Increasing nut consumption may reduce risk of coronary heart disease, stroke

Adults who increased their nut intake by a handful of nuts per day had a 29 percent relative risk reduction for coronary heart disease, a 7 percent relative risk reduction for stroke and a 21 percent relative reduction for cardiovascular disease, according to a meta-analysis of 20 prospective studies.

Lead researcher Dagfinn Aune, MS, of Imperial College London in the United Kingdom, and colleagues published their results online in BMC Medicine on Dec. 5.

“We found a consistent reduction in risk across many different diseases, which is a strong indication that there is a real underlying relationship between nut consumption and different health outcomes,” Aune said in a news release. “It’s quite a substantial effect for such a small amount of food.”

The researchers searched the PubMed and EMBASE databases from their inception until July 19, 2016, for cohort studies, case-cohort studies, nested case–control studies within cohort studies and randomized trials that evaluated any type of edible nut consumption in a mainly adult population.

Of the 20 studies, nine were from the U.S., six were from Europe, four were from Asia and one was from Australia. The analysis included 12,331 coronary heart disease cases, 9,272 stroke cases, 18,655 cardiovascular disease cases, 18,490 cancer cases and 85,870 deaths.

The researchers found that a 10 grams per day increase in tree nut intake was associated with a 27 percent relative risk reduction in coronary heart disease, an 11 percent relative risk reduction in stroke, a 25 percent relative risk reduction in cardiovascular disease and an 18 percent relative risk reduction in all-cause mortality.

Meanwhile, a 10 grams per day increase in peanut intake was associated with a 31 percent relative risk reduction in coronary heart disease, a 37 percent relative risk reduction in stroke, a 36 percent relative risk reduction in cardiovascular disease and a 23 percent relative risk reduction in all-cause mortality.

The researchers mentioned there was an indication of a stronger association between nut intake and cardiovascular disease in men compared with women. There were no differences in sexes for the other outcomes.

If the associations observed between nut consumption and mortality were causal, the researchers mentioned 4.4 million deaths in 2013 could be attributable to a nut intake of less than 20 grams per day. That estimate included 1.19 million deaths due to coronary heart disease, 469,000 deaths due to cancer, 1.07 million deaths due to respiratory disease and 139,000 deaths due to diabetes.

Still, the researchers mentioned a few limitations of their analysis, including that there was high heterogeneity in the analysis of cardiovascular disease and all-cause mortality. There was also a limited number of studies that investigated specific types of nuts.

“These findings support recommendations to increase intake of nuts to reduce risk of chronic diseases and premature mortality in the general population,” the researchers wrote. “However, in regions of the world where nuts are a major source of aflatoxin, increasing nut intake should only be recommended as long as aflatoxin contamination is avoided in the affected countries. Any further studies should investigate associations with specific types of nuts and the association between nut intake and incidence and mortality from less common diseases, adjust for more dietary confounders, clarify mechanisms underlying non-cardiovascular causes of death, and investigate associations between biomarkers of nut consumption in relation to health outcomes. In addition, further studies from other regions of the world are also needed.”