Nuts are good for you. This is a known fact, supported by an ever-growing number of studies. For instance, Medical News Today have recently reported on a major study showing that only a handful of nuts every day slashes the risk of premature death.
Diabetes risk drops by 40 percent with only 20 grams of nuts per day, and the risk of infectious diseases drops by 75 percent. Other studies have suggested that nuts can protect our memory and even boost intelligence.
But what might nuts do for our cardiovascular health? The new study — led by Marta Guasch-Ferré, Ph.D., a research fellow in the Department of Nutrition at Harvard T.H. Chan School of Public Health in Boston, MA — examines the link between the frequency of nut consumption and the incidence of cardiovascular disease.
Additionally, and in contrast with previous research on the subject, this study also looks at specific kinds of nut and their impact on cardiovascular health.
Studying nut consumption and heart health
Guasch-Ferré and her team examined more than 210,000 people, combining data from the Nurses' Health Study I and II as well as the Health Professionals Follow-up Study.
Overall, they followed the participants for a total of 32 years, with medical and lifestyle information being collected every 2 years using self-administered questionnaires.
Food-frequency questionnaires offered the researchers information about the participants' nut consumption every 4 years.
The researchers focused on major cardiovascular disease, defined as myocardial infarction, stroke, or fatal cardiovascular disease. Additionally, they looked at the total incidence of coronary heart disease, understood as fatal or non-fatal myocardial infarction, and the total incidence of stroke, either fatal or non-fatal.
During the study period, the researchers recorded 14,136 cases of cardiovascular disease, 8,390 of which were coronary heart disease and 5,910 of which were stroke.
Nuts cut risk of cardiovascular disease
Total nut consumption and total cardiovascular and coronary heart disease risk were found to be inversely related. In other words, the more nuts one consumes, the lower one's chances are of developing these conditions.
A more in-depth look at specific kinds of nut revealed that walnuts are particularly good for cardiovascular health.
Consuming walnuts two to three times every week was associated with a 19 percent decrease in cardiovascular risk, and a 21 percent decrease in coronary heart disease risk.
Eating peanuts at least twice each week was linked with a 13 percent lower risk of cardiovascular disease, and tree nuts with a 15 percent lower cardiovascular risk.
Peanut intake also correlated with a 15 percent reduction in coronary heart disease risk, and tree nuts with a 23 percent risk reduction.
Five or more servings of nuts per week correlated with a 14 percent decrease in cardiovascular risk and a 20 percent lower risk of coronary heart disease.
"In three large prospective cohort studies," the study authors conclude, "higher consumption of total and specific types of nuts was inversely associated with total cardiovascular disease and coronary heart disease."
'Raw nuts as natural health capsules'
"Our findings support recommendations of increasing the intake of a variety of nuts, as part of healthy dietary patterns, to reduce the risk of chronic disease in the general populations," says Guasch-Ferré.
She and her colleagues also note some study limitations. The sample of participants was restricted to health professionals — most of whom were white — and the method of self-reported data is always prone to errors.
However, the authors emphasize that in their opinion, there is no reason why the findings would not be generalizable to other ethnicities.
Dr. Emilio Ros, of the Endocrinology and Nutrition service at the Hospital Clínic in Barcelona, Spain, wrote an accompanying editorial, in which he comments on the significance of the findings.
"Ideally," he says, "further investigations should test the effects of long-term consumption of nuts supplemented into the usual diet on hard cardiometabolic events."
"In the meantime, raw nuts, if possible unpeeled and otherwise unprocessed, may be considered as natural health capsules that can be easily incorporated into any heart-protective diet to further cardiovascular well-being and promote healthy aging."
Dr. Emilio Ros