Nuts are rich sources of many vitamins and minerals and serve as a good plant-based protein source. Nuts are also high in fat, but these are mostly unsaturated fats that reduce LDL cholesterol and keep HDL cholesterol high, according to Dr. Walter Willett, author of "Eat, Drink, and Be Healthy." The unsaturated fats in nuts include monounsaturated fats and polyunsaturated fats. Omega-3 and omega-6 fatty acids are two types of polyunsaturated fats, and nuts contain both, though they are generally much higher in omega-6 fats than in omega-3s.
Types of Nuts
Nuts are fruits that have a hard outer shell enclosing a kernel. These meaty kernels come in many varieties. Common nuts include almonds, hazelnuts, pecans, pistachios and walnuts. Other nuts include Brazil nuts, cashews, macadamias and pine nuts. Peanuts are commonly considered nuts, but are actually legumes, related to beans and peas. However, peanuts contain fat levels much higher than other legumes, or 20 g per serving, similar to common nuts.
Types of Fat
Fat is classified into three major groups: saturated fats, unsaturated fats and trans fats. Trans fats are man-made fats present in margarine and in vegetable shortenings. Saturated fats are found mainly in animal products such as butter and marbled meat. Coconut is also high in saturated fat, which is solid at room temperature. Nuts contain some saturated fat but derive more of their fat calories from unsaturated fats, including omega-3 and omega-6 fatty acids, which are polyunsaturated fats that are essential to the diet.
Omega-6
Omega-6 fatty acids are polyunsaturated fatty acids that lower cholesterol when substituted for saturated fats. Linoleic acid, a type of omega-6, is found in relatively large amounts in nuts. Per 100 g, walnuts contain the highest amount of omega-6, equivalent to 28 g, according to AnneCollins.com. Brazil nuts are second, with 23 g per portion, followed by almonds and cashews, which contain appreciably lower amounts. Other sources of omega-6 are avocados and olives.
Omega-3
Omega-3 fatty acids such as linolenic acid, an essential fat, provide a number of health benefits. They suppress abnormal heart rhythms and reduce levels of triglycerides, a type of fat in the blood. Most nuts contain trace amounts of omega-3. Walnuts are the exception. One hundred grams of walnuts contains 5.5 g of omega-3. Other sources include plants and fish oil. The acceptable range for omega-3 in the diet is roughly 1 percent of calories, or 20 calories on a 2,000-calorie diet, equivalent to roughly 2 g of omega-3.
Considerations
According to Dr. Gabe Mirkin, the ratio of omega-6 to omega-3 fats in your diet is important. For most of history, he notes, humans have eaten about twice as much omega-6 as omega-3. These days, owing to a heavy reliance on plant oils, the ratio is more like 10-to-1 or greater. A diet that overemphasizes omega-6 is associated with health problems from heart disease and arthritis to obesity and cancer. Limiting consumption of nuts to 1 oz. and eating them as a snack instead of junk food rather than in addition to your usual snacks is a way to get the most benefit from this tasty treat.
References
- "Eat, Drink, and Be Healthy"; Walter C. Willett, M.D.; 2005
- U.S. Department of Agriculture, Agriculture Research Service, National Nutrient Database for Standard Reference, Release 17, 2004
- "Biochemistry"; Pamela C. Champe et al; 2005
- AnneCollins.com: Omega-3 and Omega-6 Essential Fatty Acids
- DrMirkin.com: Ratio of Omega-6 to Omega-3 Fatty Acids
Member Comments