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Nuts Are on a Roll

The Romans considered many nuts food of the gods. Because walnuts resemble the brain, they were used to treat head ailments during the Renaissance. The Incas made pottery in the shape of the highly prized peanut. More recently the health reputation of nuts has been on a roller coaster. A few decades ago nuts were valued for their protein, vitamins, and minerals. Then in the 1980s they were seen primarily as fat-and-calorie landmines—to be avoided by all except those trying to gain weight. But during the last decade, nuts have been on the rise, thanks to research pointing to their potential heart benefits.

An impressive array of studies—large and small, from around the world—have now found that people who eat nuts regularly cut their risk of heart disease by as much as half, compared to those who rarely or never eat nuts. In the last few years, several studies have found that 1 to 3 ounces a day of walnuts or almonds, in particular, can lower elevated blood cholesterol levels, as well as other substances in the blood (including apolipoprotein B) that have been linked to heart disease. And recently a study of more than 83,000 nurses found that those who ate an ounce of nuts at least five times a week had a 27% lower risk of Type 2 diabetes, and those who ate peanut butter five times a week had a 21% lower risk.

Given all this evidence, many researchers now think that nuts should be moved to a more prominent place on the government's food pyramid. In other words, small amounts should be part of your daily diet.

There are many substances in nuts that may explain their heart-healthy potential (and other health benefits). Nuts are rich in
n monounsaturated and polyunsaturated fats: these can lower blood cholesterol, especially when substituted for foods high in saturated fat, such as meat or cheese.

• folate and other B vitamins: these may reduce the risk of heart disease by lowering blood levels of homocysteine.

• copper, potassium, and magnesium—all three linked to heart health—and other minerals.

• vitamin E, possibly cardio-protective.

• arginine, an amino acid that helps relax blood vessels and inhibits blood clotting.

• fiber, with all its health benefits.

• phytochemicals (notably sterols, ellagic acid, polyphenols, and saponins) that may act as antioxidants and lower cholesterol.

Which nut is best

All nuts have a lot in common. Most have 160 to 190 calories and 14 to 19 grams of fat per ounce; at least three-quarters of the calories come from fat. They are also among the best plant sources of protein.
There are some nutritional differences. Walnuts are richest in heart-healthy alpha-linolenic acid (an omega-3 fatty acid similar to those in fish); almonds are richest in calcium and vitamin E; brazil nuts are the best dietary source of selenium. Macadamia nuts have the most calories and fat; chestnuts the least (just 70 calories and 1 gram of fat). And peanuts are not true nuts, but legumes (like dried beans). Similar nutritionally to nuts, peanuts contain some resveratrol, a beneficial compound found in grapes.

But don't go nuts

Nuts are, of course, high in calories: a handful can pack as many as a piece of cake (dry-roasted nuts are just as caloric as oil-roasted ones). In many of the nut studies that found benefits, people ate nuts instead of other foods. That's the best strategy, because if you gain weight from eating lots of nuts, that's bad for your heart. The good news is that nuts tend to be satisfying and, according to some studies, help reduce hunger longer than many foods.

Packaged nuts are often high in salt, too, though unsalted ones are widely available.

So don't go overboard with nuts. An ounce or two a day will do. Instead of using nuts as a snack, when you might eat large amounts, use them as part of a meal. Chopped nuts are tasty in fruit or vegetable salads, yogurt, oatmeal, home-baked breads and muffins, pancakes, casseroles, breakfast cereal, chicken salad, rice dishes, and stir-fries. When possible, substitute nuts for foods rich in saturated fat. Peanut butter, for instance, is definitely a healthier choice for a sandwich than cheese or most meats.

And spread the news: Nut butters have the same nutritional advantages as nuts. Some people shy away from commercial peanut butters, because the makers add hydrogenated vegetable oil to keep the peanut oil from separating. But USDA research has shown that these contain very small amounts of hydrogenated oil and thus almost no trans fats. There are many natural nut butters that contain no added oil.

UC Berkeley Wellness Letter, May 2003