A handful of peanuts a day keeps stroke, CVD risks at bay in Asians

Eating even small amounts of peanuts every day is enough to lower the risk of stroke and cardiovascular disease (CVD) in both men and women, as shown in a recent study from Japan.

In a cohort of 74,793 adults aged 45–74 years, the highest vs lowest quartile (4.3 vs 0 g/day) of peanut consumption conferred a reduction of 16 percent, 20 percent, and 13 percent in the risks of stroke, ischaemic stroke, and CVD, respectively. However, this benefit was not seen for haemorrhagic stroke or ischaemic heart disease. [Stroke 2021;doi:10.1161/STROKEAHA.120.031212]

“To the best of our knowledge, this is the first study to show the reduced risk for ischaemic stroke associated with peanut consumption. Our finding may be supported by biological effects of certain nutrients contained in peanut,” according to lead study author Dr Satoyo Ikehara of the Osaka University Graduate School of Medicine in Suita, Japan.

For the most part, peanuts are rich in certain nutrients that have been shown to have cardioprotective effects, Ikehara noted. Monounsaturated and polyunsaturated fatty acids can reduce the risk of CVD, whereas other nutrients such as magnesium, dietary fibre, folate, and vitamin E23 are beneficial for lowering the risks of hypertension and stroke. [Am J Clin Nutr 2015;102:1563-1573; Circulation 2014;130:1568-1578; Nutr J 2017;16:26; Eur J Clin Nutr 2013;67:96-100; Stroke 2013;44:1360-1368]

In the study, Ikehara and his team assessed the amount and frequency of peanut intake of the participants using data obtained from a validated food frequency questionnaire. The standard portion size of peanut consumption was 20 g or about 20 peanuts.

Participants with higher vs lower peanut consumption were younger, less likely to have a history of hypertension, diabetes, and smoking, and tended to be physically active. Higher peanut intake correlated positively with total energy and nutrient intake in both men and women.

Over a median follow-up of 14.8 years, there were 3,599 and 849 incident cases of stroke and ischaemic heart disease, respectively. In multivariable Cox proportional hazard models, the hazard ratios associated with the highest versus lowest quartiles of peanut consumption were 0.84 (95 percent confidence interval [CI], 0.77–0.93; p=0.002) for total stroke, 0.80 (95 percent CI, 0.71–0.90; p=0.002) for ischaemic stroke, 0.93 (95 percent CI, 0.79–1.08; p=0.27) for haemorrhagic stroke, 0.97 (95 percent CI, 0.80–1.17; p=0.81) for ischaemic heart disease, and 0.87 (95 percent CI, 0.80–0.94; p=0.004) for CVD. The estimates were similar in men and women.

“Our results were partially consistent with the results [of a combined analysis of three US cohorts that] showed that peanut consumption was inversely associated with the risks of CVD, stroke, and coronary heart disease,” Ikehara said. [J Am Coll Cardiol 2017;70:2519-2532]

“The lack of association between peanut consumption and the risk of ischaemic heart disease in this study may be due to the smaller range of peanut consumption (median peanut intake in the highest category was 4.3 g/d in this study vs 8.0–12.0 g/d in the US study) and the smaller number of cases for ischaemic heart disease (849 in this study vs 8,390 in the US study),” he admitted.

Ikehara also acknowledged peanut consumption as a potential marker of healthy dietary patterns. But he explained that their data were robust to adjustment for modified Dietary Approaches to Stop Hypertension dietary pattern score, suggesting that peanut consumption may indeed lower the risk of CVD independently of a healthy dietary pattern.

Meanwhile, in a linked commentary, Dr Walter Kernan of Yale School of Medicine in New Haven, Connecticut, US, noted, “the findings of observational research, such as the peanut study here, do not support class 1 recommendations in professional guidelines for prevention of stroke.” [Stroke 2021;doi:10.1161/STROKEAHA.121.036172]

The 2021 American Heart Association guideline for stroke prevention of in patients with stroke and transient ischaemic attack assigns a class 2a recommendation for a Mediterranean diet as “reasonable.” On the other hand, recommendations for statin therapy, antiplatelet therapy, certain diabetes drugs, carotid surgery, and exercise are stronger (class 1). [Stroke 2021;52:e364-e467]

Kernan chalked up the discrepancy in the strength of recommendations to the lack of high-quality randomized clinical trial evidence for the effectiveness of a healthy diet.

As such, the expert called for a definitive phase III diet trial in stoke patients. “This would not be easy. If trials confirm a treatment effect on hard end points, however, lifestyle treatment facilities might finally enter the fabric of healthcare… I predict that many would serve peanuts at check-in.”