Many young adults are not getting enough vitamin D, particularly during the winter months.
Young adults aged 18 to 29 years have an equal to greater risk of vitamin D insufficiency than do older adults, especially during the winter. This is one of the first studies in the United States revealing a relatively high prevalence of vitamin D insufficiency in young adults.
Vitamin D, which helps the body to absorb calcium, is made by the body when skin is exposed to sunlight. Vitamin D deficiency puts people at risk for the bone-thinning disease osteoporosis as well as chronic bone and muscle pains, and may also increase the risk of certain cancers.
To investigate vitamin D insufficiency, the researchers screened 165 men and women during March and April, at the end of winter, and 142 individuals during September and October, at the end of summer.
Young adults had a 30% increase in their vitamin D levels from the end of winter to the end of summer.
Nearly two-thirds of the end-of-summer group and 58% of the end-of-winter group reported drinking almost two glasses of milk per day, but this was not associated with higher vitamin D levels.
On the other hand, the 4 out of 10 study participants who reported taking daily multivitamin supplements during the summer and winter months had vitamin D levels 30% higher than those who did not take the supplements.
The American Journal of Medicine June 2002;112:659-662
The numbers for vitamin D deficiency are actually far worse than this study has reported because researchers are using dated optimum levels of vitamin D. They are using reference ranges from the sun deprived US populations, while they should be using reference ranges established from people who live in sub-tropical environments with regular sun exposure.
I have been measuring vitamin D levels in my office for many months and can report quite confidently that 99% of people are not getting enough vitamin D during the winter months. In another four months or so, I will know the effectives of summer sun on people in Chicago. My guess is that it is not going to improve much.
However, this study does show that proportionately the low levels of vitamin D are even worse during the winter.
I think the most interesting result of this study is that the vitamin D from milk did not help to improve low vitamin D levels. This should not be surprising because the vitamin D in milk is synthetic vitamin D2 (ergocalciferol) which isn't as effective at replacing vitamin D as the natural vitamin D3 (cholicalciferol) that is received from the sun or cod liver oil.
If you are taking a vitamin with D in it, you will want to confirm that it is not the synthetic vitamin D2 ergocalciferol.
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