Legumes and Whole Grains: Any Role in Diabetes?

Expert nutrition panels consistently recommend whole grains and legumes for people with diabetes.  Why?  And do these foods affect development of diabetes?  I found a pertinent scientific review article on the subject from 2004 in the European Journal of Clinical Nutrition.  Here are some pertinent quotes from the summary:

Epidemiological studies strongly support the suggestion that high intakes of whole grain foods protect against the development of type II diabetes mellitus (T2DM). People who consume approximately 3 servings per day of whole grain foods are less likely to develop T2DM than low consumers (<3 servings per week) with a risk reduction in the order of 20-30%.

The role of legumes in the prevention of diabetes is less clear, possibly because of the relatively low intake of leguminous foods in the populations studied. However, legumes share several qualities with whole grains of potential benefit to glycaemic control including slow release carbohydrate and a high fibre content. A substantial increase in dietary intake of legumes as replacement food for more rapidly digested carbohydrate might therefore be expected to improve glycaemic control and thus reduce incident diabetes. This is consistent with the results of dietary intervention studies that have found improvements in glycaemic control after increasing the dietary intake of whole grain foods, legumes, vegetables and fruit.

. . . it is cereal fibre that is largely insoluble [rather than soluble fiber] that is associated with a reduced risk of developing T2DM.

Thus, there is strong evidence to suggest that eating a variety of whole grain foods and legumes is beneficial in the prevention and management of diabetes. This is compatible with advice from around the world that recommends consumption of a wide range of carbohydrate foods from cereals, vegetables, legumes and fruits both for the general population and for people with diabetes.

Gluten Intolerance

A major protein in wheat is gluten.  The last few years have seen the popular emergence of gluten-free this and gluten-free that.  The idea is that gluten causes a variety of gastrointestinal, immunologic, and other problems, so wheat products should be avoided.  Certainly they should be avoided in people with celiac disease, a well-established medical condition.  I follow a few paleo blogs and know that grains and legumes are not part of that way of eating: the paleos say we are not evolved optimally to process them.    

If legumes or wheat or other grains cause problems for you, don’t eat them.  They have no essential nutrients that you can’t get elsewhere. 

Glycemic Index

In my quest to develop a healthy Diabetic Mediterranean Diet, I’m finding that grains—compared to nearly all other carbohydrate-containing food groups—tend to have a higher glycemic index (GI).   A low GI is 55 or less.  High GI is 70 or greater.  Grains in general raise blood sugar levels higher than many other sources of carbohydrates.  But this is highly variable and depends partially on preparation of the grain.  Whole grain products have a lower GI than highly processed counterparts.  For instance, white bread has a GI of 70; whole wheat bread 67.  Regular spaghetti is 38.  Table sugar’s GI must be sky high, right?  No, its just 61.  A baked potato is a whopping 85.   

Beans have a GI around 30 or 40.  And they pack a lot more fiber per serving.  For a diabetic struggling to keep blood sugars under control, which is a better choice: grains or legumes?  I’m leaning towards legumes and other components of a low-glycemic-index diet.   

Steve Parker, M.D.

PS:  [Before you correct my GI numbers, please note I’m  aware that various GI lists don’t agree with each other.]

Reference:  Venn, B.J. and Mann, J.I. Cereal grains, legumes and diabetes.  European Journal of Clinical Nutrition, 58 (2004): 1,443-1,461.


Filed under Fiber, Fruits, Grains, legumes, Prevention of T2 Diabetes, Vegetables

10 responses to “Legumes and Whole Grains: Any Role in Diabetes?

  1. Steve

    Excellent post! This needs to be thought through. It’s been a while since I’ve read about GI (and isn’t GL the new GI?).
    Anyway – a question: could it be the GI of the meal that matters more? I mean, if we dip our bread in olive oil (naturally!), dont we decrease the GI by adding that fat?
    I could be way off on this, but it does make me wonder if higher GI wholefoods are fine if the meal is “complete”.


  2. You’re right, Steve. The GI of the meal would matter more than the GI of an individual food. Problem is, there is no standardization of meal GI’s like there is for single foods. Way too many variations.

    Olive oil, other fats, and proteins – among other meal components – would tend to inhibit the rise in blood sugar after eating a carbohydrate of known GI, effectively lowering the GI. On the other hand, there are probably some foods that raise the GI of another food.

  3. Diets high in fiber are also associated with decreased cardiovascular mortality. I think it’s hard to tease out whether that’s due to fiber or the multitude of other compounds present in fruit and legumes, potentially interacting synergistically.

    This study would seem to suggest that it’s not just the fiber.

  4. Thanks for that link, Isaac.

    The fiber skeptics would say that association is no proof that fiber is helpful in preventing heart disease. They are right, of course.

    Reasonable proof would be to take 20,000 people, randomize them to either a high or low-fiber diet keeping all other things equal, and follow health outcomes for 20 years. A purist would use purified fiber supplement. We could argue about which kind and source of fiber.

    Or we could use specified amounts and types of fruits or vegetables (or a combination) as our fibers source, but then you’ve introduced mutliple variables.

    But how do you MAKE someone stay with their assigned eating plan for 20 years? You can’t.

    That’s why these observational/epidemiologic studes are sometimes the best we can do.

    BTW, I agree that long-term health benefits of fruit and veggie intake are related to more than just fiber.


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  6. annwilson01

    Try to stay away from processed foods that are lacking in nutrients and amino acids. Steer toward fresh fruits, vegetables, and nuts and oats rather than quick-oats or canned goods.
    Low GI Foods is about providing easy to understand guidelines for making Low Glycemic eating a part of your healthy lifestyle. For more Low GI Foods List Visit our site now!

  7. You capture the dilemma I’m trying to negotiate. I try to work around it as best I can by devious means.

    After being on a low GI diet for all of my (apparently) pre-diabetic years, I’m now trying to lower my overall carb intake and legumes are a challenge in that regard as they are so carbohydrate dense.

    Aside from the nutritional value of legumes their carb figures are hard to accommodate if I want to keep within the 100-130 grams of carbohydrate a day range. This spectrum is really working well for me.

    I work the bread question by making my own sourdough bread(on white flour –as the Mediterraneans do) which doesn’t skewer my blood sugar levels. But with the pulses, despite my other trade offs, I think I may be overly exclusionist.

    I’m thinking I can explore a legumous path maybe in tandem with Greek Yogurt — or utilize the power of acids, such as the lemons in a traditional hoummos mix. But no matter how I serve it, I’m still got the same number of carbs inside me.

    But then as I proceed down my chosen route — as my weight continues to fall and my blood sugars stabilize (and fall?) further — maybe then I can take up with the beans?

  8. i would wish to have more literature in as far as recommended legumes for the diabetic is concerned.

  9. Hi, Busiku.

    I haven’t found much scientific literature supporting a role for or against legumes in diabetics, in terms of health anyway. Legumes are a good source of fiber, which helps prevent constipation. Some sources say higher fiber diets help control blood sugar levels. Legumes are also a good source of energy (calories) since they are starchy. That starch, of course, tends to raise blood sugar levels, which could be detrimental.

  10. I think that everything said was actually very logical.
    However, what about this? suppose you added a little content?
    I ain’t saying your information is not good, but what if you added a title to maybe grab people’s attention?
    I mean Legumes and Whole Grains: Any Role in Diabetes?
    | Diabetic Mediterranean Diet is a little plain.

    You ought to peek at Yahoo’s home page and see how they create post titles to grab viewers to click. You might add a related video or a pic or two to grab readers interested about everything’ve got to say.
    Just my opinion, it would make your posts a little livelier.