Page 40 - Spring2009

true in the third world where vitamin A toxicity intakes in this study, however, were very low.
is virtually unheard of, yet vitamin A deficiency Even the 20 percent of people consuming the
is pervasive. most vitamin D consumed an average of less
As discussed on page 21, the analysis cited than 600 IU. If the participants were receiving
by Mercola did not even look at vitamin A sup- a lot of sunshine, the thousands of IU from that
plementation in the U.S. but was a meta-analysis source would likely have diluted any effect of
that pooled the results of nine studies conducted the vitamin D, so the strong association at low
in India, Ecuador, Indonesia, Brazil, Ghana, vitamin A intakes suggests they were not receiv-
Mexico and the Republic of Congo. Several of ing much sunshine. Basic adequacy of vitamin D
these studies have suggested that vitamin A may status would require over three times the highest
reduce the incidence of respiratory infection in intakes consumed in the study.
malnourished children but increase it in well- In order to truly indict intakes of over 5,000
nourished children, but none of them present IU of vitamin A as excessive, evidence should be
evidence that the effect of vitamin A depends provided from a population consuming adequate
on vitamin A status or that vitamin A is helpful vitamin D. As soon as someone begins taking vi-
in the Third World but harmful in the developed tamin D supplements at the levels recommended
world. by Dr. Mercola and the Vitamin D Council, they
A number of studies included in the meta- are no longer a member of the vitamin D-defi-
analysis showed vitamin A to have no effect cient population studied in the Nurses’ Health
on respiratory infections while nevertheless Study so the results of that study do not apply
reducing severe diarrhea by over 20 percent, to them. It must be emphasized, moreover, that
gastrointestinal-associated mortality by over a correlations never show causation. We can use
third, infection-associated mortality by half, and the observations in this study to hypothesize that
measles incidence by 95 percent. The general high vitamin A intakes antagonize the beneficial
picture that emerges from the scientific literature effects of vitamin D intakes when vitamin D
Although is that vitamin A consistently reduces mortality intakes are very low, but in order to demonstrate
human and from severe infectious diseases but has a more this premise, studies must be performed showing

animal complicated relationship to lower respiratory that increasing vitamin D intakes or decreasing
retinol intakes reduce the risk of colon cancer
infections that we still do not completely under-
evidence stand. compared to controls.
strongly Additionally new research has shown that Other research is now showing a connection
suggests that vitamin D protects against cancer. But a paradox between high levels of vitamin A and osteopo-
was found as those with higher vitamin D levels rosis. In fact many Scandinavian countries that
vitamin A can did not seem to have this benefit. A bright Har- regularly supplement with cod liver oil have
only exert vard researcher carefully analyzed the data in rampant osteoporosis even though they are get-
harm against the study that showed this and found that when ting adequate amounts of oral vitamin D.
We have thoroughly addressed the problems
he removed the people with high vitamin A and
the backdrop vitamin D levels, those with normal vitamin A of osteoporosis in Scandinavian countries in an
of vitamin D levels and high vitamin D levels continued to article published in the Winter 2005 issue of Wise
deficiency, it have reduced risk of colon cancer. So those that Traditions. The vitamin A in this study does not
did not take vitamin A had the protective effect come from cod liver oil but from milk and cereals
also suggests from higher levels of vitamin D. to which vitamin A is added. In the context of a
that sufficient In this report, which was based on data vitamin D-deficient diet, consumption of high
levels of drawn from the Nurses’ Healthy Study and pub- levels of synthetic vitamin A was associated with
a higher risk of osteoporosis. Although human
lished in the American Journal of Epidemiology,
vitamin A are 2007, total intake of vitamin D from foods and and animal evidence strongly suggests that vita-
even higher supplements was associated with a lower risk of min A can only exert harm against the backdrop
than once colon cancer when total vitamin A intakes were of vitamin D deficiency, it also suggests that
below 5,000 IU, but not when total vitamin A the body’s requirements for vitamin A are even
thought. intakes were above 5,000 IU. The vitamin D higher than once thought.
38 Wise Traditions SPRING 2009