Walnuts Improve Cholesterol Levels
April 7, 2000 (Atlanta) -- A handful of walnuts every day can work wonders on lowering cholesterol levels -- if it's combined with a Mediterranean heart-healthy diet.
"By incorporating a single food that is easy to consume, easy to carry, doesn't need to be cooked -- just by changing one food in an already healthy diet -- you can accomplish a great health benefit," Joan Sabaté, MD, tells WebMD. A study authored by Sabaté and his colleagues appears in this month's Annals of Internal Medicine.
"All heart-healthy diets lower total and LDL cholesterol; however, during the walnut diet we observed a 5% and 6% reduction, respectively, beyond the effects of the Mediterranean diet alone," says Sabaté. "It's significant from a statistical standpoint, but relevant from a practical point." Walnut oil could have similar effects to whole walnuts, but that has not yet been investigated.
This study expands on Sabaté's previous research to include women, people with high cholesterol, and middle-aged and older people. Also, other studies have been conducted with meals prepared in a laboratory setting, while this study involved "free-living persons" who were advised to eat a Mediterranean diet, says Sabaté, professor and chair of nutrition at Loma Linda University's School of Public Health in Loma Linda, California.
In his study, conducted in Barcelona, Spain, the 49 men and women all had high total cholesterol and high LDL ("bad") cholesterol. People with a family history of high cholesterol levels -- whether genetic or not -- were not included in the study.
All were asked to eat a Mediterranean diet composed of fresh fruits and vegetables, fish (no red meat or eggs), and olive oil for cooking. Those on the "walnut diet" substituted eight to 11 walnuts a day for part of the olive oil/fat portion of the diet. Patients followed each diet for six weeks, since it takes four weeks for cholesterol levels to stabilize after diet changes.
The overall cholesterol level decreased by 9% during the walnut diet but only by 5% when eating the no-walnut diet. Similarly, the LDL, "bad," cholesterol levels decreased by about 11% during the walnut diet and almost 6% during the no-walnut diet. Cholesterol ratios also improved with walnuts.