Health Benefits of Vitamin D and Sunlight - General Information

Vitamin D3 supplements better

New research funded by the Biotechnology and Biological Sciences Research Council (BBSRC) has shown that vitamin D3 supplements could provide more benefit than the close relative vitamin D2. The findings published in the American Journal of Clinical Nutrition could potentially lead to changes in the food industry when it comes to fortification.

Vitamin D is important for bone and muscle health and there is concern that we don't get enough of the 'sunshine' vitamin through exposure to sunlight or through diet. As a result, some foods are fortified with vitamin D. Fortification is usually with vitamin D2, as this is not derived from animals. However this new research, carried out by scientists from the University of Surrey, suggests that vitamin D3 is the more beneficial of the two types of vitamin D in raising the vitamin D levels in our blood when given as a supplement.

The research clearly showed that vitamin D3, the type of vitamin D found in foods including eggs and oily fish, is more effectively converted by the body into the hormone responsible for health benefits in humans.

Dr Laura Tripkovic, who led the study, explains: "We know that vitamin D is vital in helping to keep us fit and healthy, but what has not been clear is the difference between the two types of vitamin D. It used to be thought that both were equally beneficial, however our analysis highlights that our bodies may react differently to both types and that vitamin D3 could actually be better for us."

The researchers analysed the results of 10 separate studies, involving over 1,000 people in total, comparing the health benefits of vitamin D2 and D3, and found "a clear favouring" of vitamin D3 supplements raising vitamin D serum levels in humans.

Recommendation for vitamin D intake was miscalculated, is far too low, experts say

Researchers at UC San Diego and Creighton University have challenged the intake of vitamin D recommended by the National Academy of Sciences (NAS) Institute of Medicine (IOM), stating that their Recommended Dietary Allowance (RDA) for vitamin D underestimates the need by a factor of ten.

In a letter published in the journal Nutrients the scientists confirmed a calculation error noted by other investigators, by using a data set from a different population. Dr. Cedric F. Garland, Dr.P.H., adjunct professor at UC San Diego's Department of Family Medicine and Public Health said his group was able to confirm findings published by Dr. Paul Veugelers from the University of Alberta School of Public Health that were reported last October in the same journal.

"Both these studies suggest that the IOM underestimated the requirement substantially," said Garland. "The error has broad implications for public health regarding disease prevention and achieving the stated goal of ensuring that the whole population has enough vitamin D to maintain bone health."
The recommended intake of vitamin D specified by the IOM is 600 IU/day through age 70 years, and 800 IU/day for older ages. "Calculations by us and other researchers have shown that these doses are only about one-tenth those needed to cut incidence of diseases related to vitamin D deficiency," Garland explained.

Robert Heaney, M.D., of Creighton University wrote: "We call for the NAS-IOM and all public health authorities concerned with transmitting accurate nutritional information to the public to designate, as the RDA, a value of approximately 7,000 IU/day from all sources."

"This intake is well below the upper level intake specified by IOM as safe for teens and adults, 10,000 IU/day," Garland said. Other authors were C. Baggerly and C. French, of GrassrootsHealth, a voluntary organization in San Diego CA, and E.D. Gorham, Ph.D., of UC San Diego.

Pale people may need vitamin D supplements

Researchers at the University of Leeds, funded by Cancer Research UK, suggest that people with very pale skin may be unable to spend enough time in the sun to make the amount of vitamin D the body needs - while also avoiding sunburn.

The study, published in Cancer Causes and Control*, suggested that melanoma patients may need vitamin D supplements as well.

But researchers also noted that sunlight and supplements are not the only factors that can determine the level of vitamin D in a person's body.

Some inherited differences in the way people's bodies process vitamin D into the active form also have a strong effect on people's vitamin D levels.

The study defined the optimal amount of vitamin D required by the body as at least 60nmol/L. However at present there is no universally agreed standard definition of an optimal level of vitamin D.

Professor Julia Newton-Bishop, lead author of the study based in the Cancer Research UK Centre at the University of Leeds, said: "Fair-skinned individuals who burn easily are not able to make enough vitamin D from sunlight and so may need to take vitamin D supplements.

"This should be considered for fair-skinned people living in a mild climate like the UK and melanoma patients in particular."

Researchers took the vitamin D levels of around 1,200 people and found that around 730 people had a sub-optimal level. Those with fair-skin had significantly lower levels. Researchers chose 60nmol/L as the optimal vitamin D level in part because there is evidence that levels lower than this may be linked to greater risk of heart disease and poorer survival from breast cancer.

A consensus between health charities including Cancer Research UK says that levels below 25nmol/L are vitamin D deficient which means that these levels are associated with poor bone health. But some researchers consider that higher levels, around 60nmol/l, may be desirable for optimal health effects.

Sara Hiom, director of health information at Cancer Research UK, said: "We must be careful about raising the definition of deficiency or sufficiency to higher levels until we have more results from trials showing that maintaining such levels has clear health benefits and no health risks.