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Is asthma a disease of sunlight/vitamin D deficiency?
Yes. Asthma, to a great extent, is caused
by sun avoidance and consequent vitamin D deficiency.
Asthma, a devastating respiratory illness,
is increasing rapidly in the US. The latest statistics I
have show that the overall prevalence of asthma increased
75% from 1980-1994, and asthma rates in children under the
age of five increased more than 160%.[1]
There is little doubt that the profound
increase in asthma in the last few decades has been caused
to a great extent by our societal exodus from sunlight
exposure along with the increased use of sunscreen, which
can inhibit up to 99% of vitamin D production by the
skin.[2]
Drs Litonjua and Weiss, in a medical
hypothesis presented in 2007, made a strong case for vitamin
D deficiency as a major player in the increase in asthma
incidence among both children and adults.[3]
They hypothesized the following:
1. “… as populations grow more prosperous,
more time is spent indoors, and there is less exposure to
sunlight, leading to decreased cutaneous vitamin D
production.”
2. “Vitamin D has been linked to immune
system and lung development in utero, and our epidemiologic
studies show that higher vitamin D intake by pregnant
mothers reduces asthma risk by as much as 40% in children 3
to 5 years old.”
3. "Vitamin D deficiency has been
associated with obesity, African American race (particularly
in urban, inner-city settings), and recent immigrants to
westernized countries, thus reflecting the epidemiologic
patterns observed in the asthma epidemic."
Other research demonstrates that vitamin D
reduces the production of inflammatory chemicals (chemokines)
in the respiratory passages,[4] which would dampen the
asthmatic response.
Another study assessed the asthma risk of
children whose mothers had the highest vitamin D consumption
during pregnancy, and compared them to children whose mother
had the lowest levels.
The high-vitamin D group showed an
impressive reduced risk of asthma of 52-67%.[5] The
researchers believe that inadequate vitamin D levels in the
fetus leads to improper development of the lungs and immune
system.
Still other research, conducted on
three-year old children whose mothers were in the highest
quartile (fourth) of vitamin D consumption during pregnancy,
showed them to have a 61% reduced risk of a “recurrent
wheeze,” a symptom of asthma, when compared to those whose
mothers were in the lowest quartile.[6]
Each 100-IU increase in vitamin D
consumption resulted in a 19% risk reduction.
That's about the amount that could be
produced in the summer sunlight in one minute, or a good
tanning bed in half a minute! How sad that these women have
been frightened out of the sunlight, the natural way to
produce vast quantities of vitamin D.
[1] Centers for Disease Control.
Surveillance for Asthma - United States, 1960-1995, MMWR.
1998; 47 (SS-1).
[2] Matsuoka, L. et al. sunscreens suppress cutaneous
vitamin D3 synthesis. Journal Clini Endocrinol Metab 1987;
64:1165-68.
[3] Litonjua AA, Weiss ST. Is vitamin D deficiency to blame
for the asthma epidemic? J Allergy Clin Immunol
2007;120:1031–1035.
[4] Banerjee, A. et al. Vitamin D and glucocorticoids
differentially modulate chemokine expression in human airway
smooth muscle cells. Br J Pharmacol 2008; 155: 84–92.
[5] Devereux, G. et al. Maternal vitamin D intake and early
childhood wheezing. Am J Clin Nutr 2007;85:853-59.
[6] Camargo, C. et al. Maternal intake of vitamin D during
pregnancy and risk of recurrent wheeze in children at 3 y.
Am J Clin Nutr 2007;85:788-95.
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