The Folklore. Walnuts are the oldest tree food known to man, dating back to 7,000 BCE. Native to ancient Persia, walnuts were so coveted that only royalty were allowed to eat them. Ancient Greeks used walnuts for food, medicine, and dye for wool and cloth. They came to be called English walnuts because English merchants traded the popular nut in ports all over the world, including North America. Today, California’s Central Valley produces 99 percent of the commercial US supply of walnuts. Walnuts are just as prized today for their delicious flavor as well as their health-promoting nutrients and unique supply of plant compounds.
The Facts. English walnuts (Juglans regia) are the most popular walnut in the US, followed by black walnuts (Juglans nigra), and white walnuts (Juglans cinerea). English walnuts have a thinner shell, more easily broken than the black variety, which has a more pungent flavor. The white walnut is sweeter but not as easy to find. Walnuts are a very good source of omega-3 fatty acids, and the only nut significantly high in omega-3 ALA, linked to several health benefits. A one-ounce serving of walnuts (about 14 halves) packs 48% DV (Daily Value, based on 2,000 calories/day) of manganese and 11% DV of magnesium, both key players in bone health, and 22% of the essential nutrient, copper.
The Findings. Walnuts, rich in polyunsaturated fatty acids, have beneficial effects on cardiovascular risk factors, like lowering blood pressure and cholesterol. According to a 2019 study in the Journal of the American Heart Association, the benefits are not just due to replacing saturated fatty acid diets with unsaturated fatty acids; there are benefits to walnuts as a whole food replacement. Another study, in the journal Nutrition Research and Practice (2019) found that people with metabolic syndrome who ate 45 grams of walnuts daily for 16 weeks significantly reduced metabolic syndrome risk factors including improved HDL (“good”) cholesterol, decreased fasting glucose levels, and lower blood pressure.
The Finer Points. Harvested in late August through November, walnuts are kept in cold storage to be available year-round. They’re available in-shell or shelled, in bulk bins, and packaged whole, in halves, pieces, ground, and bottled as oil. Because of their high fatty acid content, they can go rancid easily, so store them in the refrigerator or freezer. Mix crushed walnuts into hot or cold cereals, yogurt, parfaits; sprinkle halves or pieces onto salads, sautéed vegetables, and whole grain side dishes; blend into pesto and serve 
over pasta or on bruschetta; or keep a handful nearby for a satisfying snack.
—Lori Zanteson
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