Summary: A study conducted on Japanese men and women found peanut consumption decreased the risk of cardiovascular disease and ischemic stroke.
Source: American Heart Association
Asian men and women living in Japan who ate peanuts (on average 4-5 peanuts/day) had a lower risk of having an ischemic stroke or a cardiovascular disease event compared to those who did not eat peanuts, according to new research published today in Stroke.
While previous studies have linked peanut consumption with improved cardiovascular health among Americans, researchers in this study specifically examined the link between peanut consumption and the incidence of different types of stroke (ischemic and hemorrhagic) and cardiovascular disease events (such as stroke and ischemic heart disease) among Japanese men and women.
“We showed for the first time a reduced risk for ischemic stroke incidence associated with higher peanut consumption in an Asian population,” said lead study author Satoyo Ikehara, Ph.D., specially appointed associate professor of public health in the department of social medicine at the Osaka University Graduate School of Medicine in Suita, Japan. “Our results suggest that adding peanuts to your diet has a beneficial effect on the prevention of ischemic stroke.”
Peanuts are rich in heart-healthy nutrients, such as “monounsaturated fatty acids, polyunsaturated fatty acids, minerals, vitamins and dietary fiber that help lower risk of cardiovascular disease by reducing risk factors, including high blood pressure, high blood levels of ’bad’ cholesterol and chronic inflammation,” Ikehara said.
Researchers examined the frequency of how often people reported eating peanuts in relation to stroke occurrence and cardiovascular disease. The analysis includes people who were recruited in two phases, in 1995 and 1998-1999, for a total of more than 74,000 Asian men and women, ages 45 to 74, from the Japan Public Health Center-based Prospective Study.
Participants completed a comprehensive lifestyle survey, which included a questionnaire about the frequency of peanut consumption. They were followed for approximately 15 years – through 2009 or 2012, depending on when they were originally enrolled.
The incidence of stroke and ischemic heart disease were determined by linking with 78 participating hospitals in the areas included in the study.
Researchers adjusted for other health conditions, smoking, diet, alcohol consumption and physical activity, as detailed by participants in the questionnaires. According to medical records, researchers noted 3,599 strokes (2,223 ischemic and 1,376 hemorrhagic) and 849 cases of ischemic heart disease developed during the follow-up period.
The levels of peanut consumption were ranked in four quartiles, with 0 peanuts a day as the least intake compared to 4.3 unshelled peanuts a day (median) as the highest. Compared to a peanut-free diet, researchers found eating about 4-5 unshelled peanuts per day was associated with:
20% lower risk of ischemic stroke;
16% lower risk of total stroke; and
13% lower risk of having cardiovascular disease (this included both stroke and ischemic heart disease).
A significant association was not found between peanut consumption and a lower risk of hemorrhagic stroke or ischemic heart disease.
The link between peanut consumption and lowered risk of stroke and cardiovascular disease was consistent in both men and women.
“The beneficial effect of peanut consumption on risk of stroke, especially ischemic stroke was found, despite the small quantity of peanuts eaten by study participants,”Ikehara said. “The habit of eating peanuts and tree nuts is still not common in Asian countries. However, adding even a small amount to one’s diet could be a simple yet effective approach to help reduce the risk of cardiovascular disease.”
The American Heart Association recommends eating about five servings of unsalted nuts per week; one serving is ½ ounce (2 tablespoons) of nuts. Besides peanuts, the Association also says other healthy nut options include unsalted cashews, walnuts, pecans, macadamia nuts and hazelnuts.
Several limitations were noted in the study, including the validity and reliability of peanut consumption measurements in the data collection and analysis. Bias caused by these measurements may lead to errors in the association. However, a measurement error correction analysis was performed, and the associations proved to be accurate.
Peanut Consumption and Risk of Stroke and Ischemic Heart Disease in Japanese Men and Women: The JPHC Study
Background and Purpose:
Several prospective cohort studies and a randomized clinical trial have shown the beneficial effects of peanut consumption on cardiovascular disease and its risk factors. We examined the association between peanut consumption and risk of cardiovascular disease in Japanese men and women.
We analyzed data of 74 793 participants aged 45 to 74 years who completed a lifestyle questionnaire including the validated food frequency questionnaire in the Japan Public Health Center–based Prospective Study. They were followed up from 1995 to 2009 for cohort I and from 1998 to 1999 to 2012 for cohort II. Peanut consumption was calculated from the food frequency questionnaire, and the end points were incidence of stroke, ischemic heart disease, and cardiovascular disease (stroke and ischemic heart disease).
During a median follow-up of 14.8 years, 3,599 strokes and 849 ischemic heart diseases were reported. Higher peanut consumption was associated with reduced risks of total stroke, ischemic stroke, and cardiovascular disease among men and women. The multivariable hazard ratios (95% CIs) for the highest versus lowest quartiles of peanut consumption after adjustment for age, sex, public health center, smoking, alcohol consumption, perceived stress level, physical activity, vegetable, fruit, fish, soy, sodium and total energy intakes, body mass index, history of hypertension, history of diabetes, and cholesterol-lowering drug were 0.84 (0.77–0.93, P for trend=0.002) for total stroke, 0.80 (0.71–0.90, P for trend=0.002) for ischemic stroke, 0.93 (0.79–1.08, P for trend=0.27) for hemorrhagic stroke, 0.97 (0.80–1.17, P for trend=0.81) for ischemic heart disease and 0.87 (0.80–0.94, P for trend=0.004) for cardiovascular disease, and these associations were similarly observed in both sexes.
Higher peanut consumption was associated with reduced risk of stroke, especially ischemic stroke, but not ischemic heart disease in Japanese men and women.