Hazelnuts rank #1 among tree nuts in folate content. This translates into a decreased risk of neural tube birth defects and may help to reduce the risk of cardiovascular disease and depression Hazelnuts have the highest proanthocyanidin content of any tree nut. These compounds are known for contributing astringent flavor to foods and may help reduce the risk of blood clotting and urinary tract infections.
Hazelnuts provide dietary fiber. An ounce of raw hazelnuts has 2.7 grams of dietary fiber. Dietary fiber is a cholesterol-lowering nutrient and may prevent constipation because of its laxative effect, according to the 2010 Dietary Guidelines from the U.S. Department of Health and Human Services. Healthy adults on a 2,000-calorie diet should aim for at least 28 grams of dietary fiber.
Hazelnuts are particularly high in two minerals: manganese and copper. One serving of hazelnuts supplies 65 percent of the Daily Recommended Intake (DRI) for copper and more than 90 percent of the DRI for manganese. Copper is needed for iron absorption and manganese is necessary for bone formation.