Eating walnuts daily lowers ‘bad’ cholesterol, may reduce cardiovascular disease risk: Study


According to a new study, healthy older persons who consumed a handful of walnuts (about 1/2 cup) daily for two years had a slight reduction in their low-density lipoprotein or LDL cholesterol levels.

Consuming walnuts on a daily basis also decreased the number of LDL particles, which is a risk factor for cardiovascular disease.
The study’s findings were published in the flagship publication of the American Heart Association, ‘Circulation.’

Walnuts contain a high concentration of omega-3 fatty acids (alpha-linolenic acid), which have been found to improve cardiovascular health.

“Nuts in general, and walnuts in particular, have been linked to a decreased risk of heart disease and stroke in previous research. One explanation is that they reduce LDL cholesterol levels; however, there is now another reason: they increase the quality of LDL particles “Emilio Ros, MD, PhD, co-author of the study and director of the Lipid Clinic at the Hospital Clinic of Barcelona’s Endocrinology and Nutrition Service, agreed.

“LDL particles are available in a variety of sizes. Small, thick LDL particles have been found to be more frequently connected with atherosclerosis, the buildup of plaque or fatty deposits in the arteries “Ros clarified.

“Our study extends beyond LDL cholesterol levels to examine all lipoproteins and the effect of walnut consumption on their ability to reduce cardiovascular risk,” Ros noted.

Researchers examined whether frequent walnut consumption, regardless of a person’s diet or location, had favourable effects on lipoproteins in a sub-study of the Walnuts and Healthy Aging project, a large, two-year randomised controlled experiment evaluating whether walnuts contribute to healthy ageing.

Between May 2012 and May 2016, this study included 708 healthy, independent-living people between the ages of 63 and 79 (68 percent women) in Barcelona, Spain, and Loma Linda, California.

Participants were assigned to one of two groups at random: active intervention or control. Participants in the intervention group consumed approximately a half cup of walnuts in addition to their typical daily diet, whereas those in the control group did not consume any walnuts.

After two years, participants’ cholesterol levels were determined, and lipoprotein content and size were determined using nuclear magnetic resonance spectroscopy.

This sophisticated test enables clinicians to more precisely detect lipoprotein characteristics associated with an increased risk of cardiovascular disease.

The two-year trial achieved a retention rate of 90%. (632 participants completed the study). In 628, comprehensive lipoprotein analyses were available.

Among key findings of all study participants:

  1. At 2 years, participants in the walnut group had lower LDL cholesterol levels — by an average of 4.3 mg/dL, and total cholesterol was lowered by an average of 8.5 mg/dL.
  2. Daily consumption of walnuts reduced the number of total LDL particles by 4.3 per cent and small LDL particles by 6.1 per cent. These changes in LDL particle concentration and composition are associated with a lower risk of cardiovascular disease.
  3. Intermediate Density Lipoprotein (IDL) cholesterol also decreased. It is known that IDL cholesterol is a precursor to LDL and refers to a density between that of low-density and very-low-density lipoproteins. In the last decade, IDL cholesterol has emerged as a relevant lipid cardiovascular risk factor independent of LDL cholesterol.
  4. LDL cholesterol changes among the walnut group differed by sex; in men, LDL cholesterol fell by 7.9 per cent and in women by 2.6 per cent.

“While this is not a significant reduction in LDL cholesterol, it is crucial to remember that all of our subjects were relatively healthy at the outset of the trial, free of major non-communicable diseases,” Ros explained.
“However, as would be expected in an elderly population, about 50% of individuals were receiving treatment for both hypertension and hypercholesterolemia. The average cholesterol levels of all participants in our study were normal, owing in part to statin treatment in 32% “Ros clarified.
“For those with elevated blood cholesterol levels, the reduction in LDL cholesterol following a nut-enriched diet may be significantly greater. Consuming a handful of walnuts daily is an easy method to improve cardiovascular health “Ros added.

“Many people are concerned about gaining unwelcome weight when they incorporate nuts into their diet. Our study discovered that the beneficial fats included in walnuts did not contribute to participants’ weight increase “Ros carried on.

The significant disadvantage of this study is that both participants and researchers were aware of who was eating walnuts and who was not.

However, the study included two quite separate communities with extremely different diets.

“Because the effects were identical in both groups, we may confidently extrapolate the findings to other populations,” Ros explained.

Additionally, additional research is needed to elucidate the differences in LDL cholesterol levels between men and women.

Walnuts are particularly strong in omega-3 fatty acids, the same heart-healthy fat found in oily fish, according to the American Heart Association. A small handful or 1.5 ounces of whole nuts or 2 teaspoons of nut butter is a serving.

The California Walnut Commission supported the study.


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