Back in the 1930s, thiamine, also known as vitamin B1, was
one of the first compounds to be isolated and recognised as
a vitamin, that's to say a compound essential to health
which the body cannot manufacture for itself, and which
must therefore be obtained from the diet.
The functions of thiamine within the body are highly
complex biochemically, but what's important to know is that
thiamine and its associated enzymes are essential for the
body's production of energy from food. As always with the
B complex vitamins, however, the proper functioning of
thiamine depends on an adequate supply of the other members
of the complex, and the performance of the thiamine related
enzymes in this case is particularly dependent on the
associated vitamins, riboflavin (B2) and niacin (B3).
That said; there is a characteristic disease of severe
thiamine deficiency, beriberi, which has been recognised
for several thousand years. This disease should never now
be seen outside medical text books in affluent Western
societies, but alcoholics and heavy drinkers, for whom the
absorption of adequate thiamine presents particular
problems, frequently show symptoms.
Beriberi is regarded as having "wet" and "dry" forms, the
symptoms of the former being principally observed in
problems with the cardiovascular system, including severe
fluid retention and in severe cases even congestive heart
failure. So-called "dry" beriberi is characterised by
problems with the nervous system, particularly the
peripheral nerves of the limbs, which may lead to pain and
weakness in the muscles.
Beriberi may also have serious effects on the brain, partly
through increased free radical activity, leading in extreme
cases to conditions known as Wernicke's encephalopathy
and/or Korsaloff's amnesia or psychosis. Wernicke's is
identified by characteristic physical nervous "ticks",
especially unusual movements of the eyes, whereas
Korsaloff's is the term applied when these symptoms are
accompanied by severe amnesia.
If you think these symptoms remind you of the archetypal
"street wino" you'd be right, because in advanced societies
they're most commonly found in alcoholics and heavy
drinkers, supporting the theory that malnutrition is a
major contributor to their problems. It makes sense that
this should be so. For not only do such people tend to
have very inadequate diets, but their damaged livers also
struggle to metabolise the few nutrients which they do take
in. Alcohol, of course, is also known as a powerful
diuretic, and when you consider that thiamine, in common
with the other vitamins of the B complex, is highly water
soluble, and easily excreted by the body, you have a potent
recipe for nutritional disaster.
So how much thiamine do you need to avoid this disaster?
As always, the Recommended Dietary Allowance (RDA) for
thiamine (most recently established in 1998) is set at the
level designed to prevent deficiencies in normally healthy
people. But of course, the prevention of deficiency is not
at all the same as thing as ensuring optimum health, and
the RDAs for thiamine are therefore set at the very low
levels of 1.2 mg for men and 1.1 mg for women. As the
slight differential suggests, higher intakes are required
in proportion with higher bodyweight, and particularly
muscular bodyweight. An increased intake of 1.4 mg is also
suggested for pregnant women.
A number of common every day foods provide good sources of
thiamine. A serving of fortified breakfast cereals, for
example, may provide 0.5 – 2mg, a single cup of wheatgerm 4
or more mg. A 3 oz serving of pork will contain up to 0.75
mg, lentils, peas, brown or enriched white rice 0.2 mg, and
a slice of wholemeal bread 0.1 mg.
These figures would seem to suggest that most people should
have little difficulty in achieving their RDA. But the
problem is that thiamine is notoriously fragile, and almost
any type of processing of these foods, including boiling or
even toasting bread may dramatically reduce thiamine
content.
So it's perhaps not surprising that research suggests
average intakes in Western societies may be as low as 2 mg
a day for men and 1.2 mg for women. These figures are
worryingly close to the RDAs which, as noted, are in any
case set at a level only designed for the avoidance of
outright deficiency. Being averages, it likely follows
that there must be many people who routinely fall below
them, and there are also factors to be considered which may
dramatically increase the body's demand for thiamine and
therefore the risk of deficiency.
As well as the consumption of alcohol, these include
intensive physical exercise, normal growth in adolescence,
pregnancy and breast feeding, and feverish illnesses,
particularly malaria. As with alcohol, heavy intakes of
tea and coffee have been shown to have a severely depleting
effect on the body's levels of thiamine, and this is due to
so-called "anti-thiamine factors", in addition to the loss
of the water soluble vitamin which may be attributed to the
diuretic effects of these drinks. There is also evidence
that older people may struggle to absorb sufficient
quantities of this nutrient even when their diet appears
adequate.
There is no recommended upper safe limit for the intake of
thiamine, any excess being easily excreted by the body, and
no known toxic effects. Supplementing with thiamine is
therefore recommended for the vulnerable groups listed
above, which in fact comprise a significant proportion of
the supposedly well population, and may well be beneficial
for all who seek optimal health and maximum energy levels.
The close interdependency of the B vitamins, however, means
that thiamine should be taken as part of a supplement
containing the whole complex. The proper functioning of
the vitamin also requires the presence of adequate
minerals, particularly magnesium.
----------------------------------------------------
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
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