In a new review and meta-analysis, researchers have found that nut consumption is associated with a lower risk of specific cancers but not on the risk of type 2 diabetes.
Wu L, Wand Z, Zhu J, Murad AL, Prokop LJ, Murad MH. Nut consumption and risk of cancer and type 2 diabetes: a systematic review and meta-analysis. Nutr Rev. 2015;73(7):409-425.
A systematic search and meta-analysis was performed on cohort and case-control studies and clinical trials that could provide data related to nut consumption and association with type 2 diabetes mellitus (DM2) or specific cancers.
Eligible studies included epidemiological studies (case-control and cohort) or clinical trials that reported an association between nut consumption and the outcome of DM2 or specific cancers. This meta-analysis included 36 observational studies with a total of 30,708 individuals from the general population who were followed for between 4.6 and 30 years.
Nut consumption vs diagnosis with DM2 or cancer
Individuals in the highest category of nut consumption compared to those in the lowest category had a significantly lower relative risk (RR) of colorectal cancer (RR:0.76), endometrial cancer (RR:0.58), and pancreatic cancer (RR:0.68). Overall, nut consumption was significantly associated with a reduced risk of cancer incidence (RR:0.85; 95% confidence interval:0.76-0.95). No significant association was found with other specific cancers or DM2.
This meta-analysis is the first of its kind to summarize the available evidence on the associations between nut intake and cancer incidence. The most relevant finding is the 15% reduced risk for incident cancers overall in those with the highest nut consumption vs those with the lowest.
The finding of no association between nut consumption and diabetes comes as something of a surprise. In a series of articles, Kendall and colleagues have reported that nuts, in particular almonds,1,2 and pistachios,3 have a low glycemic effect, little effect on postprandial serum glucose levels, and a dose-dependent effect on insulin response.1 Others have reported that eating nuts is associated with lower levels of inflammatory cytokines and higher levels of adiponectin,4 traits one would expect to be associated with decreased DM2 risk. These and other actions associated with nut consumption, when taken together, suggest consumption might lower DM2 risk. The absence of association seen in these results is contrary to other reviews that suggest there is an inverse relationship between incident diabetes and nut consumption.5,6 It also should not detract from the evidence for better glycemic control in those with an established diagnosis of diabetes.7
Advising patients to eat more nuts may make a significant difference in their health.
The health benefits of nuts go beyond cancer prevention. Previous studies have suggested that nut consumption may lower risk of coronary disease,8 sudden cardiac death in men9 and women,10 and the risk of developing gallstones in men11 and women.12 Eating nuts does not appear to have a negative impact on body weight, insulin resistance, or energy balance.13
Advising patients to eat more nuts may make a significant difference in their health. A good recommendation to patients is that they should eat 1 oz to 1.5 oz of nuts four to five times a week.