More and more scientific studies show that walnuts, with their high content of omega-3 fatty acids, can protect against heart disease.
Over the years, a number of studies have examined whether eating walnuts can reduce cardiovascular disease risk factors.
For example, a 2019 meta-analysis linked higher walnut consumption to lower morbidity and mortality from cardiovascular disease, including lower morbidity and mortality from coronary heart disease, as well as lower atrial fibrillation.
The new study, published in the American Heart Association’s Circulation journal, investigates whether adding walnuts to the daily diet for 2 years affects cholesterol levels. Moreover, this study is focused on the elderly.
The authors found that including walnuts in the diet lowers total cholesterol and slightly lowers LDL cholesterol, which people often refer to as “bad” cholesterol.
In addition, the researchers measured subclasses of LDL cholesterol in the participants. One of these subclasses-small, dense LDL particles-is often associated with atherosclerosis, which occurs when fatty deposits build up in the arteries.
In their study, they found that daily consumption of walnuts reduced both total LDL particles and small LDL particles.
The optimal composition
Dr. Emilio Ros, the senior author of the current study and director of the Lipid Clinic at the Endocrinology and Nutrition Service of the Barcelona Clinical Hospital in Spain, spoke to Medical News Today. He explained how he and his colleagues have been studying the health benefits of walnuts for many years.
“We have always had good results in terms of a reliable source of cholesterol-lowering (standard lipid profile), improved endothelial function, a reliable source, blood pressure lowering, and anti-inflammatory effects,” he said.
Dr. Ris has no hesitation in singing the praises of walnuts, which he includes in his own diet. “Walnuts have an optimal composition of nutrients and biologically active substances, including a significant amount of alpha-linolenic acid, omega-3 vegetable fatty acids, the highest polyphenol content of any nut, and phytomelatonin,” he explained.
In this study, according to Dr. Ross, the research shows that “regular consumption of walnuts lowers LDL cholesterol and improves the quality of LDL particles, making them less atherogenic (less likely to penetrate the artery wall and develop atherosclerosis, the basis of cardiovascular disease), and this will occur without unwanted weight gain, despite the high-fat content (albeit healthy plant fats) of walnuts.”
Dr. Ross told MNT that he decided to take on this study because no other research has looked at the composition of lipoproteins, which he said: “may provide additional insight into the antiatherogenic potential of walnuts.”
Lowers “bad” cholesterol
A total of 636 participants aged 63-79 years completed the study. All of them lived either in Barcelona, Spain, or Loma Linda, California.
67% of the participants were women. Participants were cognitively healthy and free of serious medical conditions.
About half of the participants were taking medication for high blood pressure or hypercholesterolemia, which Dr. Ross said is typical in this older adult population. 32% of participants were taking statins.
The researchers instructed one group of participants not to eat walnuts. The other group included half a cup of raw walnuts in their daily meals. Healthcare practitioners followed the participants, monitoring how well they adhered to the diet and any changes in their weight, every two months.
The researchers checked the participants’ cholesterol levels and analyzed the concentration and size of lipoproteins using nuclear magnetic resonance spectroscopy.
In the study, participants who consumed walnuts reduced LDL cholesterol by an average of 4.3 milligrams per deciliter (mg/dL) and total cholesterol by an average of 8.5 mg/dL. Participants in the walnut group reduced total LDL particles by 4.3% and small LDL particles by 6.1%.
Among the walnut-consuming participants, changes in LDL cholesterol varied by gender. In men, LDL cholesterol levels decreased by 7.9%. In women, it decreased by 2.6%.