A handful of walnuts a day for heart health and to reduce cardiovascular risk. Previous studies had already shown the ability of walnuts to reduce cholesterol, but from today we also know that walnuts are able to modify and improve the quality of lipoproteins, thus counteracting cardiovascular diseases. This emerges from a very recent scientific research published in the journal Circulation by a Spanish team (Rajaram et al, Circulation, 2021).
Dried fruit reduces cardiovascular risk
Regular consumption of dried fruit is associated with a 15% reduction in the risk of developing cardiovascular disease and a 23% reduction in heart disease-related mortality. Previous studies have had the opportunity to observe that the intake of dried fruit leads to a reduction in bad cholesterol. However, until now, no studies have been performed on how the integration of dried fruit, in particular walnuts, into the diet can change the composition of lipoproteins, the particles that carry cholesterol. In addition, the effects in older people are not known. To fill this gap, the Spanish researchers of the Lipid Clinic of the Barcelona Hospital Clinic have developed the study we are talking about today.
Walnuts and heart, the experiment
The study lasted two years and involved 708 people between 63 and 79 years old, all in good health and living in Barcelona or Loma Linda, California. The volunteers were divided into two groups. The first group was asked to take half a cup of walnuts a day for two years. The second group abstained from eating any walnuts. No changes to the usual diet were made. At the end of the two years, the participants underwent blood tests and nuclear magnetic resonance imaging to assess the size of the circulating lipoproteins. What emerged was that those who consumed walnuts had an average reduction in bad cholesterol of 4.3 mg / dL and a reduction in total cholesterol of 8.5 mg / dL. Therefore, the reduction in cholesterol, especially bad cholesterol, was observed, albeit modest. However, the most interesting result was another. In other words, the consumption of walnuts reduced the number of circulating small-sized LDL lipoproteins by 6.1%. Lipoproteins are particles capable of transporting lipids throughout the body, carrying a combination of cholesterol, triglycerides, vitamins and proteins. Lipoproteins are of different types, here we are talking about small LDL lipoproteins. These particles remain in the blood for a long time and can accumulate on the vessel walls forming plaques. Therefore, the more the number of small LDL particles, the higher the risk of blood vessel obstruction and therefore the likelihood of suffering a heart attack or stroke. Experts consider the number of small LDL lipoproteins to be an important indicator of cardiovascular risk, even better than cholesterol values. Finally, the consumption of walnuts also led to a reduction in the number of intermediate density lipoproteins, or IDLs, considered precursors of small LDL lipoproteins.
Walnuts, an always healthy choice
What emerged was independent of the geographical area in which people lived and the diet followed. Not only that, the introduction of half a cup of walnuts a day, about 14 walnuts, did not cause an increase in body weight. Therefore, walnuts are definitely a healthy food that can be included in a varied and balanced diet to protect us from cardiovascular risk.