Flavonol Intake may Influence Diabetes Risk

by | Nov 22, 2013 | 2013, Antioxidants, Diabetes, Flavonoids, Polyphenols

Written by Greg Arnold, DC, CSCS. Increased intake of flavonoids (found in foods such as tea, apples, and pears) showed a significant reduction in the risk of type II diabetes.

In 2011, diabetes cost our healthcare system $245 billion and currently affects nearly 26 million Americans, with 79 million more with “pre-diabetes”. In addition to having 2 to 4 times greater risk for stroke, diabetes is the leading cause of blindness in Americans 20-74 years of age (1).

Perhaps the most frustrating aspect of diabetes is that is a preventable disease, with diet playing the most significant role (2), especially fruit and vegetable intake (3). The health benefits from fruit and vegetable consumption lie not only in their high amounts of fiber (4), potassium (5), and magnesium (6), but also from antioxidants called polyphenols (7) and, in particular, a class of polyphenols called flavonoids. Research has suggested that flavonoids can improve blood sugar control (8) and help maintain insulin sensitivity (9).

Now a new study (10) suggests that increased flavonoid intake may influence diabetes risk. In the study, researchers analyzed dietary records of 2,915 subjects who participated in the Framingham Heart Study (11). They reported their overall dietary intake with the Harvard Food Frequency Questionnaire (12) and specific flavonoid intake using a food frequency questionnaire from previous research (13) including the flavonols quercetin, kaempferol, myricetin, and isohamnetin. The researchers classified subjects as having diabetes as a fasting plasma glucose concentration >7.0 mmol/L and a 2-hour oral glucose tolerance test glucose concentration >11.1 mmol/L.

The researchers found that compared to those with the lowest flavonol intake per day (85 milligrams per day), those with the highest flavonol intake per day (537 mg per day) had a 26% reduced risk of type 2 diabetes (p = 0.001). When looking at the types of foods that contributed to the highest levels of flavonol intake, tea, apples, and pears together contributed to 30% of the flavonol intake. The researchers also noted that 99% of all diabetes cases seen in the Framingham Study were type 2 diabetes (14).

Citing previous research showing a 16% reduced risk of type 2 diabetes in nurses (15) and a 12% reduced risk of type 2 diabetes in doctors with increased flavonol intake (16), the researchers admitted a weakness of their research (and previous research) in relying on food frequency questionnaires to estimate flavonol intake versus giving specific diets and/or nutritional supplementation to get a more specific flavonol intake. Also in an uncontrolled study other factors could be involved in the benefits found. To confirm the role of flavonoids in diabetes, a supplementation study should be done with a control group and specific amounts of flavonols added to the test group.

They concluded that “the evidence relating flavonoid class intake to risk of type 2 diabetes is promising, although still very limited” and “our knowledge of the effects of flavonoids on type 2 diabetes risk would greatly benefit from additional human intervention studies and prospective observational studies examining relations with markers of type 2 diabetes risk.”

Greg Arnold is a Chiropractic Physician practicing in Hauppauge, NY.  You can contact Dr. Arnold directly by emailing him at PitchingDoc@msn.com or visiting his web site at www.PitchingDoc.com

Source: Jacques, Paul F., et al. “Higher dietary flavonol intake is associated with lower incidence of type 2 diabetes.” The Journal of nutrition 143.9 (2013): 1474-1480.

© 2013 American Society for Nutrition

Posted September 17, 2013.

References:

  1. “Diabetes Statistics” posted on the American Diabetes Association Website
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  3. McEvoy CT, Temple N, Woodside JV. Vegetarian diets, low-meat diets and health: a review. Public Health Nutr. 2012;15:2287–94
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  10. Jacques PF. Higher Dietary Flavonol Intake Is Associated with Lower Incidence of Type 2 Diabetes.  J Nutr 2013 Sep;143(9):1474-80. doi: 10.3945/jn.113.177212
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