| Selenium and Vitamin
C Absorption |
 |
 It
was in June 21, 1999 that the possibility of counter-interactions between
inorganic Vitamin C and selenium was raised in the Danish television news.
Two days later in the Berlingske Tidende newspaper, similar reports were
published about Vitamin C inhibiting the absorption of inorganic selenium
in the body. The problem arises when selenium interacts with ascorbic acid,
it can be reduced to elementary selenium, which the body cannot utilize.
This has been shown in studies. However, the issue becomes more complex
when the human element is added into the equation, and to date, there is
a considerable lack of scientific literature on the subject.
 It
is advisable to take Multi-tabs at meal times so that the various vitamins
and minerals - including selenium - are made an integral part of and spread
within the food intake. Multi-tabs contain 50 micrograms of selenium in
the form of natrium seleniumate and between 60 and 90 mg of ascorbic acid.
This will therefore lower the local concentrations of Vitamin C and selenium
and lessen the chances of them inter-reacting. Furthermore, selenium creates
protective complexes with food components - for example with amino acids
such as methionin and cystein.
It has been shown in studies that 200 mg of ascorbic acid has no effect
on natrium seleniumate (50g). On the other hand, it even appears to improve
the bio-accessibility of selenium when ingested at meal times. There is
no evidence that food factors have any influence on selenium absorption,
an issue that should be looked into in further studies. However, when a
large dose of ascorbic acid (1g) is taken together with selenium prior to
a meal, then the selenium is not absorbed. The
crucial difference lies in taking them at meal times, then will the ascorbic
acid not affect the absorption of selenium.
On the topic of selenium absorption, it also appears that the nature of
selenium itself makes a difference. Several studies have shown that
organic selenium can be almost totally absorbed
by the body whereas the inorganic one is variable, generally over 50%.
Organic selenium is selenium that is incorporated in amino acids such as
methionin (seleno-methionin) or cystein (seleno-cystein). The body thus
recognises the selenium as amino acids and since amino acids are almost
totally absorbed by the body, it means that the organic selenium is also
absorbed in a camouflaged fashion. It is important to be aware of this,
since otherwise an inadvertent overdosage of selenium could occur.
Based on the above, there are 2 main points about
the selenium absorption issue:
1. The assertion
that selenium is absorbed badly when combined with ascorbic acid from, for
example, Multi-tabs, is undocumented. On the contrary, it has
been shown in surveys that ascorbic acid has no effect on the absorption
of selenium. In large doses, ascorbic acid can reduce the absorption of
selenium, but this can easily be countered by taking the 2 together at meal
times.
2. The fact that organic selenium
is generally absorbed better than inorganic selenium has been
documented in various studies. The absorption of inorganic selenium is,
however, still in the range of 50% and above. Here, however, it should be
noted that organic selenium, as selenium bound in amino acids, is absorbed
by the body uncritically and in an unregulated fashion as it is recognised
as an amino acid. It is prudent therefore to take caution here as there
is always the danger of selenium overdosage.
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