Walnuts Linked With Lower Blood Pressure

Walnuts, when combined with a diet low in saturated fats, were associated with reduced blood pressure in at-risk individuals, new study results suggest.

“Walnuts contain ALA, a plant-based omega-3 that may positively affect blood pressure,” Alyssa Tindall, PhD, a recent graduate in nutrition at Penn State and a author on the study, explained in a press release. “We wanted to see if ALA was the major contributor to these heart-healthy benefits, or if it was other bioactive component of walnuts, like polyphenols. We designed the study to test if these components had additive benefits.”

The researchers, publishing in the Journal of the American Heart Association, included 45 individuals at risk for cardiovascular disease in the study. After a 2-week diet run-in, participants consumed three isocaloric weight-maintenance diets for a period of six weeks each. One of these was a walnut diet (7% saturated fatty acids, 16% polyunsaturated fatty acids, 3% alpha-linolenic acidm (ALA), and 9% monosaturated fatty acids); a fatty-acid-matched walnut diet, and an oleic acid-replaced ALA diet. The primary study endpoint was central systolic blood pressure.

According to the study results, central systolic blood pressure was unchanged, as were changes in arterial stiffness. The researchers did report a treatment effect for central diastolic blood pressure (P=0.04), and a notable change following the walnut diet when compared to the oleic acid-replaced ALA diet (P=0.04). The researchers reported no differences between the walnut diet and the fatty acid-matched diet (P=0.20), or the walnut fatty acid-matched and oleic acid-replaced ALA diets (P=0.74). Lower brachial and central mean arterial pressure were significantly lowered in the walnut diet group, and all diets lowered total low density lipoprotein cholesterol (LDL-C), high density lipoprotein (HDL), and non-HDL cholesterol.

“When participants ate whole walnuts, they saw greater benefits than when they consumed a diet with a similar fatty acid profile as walnuts without eating the nut itself,” Distinguished Professor of Nutrition Penny Kris-Etherton, PhD, RD, of Penn State University, said in the press release of the study results. “It seems like there’s a little something extra in walnuts that are beneficial –maybe their bioactive compounds, maybe the fiber, maybe something else–that you don’t get in the fatty acids alone.”