By Glenn D. Braunstein, M.D. Huffpost Healthy Living
Forget the fruit smoothie and energy bar; today's fashionably health conscious leave the gym with a bottle of coconut water in one hand and a fistful of raw walnuts in the other. Once considered a big no-no for anyone looking to get in shape, or stay that way, all things nuts, including coconuts -- which are actually fruits -- suddenly have become staples. In part, the craze is being fueled by new science that's found, despite a high fat content, nuts and coconuts do have health benefits.
But are they the superfoods that some have them cracked up to be?
Cuckoo for Coconuts
Let's start with coconuts. The current fervor is both for coconut water found in the center of young, green coconuts and the oil extracted from the meat of the mature fruit. Unlike coconut milk that's pressed from coconut meat, coconut water (technically, it's a juice) is clear in color, low in calories and fat-free. It's also packed with potassium, sodium and magnesium -- the electrolytes lost through sweating. That has marketers touting the liquid as "nature's sports drink."
Plenty of people are swallowing, too. Buoyed by endorsements from the fit and famous, including Madonna and Demi Moore, who are investors in the top-selling Vita Coco brand, sales of coconut water in the United States have doubled each year between 2005 and 2011 to $400 million.
Only a few small studies, however, have researched deeply the possible benefits. In a nutshell, the research finds coconut water is as effective as traditional sports drinks and bottled water for the typical, recreational athlete's workout.
Most recent was a study conducted among a dozen fit young men at the University of Memphis. On four occasions, each blindly received a regular sports drink, bottled water or coconut water after running on a treadmill for 60 minutes. Little difference was found between the beverages in rehydration and supporting further exercise. Similarly, in a study following 10 men running in the heat for 90 minutes, sodium-enriched coconut water and the regular sports drink were found to be slightly more effective than plain water.
For hard-core athletes training intensely, however, a sports drink is likely better because it's higher in carbohydrates and sodium. In 2011, a study conducted by 45 calories and contains 11 grams of natural sugar per 8-ounce serving, whereas plain water lacks either.
As for other claims: Preliminary studies in animals suggest coconut water may help lower blood pressure and cholesterol, but so far it hasn't been proven to do so in humans. There is zero evidence that it can control diabetes, fight viruses, break up kidney stones or prevent cancer. Cancer prevention claims rest on coconut water's containing selenium, which has antioxidant properties shown to fight cancer in the lab. But many foods, including Brazil nuts, fish and shellfish, contain selenium, too.
Bottom line: Coconut water is a fine beverage, certainly healthier than typical sodas and many more sugary juices. It's not magical. If you like the taste and don't mind the $2 to $3 per container price, drink up. Just be sure to check the label. Some brands contain added sugar.
As for coconut oil, few foods have enjoyed a more radical reversal in reputation. Nearly two decades ago, the Center for Science in the Public Interest caused a major backlash with its declaration that a large box of movie-theater popcorn, sans butter, had as much saturated fat as a half-dozen Big Macs, because it was popped with coconut oil. The advocacy group has revisited the concession stand in 2009 and found that little had changed. Even so, coconut oil is prominently displayed in health food stores and sales are reportedly booming. One reason is the oil's popularity as a replacement for butter among vegan chefs (those who won't use any animal products). As a saturated fat, coconut oil is solid at room temperature and may be used to create a perfect piecrust or buttercream-like cake frosting.
Researchers also note that early studies that warned of coconut oil's artery-clogging evils were conducted primarily on partially hydrogenized, rather than virgin oils. The hydrogenation process creates additional, unwanted transfats, plus it destroys some of the good, essential fatty acids and beneficial antioxidants in virgin coconut oil. Virgin coconut is still 90 percent saturated fat and contains natural transfats; these just arguably may not be as bad as the processed kind. Coconut oil is known to significantly boost HDL (aka "good cholesterol"). However, claims that it also lowers LDL ("bad cholesterol") were reported by a small study in laboratory rats, but evidence is insufficient that it does so for humans.
The American Heart Association recommends using coconut oil sparingly. It advises we limit coconut oil, and all saturated fats to less than 7 percent of our daily calories and transfats to less than 1 percent.
Peruse the Internet and you'll also find claims boasting virgin coconut oil as a prevention and a cure for Alzheimer's disease. Neither is proven. Scientific, clinical, reliable studies of coconut oil and the disease are lacking, according to the Alzheimer's Association.
Researchers, however, have begun to study the impact of walnuts on improving cognitive decline in rats. In a study at Tufts University, researchers fed 344 aging rats diets consisting of varying percentages of walnuts for eight weeks, before testing them as they performed tasks. Rats on walnut-rich diets demonstrated improvement in working memory as they ran a water maze, although those who ate the largest amount of walnuts (9 percent of their diet) showed long-term memory impairment. Those fed a 2 percent walnut diet demonstrated improvement in walking on the rod, while those consuming the 6 percent walnut regiment improved in walking on the medium plank. Like all animal studies, this one is too preliminary to extrapolate to humans.
Nuts Can Lower Bad Cholesterol
Whether walnuts prove to be a potent brain food for our aging population, they and other nuts boast many other health benefits. In 2003, the U.S. Food and Drug Administration authorized several nuts, including walnuts, almonds, peanuts, pine nuts, hazelnuts and pistachios, to be promoted as helpful in reducing the risk of heart disease and cholesterol problems. For point of emphasis: We're talking raw nuts, not those salted, oil roasted or candy coated.
Potent in polyunsaturated fatty acids, nuts can improve cholesterol levels, which in turn decreases our risk for heart disease. Epidemiological studies show that people who eat nuts several times a week have between a 30 percent and 50 percent lower risk of heart disease and heart attacks than those who rarely eat them.
Fats in nuts also may help reduce the risk of type 2 diabetes . Omega-3 fatty acids, in particular, may decrease the risk of coronary artery disease and protect against irregular heartbeats. Nuts are a good source of protein and fiber, too.
Walnuts may even improve our stress response. Researchers at Penn State University tested their effect on 20 adults with elevated LDL levels. Each subject went on one of three diets identical in the amount of calories, protein and fat; one diet contained no walnuts, while another included walnuts and a tablespoon of walnut oil. A third diet included walnuts, walnut oil and 1.5 tablespoons of flax seed oil. Researches then induced stress by having participants give a speech or immerse a foot in cold water. Participants whose diets included walnuts and walnut oil had a lower resting blood pressure rate and lower blood pressure response to stresses in the lab than those who did not eat any walnuts. Those whose diets also included flax seed oil did not show any difference as compared with those who ate only walnuts and walnut oil.
From walnuts to pistachios, nuts are packed with health benefits. If you don't want to pack on the pounds, keep in mind that a little of them goes a long way. With nuts at about 185 calories per ounce, don't go nuts gobbling them down; a handful a day is great. Be sure, too, that you don't simply add them to your daily regime; replace them for other fats -- preferably saturated ones such as those in potato chips. As you pass this potentially healthy snack around, enjoy and for once, say with correct gusto when you share: Nuts to you!