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A recent study investigates whether regularly consuming walnuts might reduce cholesterol. Crissy Mitchell/Stocksy
  • After a 2-year study, participants who consumed about half a cup of walnuts each day had lower levels of low-density lipoprotein (LDL) cholesterol compared with their levels at the beginning of the study.
  • These individuals also experienced a reduction in total cholesterol.
  • The research was supported by a grant from the California Walnut Commission.

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

A growing body of scientific research suggests that walnuts, which are highTrusted Source in omega-3 fatty acids, may protect against heart disease.

Over the years, a number of studies have investigated whether consuming walnuts might reduce cardiovascular risk factors.

For instance, a 2019 meta-analysisTrusted Source links higher walnut consumption with a lower cardiovascular disease incidence and mortality, including lower coronary heart disease incidence and mortality and lower atrial fibrillation.

A new study, which appears as a research letter in the American Heart Association journal CirculationTrusted Source, investigates whether the addition of walnuts to the daily diet for 2 years influences cholesterol levels, specifically. Moreover, this study focuses on older adults.

The authors found that including walnuts in the diet decreased the total cholesterol and modestly lowered levels of LDL cholesterol, which people often refer to as “bad” cholesterol.

Additionally, the scientists measured the participants’ subclasses of LDL cholesterol. One of these subclasses — small dense LDL particles — are more 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 the number of total LDL particles and small LDL particles.

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An optimal composition

Dr. Emilio Ros, senior author of the current study and director of the Lipid Clinic at the Endocrinology and Nutrition Service of the Hospital Clínic of Barcelona in Spain, spoke with Medical News Today. He explained how he and his colleagues have studied the health benefits of walnuts for many years.

“We always obtained good results regarding cholesterol loweringTrusted Source (standard lipid profile), improved endothelial functionTrusted Sourcereduced blood pressureTrusted Source, and anti-inflammatory effects,” he said.

Dr. Ros does not hesitate to sing the praises of walnuts, which he includes in his own diet. “Walnuts have an optimal composition of nutrients and bioactives, including sizable amounts of alpha-linolenic acid, the vegetable omega-3 fatty acid, the highest polyphenol content of all nuts, and phytomelatonin,” he explained.

In this study, the research indicates, according to Dr. Ros, that “regularly eating walnuts will lower your LDL cholesterol and improve the quality of LDL particles, rendering them less atherogenic (less prone to enter the arterial wall and build up atherosclerosis, the basis of cardiovascular diseases), and this will occur without unwanted weight gain in spite of the high fat (healthy vegetable fat, though) content of walnuts.”

Dr. Ros told MNT he elected to take on this study because no other research had looked at lipoprotein composition, which, he said, “can provide additional insight into the antiatherogenic potential of walnuts.”

Lowered ‘bad’ cholesterol

In total, 636 participants aged 63–79 years completed the study. They all resided in either Barcelona, Spain, or Loma Linda, CA.

Of the participants, 67% were female. The participants were cognitively healthy and had no significant health conditions.

About half of the participants were taking drugs for high blood pressure or hypercholesterolemia, which, according to Dr. Ros, is typical for this older adult population. Of the participants, 32% were taking statins.

The researchers instructed one group of the participants not to eat any walnuts. The other group incorporated half a cup of raw walnuts into their daily meals. Health practitioners monitored the participants, looking for how well they were following their diet and any changes to their weight, every other month.

The researchers tested the participants’ cholesterol levels and analyzed the concentration and size of lipoproteins with nuclear magnetic resonance spectroscopy.

Over the course of the study, the participants who consumed walnuts reduced their LDL cholesterol levels by an average of 4.3 milligrams per deciliter (mg/dl) and their total cholesterol by an average of 8.5 mg/dl. The participants in the walnut group reduced their number of total LDL particles by 4.3% and of small LDL particles by 6.1%.

Among the participants who consumed walnuts, LDL cholesterol changes differed by sex. In males, LDL cholesterol fell by 7.9%. In females, it fell by 2.6%.