Whole grain foods may significantly lower risk of Type 2 Diabetes

Increased consumption of whole grains and whole grain foods can significantly lower the risk of Type 2 Diabetes (T2D), finds a recent study. The study was published in the journal, 'The BMJ' 2020.

Consumption of whole grains can reduce the risk of developing several major chronic diseases like T2D, cardiovascular disease, obesity, and some types of cancer because of the high content of dietary fibre, antioxidants, and phytochemicals. These can reduce fat mass, increase resting metabolic rate and insulin sensitivity, improve the lipid profile, and reduce systemic inflammation.

Researchers at the Harvard school of Public Health examined the association between the intake of whole grain foods and the risk of type 2 diabetes. The study was a prospective cohort and included 158 259 women and 36 525 men who did not have type 2 diabetes, cardiovascular disease, or cancer at baseline. The participants were taken from the Nurses' Health Study (1984-2014), Nurses' Health Study II (1991-2017), and Health Professionals Follow-Up Study (1986-2016), United States by using the questionnaires. The key outcome measure was the Self-reports of incident type 2 diabetes by participants identified through follow-up questionnaires and confirmed by a validated supplementary questionnaire.

The key findings of the study were:

1. 18 629 participants with type 2 diabetes were identified.
2. Total whole grain consumption was categorized into five equal groups of servings a day for the three cohorts.
3. participants in the highest category for total whole grain consumption had a 29% lower rate of type 2 diabetes compared with those in the lowest category.
4. For individual whole grain foods, pooled hazard ratios for type 2 diabetes in participants consuming one or more servings a day compared with those consuming less than one serving a month were 0.81 for whole grain cold breakfast cereal, 0.79 for dark bread, and 1.08 for popcorn.
5. For other individual whole grains with lower average intake levels, comparing consumption of two or more servings a week with less than one serving a month, the pooled hazard ratios were 0.79 for oatmeal, 0.88 for brown rice, 0.85 for added bran, and 0.88 for wheat germ.
6. Spline regression showed a non-linear dose-response association between total whole grain intake and the risk of type 2 diabetes where the rate reduction slightly plateaued at more than two servings a day (P<0.001 for curvature).
7. For whole grain cold breakfast cereal and dark bread, the rate reduction plateaued at about 0.5 servings a day.
8. For consumption of popcorn, a J shaped association was found where the rate of type 2 diabetes was not significantly raised until consumption exceeded about one serving a day.
9. The association between higher total whole grain intake and lower risk of type 2 diabetes was stronger in individuals who were lean
   than in those who were overweight or obese (P=0.003 for interaction), and the associations did not vary significantly across levels of physical activity, family history of diabetes, or smoking status.

Thus, the researchers concluded that Higher consumption of total whole grains and several commonly eaten whole grain foods, like whole grain breakfast cereal, oatmeal, dark bread, brown rice, added bran, and wheat germ, was significantly associated with a lower risk of type 2 diabetes and also recommended on increasing whole grain consumption as part of a healthy diet for the prevention of type 2 diabetes. 

For further reading, click the following link: https://doi.org/10.1136/bmj.m2206