Nut intake not linked to T2D development, but peanut butter may reduce risk

Consumption of peanut, tree nut, or total nut shows no significant association with the risk for type 2 diabetes, a recent study has shown. However, peanut butter consumption appears to lower the risk for this disease.

The investigators systematically searched the databases of PubMed and Cochrane through 12 August 2020. They used the inverse variance method with fixed-effects models to pool data across studies, expressed as risk ratios (RRs) or odds ratios (ORs) with 95 percent confidence intervals (CIs) for prospective cohort and cross-sectional studies, respectively.

In addition, the Cochran Q test and I² statistics were used to test and quantify heterogeneity, respectively. Dose-response meta-analyses was also carried out.

Eight studies (five prospective and three cross-sectional) were eligible for the quantitative synthesis. In meta-analysis of cross-sectional and prospective cohort studies, comparing the highest with the lowest categories, total nut consumption was nonsignificantly associated with T2D.

On the other hand, meta-analyses of prospective cohort studies revealed an inverse association between peanut butter intake and T2D incidence (RR, 0.87, 95 percent CI, 0.77–0.98; I², 50.6 percent; p_{heterogeneity}=0.16), but no association was seen between peanuts or tree nuts consumption and T2D.

In prospective cohort studies, no evidence was found of either a linear or a nonlinear dose-response gradient for total nut and peanut consumption. Of note, the certainty of the evidence using NutriGrade was very low for all exposures.

“Previous meta-analyses, with some methodological controversies, have assessed the relation between nut consumption and T2D risk and pointed to contradictory results, making desirable the performance of an updated meta-analysis,” the investigators said.