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Why
Niacin Is A Small But Vital Part Of Your Anti-Oxidant Rich Diet
In its derivative form of
nicotinamide, niacin is required by the body for the production
of coenzymes known as, if you’ll forgive the jargon,
nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine
dinucleotide phosphate (NADP).
The importance of NAD and NADP may
be shown by the fact that over 200 of the body’s other
enzymes are dependent on an interaction with them for an almost
infinite variety of vital functions.
The antioxidant enzymes, superoxide
dismutase, catalase and glutathione, for example, are the
body’s first line of defence against highly damaging
superoxide free radicals and work in a closely complementary
fashion. Each of these anti-oxidant enzymes is formed by
the body from the amino acids in the proteins in your diet, and
each is needed for the others to function correctly.
This holistic functioning of the
body is also reflected in the dietary requirements for the
successful production of the enzymes. As well as a good
supply of first-class protein, ie that containing each of the
essential amino acids, a wide variety of vitamins and minerals
are required to allow optimal levels of enzyme manufacture.
So for example, vitamin E cannot do
its work in the absence of an adequate supply of active vitamin
C. In its turn, vitamin C cannot remain active without the
presence of glutathione. And although it is the most
prevalent anti-oxidant enzyme in the body, glutathione cannot act
effectively in the absence of the trace mineral, selenium, and
vitamins of the B complex, including B3 and B6.
In addition to its importance in
assisting with the manufacture of anti-oxidant enzymes, there is
also some evidence that levels of niacin above those required for
the avoidance of deficiency may have some protective effect
against the DNA cell damage that may be a precursor to the
development of cancer.
Intense attention has also been paid
to the apparent effectiveness of niacin (or nicotinic acid) in
reducing blood levels of Low Density Lipids (LDLs), the so-called
“bad” cholesterol, an effect recognised since 1955.
It has also been demonstrated by numerous research reports that
levels of High Density Lipids (HDLs), or “good”
cholesterol may be raised by niacin. This has given rise to
extravagant claims for niacin as a natural alternative to
conventional heart drugs, including statins. But it has to
be stressed that the beneficial effects appear to require
pharmacological doses of several grams a day, which should only
be taken under medical supervision.
In fact the recommended upper safe level of niacin intake has
been set by the Food and Nutrition Board at 35 mg a day to avoid
the unpleasant flushing of the face and body which is a common
side effect of high doses. At the other end of the scale,
the most important extreme deficiency disease relating to vitamin
B3 is known as pellagra.
Symptoms of pellagra affect the
skin, the digestive system and the brain, so sufferers may
develop a heavily pigmented rash on areas of the skin exposed to
sunlight; they may experience vomiting and diarrhea and symptoms
similar to the early signs of dementia. In the most extreme
cases pellagra can even be fatal if allowed to progress
untreated.
Fortunately, however, as little as
11 mg of niacin a day has been shown to be sufficient for the
prevention of pellagra, and the disease should never now be seen
in affluent Western societies. But the Recommended Dietary
Allowance (RDA) has been set at a slightly higher, safety, level
of 16 mg for men and 14 mg for women To put this in
perspective, a small 3oz serving of lean chicken or turkey will
provide between 5 and 7 mg, beef 3 mg; and salmon or tuna (a
particularly rich source) between 8 and 11 mg. An
unfortified cup of cereal may provide 5 mg, fortified perhaps as
much 20 mg or more.
Milk, nuts, beans and leafy green
vegetables may be useful secondary sources, but it should be
noted, however, that unrefined grains such as corn or wheat (even
in the form of wholemeal bread) are relatively poor sources
because the niacin they contain is not easily absorbed by the
human digestive system.
The RDA of 16mg should be easily
achieved through a normally well balanced daily diet, and should
be enough to prevent deficiency disease, but as always in
nutrition, mere absence of disease is not at all the same thing
as optimal health. So the sensible approach to
supplementation, and the one recommended by numerous authorities
to ensure maximum benefits, appears to be to take a multi-vitamin
or B complex supplement sufficient to raise niacin intake to
around 20 mg a day.
Steve Smith
July 2007
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