More evidence that routine multivitamin use should be avoided

[pnwmom]

46. No medical authorities recommend that black people "top up" their

Last edited Sun Dec 22, 2013, 05:47 AM - Edit history (3)

Vitamin D production by using a tanning bed. But the Harvard School of Public Health, the National Institutes of Health, the National Cancer Institute and others recommend Vitamin D supplements for people with low vitamin D levels, which is more common in higher latitudes and among people with darker skin.

The reason for this particular study including only black people was to study the effects of vitamin D supplementation ON BLACK PEOPLE, "idiot."


The point of the study was NOT to compare the effects across different groups, so it is not a flaw that it didn't do so -- it was a purposeful part of the study design. Including a handful of black people in a study with a broad cross-section of people would have yielded no meaningful results for the subgroup of black people they wanted to study.

There is nothing flawed about limiting a study to any particular group, as long as you don't assume the results apply to the larger population.

That being said, there have been numerous studies showing that Vitamin D supplementation is helpful for many people. You're just flat out wrong to say that Vitamin D supplements are never needed.


From the Harvard School of Public Health

If you live north of the line connecting San Francisco to Philadelphia and Athens to Beijing, odds are that you don’t get enough vitamin D. The same holds true if you don’t get outside for at least a 15-minute daily walk in the sun. African-Americans and others with dark skin, as well as older individuals, tend to have much lower levels of vitamin D, as do people who are overweight or obese.

Worldwide, an estimated 1 billion people have inadequate levels of vitamin D in their blood, and deficiencies can be found in all ethnicities and age groups. (1-3) Indeed, in industrialized countries, doctors are even seeing the resurgence of rickets, the bone-weakening disease that had been largely eradicated through vitamin D fortification. (4-6)
Why are these widespread vitamin D deficiencies of such great concern? Because research conducted over the past decade suggests that vitamin D plays a much broader disease-fighting role than once thought.

Food sources: Very few foods naturally contain vitamin D. Good sources include dairy products and breakfast cereals (both of which are fortified with vitamin D), and fatty fish such as salmon and tuna. For most people, the best way to get the recommended daily intake is by taking a supplement, but the level in most multivitamins (400 IU) is too low; encouragingly, some manufacturers have begun adding 800 or 1,000 IU of vitamin D to their standard multivitamin preparations.

Getting vitamin D from the sun: Correctly applied sunscreen reduces our ability to absorb vitamin D by as much as 90 percent. At higher latitudes (in the northern U.S., for example), exposure to the sun in winter will not form vitamin D (due to the angle of the sun's rays), so a supplement is advisable.

http://jn.nutrition.org/content/136/4/1126.full

Vitamin D insufficiency is more prevalent among African Americans (blacks) than other Americans and, in North America, most young, healthy blacks do not achieve optimal 25-hydroxyvitamin D [25(OH)D] concentrations at any time of year. . . . Clinicians and educators should be encouraged to promote improved vitamin D status among blacks (and others) because of the low risk and low cost of vitamin D supplementation and its potentially broad health benefits.

From the National Institutes of Health:

http://www.nlm.nih.gov/medlineplus/druginfo/natural/929.html

Nevertheless, vitamin D deficiency is more common than you might expect. People who don’t get enough sun, especially people living in Canada and the northern half of the US, are especially at risk. Vitamin D deficiency also occurs even in sunny climates, possibly because people are staying indoors more, covering up when outside, or using sunscreens consistently these days to reduce skin cancer risk.

Older people are also at risk for vitamin D deficiency. They are less likely to spend time in the sun, have fewer “receptors” in their skin that convert sunlight to vitamin D, may not get vitamin D in their diet, may have trouble absorbing vitamin D even if they do get it in their diet, and may have more trouble converting dietary vitamin D to a useful form due to aging kidneys. In fact, the risk for vitamin D deficiency in people over 65 years of age is very high. Surprisingly, as many as 40% of older people even in sunny climates such as South Florida don’t have enough vitamin D in their systems.

Vitamin D supplements may be necessary for older people, people living in northern latitudes, and for dark-skinned people who need extra time in the sun, but don’t get it.

The National Cancer Institute:

http://www.cancer.gov/cancertopics/factsheet/prevention/vitamin-D

IOM states that people should not try to increase vitamin D production by increasing their exposure to sunlight because this will also increase their risk of skin cancer