Are Vegetarian Diets Any Good For Diabetes?

Plant-based diets may offer special benefits to people with diabetes, according to a recent review article by U.S. researchers who reviewed the pertinent English language literature published since 1966.  They found 116 potentially relevant articles, 10 of which were directly related to diabetes management and glucose control.

The authors failed to define “vegetarian” early on.  Some vegetarians eat eggs, some eat cheese, some drink milk.  I assume vegans eat no animal products whatsoever.  On the last page of the review the authors write that a vegetarian “does not eat meat, fish, or poultry” although it’s not clear if that applies throughout the review.  There are many references to “low-fat vegetarian” diets, with little or no mention of moderate- or high-fat vegetarian diets.

The authors often refer to vegetarian diets as “plant-based.”  No doubt, they are.  But even the healthy Mediterranean diet is considered plant-based, while clearly not vegetarian.

It’s also unclear whether they focused on type 1 or type 2 diabetes.  My sense is, probably type 2.

Here are the major points: 

  1. Are vegetarians less likely to develop diabetes?  Observational studies have found a lower prevalence of diabetes among vegetarians compared to non-vegetarians, especially among Seventh Day Adventists.  In other studies, meat consumption is linked to higher risk of diabetes among women. 
  2. Do vegetarian diets help control diabetes?  Several small studies showed that low-fat near-vegetarian and vegan diets improved glucose control and insulin sensitivity and reduced diabetes medication use, compared with a traditional diabetes diet – which is typically low-fat and high-carb.  I’m not sure, but I assume that the intervention diets were not heavy in refined, processed carbohydrates, but instead consisted of natural whole plant foods.  “Weight loss accounts for much although not all, of the effect of plant-based diets on glycemic control,” they write.
  3. Heart disease is quite common in older diabetics.  Do vegetarian diets offer any cardiac benefits?  They cite Dr. Ornish’s Lifestyle Heart Trial of a low-fat vegetarian diet and intensive lifestyle intervention: smoking cessation, stress management (meditation?), mild exercise, and group meetings.  Dr. Ornish’s program reduced LDL cholesterol by 37%, reversed heart artery blockages in 82% of participants, and found 60% lower risk of cardiac events compared to the control group. Dr. Ornish’s Multisite Lifestyle Cardiac Intervention Program also documented impressive cardiac results at 12 weeks, but had no control group.  Dr. Caldwell Esselstyne is also mentioned in this context.
  4. Vegetarian diets are linked to lower blood pressure, which may help prolong life and prevent heart attacks and strokes.
  5. Antioxidant-rich foods like fruits and vegetables—common in the Mediterranean diet and vegetarian diets—may lower cardiovascular disease risk. 
  6. People with diabetes are at risk for impaired kidney funtion.  In women with impaired baseline kidney funtion, high animal protein intake is associated with continued kidney deterioration. 
  7. A small study showed dramatic improvement in type 2 diabetics with painful neuropathy over 25 days on a low-fat vegan diet and a daily 30-minute walk.  Many participants were able to reduce diabetes drug dosages.
  8. Do any diabetes advocacy associations endorse vegetarian diets for people with diabetes?  The American Dietetic Association deems that vegetarian and vegan diets, if well-planned, are nutritionally adequate. I don’t know the position of the American Diabetes Association.  Vegetarians need planning to get adequate vitamin D, B12, and calcium.
  9. “Low-fat vegetarian and vegan diets do not require individuals to limit energy or carbohydrate intake….”  If true (and these guys should know), that might broaden the diet’s appeal.
  10. I saw no mention of decreased overall mortality in vegetarians.

My Comments

Have you heard of the Physicians Committee for Responsible Medicine?  Their president is Neal Barnard, the lead author of the study at hand.  He has a new book on reversal of diabetes with a low-fat vegetarian diet.

The authors cite a journal article (reference #16) in support of plant-based diets, but the article doesn’t mention a vegetarian or vegan diet—it’s high-carb, high-fiber diet.  I didn’t review all 92 of their references to see if any others were misleading.

“Plant-based diets” must be a euphemism for vegetarian diets.  Too many people shut down when you talk to them about vegetarian diets.

I won’t rule out the possibility that vegetarian/vegan diets may be helpful in management of diabetes.  Such diets are, of course, 180 degrees different from the very low-carb diets I’ve reviewed favorably in these pages!  Both models, ideally, move away from the over-processed, concentrated carbohydrates so prevalent in Western culture.  Perhaps that’s the unifying healthy theme, if there is one. 

Or different sub-types of diabetes respond better to particular diets.

I heartily agree with the authors that larger clinical trials of vegetarian diets in diabetics are needed.  I’d love to see a long-term randomized controlled trial comparing a very low-carb diet diet with a low-fat vegetarian diet.  That’s the best way to settle which is better for diabetics: vegetarian or low-carb.

It’ll never be done.

Has a vegetarian diet helped control your diabetes?

Steve Parker, M.D.

Reference:  Barnard, Neal, et al.  Vegetarian and vegan diets in type 2 diabetes managementNutrition Reviews, 67(2009): 255-263.   doi: 10.1111/j.1753-4887.2009.00198.x


Filed under coronary heart disease, Diabetes Complications, Vegetarian Diet

19 responses to “Are Vegetarian Diets Any Good For Diabetes?

  1. Vivian

    No. I was a 12 year vegetarian when I diagnosed with Diabetes. To be fair, I was more a grain and bean-heavy vegetarian, than a whole food fruit & veg vegetarian (I was not a vegan). Since then I’ve switched to a paleo-type approach to eating and now my diabetes is completely controlled, without medication. The only carbs I ingest are from whole fruits and vegs, but they are a small part of my diet.

  2. I think you hit the nail on the head with moving away from highly processed foods. I would imagine this applies to both meats and carbs.

  3. Vivian-

    Congratulations on the diabetes control with diet! The paleo diet, for those unfamiliar with it, is relatively low-carb and low-glycemic index.

  4. I would have thought a vegetarian diet is somewhat carbohydrate heavy. It certainly can be, and that’s a problem. If one doesn’t eat meat – what is left? – especially, if the diet is also low-fat: hmm, veggies and more veggies and fruit. I’m not sure people live off that alone. They usually add lots of bread, tortillas, pitas and pasta to that diet. Vegetarians also tend to eat a lot of soy. Soy is not a such good product in the States and Canada. It can contribute to hypothyroidism and any one with that condition or Hashimoto’s thyroiditis should avoid soy products, except for tofu, perhaps, and fermented soy products. There is some controversy surrounding soy products for males, because of the phytoestrogens. Hypothyroidism itself is a risk factor for Diabetes 2 (and Hashimoto’s for Type 1 Diabetes), therefore, avoiding soy is wise in my opinion.

  5. Steve

    There’s not just veggies and fruit left – there’s nuts and cheese for example also (assuming not vegan).

    Although not exactly vegetarian (have heard it called pescitarian – which I think sounds terrible, or also flexi-tarian which I think sounds great) – I put together a typical weekday menu for myself and analysed it. One of the protein sources was fish (240 calories of tinned wild alaskan pink salmon) – everything else was vegetarian.

    What surprised me was that the macro-nutrient percentages came out at 38% carbs, 18.5% protein, and 43.5% fat (predominantly from nuts & olive oil – with a bit coming from whole milk products).

    I expected carbs to be higher. Am pleasantly surprised. This was a well balanced menu, with wholegrains, legumes, veggies, fruits etc.

    I’m extremely encouraged – who said you have to be mediterranean and high carb?


    • Steve

      Just for fun, I cancelled the fish and replaced with 2 eggs and extra lentils (exact same calorie count as the fish). Keeping it vegetarian (although certainly not vegan).

      Came out 41.5% carbs, fat stayed at 43.5% and protein still a reasonable 15%.

      Not bad!

      A Vegetarian & Mediterranean medley – if I was going to be vegetarian, this would appeal to me.


  6. Thanks for sharing, Steve.

    Yes, Jennifer, a vegetarian diet would be carb-heavy. Unless it had LOTS of plant-based oils.

    • Paul B

      I think a vegetarian diet can be low carb, or at least low sugar without being high in fat. Dr. Fuhrman’s approach in Eat to Live might be an example (though he’s not proposed exclusively vegetarian). It would have to emphasize low-sugar fruit such as kiwi, citrus and berries, legumes and lots of vegetables. Fats are limited for nuts and seeds. It isn’t necessarily low carb, but is low sugar.

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  8. Jessica

    Hi, I’m a little late but wanted to contribute my story here. My dad was diagnosed “prediabetic” and sometime after that started on a vegetarian—but not vegan—diet (for reasons of conscience more than health). He also adopted a dog he started walking, and my mom went vegetarian also and was trying to lose weight, so they basically cut out meat and added some high fiber breads and a lot of vegetables. They still eat white flours and cheese and sweets. My dad’s blood sugars went way down, along with his cholesterol, and he got a clean bill of health. He also lost weight, and I’m sure that and the added physical activity contributed to his diabetes reversal, but it’s all kind of wrapped together.
    I’ve been vegetarian for longer than they have, but I tend to eat a lot of breads, pastries, and cheese, and I gained weight at first. However, my diet now involves more salad, fruits, vegetables, lots of nuts (especially raw almonds and walnuts), oats, other whole grains, and beans. Whole grains are actually a pretty good source of protein, in addition to fiber. I think it’s definitely possible to have a low-carb vegetarian diet.
    Here is a study finding better results with a low-fat vegan diet that was 80% carbs when compared with the ADA diet:
    I’m skeptical of the low-fat thing, though, considering the research supporting the Mediterranean diet.

  9. Hey, thanks for chiming in, Jessica. I’m glad your father got such good results!


  10. coralf

    As was the case with Vivian, I was vegetarian for 20 years when I was diagnosed and was on a wholefood diet which clearly has too many carbs for a diabetic. Have adjusted my vegetarian diet’s carb load, I am now enjoying far better glucose control. It is very difficult when I am not in control of the food though and eating out is tricky.

    What I did want to share, was, that before being diagnosed, I ended up in a situation wherein I had to bring my insulin dependant father to live with me. On my high carb, vegetarian diet he had to lower is insulin doses significantly.

    Of course he had to lower them even more after I switched to low carbing.

  11. Thanks for the article.. I have just recently found the vegan lifestyle and I love it. It seems like I just can’t take in enough information.

  12. Lynda

    I too would like to see “real” studies. Neal Barnard and the PCRM are a closely associated branch of PeTA, and the “studies” they put forth are far from scientific. It is their mission to stop all animal husbandry; pets, horses, meat, eggs, fish, etc., and they only employ vegans to “prove their point” that all animal products are bad for you.

    Just for the record, I was a vegetarian for 17 years, always sick and put on a massive amount of weight. As a vegan I became very ill, hypothyroid and infertile. In the next 20 years as a pescatarian I lost a bit of weight and regained some health, but as well as chronic anaemia, I was diagnosed on the edge of diabetes 2. I reintroduced meat and took extra fish oil, and my blood sugar/insulin resistance levels are now fine.

  13. Marta Laliberte

    I always like the vegetarian diet because it makes my body even healthier. *.;.;

    Brand new brief article on our very own blog

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