Regular consumption of tofu, soy protein may lower T2D risk

Higher intakes of tofu, soy protein and soy isoflavones, but not total legumes or total soy, appear to reduce the risk of developing type 2 diabetes (T2D), suggests a study.

Relevant prospective cohort studies were searched up to August 2019 in the following databases: PubMed, Embase and Ovid. The investigators pooled study-specific, multivariable-adjusted relative risk (RR) and 95 percent confidence intervals (CIs).

Fifteen unique cohorts were identified, including 565,810 individuals and 32,093 incident cases. The summary RRs of incident T2D were as follows: 0.95 (95 percent CI, 0.79–1.14) for total legumes, 0.83 (95 percent CI, 0.68–1.01) for total soy, 0.89 (95 percent CI, 0.71–1.11) for soy milk, 0.92 (95 percent CI, 0.84–0.99) for tofu, 0.84 (95 percent CI, 0.75–0.95) for soy protein, and 0.88 (95 percent CI, 0.81–0.96) for soy isoflavones.

There was high heterogeneity for total legumes (I², 84.8 percent), total soy (I², 90.8 percent) and soy milk (I², 91.7 percent). Potential sources of heterogeneity for total legume or soy milk were not clear. However, heterogeneity for total soy was predicted by geographic location (Asia, US; p=0.04) and study quality (high, moderate or low; p=0.02).

Dose–response analysis revealed significant linear inverse associations for tofu, soy protein and soy isoflavones (p_all<0.05). Overall quality of evidence was moderate for total legumes and low for total soy and soy subtypes.

“Our findings support recommendations to increase intakes of certain soy products for the prevention of T2D,” the authors said. “However, the overall quality of evidence was low and more high-quality evidence from prospective studies is needed.“