Vitamin D guidelines may be changed following new study


A new study finds that, contrary to popular belief, vitamin D-2 and D-3 do not have equal nutritional value. With vitamin D deficiency on the rise, the authors call for a rethink of official guidelines.
Vitamin D is a vital nutrient, helping the gut to absorb calcium while keeping calcium and phosphate at the right concentrations to support healthy bone growth and maintenance. Without adequate levels in the body, bones can become brittle and misshapen.
Low vitamin D levels have also been linked with a range of other conditions, including cardiovascular disease and cancer.
Vitamin D is not naturally present in many foods. Instead, the bulk of our requirement is synthesized in the skin after exposure to ultraviolet light from the sun.
Despite the importance of vitamin D, many people in the United States do not have sufficient levels in their bodies. For example, one study found that overall, more than 40 percent of the U.S. population were vitamin D deficient. So much so, that some authors have referred to vitamin D deficiency as a pandemic.
Furthermore, in one study published in 2009, only 3 percent of black people in their sample of thousands of U.S. individuals had the recommended vitamin D levels, representing a decrease of 9 percent over the previous 20 years.
For this reason, it is becoming increasingly important to understand how the vitamin works and to ensure that the right type of supplements are reaching individuals most at risk.
There are two types of vitamin D, which are known as D-2 and D-3. The former is derived from plant sources, particularly fungi, while the latter comes from animal sources.
The two types of vitamin D are very similar, differing only in the structure of their side-chains, and it is generally accepted that both perform similarly well as a supplement. In fact, on the National Institutes of Health website, they write, “The two forms have traditionally been regarded as equivalent.”
Researchers from the University of Surrey in the United Kingdom recently set out to test whether or not this widely held belief is correct. They wanted to understand which of the two nutrients raises levels of vitamin D in the body most effectively.
The researchers measured vitamin D levels in 335 South Asian and white European women over two winter periods. They chose winter because, due to a reduction in sunlight exposure, vitamin D levels tend to be lower at this time.

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