A new study has cited the special combination of nutrients in walnuts as accounting for these special benefits. In addition to providing a significant concentration of ALA, walnuts contain many vitamins, minerals, protein, fiber, melatonin, L-arginine and several other important nutrients.
Sheila G. West, lead author of the study said: "Our findings suggest that the special kind of fatty acids that are present in walnuts can improve the function of arteries and allow them to dilate better."
ALA is essential for optimal function of every cell in the human body but since the body can not create this "good" fat, it is obtained from foods.
The study, which was presented at the American Heart Association's 5th Annual Conference on Arteriosclerosis, Thrombosis, and Vascular Biology in San Francisco involved taking 13 adults who all suffered from high cholesterol. The subjects were randomly assigned to eat three different diets for six weeks each.
The diets consisted of the high-fat, high cholesterol diet. The other two being of similar fat content but lower in saturated fat and cholesterol.
One diet was the average high-fat, high-cholesterol American diet. The other two diets had similar total fat counts as the American diet but were lower in saturated fat and high in polyunsaturated fatty acids.
In both of the low saturated fat diets, volunteers got half of their total fat from walnuts and walnut oil
The study found that the low saturated fat group had a sevenfold improvement in artery function, compared with the all-American diet group. While the study was relatively small, the findings indicate that walnuts and offered an important benefit to arteries.
Another study published in April's issue of Circulation 2004;109:1609-1614 revealed substituting walnuts for monounsaturated fatty acids in the Mediterranean diet improves endothelial function.
The walnut diet increased endothelium-dependent vasodilation (EDV) by 64 per cent and reduced levels of vascular cell adhesion molecule-1 by 20 per cent. In addition, as in previous studies, the walnut diet decreased total cholesterol and low-density lipoprotein (LDL) cholesterol.
In March 2004, the Food and Drug Administration awarded walnuts a qualified health claim (QHC) which was the first for a whole food. This was based on the decade of supporting evidence which supported the health benefits of walnuts.
The National Academy of Sciences recommends a daily intake of 1.6 and 1.1 grams of ALA for men and women respectively. With 2.5 grams of ALA, one ounce of walnuts more than fulfils this requirement.