I love nuts, and I'm happy to assure you that they do have a place in a healthy diet. True, nuts are high in fat, but most of them contain monounsaturated fat that is good for the heart. In fact, eaten in moderation, nuts can lower your risk of heart disease and heart attack. The ongoing Nurses Health Study at Brigham and Women's Hospital in Boston and the Harvard School of Public Health, which is monitoring the health of 86,000 nurses, found that those who ate more than five ounces of nuts per week (about the total you would get by eating a single airline packet daily) had one third fewer heart attacks than those who rarely or never ate nuts. Other studies have supported these findings.
In addition to their healthy fat profile, nuts provide you with vitamin E, trace minerals, fiber, and in the case of walnuts, vital omega-3 fatty acids. (Remember that peanuts are legumes, not nuts, and have a less desirable fatty acid profile.)
I enjoy nuts, eat them frequently and also use them in cooking. I buy mostly raw, unsalted nuts and store them in the refrigerator until I need them. You can toast nuts yourself by stirring them about in a dry skillet over medium-high heat or spreading them on a baking sheet placed in a 350 degree oven; toss them occasionally until they are done to your liking. Use them up quickly. Unsaturated nut oils oxidize quickly on exposure to heat, light and air, creating rancidity that makes them smell and taste bad (like oil paint). Rancid oils are carcinogenic. Roasted, chopped, and ground nuts go rancid more quickly than whole raw ones. Always smell nuts before you eat them or add them to recipes to be sure they are fresh.
Despite their beneficial nutritional profile, nuts are relatively high in calories, so enjoy them in moderation. I usually eat a handful per day - my favorites are cashews, almonds and walnuts.
Andrew Weil, M.D.