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What Are Your Optimal Levels Of Vitamin C Intake?
Author: ©Steve P Smith
Amongst the general public today, vitamin C is probably the most
popular of all nutritional supplements, perhaps principally because
it is widely believed to be effective as a cure for the common
cold. But there is much more to the nutrient than this, as was
demonstrated by the celebrated Dr Linus Pauling, whose pioneering
work hailed optimal intakes of vitamin C as a powerful weapon
against flu, heart disease and even cancer.
Pauling's
books became extremely popular, but it almost goes without saying
that the medical establishment was quick to ridicule his ideas
and still largely refuses to recognize the value of large doses
of vitamin C. Not that either the public or Pauling, a double
Nobel Laureate, seemed to care much. He regularly took doses of
well in excess of 1,000 mg daily, and was working almost until
the end of his incredibly active 93 year life.
As well
as the happy coincidence of Pauling's longevity, if coincidence
it is; a great deal of research now supports his claims for vitamin
C, as well as recognizing it as one of nature's most powerful
anti-oxidants and anti-ageing nutrients. But despite this, the
Recommended Dietary Allowance (RDA) remains set at just 60 mg;
and, more worryingly still, research suggests that around a quarter
of people in the affluent western world, including America and
the United Kingdom, manage to consume only about 40 mg of vitamin
C a day, just 2/3rds of this already very low RDA.
Despite
repeated lectures from government and health agencies to eat five
portions of fruit and vegetables a day, it seems that many people
still do not do so. And even for those who do, the amount of vitamin
C yielded from these foods, grown as they are on nutrient depleted
soils, is likely to be low; and will be depleted further by pesticides,
transport, storage, processing and cooking.
And
as if this were not enough, vitamin C is used up easily once in
the body; both by combating the free radicals released by normal
oxidative biochemical reactions and by the toxic stresses produced
by environmental pollution. The use of alcohol, tobacco and other
drugs, including common medications, is also highly destructive
of vitamin C.
Given
all these factors, it's hard to think many of us are getting optimal
levels of vitamin C, an observation that's strongly supported
by a look at intakes in the animal kingdom.
What
particularly interested Pauling was that human being are unusual,
though not unique, amongst animals in that we are unable to manufacture
vitamin C within our bodies. Little in nature is ever wasted,
and Pauling argued, logically enough, that animals which do manufacture
their own vitamin C would only make as much as their health demanded.
It seems, however, that most animals produce around 30 mg of vitamin
C per kilo of body weight, and this figure rises dramatically
when the organism is under particular stress. For an adult human
weighing, say, 75kg (165 pounds), the figure of 30 mg would equate
to a vitamin C requirement of 2,250 mg, which of course must be
obtained from the daily diet or through supplements.
But
in case this figure seems high, it is fortunately possible to
compare typical human intakes with those of closest genetic relatives
in the animal kingdom, the great apes, who are also unable to
synthesis vitamin C within their bodies. Interestingly, the diets
prepared for chimpanzees and gorillas in captivity, presumably
with their optimal health as the intention, seem typically to
yield between 20 and 30 mg of vitamin C per kilo of the animals'
bodyweight. And a 1940s study of gorillas in the wild estimated
a vitamin C intake from their food of around 4,500 mg, typically
around 22.5 mg per kilo of the animal's bodyweight.
And
of course, it needs to be remembered that these creatures in the
wild are likely to be subject to far less environmental stress
and fewer toxins than human beings, thereby making better use
of the larger amounts of vitamin C they consume, and further emphasizing
the inadequacy of most human's intakes.
In the
face of all this evidence, given that humans are estimated to
be around 98% genetically identical to the great apes, an intake
of 1,000 – 2,000 mg a day for a typical adult would not seem
excessive; and the RDA, in fact, appears pitifully low.
Happily,
these optimal intakes of vitamin C are easily achieved through
supplementation, and there are no known problems of toxicity at
any level. But it is probably best to stagger the intake of high
doses through the day, to maximize absorption and maintain saturation
levels in blood and tissue at all times.
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