Going Nuts for Health  

Research currently supports roughly an ounce of nut intake daily, and nutrient profiling suggests the importance of eating unprocessed nuts

By: Dr. David L. Katz*

    At the height of the fat-phobia era in American dieting, nuts were exiled from the health-conscious diet. Their return signifies not only progress in our understanding of the finer points of healthful eating, but a general principle as relevant to soup, as to nuts.
    There are only three macronutrient classes -- carbohydrate, fat, and protein -- and eating well has never been or will be about deciding which of them to jettison. Eating well -- for both health and lasting weight control -- is always about choosing wisely from the foods that populate each nutrient class. Or in the words of nutrition writer Michael Pollan: “Eat food, mostly plants, not too much.”
    So we have learned that not all fat, and not all foods containing fat, are created equal. For the most part, nuts are good for us, with a growing body of research shedding light on just how good, and in what ways.
    While nuts are indeed rich in fat content, it is, for the most part, of the healthful variety. The dietary fats that cause harm include trans fat (first and foremost), followed by saturated fat. The unsaturated fats, including both monounsaturates and polyunsaturates, tend to promote health. And some varieties of unsaturated fat, such as the omega-3 polyunsaturates often associated with fish oil, are potentially important enough to add to the diet intentionally.
    In fact, the subtleties of dietary fat and health run deeper still. Not all varieties of saturated fat are created equal, and some of these, too, may be harmless at worst. But that’s a story for another day. All the same subtleties apply to carbohydrate, which includes everything from lentils to lollypops.
    Nuts, which contain fat, protein, and carbohydrate, are generally good food. The fat in nuts tends to be poly- and mono-unsaturated, and some of the most nutritious nuts, such as walnuts, are a good source of omega-3 fat.
    Along with healthful fat content, nuts tend to be a good source of fiber; minerals including potassium, magnesium, and calcium; vitamin E; and high quality protein. The one potential downside to nuts in their native state is the high calorie content they provide, although the jury is out on the effects of nut consumption on weight. It appears thus far that nuts are particularly good at satisfying appetite, in which case the calorie cost of nuts may be a price well paid.
    The other concern about nuts is what we do to them. Often, they are not in their native state when consumed. By the time we’re done roasting, coating, and salting, the nutritional profile of a naturally nutritious nut may be a shadow of its former self.
    These effects are nicely displayed using the Overall Nutritional Quality Index (ONQI; see www.onqi.com) to compare nuts prepared in different ways. The ONQI generates a score on a scale from 1 to 100, with 100 being the best, for any food based on its overall nutritional profile. Raw walnuts, almonds, and pecans all get a very impressive ONQI score of 82, putting them up in the range of some fruits and vegetables, as well as wild salmon. Oil roasted almonds drop to a score of 66. Honey roasted almonds get a 57. Almonds roasted in oil and salted get a 44.
    Not all nuts are equally nutritious. Raw pistachios are quite good, with an ONQI score of 70, but not up there with the nutty superstars. Cashews are noteworthy as the nutritional black sheep of the family (too bad; they sure are tasty!) with an ONQI score of 24. Peanuts, boiled and salted, get a 39.
    The scientific evidence of health benefits from nut consumption is getting stronger all the time. Long-term observational studies, such as the Nurses’ Health Study at Harvard, show an association between regular intake of nuts and seeds and reduced risk of heart disease. Intervention trials have shown that almonds can improve cholesterol levels and help stabilize blood glucose and insulin levels. Walnuts have been shown to improve blood flow and the FDA has even approved a health claim that walnuts, added to the diet, may reduce the risk of heart disease.
    There are hints in the scientific literature that eating nuts may help control diabetes and improve associated health outcomes, but this evidence is still a work in progress. My lab hopes to contribute to that progress with a clinical trial now beginning.
    More research is clearly warranted to determine just how beneficial nuts are, what dose is optimal, and who benefits most. Research currently supports roughly an ounce of nut intake daily, and nutrient profiling suggests the importance of eating unprocessed nuts.
    So for now, there is sufficient evidence available to indicate that it is a good idea to go a bit nuts for health. Just go nuts in moderation!

* David L. Katz, MD, MPH, FACPM, FACP; Director, Prevention Research Center, Yale University School of Medicine and medical contributor for ABC News. He may be reached at www.davidkatzmd.com.)