risk of diseases such as heart disease, diabetes, and cancer.”
Even more recently, the 2015 Dietary Guidelines Advisory Committee reported that a diet “that is higher in plant-based foods, such as vegetables, fruits, whole grains, legumes, nuts, and seeds, and lower in animal-based foods, is more health promoting.” And just this week, US News and World Report ranked plant-based diets (the DASH diet and the Mediterranean diet) as the healthiest.
These recommendations have been endorsed by nutritionists, doctors, and public health officials. But, the data on which they are based are not perfect. This new study is among the strongest to date supporting the notion that a healthy diet can lower your risk of a chronic disease such as diabetes.
Of course, there are caveats
Is this the last word on the connection between diet and prevention of diabetes? Not by a long shot.
For one thing, this study examined trends among thousands of people over time. While that allows some observations (and even predictions) about large groups of people in aggregate, it does not allow accurate predictions for an individual. You could follow a healthy diet all your life and still develop diabetes. And not everyone who chooses an animal-based diet that is high in refined sugars will develop diabetes.
The information about diet was self-reported, so some inaccuracy is inevitable. And for some foods, the designation of “healthful” is somewhat subjective.
In addition, such studies are unable to say that diet is the key reason for the findings. Some other factor — exercise, genetics, or a host of other possibilities in combination — might matter more than diet alone. However, the dose response (as defined above) does suggest that diet is playing a significant role.
And in conclusion….
Given the dramatic increase in the incidence of diabetes in this country, studies that identify preventive approaches are worthy of attention. Besides providing some of the strongest support to date for recommendations for healthier diets, perhaps the biggest impact of a study like this should be for people at increased risk of disease. For example, a person who is overweight, has “pre-diabetes” (a high blood sugar that’s not quite high enough to be diagnostic of diabetes), or a strong family history of diabetes might take this data to heart and commit to changing their diet.
Studying the impact of dietary (or any other) recommendations is an important way to validate the guidelines’ usefulness. This new study is a good example.
About the Author
Robert H. Shmerling, MD, Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing
As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles.
No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.
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