In recent months, published studies have concluded that low levels of Vitamin D are a predictor of heart attack risk or aggressive prostate cancer.
In May, the U.S. Food and Drug Administration finalized a new Nutrition Facts label for packaged foods. Among the changes, which take effect in 2018: Labels must include amounts of Vitamin D, widely known as the “sunshine vitamin” inasmuch as our bodies produce it when we are exposed to the sun.
We have long known that Vitamin D is vital to bone health. But disagreement over how much Vitamin D people actually need – and whether Vitamin D supplementation is necessary – continues to be debated.
“It’s like the vitamin of the decade,” said Deeptha Sukumar, an assistant professor in the Department of Nutrition Sciences at Drexel University. Sukumar, whose studies include bone metabolism, recently received funding from the American Heart Association for a four-year research project looking at Vitamin D supplementation and heart health. She is recruiting participants.
She spoke to us recently about Vitamin D and her work.
What do you make of recent research that suggests a greater need for Vitamin D?
We don’t really have solid evidence. There are all these conditions associated with lower levels of Vitamin D, but research is showing that with supplements, these conditions don’t go away. So is it just a marker of your health, or is it lower Vitamin D that causes these conditions? People who are obese generally have low levels of Vitamin D. As we started looking into this, we decided to give them supplements and see if their obesity went away. Their Vitamin D levels got higher, but they were still obese.
Researchers have shown how people with heart disease, diabetes and some cancers have lower levels of Vitamin D. Beautiful animal studies suggest that Vitamin D supplements can reverse some of these conditions. Unfortunately, with clinical trials, we are not seeing the same results with humans.
What’s the optimum level of Vitamin D, and how many Americans do not meet it?
In 2011, the federal Institute of Medicine finalized a blood level, which had not been set before, of at least 20 nanograms per milliliter. Some disagreed and said it should be greater than 30. The IOM recommendations are based on evidence from many, many studies.
At this point, there are multiple trials that are examining the effect of Vitamin D supplementation. But so far, we do not have evidence to support that levels higher than 20 nanograms per milliliter have extra benefits.
As far as Americans who do not meet the optimum level, it really depends on what population you’re looking at. The rate of Vitamin D deficiency might be high in Philadelphia in the winter. It might not be as high in Florida because they get a lot of sun. But a study by NHANES [National Health and Nutrition Examination Survey, of the Centers for Disease Control and Prevention] that surveyed 4,000 people throughout the U.S. found that at least 40 percent were deficient in Vitamin D. The deficiency rate was higher in African Americans, about 82 percent. It was alarming.
Why are we deficient?
For African Americans, in particular, it is because they have a darker skin tone and are not able to convert Vitamin D in their skin into the active form of the vitamin. Anyone who has darker skin has this problem.
For many others, the summer is the only time, especially in Philadelphia, when people can get their Vitamin D from the sun. If people are going to be using a sunscreen with an SPF that’s more than 8, and if they’re following the label instructions to reapply regularly, they probably are not getting enough Vitamin D. But people aren’t very compliant with sunscreen use, so they probably get some Vitamin D anyway.
Also, vitamin D is stored in our fatty tissue, so someone who is extremely obese is likely to have low levels. That’s because if Vitamin D is stored – or sequestered – in the fatty tissue, there is a lower circulating level and, thus, a lower amount available to perform other functions in the body. Some medications deplete Vitamin D stores in the body, or they interfere with the conversion into the active form.
People who are at risk of being deficient – if they are obese or have darker skin or are elderly, because their skin doesn’t convert Vitamin D as efficiently as when they were younger – should monitor their Vitamin D levels closely. An annual check with your physician should be perfect. It should be done during winter, when levels tend to be lowest.
What’s the best way to raise your Vitamin D level?
In summer, 10 to 15 minutes of exposure to sunlight, every day, to your arms, legs and face, without sunscreen. The Skin Cancer Foundation recommends the use of sunscreen. But right now, we don’t know what level of sun exposure raises someone’s risk of skin cancer. We do know that 10 to 15 minutes a day can definitely raise your Vitamin D level.
Another way to raise your level is to eat foods that are rich in Vitamin D. More and more foods are being supplemented with Vitamin D, but that was not true just three or four years ago. Right now, most breakfast cereals and orange juices are fortified with Vitamin D, plus most yogurts and milk.
If you consume three to four servings of dairy a day – milk, cheese, yogurt – combined with salmon or tuna twice a week, you should be able to maintain the recommended level. Or you can drink orange juice fortified with Vitamin D. Eggs and mushrooms are also good sources of Vitamin D.
What about supplements?
If your Vitamin D levels are diagnosed as being deficient, then yes, you probably have to take a supplement. Then, once the optimum level is reached, you could maintain it with adequate food intake and/or sun exposure.
If you are taking a supplement, take it with a meal, because Vitamin D is fat-soluble.
But if your levels are normal – if you are active, out in the summer between 10 a.m. and 3 p.m. at least three times a week, if you consume dairy and at least a couple servings of fish – based on current evidence there is no need for you to take a supplement of Vitamin D. In the winter, however, you may consider a supplement if your dietary intake is not adequate.