What can you add to a wide variety of dishes, from cereals to salads, that are crunchy, satisfying, and tasty – as well as heart-healthy? The answer is nuts. While all nuts are packed with beneficial nutrients, walnuts may be especially beneficial for cardiovascular health, according to a recent study published in the journal Circulation that corroborates prior research in this area.
What is the purpose of the study?
The Walnuts and Healthy Aging research was a randomized controlled experiment funded by the California Walnut Commission. It followed healthy older persons in two towns. Researchers divided 708 adults aged 63 to 79 residing in Loma Linda, California, or Barcelona, Spain, into two groups for the study. For two years, one group consumed a half-cup of walnuts daily, while the other group did not.
After two years, the walnut group had somewhat reduced average levels of dangerous low-density lipoprotein (LDL) cholesterol. Notably, roughly a third of participants were taking cholesterol-lowering statins, indicating that both groups' average cholesterol levels were already within the normal range. According to the study, the cholesterol-lowering effects of walnuts may be more obvious among persons who have increased cholesterol levels. There is no way to tell if this is true based on current data.
"This latest experiment verifies what other research has discovered, namely that eating walnuts appears to lower cholesterol levels," says Dr. Deirdre Tobias, obesity and nutritional epidemiology at Harvard-affiliated Brigham and Women's Hospital. Additionally, the current research lasted significantly longer than previous walnut investigations. However, it is unclear whether foods were substituted for walnuts in the participants' diets, which could impact the amount of the advantages observed by the researchers. For instance, Dr. Tobias notes that substituting walnuts for unhealthy, ultra-processed snacks would probably have a bigger benefit than a lateral shift from healthy to walnuts.
Reduced amounts of harmful blood fats, no weight gain
Additionally, the researchers determined the concentration and size of LDL particles. Smaller, denser LDL particles are more likely to cause atherosclerosis, the development of fatty plaque in arteries that is the hallmark of the majority of cardiovascular disease and resulting in heart attacks or strokes.
These smaller particles were found in lower concentrations among walnut eaters. Additionally, they had lower levels of intermediate-density lipoproteins (IDL), which are associated with an increase in cardiovascular risks. And despite the fact that a half-cup of walnuts contains approximately 185 calories, the walnut eaters did not gain any weight.
Earlier research has established that those who consume nuts on a daily basis have a lower risk of developing heart disease, and numerous studies have focused specifically on walnuts. In 2018, Harvard researchers and two Spanish colleagues conducted a meta-analysis and systematic review of studies on the effect of walnut consumption on blood lipids and other cardiovascular risks. The evaluation includes 26 randomized controlled studies with a total of over 1,000 participants. It discovered that diets rich in walnuts resulted in decreased total cholesterol, LDL cholesterol, and triglycerides, the most prevalent type of fat in the bloodstream.
What makes walnuts unique?
While all nuts contain beneficial unsaturated fats, walnuts are particularly high in alpha-linolenic acid (ALA). This is a precursor of the omega-3 fatty acids EPA and DHA, which are abundant in fatty fish and have been shown to protect the heart. Our bodies convert ALA to EPA and DHA, albeit the conversion efficiency varies by individual.
Additionally, walnuts are typically consumed raw. As a result, they contain more antioxidants than roasted nuts. (Antioxidants contribute to the prevention or reduction of artery-damaging oxidation, which contributes to heart disease.)