• A review of 14 studies shows that people who ate nuts five times a week had a significantly lower rate of heart disease than those who ate less or none (Coron Artery Dis, 2016 May;27(3):227-32). The rate of heart disease decreased by 10 percent for every serving per week of increased intake of nuts.
• Another review of the world's literature showed that higher nut consumption is associated with reduced risk of death from heart attacks and deaths from all causes (Br J Nutr, 2016 Jan 28;115(2):212-25).
• Of 20,742 male physicians followed for 10 years, those who took in more nuts had lower rates of death from all causes and death from heart disease during the study period (Am J Clin Nutr, February 2015;101(2):407-412).
• Eating nuts is associated with reduced death rate from heart attacks in many different ethnic groups including African Americans, poorer European-descent Americans, and Chinese living in Shanghai (JAMA Intern Med, 2015 May;175(5):755-66).
Nuts Appear to Lower Cholesterol and Blood Pressure
A review of 61 studies showed that nuts lower total cholesterol, the bad LDL cholesterol, ApoB and triglycerides (Am J Clin Nutr, Dec 2015;102(6):1347-56). It did not make much difference what nuts were studied. For example, a review of 13 studies showed that walnuts significantly lowered total cholesterol and the bad LDL cholesterol (Am J Clin Nutr, 2009 Jul; 90(1): 56-63), while almonds were found to increase the good HDL cholesterol (J. Nutr, October 1, 2015;145(10):2287-2292). Similar results would probably be obtained with other varieties of nuts.
Nuts are Anti-Inflammatory
Many studies show that people who eat nuts have lower risk for the diseases linked to inflammation, such as heart attacks and diabetes. Harvard researchers followed more than 5000 people and found that those who ate five or more servings of nuts per week had a 20 percent lower level of the blood marker of inflammation called C-reactive protein (CRP), and a 16 percent lower interleukin 6 (IL6) than those who rarely ate nuts (Am J Clin Nutr, September 2016;104(3):722-728). One serving of nuts was defined as one ounce, which is about 1/4 cup of tree nuts or peanuts, or one tablespoon of peanut butter. The apparent benefits of nuts were similar regardless of the type of nuts people ate, although no benefit was seen with peanut butter. When the subjects ate three servings per week of nuts in place of red meat, processed meat, eggs or refined grains, they had even lower levels of CRP and IL6. This suggests that you cannot expect to prevent a heart attack just by eating nuts. In addition to eating nuts and other anti-inflammatory foods, you also need to restrict the foods that increase inflammation. See Anti-Inflammatory and Pro-Inflammatory Foods
Nuts (in Moderation) Don't Make You Fat
All types of tree nuts and peanuts contain a variety of nutrients including magnesium, calcium, iron, fiber, L-arginine, antioxidants and fatty acids such as alpha-linolenic acid. Nuts are rich sources of fats, but many studies show that the fat in nuts is absorbed very poorly and so is not a major cause of weight gain (American Journal of Clinical Nutrition, Jan 2015;101(1):25-33). The fat in nuts is located inside the cells, and even after prolonged chewing, most of the cells remained intact and the fat was still inside the cells when it reached the intestines. Since fat is absorbed only after it is released from the nut cells, most of the fat cannot be absorbed in the upper part of your intestinal tract. This explains why the amount of calories you get from eating nuts is lower than what you read on the labels. See Why Nuts Won't Make You Fat
The dark reddish, papery skin on peanuts, called the testa, is healthful because it is full of antioxidants, resveratrol and fiber. Peanut processors usually remove the skins and sell them for animal feed. The most healthful peanuts are those that are still in their shells, or shelled peanuts that still have their skins. Whole tree nuts with their skins intact are also more nutritious than those that have had the skins removed. Raw nuts are probably more healthful than those that have been roasted or cooked in oil, but the differences are not large enough to be noted in the various studies.
• People who eat nuts five times a week are at reduced risk for obesity, diabetes and heart attacks. Nut eaters may be protected because nuts lower markers of inflammation, blood pressure and cholesterol.
• Nuts do not appear to be associated with weight gain, even though they are full of fat. They are probably the most healthful of all the popular snack foods, as long as the portion size is reasonable. My guideline is to snack on no more than a handful of nuts at a time.