Heart disease is the leading cause of death among people living in the United States, claiming the lives of roughly 655,000 people every year. Having high levels of low-density lipoprotein (LDL), or “bad” cholesterol, increases a person’s risk of heart disease. Findings from a new study suggest that eating walnuts reduces LDL cholesterol.
Walnuts contain a variety of bioactive compounds that exert antioxidant, anti-inflammatory, and anti-cancer properties. They are also excellent sources of alpha linolenic acid (ALA), an omega-3 fatty acid that plays important roles in human health. ALA is necessary for the production of eicosanoids, a class of signaling molecule that regulates blood clotting, blood pressure, blood lipid levels, immune function, inflammation, pain and fever, and reproduction.
The investigation was part of the Walnuts and Healthy Aging study, an intervention study of health and cognition in approximately 700 healthy older adults (63 to 79 years old) recruited from diverse geographical locations in the United States and Spain. Over a period of two years, half of the participants in each location followed their normal diets but added one serving (a small handful) of walnuts to their diet per day. The other half followed their normal diets but did not add walnuts.
The study investigators measured the participants' triglycerides, total cholesterol, LDL, and high-density lipoprotein (HDL) blood concentrations at the beginning and end of the intervention. They also measured intermediate-density lipoproteins (IDL) and LDL particle number. IDL is a precursor to LDL. In recent years it has emerged as an important cardiovascular risk factor independent of LDL cholesterol. LDL particle number is a measure of small LDL particles in a person’s blood. Evidence suggests small LDL particles are more atherogenic than large ones.
The effects of adding walnuts to the diet were consistent across both geographical locations. Among those who ate walnuts, total cholesterol concentrations decreased by 4.4 percent, LDL decreased by 3.6 percent, and IDL decreased by 16.8 percent. Triglycerides and HDL cholesterol concentrations did not change. Total LDL particles decreased by 4.3 percent, and small LDL particle number decreased by 6.1 percent. Interestingly, the LDL-lowering effects of the walnut diet differed by sex, with a 7.9 percent decrease in LDL among men and a 2.6 percent decrease among women.
These findings suggest that walnuts exert potent lipid-lowering effects in healthy older adults and align with previous research demonstrating that foods rich in omega-3 fatty acids benefit cardiovascular health.
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