Fish is good for you, but watch out for mercury. Limit your salt, but don’t cut it out entirely. Today’s nutritional debates leave consumers starved for the bottom line. Here it is for five key ingredients.

Levi Brown

Milk

The Conventional Wisdom
Drink up! There’s a reason why Mom served it: It’s rich in protein and calcium, which are important for healthy muscles and bones.

But Wait...
Milk is a complex nutritional package designed by nature to promote growth after birth, so it’s full of naturally occurring hormones and other specialized ingredients. But are they helpful for adults? Experts are not so sure. In recent years, research has questioned dairy as a possible link to a host of ailments, from acne (as reported in a 2012 study published in the Journal of the American Academy of Dermatology) to childhood obesity (according to a 2013 article in the journal Archives of Disease in Childhood) to even prostate cancer (suggested in a 2012 Nutrition & Metabolism paper).

Finding a Balance
According to the National Academy of Sciences, you should aim for 1,000 milligrams of calcium daily. But at the same time, the Harvard School of Public Health advises that you need to limit dairy (milk, cheese, and yogurt combined) to one to two servings a day. Two servings of milk offer 600 milligrams of calcium. (As is the case with other forms of dairy, milk is among the most highly concentrated sources of calcium available, and it is easily absorbed by the body.) To make up for the rest of your calcium needs, add to your diet beans, certain types of tofu (look for calcium in the ingredient list), broccoli, and leafy greens. One and a half cups of cooked kale has almost as much calcium as eight ounces of milk. And though calcium from plant sources may be tougher for the body to absorb (some greens contain oxalates, compounds that interfere with the release of calcium), small amounts can add up.

But what if you crave more milk than the daily dairy allowance? Try soy, rice, oat, or nut milks, which, unlike cow’s milk, usually contain no saturated fat, no cholesterol, and no growth hormones.

Salt

The Conventional Wisdom
Excess sodium increases the risks of high blood pressure, heart disease, and stroke. Salt should be avoided whenever possible.

But Wait...
We may be in danger of taking the salt-cutting crusade too far, say critics—who include, yes, the salt industry but also some independent scientists. After all, sodium is essential for muscle contraction (like the kind needed for the heart to beat), nerve-impulse transmission, pH balance, and hydration. While research findings supporting a low-salt diet have made headlines, some scientists are beginning to doubt the safety of extremely low-salt regimens for some groups of people.

Finding a Balance
There’s no conclusive evidence that lower amounts of salt are beneficial, says a 2013 report from the Institute of Medicine, which is part of the National Academy of Sciences. But you certainly don’t need the 3,400 milligrams of sodium a day that Americans, on average, currently consume. The U.S. Department of Agriculture (USDA) recommends less than 2,300 milligrams (just under a teaspoon) for healthy people and 1,500 milligrams for those with certain risk factors, such as being age 51 or over or having diabetes. How can we stop overdoing it? The fastest way is to limit processed foods. “It’s these items, not our salt shakers, that supply over 70 percent of the sodium in our diets,” says Linda Van Horn, Ph.D., a research nutritionist at the Feinberg School of Medicine at Northwestern University, in Evanston, Illinois. Salt is a preservative and a flavor enhancer, which is why it’s in almost anything that you buy in a box, a can, or a bag. What packs a high amount of salt isn’t always obvious: The salt content in soups, breads, and even breakfast cereals (some of which have higher salt-to-calorie ratios than chips) can quickly add up.

So read labels carefully when you shop. Even better, cook at home, where you can control the salt. If you consumed a lot of salty products in one day (French-fry binge!), be extra mindful the next. And use lemon juice, vinegar, herbs, onions, or garlic—not extra salt—to amp up the flavor of your food.

Fish

The Conventional Wisdom
Long-chain omega-3 fatty acids have been linked to heart, vision, and brain health, and they are in greater abundance in seafood than in any other food, including flaxseed and walnuts. The healthiest diets in the world, such as the Mediterranean and the Japanese, are chock-full of fish.

But Wait...
All fish are at risk of being tainted with mercury, say environmentalists, but some types are much more likely to harbor this toxin than others. When mercury builds up in the body over time, it can lead to neurological and reproductive diseases and impair immune function. Farmed fish (which can be more affordable than wild and make up half the fish that the world consumes) can be exposed to mercury, too. In addition, farmed fish are sometimes treated with antibiotics.

Finding a Balance
To maximize nutritional benefits, aim for 3½ ounces of fish at least twice a week, as recommended by the American Heart Association. To minimize toxins, eat the right species: The safer sources that are rich in omega-3s are small to medium-size cold-water fish (such as anchovies, sardines, and wild salmon) and mussels. Their size and short life spans limit absorption of the heavy metals and contaminants found in larger sea life. Whereas wild and farmed mussels are usually equally nutritious and safe, salmon and other fish are often healthier and more environmentally sound when they’re wild, says Joyce Nettleton, a Denver-based nutrition consultant specializing in seafood nutrition and omega-3 fatty acids. Avoid swordfish, king mackerel, and tilefish, which are large and live long lives. Albacore tuna is safe when limited to six ounces a week, but steer clear if you’re pregnant or breast-feeding.

In general, go for variety. You don’t always have to eat, for instance, fresh wild salmon. Frozen or canned is just as omega-3–rich as fresh and considerably cheaper. White, flaky varieties of fish (tilapia, flounder) and clams don’t pack as many omega-3s as the varieties mentioned above, but they do contain some. Plus, they are generally safe to eat. If every so often you end up eating, say, farmed salmon, don’t sweat it. “You don’t have to be perfect every time,” says Andy Sharpless, the CEO of Oceana, an organization for international ocean conservation. “You just need to be good in the long run.”

Sugar

The Conventional Wisdom
These days, nobody would claim that sugar is a health food, but it is a quick energy-spiker and mood-lifter. And if we over-indulge? No worries. It’s just calories, not something really bad, like saturated fat. All it takes to make up for the calories is a little extra time on the treadmill. Right?

But Wait...
A high amount of sugar is worse than not healthy—it’s harmful, say some obesity experts, in large part because sugar is so prevalent that you end up eating more than your body can comfortably process. This throws your insulin levels off balance. Stored as fat, excess sugar also increases the risks of heart disease, diabetes, and obesity. “Sugar in excess is a toxin,” says Robert Lustig, M.D., a professor of pediatrics at the University of California, San Francisco. “Like alcohol, a little sugar is fine, but a lot is not.”

Finding a Balance
A 2007 American Journal of Clinical Nutrition study reported that, indeed, obesity rates have risen sharply and consistently with the dietary rise of added sugar (meaning sugar that doesn’t occur naturally in a food, as in fruit). So how can we literally enjoy our cake and eat it, too? Advice varies on exactly where that line between a safe amount of sugar and “too much” should be drawn. Most of the recommended limits for added sugar are challenging for most Americans. The American Heart Association advises no more than 100 calories of added sugar a day for women, which is about six teaspoons. Men, who have more muscle and burn calories more efficiently, are allowed 150 calories. Health experts, such as David Katz, M.D., at Yale University, advise up to 200 calories of added sugar for a diet of 1,500 to 2,000 calories a day (a fair range for most healthy women). Two hundred calories of added sugar is less than what’s in half an average-size coffee-shop muffin—for the whole day. Most Americans eat at least twice that daily.

But don’t give up trying! Even small reductions help. Start by reading labels. Of the 85,451 packaged food items in an average American grocery store, 74 percent have added sweeteners, whether in the form of a natural sweetener (like fruit juice) or the more obvious refined white sugar and high-fructose corn syrup. They all eventually get broken down into glucose. So to your body, they are essentially the same. Even healthful foods can be packed with sugar. Some yogurts, for instance, contain up to 29 grams of sugar per serving: the equivalent of more than seven teaspoons. Forgo sugary beverages and sweeteners in foods that don’t need them (salad dressing, pasta sauce). Try getting sugar from fruits, and enjoy the refined sort only where it counts, such as the occasional chocolate doughnut. If you love pastries, bake them yourself. Chances are, you’ll be using less sweetener than a commercial bakery does, says Lustig.

Grains

The Conventional Wisdom
Whole grains, such as brown rice and oatmeal, are necessary in a healthy diet. Unlike the refined variety (found in white, enriched starches), whole grains have their bran and germ components intact, so they retain more protein and fiber, which helps to slow down the digestive process—promoting a feeling of fullness, stabilizing blood sugar, and lowering cholesterol. “In all the large studies, eating whole grains is associated with good health outcomes,” says Katz.

But Wait...
You don’t really need grains, whole or otherwise, say critics, among whom the most vocal are the gluten-free and paleo-diet proponents. You can get as much fiber and minerals from fresh fruits and nonstarchy vegetables (such as kale and broccoli), which, these critics claim, are also easier for the body to digest.

Finding a Balance
Whole grains, in fact, are essential. “They contain unique phytonutrients, which, as part of an overall healthy diet, may help prevent cardiovascular conditions and cancer. Whole grains cannot be replaced with a produce swap,” says Suzanne Steinbaum, M.D., the director of the department of women and heart disease at Lenox Hill Hospital, in New York City. Aim to make whole grains at least half your daily grains (three ounces a day is a good goal), says the USDA, along with 1½ cups of fruit and 2½ cups of vegetables. Since there are plenty of gluten-free whole grains (including quinoa, amaranth, buckwheat, brown rice, oats, and millet), even those with celiac disease or gluten intolerance can work this recommendation into their diets.

When shopping for grains and breads, says Steinbaum, check the ingredient list: Make sure that there are no additives or added sugars. Also keep in mind that even if the packaging touts whole-grain content, the claim won’t be substantive unless “whole grain” or “whole wheat” appears first on the ingredient list. Don’t have time to cook whole-grain barley or rice? Even pearled and quick-cooking versions include more fiber nutrients than white rice, so you’re still on the right track.

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