Why It’s Time to Go Natural with Vitamin D: The Latest Wisdom on a Supernutrient

Regular doses of sunshine from March through October can help your body produce enough vitamin D to last all year long.

In recent years, the growing reputation of vitamin D as a “supervitamin” has prompted many people to view high-dose supplements as insurance against a variety of age-related diseases and conditions. A vast body of evidence shows that vitamin D plays an essential role in maintaining strong, healthy bones, muscles and skin; a balanced mood; and an efficiently functioning brain and immune system. A number of studies also suggest that low vitamin D levels may increase the risk of a host of degenerative diseases ranging from heart problems and cancer to diabetes, arthritis, and Alzheimer’s. These findings all contribute to the widespread perception that increasing our blood levels of vitamin D with supplements will lead to a longer, healthier life. However, the link between vitamin D supplementation and improved health and longevity is not as straightforward as it sounds.

What the Latest Scientific Research Says About the Sunshine Vitamin?

The jury is still out on many of the claims made for vitamin D, but to date, the evidence suggests that relying on natural sources of vitamin D is the safest, most effective approach to capitalizing on its health benefits. The answers to the following questions explain why, for most people, supplements are not only unnecessary, but also, in some cases, potentially harmful.

How much vitamin D do you need in your blood to avoid a deficiency?

The question of whether you have a deficiency depends on the source you consult. The cutoff for adequate levels of vitamin D varies widely across testing labs, typically falling between 30 and 50 nanograms per milliliter (ng/mL). Some health organizations set the bar as high as 60 ng/mL However, a large study by the Institute of Medicine (IOM), a leading nonprofit healthcare organization affiliated with the National Academies of Science, sets the threshold for deficiency at 20 ng/mL

Is vitamin D deficiency common?

Reports in the popular press suggest we’re in the midst of a D-deficiency epidemic, with the rate of inadequate levels among U.S. adults and teenagers reaching as high as 75 percent. In fact, the rate of deficiency depends on how you define deficiency. When the IOM definition of deficiency (less than 20 ng/mL) is applied, only 10 percent of Americans are deficient.

Should I have my vitamin D levels checked?

Different labs and different test methods can produce different results, depending on their reporting standards, test methods, and proficiency level. For these reasons, an independent panel of preventative medicine experts recently advised against routine vitamin D testing. The panel concluded that the cost of testing and the risk of overtreatment outweighed the potential benefits.

How much vitamin D is required to maintain health?

The recommended dietary allowance (RDA) is 400 to 600 IU a day. High dose vitamin D supplements that far exceed the RDA can lead to harmful side effects including hardening of soft tissues.

Should I take a vitamin D supplement, just to be on the safe side?

To date, there is no strong evidence that taking vitamin D supplements prevents disease or improves health. Despite all the research showing a link between low vitamin D levels and various diseases, no study has yet proved that vitamin D deficiency causes these health problems. In fact, a recent review of this research suggests that a deficiency is more likely to be the consequence of ill health. Even the widespread practice of taking vitamin D to prevent osteoporosis has been called into question by the National Institute of Health (NIH). While severe vitamin D deficiencies can lead to bone softening and weakness in both children and adults, these conditions are quite rare in developed countries. Experts disagree about whether vitamin D supplementation helps prevent fractures in individuals who already suffer from osteoporosis. Some studies show that nursing home residents with osteoporosis may benefit from a combination of vitamin D therapy and calcium supplementation. However, these findings don’t apply to older adults who live in the wider community.

What’s the bottom line?

Both science and common sense suggest that the best approach to maintaining optimal levels of vitamin D is to get adequate sun exposure and to include whole-food sources of vitamin D–rich foods in your diet. Many articles on this topic insist that this approach is impractical. This argument is based on two popular misconceptions: (1) that people who live in a northern regions or practice sun protection don’t absorb enough sunlight to synthesize vitamin D and (2) that very few foods contain enough of this nutrient to make up the difference. The truth is, not only does a little sun exposure go a long way, but a diverse whole food diet generally also provides enough vitamin D to naturally supplement the amount we derive from spending time outdoors. Because our fat cells store vitamin D, even people who get minimal UV rays from November through February can stockpile a year-round supply without damaging their skin. Depending on your skin tone, you can build up an adequate store of the sunshine vitamin by exposing your bare arms and legs to as little as 10 to 60 minutes of sun between 10 a.m. and 4 p.m. two to three times a week, from late March through October. Always protect the delicate skin on your face and neck with sun block and, if you’re fair skinned, restrict unprotected time in the sun to 10 to 15 minutes during June through August. You don’t need to risk sunburn or get a tan to optimize your blood levels of vitamin D. Nor do you need to choke down spoonfuls of cod liver oil. Many delicious and healthful foods from fatty fish, shrimp, oysters, and pork to eggs, dairy products, and mushrooms are good sources of vitamin D. Foods that are high in vitamin D3, such as egg yolks, meat, and cheese are generally more effective in raising blood levels that the vitamin D2 in plant sources. If you’re worried about your calorie or fat intake, consider that a single serving of wild salmon is enough to meet the RDA (farmed fish has far less) and that, in combination with modest doses of sunlight, a few portions of dairy, eggs, or meat can also do the trick.