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

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

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

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


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.


Believe It or Not: 10 Popular Claims About Vitamin D

As my last post about sunscreen noted, the quality of the anti-aging and wellness advice you consume is  a lot more important than the quantity. The recent buzz about the “sunshine vitamin” is a case in point.

vitamin d facts and fiction

Upping your vitamin D IQ: Question nutrition authorities. Image: Ambro /

Test Your Vitamin D Knowledge Quotient

The more you hear and read about vitamin D in the media, the less sure you may be about its relationship to your dietary choices, sun protection practices, and overall health. The following quiz is designed to help you check some popular claims and assumptions about vitamin D against the scientific evidence to date.


1. A lack of vitamin D is associated with serious health problems.

2. More than 75% of Americans don’t get enough vitamin D to protect their bones.

3. Lab tests are a highly accurate and reliable way of diagnosing vitamin D deficiency.

4. Scientists have confirmed that high vitamin D levels help prevent non-Hodgkin lymphomas and stomach cancer.

5. Increased vitamin D intake reduces the symptoms of psoriasis.

6. Significantly overweight individuals have a higher risk of vitamin D deficiency.

7. Dark-skinned individuals may need more sun exposure to maintain adequate vitamin D levels.

8. To be on the safe side, we should all take high-dose vitamin D supplements.

9. Getting enough vitamin D from natural food sources can be difficult.

10. Scientists keep changing the rules of sun safety and good nutrition.


1. True: Vitamin D deficiency causes rickets and osteomalacia, a painful disease that softens bones and diminishes muscle strength. Low vitamin D levels are also a contributing factor in osteoporosis. Studies also suggest that treatment with vitamin D in conjunction with calcium increases bone density and reduces the incidence of fractures in postmenopausal women. (The treatment has shown no significant effect on pre- and peri-menopausal women, however.)

2. False: An in-depth study by the National Academies of Science’s Institute of Medicine (IOM) found that despite vitamin D intakes that fall somewhat below minimum recommended levels, most of us have high enough blood levels of vitamin D to maintain healthy bones.

3. False: According to an American Association for Clinical Chemistry (AACC) news magazine article, the current lack of standardized procedures and objective measures for diagnosing vitamin D deficiency has undermined the value of routine vitamin D testing. The article also notes that many physicians remain unclear about which blood test to order and what the results mean. IOM researchers believe this problem has led to the false impression that an epidemic of vitamin D deficiencies is sweeping North America. Their reassessment of the data indicates the proportion of Americans at risk is approximately 10%.

4. False: While a number of studies have suggested vitamin D may help prevent stomach malignancies and non-Hodgkin lymphomas, as well as colo-rectal, ovarian, esophageal, kidney, and pancreatic cancers, a recent National Cancer Institute (NCI) report based on an extensive review of existing data revealed no clear or consistent link between cancer risk and vitamin D intake. Nevertheless, the jury is still out on the role potential role of vitamin D in treating a variety of medical conditions, including depression, heart disease, diabetes, and autoimmune disorders, as well as some cancers.

5. False: The latest studies showed no relationship between higher blood levels of vitamin D and improvement in the symptoms of psoriasis. Topical vitamin D ointments and creams, however, are effective psoriasis treatments.

6. True: Thick layers of subcutaneous fat interfere with the release of vitamin D into the bloodstream. Many other health and lifestyle factors can also increase the risk of vitamin D deficiency, including lactose intolerance, impaired fat absorption, vegetarian gastric bypass surgery, and restricted sun exposure. Breast-fed infants may also be a higher risk for vitamin D deficiency.

7. True: Higher levels of melanin (brown pigment) in the skin limit the amount of UV radiation the body can absorb.

fatty fish and vitamin D

Sardines: Big vitamin D doses come in little canned fishes. Image: Carlos Porto /</a></p>


8. False: When it comes to vitamin D, you can get too much of a good thing. In doses higher than 4,000 IUs daily, vitamin D can lead to heart damage and arrhythmias, as well blood vessel and kidney damage. How much vitamin D is enough? As general guidelines, the NIH suggests between 400 and 600 IUs daily for adults under the age of 70 and 800 IUs for older people.

9. True: Unless you happen to be a big fan of cod liver oil or fatty fish, your dietary sources of vitamin D can be pretty limited.  If  your palate favors neither sardines, salmon, nor mackerel as menu options, try adding a daily mealtime serving of a vitamin D-fortified dairy product or cereal. The following table provides some useful guidelines.

Food Sources of Vitamin D: IUs* per serving

Cod liver oil, 1 tablespoon: 1,360

Salmon (sockeye), cooked, 3 oz.: 447

Mackerel, cooked, 3 oz.:  388

Tuna fish, canned in water, 3 oz.: 154

Milk (fortified**), 1 cup:  115-124

Orange juice (fortified**), 1 cup: 100

Yogurt (fortified), 6 oz.: 80

Beef Liver, cooked, 3.5 oz.: 49

Sardines, canned in oil, 2: 46

Egg, 1 large: 41

Fortified** cereal, 1 cup: 40

Swiss Cheese, 1 oz.: 6

* IUs = International unit*

*Amounts may vary.Source: National Institute of Health Office of Dietary Supplements:

10. False: The widespread impression that yesterday’s recommended skincare habits are today’s risky behaviors and vice-versa doesn’t really stand up under scrutiny. While “scientific “truth” will always remain subject to revision, advertising claims and sensational headlines In fact, the weight reliable scientific evidence still stands firmly on the side time-tested skincare do’s and don’ts. That’s why it’s so important to consider the source of your information before you decide to act on it.


Natural Wisdom: The Beauty of the Middle Path

Until science provides more definitive answers on vitamin D, my advice is to take the long view and use common sense. Instead of rushing to adopt radical nutritional theories or throw sun safety precautions to the wind, consider the big picture. Although our lifestyles continue to change as civilization progresses, our basic nutritional needs and physical vulnerabilities remain the same. It’s wise to remember that fact before rushing to extremes.

ON BALANCE: If one way be better than another, then you may be sure it’s Nature’s way.  Aristotle