Could a common nutrient be the antidote to an overweight America? Explore the surprising benefits of a vitamin that’s hiding in plain sight
By Alisa Bowman, Photographs by Kenji Toma
It was supposed to be a routine study.
At the University of Minnesota 2 years ago, Shalamar Sibley, M.D., was examining how calorie reduction might affect hormone pathways. On a hunch, she decided to test one more variable: vitamin D. “Researchers have been tracking the relationship between low vitamin D and obesity,” says Dr. Sibley. “So I wondered if people’s baseline vitamin D levels would predict their ability to lose weight when cutting calories.”
Her hunch paid off—big time. People with adequate vitamin D levels at the start of the study tended to lose more weight than those with low levels, even though everyone reduced their calorie intake equally. In fact, even a minuscule increase in a key D precursor caused the study participants to incinerate an additional half pound of flab.
Dr. Sibley’s study is just the latest indication that vitamin D could be our special ops agent in the war against body fat. “In the past decade, there’s been an explosion of research on vitamin D,” says Anthony Norman, Ph.D., a professor emeritus of biochemistry at the University of California at Riverside. For example, a study at Laval University in Quebec City found that people who consumed more dietary vitamin D had less belly fat than people who ate less.
What’s the big deal about D? It comes from milk and exposure to sunlight, right? Well, not really. Or at least, not enough of it does. More than a third of American men are deficient in the nutrient—even young, healthy men who live in sunny states. And many more American men—over 50 percent—have suboptimal levels.
“Vitamin D deficiency is one of the most commonly unrecognized medical conditions,” says Michael F. Holick, M.D., Ph.D., a professor of medicine at Boston University medical center and author of The Vitamin D Solution. “And that deficiency negatively affects every cell in your body—including your fat cells.”
Gimme a D! Gimme Another D!
One reason vitamin D has flown under the research radar for so long is because it’s more than just a vitamin—it’s also a hormone, one that plays a role in a remarkable range of body processes. “In the past 20 years, we’ve found D receptors on up to 40 different tissues, including the heart, pancreas, muscles, immune-system cells, and brain,” says Norman. He should know, having discovered the vitamin D receptor on intestinal cells back in 1969. So think of vitamin D as your body’s multitasking marvel: Heart disease? Adequate D might be equal to exercise in its ability to ward off this number one killer of men. Blood pressure? D helps keep it down. Diabetes? Yep, studies show that D can combat this, too. Now add to this list the potential to ward off memory loss, certain cancers (including prostate), and even the common cold, and it should come as no surprise that D may also help solve the riddle of your expanding middle. Here’s the rundown on the many benefits of boosting your vitamin D.
1 You’ll eat less but feel more satisfied.
When you have adequate vitamin D levels, your body releases more leptin, the hormone that conveys a “we’re full, stop eating” message to your brain. Conversely, less D means less leptin and more frequent visits to the line at the Chinese buffet. In fact, an Australian study showed that people who ate a breakfast high in D and calcium (a mineral that works hand in hand with D) blunted their appetites for the next 24 hours. Vitamin D deficiency is also linked to insulin resistance, which leads to hunger and overeating, says Liz Applegate, Ph.D., director of sports nutrition at the University of California at Davis.
2 You’ll store less fat.
When you have enough D in your bloodstream, fat cells slow their efforts to make and store fat, says Dr. Holick. But when your D is low, levels of parathyroid hormone (PTH) and a second hormone, calcitrol, rise, and that’s bad: High levels of these hormones turn your body into a fat miser, encouraging it to hoard fat instead of burning it, says Michael B. Zemel, Ph.D., director of the nutrition institute at the University of Tennessee. In fact, a Norwegian study found that elevated PTH levels increased a man’s risk of becoming overweight by 40 percent.
3 You’ll burn more fat—especially belly fat.
Vitamin D can help you lose lard all over, but it’s particularly helpful for the pounds above your belt. Studies at the University of Minnesota and Laval University found that D triggers weight loss primarily in the belly. One explanation: The nutrient may work with calcium to reduce production of cortisol, a stress hormone that causes you to store belly fat, says Zemel.
4 You’ll lose weight—and help your heart.
One of Zemel’s studies found that a diet high in dairy (which means plenty of calcium and vitamin D) helped people lose 70 percent more weight than a diet with the same number of calories but without high levels of those nutrients. What’s more, a German study showed that high levels of vitamin D actually increased the benefits of weight loss, improving cardiovascular risk markers like triglycerides.
Why Not Just Step Outside?
When sunlight hits your skin, your body’s built-in vitamin D factory kicks into operation, producing a form of the nutrient that lasts twice as long in your bloodstream as when you consume it through food or a supplement. The problem, of course, is a little thing called skin cancer: In order to manufacture enough D, you’d need to be in the sun during the peak hours of 10 a.m. to 3 p.m. without sunscreen, says Dr. Holick. But even if you could take cancer out of the equation, the amount of sunlight-derived D your body can produce depends on your location. People who live north of the equator probably make only 10 to 20 percent as much D in April as they do in June. And come December, a northerner’s skin can produce hardly any D, says Dr. Holick. Even living in a sunny city is no guarantee of adequate natural D. Air pollution filters UVB rays, so less of them are able to reach your skin. That’s one reason folks who live in Los Angeles and Atlanta tend to be deficient despite their sunny locations.
So Supplements Are the Answer?
Supplementing is a good idea. In fact, the Institute of Medicine recently unveiled a new D recommendation for food and/or supplements: 600 international units (IU) a day. But even that might not be enough. “The Institute of Medicine is extremely cautious,” says the University of California’s Norman. “Its guidelines are based on what it considers good for bone health, but that doesn’t address what’s needed to benefit the immune system, pancreas, muscles, heart, and brain.” Instead, Norman argues that men may need a 1,000 to 2,000 IU supplement plus a D-rich diet. Turns out, this view is shared by a group of experts in all things hormonal: The Endocrine Society recently released a revised recommendation of 1,500 to 2,000 IU a day for good health.
Still, even that elevated recommendation is just a starting point. If you’re overweight (that is, if your body mass index, or BMI, is over 25), you probably need more D. Body fat traps vitamin D in a Georges St-Pierre–style choke hold, preventing it from being used in your body. And the heavier you are, the more D is trapped and the less is available in your bloodstream. According to Dr. Holick, obese people (those with BMIs above 30) require two to five times the vitamin D that lean people need—a dosage that should be monitored by a doctor, of course. It’s less clear how much vitamin D you need if you are overweight but not obese, but somewhere between 2,000 and 4,000 IU is a safe bet, says Dr. Holick.
The other problem with trying to ingest all that D from a handful of pills is that you may not reap the fat-burning benefits you were hoping for. “Dietary sources of D usually contain complementary nutrients that also contribute to weight loss,” says Dr. Holick. Bottom line: A supplement is just that.
For More D, Cook This
Superdose yourself with over 1,400 IU by eating this dinner.
Grilled wild salmon, 900 IU
Lightly brush 6-ounce fillets with olive oil and sprinkle them with salt and pepper. Grill them skin side down for about 5 minutes; then flip them and grill until the flesh flakes when you prod the centers with a fork, 3 to 5 minutes more.
Dill-yogurt sauce, 30 IU
Serve the salmon with this quick yogurt sauce; a batch serves four. Mix 1 cup of vitamin D– fortified plain yogurt with half a cucumber (grated), 1 tablespoon of lemon juice, 2 teaspoons of chopped fresh dill, 1 minced garlic clove, and salt and pepper to taste.
Balsamic-glazed mushrooms and onions, 400 IU
You won’t find a lot of vitamin D in most produce—except Monterey Mushrooms, a brand of specialty mushrooms that have been exposed to UVB light. Use them in this easy side: On a baking sheet, toss 3 ounces of sliced mushrooms and ½ cup of sliced onions with olive oil and good-quality balsamic vinegar. Roast at 350°F until the mushrooms are lightly browned and glazed, about 40 minutes, stirring occasionally. Toss with chopped parsley.
And for Dessert…
Berry smoothie, 120 IU
In a blender, puree a handful of berries with a cup of D-fortified yogurt or kefir. Pour into a bowl; top with more berries and add cinnamon, which works along with D to help control blood sugar and insulin response.
Meet the Vitamin D Family
You can do better than bland white fish like flounder: Fatty varieties, such as salmon and mackerel, contain up to four times the vitamin D of lean fish. What’s more, these oily options also offer higher levels of omega-3 fatty acids—and omega-3s act in concert with vitamin D to promote weight loss and inhibit cancer-cell growth. “Of course you get the added benefit of appetite-suppressing protein, too,” says Chris Mohr, Ph.D., R.D., a consulting sports nutritionist for the Cincinnati Bengals.
Supercharge your D: Pick wild and not farm-raised salmon. A Boston University study found that farmed salmon has just 25 percent of the D of its wild cousins. Wild salmon derive their D from eating nutrient-rich plankton; farmed fish eat feed pellets, which are low in D.
Most milk products boast calcium as well as vitamin D, and you’ve already read about how calcium helps reduce levels of fat-storage hormones. Dairy is also rich in the amino acid leucine, which helps stimulate muscle growth and fat burning. The D and leucine may be why dairy sources of calcium are twice as effective as calcium supplements at promoting weight loss, says Zemel.
Supercharge your D: Choose D-fortified dairy products. All milk is fortified with 100 IU of vitamin D per serving, but yogurt and other dairy foods are hit or miss. Some yogurt brands are fortified with as much as 30 percent of the daily value per 6-ounce serving, while others aren’t fortified at all. This is also true of cereal, orange juice, and other fortified foods. Check labels to make the best choices.
Like fatty fish, eggs contain omega-3s and protein as well as vitamin D. Small wonder that eating an egg at breakfast while reducing calories can improve weight loss by 65 percent and reduce appetite throughout the day, according to two Saint Louis University studies.
Supercharge your D: Pick omega-enriched eggs, not conventional eggs. Eggland’s Best eggs, for example, are higher in omega-3s and also contain double the D.
Are You D-ficient?
If any of the following describes you, you might be deficient in vitamin D. To find out for sure, ask your doctor for a 25-hydroxyvitamin D test. You want to clock in above 40 nanograms per milliliter.
You’re in middle age or older.
The older you are, the harder it is for your skin to make D. In a Boston University study, 36 percent of men and women under age 30 were D deficient by the end of winter. That rate jumped to 42 percent for people over 50.
You’re a person of color.
The melanin pigment in your skin acts as a natural sunscreen, helping block UVB rays. The darker your skin (or the deeper your tan), the higher your natural SPF and the more sunlight your skin requires to make D.
Your body mass index is over 30.
Being obese increases your vitamin D needs by two to five times. Calculate your body mass index at nhlbisupport.com/bmi. Have a BMI over 30 but don’t think you’re fat? Ask for a skin fold test at your gym.
You’re a northerner.
Imagine a line running from Los Angeles to Atlanta and then to the Atlantic coast. If you live north of that line, there’s not enough sunlight for your skin to make adequate D between November and March, says Dr. Holick.