The Iowa Women’s Health Study, which involved 40,000 older women, confirmed the protective effects of nuts against CVD—the higher the nut intake, the greater the protection. That was significant because as women age, they lose the CVD protection that’s attributed to estrogen.
The Physicians’ Health Study found that eating nuts appears to protect against sudden death from heart disease. Doctors in the study who ate nuts at least twice a week showed a significantly reduced risk of sudden death. That’s in line with research showing that certain fatty acids, particularly omega-3s, stabilize errant heart rhythm, the primary cause of sudden cardiac death.
Several studies show that eating walnuts can help improve blood lipids. Walnuts lower low-density lipoprotein (LDL) and total blood cholesterol, which is good for cardiovascular health, chiefly because they contain alpha-linoleic acid. Another study compared diets rich in either almonds or olive oil. Like many nuts, olive oil contains monounsaturated fats and is a primary ingredient in Mediterranean diets. The group on the almond-based diet, however, experienced a 16 percent drop in total cholesterol, with a 19 percent decline in LDL cholesterol. No changes occurred in the olive-oil group. Levels of high-density lipoprotein (HDL)—the good cholesterol—remained stable in the almond group.
The plant protein in nuts averages 14 to 26 percent by weight. Nutritionists sometimes criticize plant protein because its amino acid balance is inferior to that of animal protein, such as the kind in milk and eggs. In certain respects, however, plant proteins have properties that animal-based proteins don’t. The amino acid arrangement in plant proteins seems to help lower blood lipids in a way that’s not true of animal proteins. Comparisons between casein, a milk protein, and soy bear that out, and nut protein is similar to that of soy.
Nuts are rich in the amino acid arginine, which protects against CVD because it’s the direct dietary precursor of nitric oxide synthesis. No dilates blood vessels and lowers blood pressure, prevents the structural changes in arteries that foster atherosclerosis and inhibit internal blood clots, the primary immediate cause of most heart attacks and strokes.
Nuts are one of the richest food sources of alpha-tocopherol, or vitamin E, a dietary antioxidant associated with helping prevent CVD. Almonds and hazelnuts are rich sources of alpha-tocopherol, while walnuts and pecans are high in gamma-tocopherol, a form of vitamin E more potent than the alpha version in preventing prostate cancer.
Folic acid, a B-complex vitamin, lowers the blood level of a potentially toxic by-product of amino acid metabolism called homocys-teine. Some studies suggest that as much as half of all CVD stems from elevated homocysteine, which is also linked to such other diseases as Alzheimer’s. Nuts are rich in folic acid, and peanuts have four times more of it than other nuts.