L-carnitine is a compound derived from lysine, one of the
eight essential amino acids required by the body. Although
it is often described as a vitamin, L-carnitine is better
thought of as a micronutrient which can be manufactured
within the body. Dietary sources are important, however,
because the amount of L-carnitine required by the body may
sometimes exceed its ability to produce it.
The very name "carnitine" is derived from the Latin
"carnus", which also of course gives us the term
"carniverous". So it should be no surprise that red meat
is the richest food source of this nutrient. 3 oz of beef
steak, ground beef or mince will typically provide around
80 mg of L-carnitine; a similar serving of pork or bacon
perhaps 20-25 mg. For those unable or unwilling to consume
red meat, other sources are unfortunately much less
productive. A half pint glass of milk may provide 8mg,
fish 5mg and lean chicken a mere 3 mg. Non-animal foods
are a relatively poor source of L-carnitine.
Conventional medical wisdom, however, is that even
vegetarians should be able to produce enough L-carnitine
from their diets to avoid symptoms of deficiency. But as
always in matters of nutrition, the avoidance of deficiency
is not at all the same thing as the achievement of optimum
health.
So alternative practitioners and advocates of nutritional
therapy are ever keen to stress the potential benefits of
supplementation with the acetyl–L-carnitine form of this
compound, which is much the most easily absorbed.
Acetyl-L-carnitine has been hailed as an anti-oxidant, as a
weapon in the treatment of both chronic and acute heart
disease, as an aid to the production of energy, and as a
boost for cognitive function.
Although the evidence is not yet clear cut, it has been
suggested that acetyl-L-carnitine may play a role in
reducing the production of the stress hormone, cortisol, an
over supply of which is implicated as a factor in premature
ageing and its associated diseases. It is believed that
too much cortisol may suppress levels of
dehydroepiandrosterone (DHEA), the key adrenal hormone,
lavish levels of which are believed to help protect against
the degenerative diseases commonly associated with ageing
in the affluent West. Levels of DHEA begin to decline from
about the early twenties onwards, just as levels of
cortisol begin to rise, potentially creating a vicious
circle of bodily decline.
Supplementing the diets of laboratory rats with
acetyl-L-carnitine has been shown to increase tissue levels
of L-carnitine, which are known to decline naturally with
age, and to improve the metabolism of energy within the
cell mitochondria. This research has generated
considerable interest, although conventional medicine is
not yet persuaded of its long term implications, if any,
for human health, pending the results of the large scale
clinical trials which are planned.
The evidence is much more clear cut, however, for
L-carnitine's role in tackling heart disease. A number of
studies have indicated that L-carnitine supplementation may
be effective in restricting the damage to the heart muscle
that typically follows a myocardial infarction (heart
attack) and in improving the survival rates and exercise
tolerance of those suffering from progressive heart failure
or angina.
Research also suggests that L-carnitine supplementation in
the form of acetyl-L-carnitine may slow the advance of
Alzheimer's and other forms of dementia in the elderly.
Nutritional therapists also claim that such supplementation
can enhance memory and other cognitive function in healthy
young adults; a claim that conventional medicine is of
course reluctant to accept.
One potential problem with carnitine supplementation,
however, is that absorption rates are relatively poor; only
up to around 20% as opposed to perhaps 75% from L-carnitine
from food sources. Acetyl-L-carnitine, however, is much
the easiest to absorb, and supplements in this form are
readily available and recommended by some authorities in
quantities of between 500 and 1,000 mcg; so that even at
low rates of absorption a plentiful supply may be obtained.
As already noted, carnitine is a perfectly natural
substance, manufactured in the body, and supplementation in
these kind of quantities has not been shown to give rise to
any side effects other than minor gastric upset in rare
cases.
So as ever, the sensible and cost effective precaution
appears to be to combine supplementation with a normal
daily diet already well supplied with foods rich in
acetyl-L-carnitine.
----------------------------------------------------
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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