In the largest study of its kind, Harvard scientists found that people who ate a handful of nuts every day were 20% less likely to die from any cause over a 30-year period than those who didn’t consume nuts. The study also found that regular nut-eaters were leaner than those who didn’t eat nuts, a finding that should calm any fears that eating nuts will make you gain weight.
The report also looked at the protective effect on specific causes of death. “The most obvious benefit was a reduction of 29% in deaths from heart disease—the major killer of people in America,” according to Charles S. Fuchs, director of the Gastrointestinal Cancer Treatment Center at Dana-Farber, the senior author of the report and a professor of medicine at Harvard Medical School. “But we also saw a significant reduction—11% —in the risk of dying from cancer,” added Fuchs.
The study couldn't determine whether any specific type or types of nuts were crucial to the protective effect. The reduction in mortality was similar both for peanuts (a legume) and for tree nuts—walnuts, hazelnuts, almonds, Brazil nuts, cashews, macadamias, pecans, pistachios, and pine nuts.
Several previous studies had found an association between increasing nut consumption and a lower risk of diseases such as heart disease, type 2 diabetes, colon cancer, gallstones, and diverticulitis. Higher nut consumption also has been linked to reductions in cholesterol levels, oxidative stress, inflammation, excess weight, and insulin resistance. Some small studies have linked an increase of nuts in the diet to lower total mortality in specific populations. But no previous research studies had looked in such detail at various levels of nut consumption and their effects on overall mortality in a large population that was followed for more than 30 years.
Nuts are my favorite "go-to" snack
Nuts make the perfect in-between-meals snack for people on the move. They're delicious, easy to transport (I always carry a small bag of them in my handbag—very handy for blood-sugar lows during long car journeys) and never get boring because they vary so widely in flavor and texture.
Because of their high fat content, they can sustainably nip hunger pangs in the bud. This makes them a more satisfying snack than starchy or sugary tidbits such as crackers, cookies or candy bars, which briefly cause your blood-sugar levels to climb, only to drop soon thereafter, causing you to feel hungry again an hour later and launching your ride on the blood-sugar rollercoaster.
The fats in nuts are of the healthy variety for which the Mediterranean Diet is famous: mostly monounsaturated, with some polyunsaturated and saturated fats. Walnuts are particularly rich in polyunsaturated omega-3 fatty acids. Other nuts, such as hazelnuts and almonds, are lower in omega-3s but contain healthy monounsaturated fats and high levels of antioxidant compounds that protect our cells from oxidation.
Nuts are also a wonderful ingredient for use in cooking and baking. Not just cakes benefit from the addition of nuts (in many recipes, you can simply replace some of the flour with ground nuts), but savory dishes too. In my weekly meal plan, Everyday Mediterranean, I often use nuts, either as garnish (e.g. pine nuts or walnuts sprinkled over soups, salads or casseroles) or as integral parts of the dish, to thicken a sauce or add crunch and body.
In October I dedicated a whole issue of Everyday Mediterranean to walnuts ("Totally Walnuts!"), because while many people eat other nuts (especially almonds and peanuts), walnuts are often overlooked. That's a real shame, as they have one of the most attractive fatty-acid profiles of all nuts.
According to NutritionData.com, English walnuts contain 4 times more omega-6 fatty acids than omega-3s, close to the 2:1 ratio considered ideal for human health. Omega-3s have anti-inflammatory, anti-cancer, cholesterol-regulating and bone-strengthening properties, support nervous-system health and have a wide range of other benefits. While most of us get more than enough omega-6s (too many of which can promote inflammation and cancer growth), many people are low in omega-3s.
Other nuts have less-attractive omega-6-to-3 ratios: according to NutritionData.com, pecan nuts have an omega-6-to-3 ratio of 20:1; that of hazelnuts is 90:1. Almonds have next-to-no omega-3s, resulting in a ratio of 2000:1, whilst peanuts are practically off the charts with a ratio of 5677:1!
Walnuts' health benefits aren't just limited to omega-3s, though. Additional cancer-protective compounds in walnuts include vitamin E (especially gamma tocopherol), ellagic acid (an antioxidant present in various nuts and fruits) and phytosterols, plant compounds with a range of cancer-inhibiting and cholesterol-regulating mechanisms.
This doesn’t mean you should only eat walnuts, however. Other nuts have other health benefits; for instance, hazelnuts (my other favorite) help to calm inflammation (NutritionData.com gives them an “inflammation rating” of 435, judging them to be “strongly anti-inflammatory”) and contain more than 50% of monounsaturated fats, making them more resistant to oxidation (rancidity) than other nuts. (The oils in most nuts are rather fragile and prone to oxidation when exposed to heat, light or oxygen. Always eat them as fresh as possible, don't overheat them when cooking with them, and store them in a dark, cool place.)
Pistachios have an omega-6-to-3 ratio of 52 and contain a respectable 13% protein. In addition, the antioxidants in these nuts are thought to reduce risk of heart disease by lowering oxidized LDL (low-density lipoprotein) in people with high cholesterol, as well as improving erectile dysfunction in some men.
Peanuts, meanwhile, are higher in protein than other nuts (16% of calories, vs. only 8% for walnuts and hazelnuts; that’s because they’re legumes). When eating peanuts, make sure they’re fresh and have been stored in dry, cool conditions; peanuts grown in warm, damp regions or that have been inadequately stored may be tainted by so-called aflatoxins, toxic compounds produced by molds that increase the risk of liver cancer.
A word of caution regarding all nuts: while the fats in nuts are healthy, they are also high in calories, and if eaten in large quantities they can contribute to weight gain. One of my clients experienced this after I suggested that she swap the butter on her breakfast toast for almond butter. A few weeks later she called me to complain that she had gained weight, and she was blaming the almond butter. Gently I asked her how much she had been eating. “Oh, about a jar a week—I love it so much, I’m eating it straight out of the jar,” she said. Case closed.
To help you increase your nut consumption (without going overboard...), you can download one of my recent walnut recipes (gluten-free and free of charge) here. To your good health!
(c) Conner Middelmann-Whitney. Conner is a nutritionist and health writer specializing in the Mediterranean Diet. She is based in Boulder, Colorado and offers online nutrition coaching as well as publishing "Everyday Mediterranean," a weekly recipe- and meal-planning service for busy people who want to "Mediterraneanize" their diet. For more information about her work, see her website: www.nutrelan.com.