This systematic review set out to establish whether whole grains specifically contribute to a reduction in the risk of developing type 2 diabetes.
In healthy indivduals, is consumption of whole grains associated with a reduced risk of type 2 diabetes.
The reviewers were also interested in the effects on cardiovascular disease and weight.
The reviewers found and analysed the findings of 45 prospective cohort studies and 21 randomised controlled trials (RCT). They found that, compared with people who did not consume whole grains, people who ate three to five servings per day (48-80g) had:
- a relative risk (RR) of 0.74 (95% CI: 0.69, 0.80) for developing type 2 diabetes
- a RR of 0.79 (95% CI: 0.74, 0.85)] for cardiovascular disease, and
- consistently less weight gain during an average 8-13 years of follow-up.
- The literature search was carried out in February 2012.
- Were the different studies comparable and does it make sense to combine them?
- What was the quality of the studies?
- What other analyses did they carry out? Were they all specified in advance or were they data-driven?
- Could these results be explained by other factors such as associated dietary or lifestyle behaviours?
- What sensitivity analyses were carried out? What were the results when the analysis was limited to RCTs only?
Ye EQ, Chacko SA, Chou EL, Kugizaki M, Liu S. Greater Whole-Grain Intake Is Associated with Lower Risk of Type 2 Diabetes, Cardiovascular Disease, and Weight Gain. J Nutr. 2012 May 30. [Epub ahead of print]