The entire complex of B vitamins is essential for health,
and they're known as the B complex for the very good reason
that they interact closely together in the performance of
all their vital functions. All the vitamins of the complex
are usually found together in food, and since all are water
soluble, they may also be excreted together from the body.
A deficiency in one of the complex is therefore usually
accompanied by a corresponding deficiency in each of the
others.
That said, there are particular deficiency characteristics
which can be identified for each B vitamin.
Vitamin B12 (sometimes known as cobalamin because of the
cobalt ion in its composition) is one of the most important
of the complex, and also one of those in which deficiencies
are most likely. These deficiencies are largely
attributable to difficulties in absorption of the vitamin,
which are a particular problem for the elderly.
Vitamin B12 is required for the body's manufacture of the
essential amino acid, methionine, and the associated
enzyme, methionine synthase. An inadequate supply of this
enzyme may lead to an excess of homocysteine, a naturally
occurring protein within the body, which has been
associated with an increased risk of cardiovascular
disease. At least 80 separate studies have noted this
association and it seems that the increase in risk is not
negligible. In fact a large study in Europe in 1997 found
that people with blood homocysteine levels in the top 20%
of the range faced a more than doubled risk of
cardiovascular disease.
Whilst elevated homocysteine levels are strongly associated
with a deficiency of vitamin B12, deficiencies of vitamins
within the B complex are seldom if ever found in isolation,
and are therefore seldom remedied by single vitamin
supplementation. It is not just vitamin B12, but vitamins
B6 and folic acid, for example, that have been found to be
associated with excess homocysteine, and which should
therefore always be taken together, preferably as part of a
supplement containing the whole B complex.
Given that elevated homocysteine levels are accepted as a
risk factor for cardiovascular disease, and that
supplementation with the vitamins mentioned above is known
to reduce homocysteine levels, you might think it only
commonsense to suppose that an adequate intake of these
vitamins, including B12, would be a protector against
cardiovascular disease. And there are many nutritionists,
of course, who strongly agree with this apparently logical
position. Perhaps surprisingly, then, conventional
medicine remains reluctant to accept it pending the outcome
of further large scale placebo trials.
Science must have its definitive answer no doubt, and it is
a quest which must be respected, but in this case, given
the relatively small amounts of these vitamins required by
the body, and the absence of any reported toxicity or
adverse side effects, it might be wondered whether from the
point of view of the seeker after health, particularly
those no longer in the first flush of youth, it is really
worth running the risk of a deficiency.
And even orthodox opinion recognises that the risk is real,
even though it is unlikely to be caused by an inadequate
dietary supply. The Recommended Dietary Allowance (RDA)
for vitamin B12 is only 2.4 mcg a day, an amount which
should be readily obtainable, except perhaps for those
following a strict vegetarian regime, given that a single 3
oz serving of fish or red meat may provide this quantity.
For those with a taste for it, sea food may provide a great
deal more, and chicken, turkey, eggs, milk and cheese are
also useful, though less lavish, sources.
Deficiencies may well result, however, from problems with
the absorption of the vitamin, particularly in older
people, and it has been estimated that deficiency may
affect 10% -15% of individuals over the age of 60.
This is because good absorption of vitamin B12 from food
is heavily dependent on the normal stomach acid and
digestive enzymes, the quantity and effectiveness of which
decreases substantially as the body ages, and on the
presence in the stomach of a specialised protein known as
Intrinsic Factor. The correct action of Intrinsic Factor
requires the presence of adequate calcium in the body,
another nutrient in which the elderly, of course, are
notoriously likely to be deficient.
Absorption of B12 from supplements is much less
problematic, however, because stomach acid and digestive
enzymes are not required to release the vitamin from its
protein bindings. So this is a rare case in which even
conventional medical "wisdom" recognises the value of
supplementation, at any rate for the over 50s.
But given that sub-optimal levels of vitamin B12, if not
outright deficiencies, are commonly found even in younger
individuals, and that cardiovascular disease is a problem
which may develop insidiously and without symptoms over
many years, there would seem to be strong arguments for
supplementation even amongst the wider population.
----------------------------------------------------
Steve Smith is a freelance copywriter specialising in
direct marketing and with a particular interest in health
products. Find out more at
http://www.sisyphuspublicationsonline.com/LiquidNutrition/In
formation.htm
No comments:
Post a Comment