Consuming approximately 12 cup of walnuts daily for two years significantly reduced low-density lipoprotein (LDL) cholesterol, also known as “bad cholesterol,” and the number of total LDL particles and small LDL particles in healthy, older adults, according to new research published today in the American Heart Association’s flagship journal Circulation.
For two years, healthy older adults who had a handful of walnuts (approximately 12 cup) daily saw 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.
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 reason is that they reduce LDL cholesterol levels; however, there is now another reason: they improve the quality of LDL particles “Emilio Ros, M.D., Ph.D., director of the Lipid Clinic at the Endocrinology and Nutrition Service of the Hospital Clnic of Barcelona in Spain, stated as a co-author of the study. “LDL particles are available in a variety of sizes. Small, dense LDL particles have been found to be more frequently connected with atherosclerosis, the buildup of plaque or fatty deposits in the arteries. Beyond LDL cholesterol levels, our study examines all lipoproteins and the effect of daily walnut consumption on their capacity to reduce cardiovascular risk.”
Researchers examined whether frequent walnut consumption, regardless of a person’s diet or location, had favorable effects on lipoproteins in a sub-study of the Walnuts and Healthy Aging project, a comprehensive, two-year randomized controlled trial exploring whether walnuts contribute to healthy aging.
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 the most significant findings of all study participants:
At two years, participants in the walnut group had significantly lower LDL cholesterol – by an average of 4.3 mg/dL – and much lower total cholesterol – by an average of 8.5 mg/dL.
Consumption of walnuts on a daily basis decreased overall LDL particle count by 4.3 percent and small LDL particle count by 6.1 percent. Changes in the concentration and content of LDL particles are related with a decreased risk of cardiovascular disease.
Cholesterol in Intermediate Density Lipoproteins (IDL) also decreased. IDL cholesterol is a precursor to LDL cholesterol and has a density in between low-density and very-low-density lipoproteins. IDL cholesterol has emerged as a significant lipid cardiovascular risk factor independent of LDL cholesterol over the previous decade.
LDL cholesterol alterations were observed differently between men and women in the walnut group; men’s LDL cholesterol decreased by 7.9 percent, while women’s LDL cholesterol decreased by 2.6 percent.
“While this is not a significant reduction in LDL cholesterol, it is crucial to remember that all of our individuals were fairly healthy at the outset of the research, free of major non-communicable diseases. However, as would be expected in an elderly population, nearly half of individuals were receiving treatment for both hypertension and hypercholesterolemia. Due in part to statin treatment in 32% of our trial participants, the average cholesterol level for everyone in our study was “”Standard,” Ros stated. “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 support cardiovascular health. Many people are concerned about gaining unwelcome weight when they incorporate nuts into their diet “Ros said. “Our study discovered that the beneficial fats included in walnuts did not contribute to participants’ weight gain.”
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.