Eating walnuts daily lowers ‘bad’ cholesterol and lowers the risk of cardiovascular disease (CVD) in older adults, a new randomised control trial finds.
By eating 30–60g of walnuts daily, healthy older adults lowered their total cholesterol, low-density lipoprotein cholesterol (LDL-C, bad cholesterol), total LDL particle and small LDL particle number by 4.4%, 3.6%, 4.3% and 6.1%, respectively.
“Prior studies have shown that nuts in general, and walnuts in particular, are associated with lower rates of heart disease and stroke. One of the reasons is that they lower LDL-cholesterol levels, and now we have another reason: they improve the quality of LDL particles,” Emilio Ros, MD, PhD, director of the Lipid Clinic at the Endocrinology and Nutrition Service of the Hospital Clinic of Barcelona in Spain, said in a press release.
The study, “Effects of Walnut Consumption for 2 Years on Lipoprotein Subclasses Among Healthy Elders,” was published in Circulation.
High cholesterol, particularly LDL-C, is an established risk factor for CVD. People typically develop high cholesterol levels by eating unhealthy diets rich in saturated fats. And that’s why health professionals recommend prioritising plant-based diets containing heart-healthy mono- and polyunsaturated fats.
Nuts are rich sources of monounsaturated fats, and many studies show that diets including nuts have a cholesterol-lowering effect. Besides monounsaturated fats, walnuts are rich sources of omega-3 fats, phytosterols, antioxidants, fibre and vitamin E, compounds that promote heart health.
Although past studies show the benefits of nuts on cholesterol levels, no trials have investigated how supplementing the diets of older adults with walnuts benefits their cholesterol levels and other heart health metrics.
To learn more, researchers recruited 708 healthy participants from Barcelona and California with different diets into the two-year Walnuts and Healthy Aging (WAHA) study.
After providing informed consent, participants were divided into a walnut-free (control) or walnut-supplemented diet. Participants in the walnut-supplement diet ate 30–60g of walnuts daily. Every two months, the researchers recorded the participants’ compliance, tolerance, medication, and body weight.
The researchers also measured the participants’ fasting blood glucose, total cholesterol, LDL-C, triglycerides, and high-density lipoprotein cholesterol (HDL-C) at the beginning of the study and after years.
A total of 636 people completed the study and 628 had full data for lipoprotein analyses. The average age of the participants was 69 years. A total of 67% were women and 32% were using statins. The mean baseline LDL-C and triglycerides were 117 and 105 mg/dL, respectively.
After two years, participants in the walnut-supplemented group lost a mean weight of 0.06kg and the control group lost 0.51kg. Participants in the walnut group ate more calories, with higher fat, fibre and omega-3 intake compared to the control group.
“Eating a handful of walnuts every day is a simple way to promote cardiovascular health. Many people are worried about unwanted weight gain when they include nuts in their diet,” Ros said.
While fasting glucose levels were similar in both groups, participants in the walnut group had significantly lower total cholesterol, LDL-C and IDL-C compared to the control group. The walnut group also significantly reduced total LDL particles and small LDL particles by 4.3% and 6.1%. And notably, men had more considerable decreases in LDL-C than women, 7.9% vs. 2.6%, respectively.
“While this is not a tremendous decrease in LDL cholesterol, it’s important to note that at the start of the study, all of our participants were quite healthy, free of major non-communicable diseases. However, as expected in an elderly population, close to 50% of participants were being treated for both high blood pressure and hypercholesterolemia. Thanks in part to statin treatment in 32%, the average cholesterol levels of all the people in our study were normal,” Ros said.
“For individuals with high blood cholesterol levels, the LDL cholesterol reduction after a nut-enriched diet may be much greater. More research is needed to clarify the different LDL results in men and women,” he added.
A major strength of the study is that participants ate their usual diets with or without walnuts, making the results more relevant to the general population and closer to real-life than controlled, experimental settings.
Based on the findings, the researchers concluded that adding walnuts to a healthy dietary pattern may be helpful to lower blood lipids that raise CVD risk.
The take-home message
Moderate amounts of walnuts are a great addition to your diet. They are rich sources of fibre, omega-3 fats and several other beneficial compounds that benefit your heart and overall health. Although they have a high-fat content, you shouldn’t avoid eating them. In moderate quantities, the fats they contain are health-promoting.
Remember that one food will not alter your health. Your overall dietary pattern ultimately determines your health status. Want a healthy way to add walnuts to your diet? Check out California Walnut ‘Meatballs’ with Mediterranean CousCous and Parsley Dressing.