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V itamin D: enough already?
Rev Assoc Med B ras 2015; 61(4):291-292 291
EDITORIAL
Vitamin D: enough already?
V itamina D: já temos o suficiente?
Arnaldo L ichtenstein1
1General Practice and Propedeutics Service, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo (FMUSP), São Paulo, SP, Brazil
We are at a historic moment in relation to vitamin D, and
researchers are divided into two groups. Believers who
think we should supplement it orally for almost the en-
tire population, similar to what is done with fluoride add-
ed to water, iodine added to salt and folic acid prescribed
for all pregnant women. On the other hand, skeptics think
there is a possible exaggeration, as seen in the past with
the widespread use of hormone replacement or prolonged
use of bisphosphonates.
History shows real examples of great successes and
big mistakes with such positions.
The vitamins industry has a turnover in the United
States of 28 billion dollars annually. There has been a
growth in sales, from 30% in 1988-1994 to 39% in the
years 2003-2006; consumption also increased from 42 to
53% of the population. Regarding only supplements con-
taining vitamin D, sales rose from 50 million dollars in
2005 to 600 million dollars in 2011.
All this in spite of robust data that supplementa-
tion of vitamins in non-malnourished people does not
prevent deaths, cardiovascular disease, cancer and cog-
nitive decline. In addition, antioxidants such as beta-
carotene, vitamin E and possibly higher doses of vita-
min actually increase mortality. Supplementation of
folic acid and B complex has no benefit either, when
done indiscriminately. All these data were part of an ed-
itorial in the Annals of Internal Medicine in 2013, entitled
Enough is Enough, giving an end to the waste of money.1
Nevertheless, in this article the authors warn that, in
the case of vitamin D, studies on prevention of falls
could be useful.
I also remember the controversy generated by the win-
ner of two Nobel prizes Linus Pauling, who advocated
the consumption of large doses of vitamin C routinely.
Knowledge of rickets comes from the early Christian
era, with Sorano of Ephesus and Galen, who proposed
breastfeeding up to 2 to 3 years of age (prohibiting colos-
trum). In 1650, rickets started to be treated with cod liv-
er oil by Francis Glisson, a professor from the University
of Cambridge.2
In England, Edward Mellanby, in experiments with
dogs, also found that cod liver oil reversed rickets. This
inspired Elmer Mc Collum to describe, in 1922, vitamin
D (which he initially thought was vitamin A).
German pediatricianKurt Huldschinsky found that rick-
ets could be cured with ultraviolet rays, even before the dis-
covery of vitaminD. There was no sun in Berlin at that time.
Harry Goldblat and Miss K. M. Soames published in 1922
the relationship between ultraviolet rays and vitamin D.
Vitamin D was isolated in Germany by Windaus, who
was awarded the Nobel Prize, and also by British, Dutch
and American scientists.
The extra-skeletal actions of vitamin D are known for
over a century. Initially, it was used to treat tuberculosis
(then, phtisis). In 1848, at the Royal Brompton Hospital,
English physicians conducted a controlled study for tuber-
culosis. 542 patients received cod oil (3.6 mL, three times/
day, increasing to 42 mL/dose) versus 535 who did not. In
the end, 33% of patients in the control group had wors-
ened or died, compared with 19% in the treated group. In
the treated group, increase in weight was seen in 70% of
patients, while 21% lost weight and 7% remained the same.
Weight was not assessed in the control group. Keep inmind
that Koch’s bacillus was isolated in 1892, the first radio-
graphs were made in 1895, and statistical analyzes appeared
in 1922 (Fisher). This study certainly would not be accept-
ed today. Interestingly, the author who reviewed the study
says that at that hospital, in the 1960s, all the doctors would
prescribe cod liver oil routinely, without knowing why.3
Biological plausibility cannot justify its use.4 Over
3,000 binding sites for vitamin D have been identified in
the human body, in approximately 3% of all genes. For
decades, we have used clinical evidence, rather than the-
oretical possibilities or personal opinions, to recommend
a treatment.
How to explain the great disparity between the re-
sults of observational studies (where there is a clear rela-
tionship between low levels of vitamin D and the studied
event) and interventional studies (vitamin D supplemen-
tation does not reduce the studied event)?5-8