A walnut is the edible seed of any tree of the genus Juglans, especially Juglans Regia- the Persian walnut.

Broken nutmeats made with the eastern black walnut and the food made with butternut meats are commercially available.

A study has suggested that consumption of walnuts increases fat oxidation but reduces carbohydrate oxidation.

So walnut consumption may improve the use of body fat in overweight adults.

Aged rats fed diets containing 2% to 6% walnuts showed reversal of age-associated motor and cognitive function.

But the higher 9% walnut diet impaired performance.
Compared to certain other nuts, raw walnuts contain the highest level of antioxidants.