Until recently, eating nuts was taboo for people interested in fat loss. This stigma stemmed from nuts’ fat content, which varies from 45 to 74 percent. At first glance steering clear of nuts makes sense, since fat is the most concentrated source of calories’about nine per gram. That makes fat more than twice as energy dense as protein and carbs, which each average about four calories per gram.
Recent research, however, has clarified the issue. Not all forms of fat act alike metabolically. Take saturated fat, for example, which (with the exception of coconut fat) is solid at room temperature. It’s linked to cardiovascular disease and diabetes’to CVD because it’s a direct substrate of, or starting substance for, the synthesis of cholesterol in the liver, and to type 2 diabetes because it changes the characteristics of cellular membranes, making them harder and less permeable to the effects of insulin.
Nuts contain little saturated fat and no cholesterol. They’re rich in polyunsaturated and monounsaturated fats, which are more healthful than saturated fat. While there’s no dietary requirement for saturated fat, your body needs two types of unsaturated fat: linoleic acid (omega-6) and alpha-linoleic acid (omega-3). Both are abundant in nuts, although only walnuts contain alpha-linoleic acid. In fact, you can get the entire suggested intake of alpha-linoleic acid from just four walnuts.
Only in the recent past have nuts been so hotly debated. Ancient civilizations prized them because they were far more stable and available than grains. The sixth-century-B.C. Persians considered pistachios a delicacy. The Book of Genesis mentions almonds in several passages. Sometime in the late 20th century, though, nuts fell into disrepute because they were ‘fattening.’
Nuts fall into two basic categories: tree nuts and peanuts. Peanuts are actually a legume, or bean, but they share many nutritive characteristics with true nuts. One ounce of nuts, or about a half cup, averages 170 calories and 15 grams of fat (only two of those grams from saturated fat). The basics, though, don’t capture the many healthful properties that nuts have.
Nuts as Cardiovascular Protection
Several studies show that nuts are potent cardiovascular defenders. One project that tracked 30,000 Seventh-Day Adventists examined the connection between 65 foods and the incidence of CVD among church members. Of all the foods monitored, nuts had the strongest disease-prevention effects. Compared to those who ate nuts less than once a week, those who ate them one to four times weekly showed a 25 percent reduced risk of cardiovascular mortality. Church members who ate nuts five or more times a week showed a 50 percent decreased risk. The protective effects of nuts were about the same for men and women and persisted despite such other risk factors as blood pressure and bodyweight.
The Iowa Women’s Health Study, which involved 40,000 older women, confirmed the protective effects of nuts against CVD’the higher the nut intake, the greater the protection. That was significant because as women age, they lose the CVD protection that’s attributed to estrogen. The Physicians’ Health Study found that eating nuts appears to protect against sudden death from heart disease.1 Doctors in the study who ate nuts at least twice a week showed a significantly reduced risk of sudden death. That’s in line with research showing that certain fatty acids, particularly omega-3s, stabilize errant heart rhythm, the primary cause of sudden cardiac death.
Several studies show that eating walnuts can help improve blood lipids. Walnuts lower low-density lipoprotein (LDL) and total blood cholesterol, which is good for cardiovascular health, chiefly because they contain alpha-linoleic acid.
Another study compared diets rich in either almonds or olive oil.2 Like many nuts, olive oil contains monounsaturated fats and is a primary ingredient in Mediterranean diets. The group on the almond-based diet, however, experienced a 16 percent drop in total cholesterol, with a 19 percent decline in LDL cholesterol. No changes occurred in the olive-oil group. Levels of high-density lipoprotein (HDL)’the good cholesterol’remained stable in the almond group.
How nuts protect the cardiovascular system is something of a mystery. Although they favorably change blood lipids, that alone can’t explain the 50 percent reduction in CVD mortality observed in various studies of those who eat nuts several times a week. For example, for every 1 percent drop in LDL, the risk of cardiovascular disease drops by 1.5 percent. Research shows that nuts lower LDL by a maximum of 16 percent, which means that the average drop in CVD should be no more than 24 percent.
So something else in nuts must provide protection against cardiovascular disease. ALL Nuts as Nutrition
The plant protein in nuts averages 14 to 26 percent by weight. Nutritionists sometimes criticize plant protein because its amino acid balance is inferior to that of animal protein, such as the kind in milk and eggs. In certain respects, however, plant proteins have properties that animal-based proteins don’t. The amino acid arrangement in plant proteins seems to help lower blood lipids in a way that’s not true of animal proteins. Comparisons between casein, a milk protein, and soy bear that out, and nut protein is similar to that of soy.
Nuts are rich in the amino acid arginine, which protects against CVD because it’s the direct dietary precursor of nitric oxide synthesis. NO dilates blood vessels and lowers blood pressure, prevents the structural changes in arteries that foster atherosclerosis and inhibit internal blood clots, the primary immediate cause of most heart attacks and strokes.
Walnuts, pecans and almonds contain various concentrations of omega-3 fats, which lower elevated blood triglyceride, or fat, levels. They also prevent cardiac arrhythmia, which can lead to sudden cardiac death.
A high intake of dietary fiber is associated with a lower CVD risk, and nuts average 4 to 11 percent fiber by weight. They contain as much as 25 percent soluble fiber, the kind usually linked to lower blood-lipid levels.
Nuts are one of the richest food sources of alpha-tocopherol, or vitamin E, a dietary antioxidant associated with helping prevent CVD. Almonds and hazelnuts are rich sources of alpha-tocopherol, while walnuts and pecans are high in gamma-tocopherol, a form of vitamin E more potent than the alpha version in preventing prostate cancer.
Folic acid, a B-complex vitamin, lowers the blood level of a potentially toxic by-product of amino acid metabolism called homocysteine. Some studies suggest that as much as half of all CVD stems from elevated homocysteine, which is also linked to such other diseases as Alzheimer’s. Nuts are rich in folic acid, and peanuts have four times more of it than other nuts.3
Nuts are also mineral rich. Just one ounce of nuts has 8 to 20 percent of the daily requirement of CVD-fighting magnesium, which is also essential for protein assimilation, proper insulin activity and the activation of more than 300 enzymes. The same ounce also contains 18 percent of the daily requirement of copper. Copper deficiency is linked to declines in HDL’the good cholesterol’in the blood. You need copper for the structural integrity of the aorta, the large artery leading out from the heart. Long-term copper deficiency can lead to aortic rupture and sudden death, as well as colon cancer.
The abundance of phytochemicals in nuts’including flavonoids, resveratrol, ellagic acid, luteolin, tocotrienols, isoflavones, saponins, plant sterols and tannins’offers potent health benefits.
Fat? Naw, Nuts!
Research shows that, contrary to popular belief, nuts are linked more to weight loss and stabilization than weight gain. As the great bodybuilding trainer Vince Gironda told us, ‘Fat burns fat.’ Although considered heresy when he first voiced it some 40 years ago, Vince’s opinion has been confirmed by the experts. Polyunsaturated and monounsaturated fats foster fat oxidation because they’re precursors of chemicals known as eicosanoids. The popular Zone diet is entirely based on controlling eicosanoid synthesis by manipulating insulin release.
Nuts help optimize body composition, producing high satiety or appetite-suppression, leading to less total calorie intake and subsequent weight loss. Here’s why:
‘The body doesn’t absorb all the energy stored in nuts. When five healthy research subjects ate 76 grams of peanuts daily for four to six days, they excreted 18 percent of the dietary fat the peanuts contained, and their stools showed evidence of undigested nuts. Although fiber also causes fat excretion, the nuts behaved the same way regardless of the subjects’ other fiber intake.That’s because of either the way fat is stored in nuts or their fiber content. ‘Nuts promote satiety, thus diminishing appetite’an effect that’s more notable with whole nuts; nut butters, such as peanut butter, are much more calorie rich and more easily digested.
‘As Vince Gironda explained, unsaturated fats, abundant in nuts, increase diet-induced thermogenesis, which means calories are burned off as heat instead of being stored as bodyfat. One study found that eating peanuts for 19 weeks led to an 11 percent increase in resting energy expenditure.4
‘Unlike some forms of fat, the fat in nuts doesn’t interfere with normal glucose metabolism or cause insulin resistance. In fact, some studies show that nuts, mainly because of their magnesium content, help guard against type 2 diabetes.
So can you eat any amount of nuts with impunity? Not at all. Small portions will displace your desire for more food, but nuts are high in calories, and eating pounds of them will make you gain weight. A famous Muscle Beach powerlifter years ago named Bill ‘Peanuts’ West earned his nickname because when he first arrived in California, he was so poor that he subsisted entirely on peanuts. That diet, along with his enthusiastic lifting, added pounds of weight and muscle to his previously thin frame.
Recently, researchers at Texas A&M University genetically engineered peanuts that contained 70 percent more oleic acid, a monounsaturated fatty acid, than regular peanuts. Oleic acid helps lower LDL in the blood, although it has no effect on HDL. The superpeanuts may help make nuts an even more healthful food than they already are.
Don’t be misled by the false allegations against nuts. The truth is that not eating nuts judiciously is, well, nuts.
1 Albert, C.M., et al. (2002). Nut consumption and decreased risk of sudden cardiac death in the Physicians’ Health Study. Arch Intern Med. 162:1382-87.
2 Spiller, G.A., et al. (1998). Nuts and plasma lipids: an almond-based diet lowers LDL-C while preserving HDL-C. J Amer Coll Nutr. 17:285-90. 3 Alper, C., et al. (2003). Peanut consumption improves indices of cardiovascular disease risk in healthy adults. J Amer Coll Nutr. 22:133-41. 4 Alper, C.M., et al. (2002). Effects of chronic peanut consumption on energy balance and hedonics. Int J Obes. 26:1129-37. IM