No Diabetes Benefit from Soy Supplements: New Study

Soy supplements may not improve blood glucose control in women with prediabetes (a condition in which blood glucose levels are elevated, but not high enough for a diagnosis of diabetes) or recently diagnosed with Type 2 diabetes, according to a recent study in the American Journal of Clinical Nutrition. Past research into soy’s effects on diabetes has yielded conflicting results.


Laboratory research has suggested that estrogen-like compounds in soy known as soy isoflavones might help to lower blood glucose levels. To test this theory, researchers at the Chinese University of Hong Kong recruited 180 postmenopausal women who either had prediabetes or had recently been diagnosed with Type 2 diabetes and had not yet begun treatment. The women were randomly assigned to one of three groups: one took a supplement containing milk protein, one a supplement containing milk protein and soy isoflavones, and the third a supplement containing soy protein and additional soy isoflavones each morning for six months. Aside from the addition of the supplement, the participants were instructed to maintain their usual diets.

At the end of the trial period, neither the soy protein with additional isoflavones nor the milk protein with isoflavones showed any clear benefit in controlling blood glucose or insulin levels. According to the researchers, the soy supplement had a “marginally favorable benefit” on the women’s blood glucose levels two hours after eating, but not enough to indicate that soy or isoflavone supplements are useful for lowering blood glucose in older women with prediabetes or Type 2 diabetes.

Nonetheless, the researchers note that this appears to be the first controlled clinical trial investigating the use of soy supplements in people with prediabetes and early Type 2 diabetes and suggest that “Additional studies that are based on longer trials using different soy and phytoestrogen regimens are warranted.”

To learn more, read the article “Soy supplements show no diabetes benefit in study” or see the study’s abstract in the American Journal of Clinical Nutrition.

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  • Anonymous

    Sugar and White flour are the main things that effec type 2 diabetics. Sugar and white flour are as addicting as drugs or alcohol. Food adiction is not often mentioned but I know from my own battle with type 2 that it’s true. I found recovery from food addiction, and I’m off all MEDS.

  • Mike

    There is a post and poll for “Should dietary supplements with clinical evidence be incorporated in the diet”.

    In this post “Soy Beverage Enriched with Bioactive Peptides from Soy and Whey Proteins Lower Blood Sugar and HbA1c in a Multicenter Clinical Study”. I have deliberately removed the companany name and web site as this should not be used for promotional purposes but for scientific and rational discussions.

    The following is the reply to that post.

    This seems to have credible research and I completely support products like this. However, the biggest challenge is to find the credible research and ethical manufacturers. These days everybody is making shortcuts to make quick money.

    I do not agree for regulation by FDA on dietary supplements but at the same there got to be a mechanism to crack down products with false claims.

    This is definitely an interesting topic for discussion.

    I really would like to see a stimulating discussion on this.

    What I have seen so far on “soy research” is a mixed bag because the research reporting is not CONSISTENT. To make it simple irrespective of using soy flour, soy protein concentrte, soy protein isolate, soy milk, etc., people report it as simly “soy”. However, there are big differences between these products. For this reason recently NIH gave guidelines so that in the future it will be consistent.