MedWire News: High intake of fiber and magnesium decrease the risk for developing Type 2 diabetes, show results from the Hawaii component of the Multiethnic Cohort (MEC).
The researchers also observed that individuals with the highest glycemic load had a significantly increased risk for Type 2 diabetes.
The MEC was set up during 1993–1996 and included men and women aged 45–75 years. The original cohort consisted of a California and a Hawaii group, but this analysis is limited to the Hawaii component (n=75,512) due to availability of data about diabetes incidence. Individuals in the Hawaii group were mostly from Caucasian, Japanese–American, and Native–Hawaiian ethnic backgrounds.
All participants completed a validated quantitative food frequency questionnaire at baseline, after which they were followed up for 14 years. Overall, 8587 individuals developed incident Type 2 diabetes over the study period.
Writing in the Journal of Nutrition, Gertraud Maskarinec (University of Hawaii, Honolulu, USA) and co-authors report that men and women in the highest quintile for fiber intake (14.2 g/[4184 kJ/day] or more) were 25% and 5%, respectively, less likely to develop Type 2 diabetes than those in the lowest quintile (less than 7.4 g/[4184 kJ/day]).
When fiber type was taken into consideration, high intake of vegetable fiber (5.3 g/[4184 kJ/day] or more) reduced the risk for Type 2 diabetes in men by 22%, but not women. High intake of grain fiber (4.8 g/[4184 kJ/day] or more) reduced the risk for Type 2 diabetes by 10% in men and women alike.
Of note, adjusting for body mass index did not significantly influence these associations. However, there was noticeable variation between ethnic groups.
Magnesium intake of 185.4 mg/(4184 kJ/day) or more compared with less than 129.3 mg/(4184 kJ/day) reduced the risk for developing Type 2 diabetes by 16–23% in women and men, which “due to its strong correlation with fiber, may explain the protective effect of fiber,” say the researchers.
In addition, Caucasian men and women and Native Hawaiian women in the top quintile for glycemic load had a significantly increased risk for incident Type 2 diabetes compared with those in the bottom quintile. This association was not seen in Native Hawaiian men or in Japanese–American individuals, however.
“These findings suggest that protection against diabetes can be achieved through food choices after taking into account body weight, but, due to differences in commonly consumed foods, risk estimates may differ by ethnic group,” conclude Maskarinec et al.
They add that the results of this research agree with those of previous studies showing a protective effect of dietary fiber against Type 2 diabetes.
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