Author: Winston Craig, MPH, PhD, RD.
Typically, Americans consume less than one oz of nuts and nut butters per day. Nuts account for only 2.5 percent of the total fat intake in the U.S. Mediterranean countries consume about twice the level of nuts consumed by Americans.
Furthermore, an ounce of nuts typically contains 2-5 grams of polyunsaturated fat. Brazil nuts and walnuts are exceptions since they contain higher levels of polyunsaturated fat (7 g and 11 g per ounce, respectively). The polyunsaturated fat in the nuts will also lower blood lipid levels.
The table below summarizes the amount and type of fat present in a variety of nuts.
Amount and Type of Fat in Various Nuts
|Type of Nut||Saturated Fat (%)||Monounsat. Fat (%)||Polyunsat. Fat (%)|
Nuts also contain a number of important vitamins and minerals. On average, 1 ounce of nuts contain 170 mg potassium and 60 mg of magnesium. In addition, most nuts have substantial amounts of zinc, copper, and protective phytochemicals such as ellagic acid and flavonoids. Almonds and hazel nuts also have high levels of -tocopherol whereas pecans and walnuts are rich in -tocopherol. The tocopherols are a form of vitamin E known to prevent unwanted oxidation of LDL cholesterol.
A number of studies report that frequent nut consumption is associated with a reduced risk of coronary heart disease (CHD). In the Adventist Health Study, people who ate nuts 1-4 times a week had a 25% reduced risk of CHD while those who ate nuts five or more times a week experienced a 50% reduction in risk of CHD, compared to people who ate nuts less than once a week. The protective effect of nuts was seen after adjustment for many known risk factors for heart disease. The nuts consumed in Adventist Health Study were largely tree nuts (walnuts and almonds) with lesser amounts of peanuts. Watch below a short summary of the benefits of eating a handful of nuts a day as explained by Prof. Joan Sabate from Loma Linda University, one of the pioneers in nut research:
The Women’s Health Study in Iowa also found an association between nut consumption and decreased risk of heart disease. The Heart Study from the University of Nevada, Reno found that frequent consumers of nuts tend to have lower body weights and are more health conscious than those not eating nuts.
Clinical trials have demonstrated the effective-ness of diets containing almonds and walnuts to lower blood cholesterol levels by 10-15 percent. The most recent feeding study, conducted at Loma Linda University, found that a diet in which 20% of the calories came from walnuts (3 oz a day) produced a 16% decrease in LDL cholesterol levels after 4 weeks compared with a similar diet not containing the nuts. Walnuts are different from most other nuts in that they contain a substantial amount of alpha-linolenic acid (omega-3 fat). Data from the Multiple Risk Factor Intervention Trial (MRFIT) suggests that higher levels of alpha-linolenic acid in the blood are associated with lower risk of stroke in the middle-aged men at high risk for cardiovascular disease.