Nutrients
Walnuts are an excellent source of antioxidants and the minerals manganese, copper, phosphorus, and magnesium. Walnuts are a very good source of protein, dietary fiber, the amino acid arginine, omega-3 fatty acids and alpha-linolenic acid (ALA). Walnuts are unique because they are rich in n-6 (linoleate) and n-3 (linolenate) polyunsaturated fatty acids.

Cardiovascular Health
Alpha-linolenic acid (ALA) is an n-3 polyunsaturated fatty acid found mainly in plant sources, especially walnuts. There have been numerous clinical studies that suggest that alpha-linolenic acid (ALA) intake reduces the incidence of coronary heart disease. Alpha-linolenic acid (ALA) in walnuts may reduce cardiovascular risk through a variety of biologic mechanisms, including platelet function, inflammation, endothelial cell function, arterial compliance, and arrhythmia.
Walnuts also contain other potentially cardioprotective constituents including phytosterols, tocopherols, squalene and the amino acid arginine.
Walnuts are rich in the antioxidant ellagic acid, and in a preliminary study, it has been suggested that the ellagic acid present in walnuts has a high anti-atherogenic implicating the beneficial effect of a walnut-enriched diet on cardio protection.

Cholesterol
A diet supplemented with walnuts has been shown to significantly reduce total and LDL cholesterol levels.

Alzheimer’s Disease
Fibrillar amyloid beta-protein (Abeta) is the principal component of amyloid plaques in the brains of patients with Alzheimer's disease. Over 90% inhibition of Abeta fibrillization from walnut extract was observed in a laboratory study, suggesting that walnuts may reduce the risk or delay the onset of Alzheimer's disease by maintaining Abeta in the soluble form.

Weight Loss
There is some concern amongst dieters about incorporating walnuts into a weight loss program due to the high fat content. A 12-month study of 90 participants has demonstrated that weight gain from daily consumption of walnuts has been shown to be insignificant.