Mother Nature is trying to tell you something when you crack open a walnut. The little heart-shaped nut offers some powerful cardiovascular benefits. So powerful, walnuts were the first food to receive an FDA-qualified health claim in 2004, allowing companies to say on their packaging that eating 1.5 ounces every day can reduce the risk of heart disease.
The muscle behind walnuts' heart-health profile is omega-3 fatty acids, particularly alpha-linolenic acid (ALA). Aside from raising HDL cholesterol (the so-called good cholesterol), researchers have found that ALA helps keep your blood flowing smoothly through your arteries—even after you eat a lot of saturated fats, which can harden the arteries, potentially contributing to heart attack and stroke. "What we're learning is that specific fats have specific benefits and risks," explains Dr. Michael Roizen, chief of anesthesiology and critical-care medicine at the Cleveland Clinic and author of "You: On A Diet." "The fat found in walnuts actually decreases inflammation in the arteries and helps keep them flexible."
Walnuts are also rich in antioxidants. These natural compounds, found in plants, help rid the body of unstable molecules called free radicals, which can lead to cancer. Early research is also showing that walnuts may offer some protection against the bone-thinning disease osteoporosis. And they're good for your teeth, too. "Walnuts can lower the acidity made by sweets and fruit juices," says nutritionist Keith Ayoob, associate professor of pediatrics at the Albert Einstein College of Medicine. "If you can't brush, chew a few walnuts at the end of a meal and you'll get some good cavity protection."
Because of their fat, fiber and protein content, walnuts are also one of those nutrient-dense foods that help increase satiety, that feeling of fullness you get after a meal. Roizen recommends eating six walnuts twice a day, 30 minutes before lunch and 30 minutes before dinner. Not only will you feel full, but you'll get the health benefits, too.
For a good nut, walnuts can go bad fairly quickly. Especially if you compare them to dry roasted almonds, which can last three to four years. The folks from Whole Foods recommend storing shelled walnuts in the refrigerator in an airtight container, which will keep them fresh for about six months. Freeze them and they will last for one year. You should store unshelled walnuts in the refrigerator, too. But they will keep for up to six months in any cool, dark place. Storage may be moot. Considering how good they taste and their health benefits, it's unlikely you'll keep a package around longer than a week.