Plants, like animals, require anti-oxidants to protect
themselves from free radical damage to their cells, and the
protective substances they have evolved are known as
phytochemicals.
So one of the major reasons for the common advice for
everyone to eat a diet rich in fresh fruit and vegetables
is that such diets will also of course be rich in these
phytochemicals, the plant anti-oxidants that appear to have
a tremendously positive effect on health. Numerous studies
have reported the benefits of such a diet in fighting
cardiovascular disease, cancer, cognitive degeneration and
diabetes – the characteristic diseases, in fact, of Western
affluence. But the science remains in its infancy, so
although thousands of phytochemicals are already known
about, this is probably just the beginning.
For example, the class of phytochemicals known as
carotenoids alone numbers more than 600. These are the
highly coloured molecules formed naturally by plants, which
lend them their characteristic yellow, orange or red
pigments.
Only a few of these carotenoids have so far been the
subject of serious research, but it's known that in plants
the carotenoids function as anti-oxidants in neutralising
the so-called "singlet oxygen" molecule, which forms during
photosynthesis. It's less clear, however, whether this
particular kind of reaction is significant for animal or
human health.
What is clear, however, is that certain of the carotenoids
– notably alpha and beta-carotene and beta-cryptoxanthin
are significant as anti-oxidants because they are readily
synthesised by the body into vitamin A. The most important
of these "pro-vitamin A" carotenoids are beta and
alpha-carotene.
Certain types of food such as pumpkins, raw, cooked or
canned carrots and winter squash are rich in both alpha and
beta-carotene (as well as the other carotenoids), so eat
these and you will be getting both.
The principal differences are that beta-carotene is present
in greater quantities and that the body converts about
twice as much of the beta-carotene it absorbs into vitamin
A when compared with alpha-carotene, the relevant figures
being 40% and 20% respectively. A given quantity of any of
these foods will typically contain only between a quarter
and two-thirds as much alpha as beta-carotene. For these
reasons only the figures for beta-carotene are given here.
So an 8 fl oz can of carrots will typically contain around
21,955 mcg of beta-carotene, canned pumpkin 17,000, a cup
of cooked carrots around 13,000. Beta-carotene is also
present in a wider variety of foods such as turnip green
10,593 mcg and kale 11, 470 mcg per cup respectively.
In both cases the anti-oxidant effects of the vitamin A
produced are enhanced by the unconverted alpha and
beta-carotene which continue to act as anti-oxidants in
their own right, and being highly fat soluble are
particularly valuable in protecting the delicate fatty
structures of the body's cells such as the membranes.
Along with other fat soluble anti-oxidants, alpha and
beta-carotene also appear to assist in preventing the
oxidation of the low density blood lipids (LDL), the
so-called "bad" cholesterol which is widely believed to be
a major precursor of cardiovascular disease.
Perhaps surprisingly, the effective absorption of
beta-carotene particularly depends on the presence of this
"bad" cholesterol. But with the obvious exception of
artificially introduced toxins, if a substance is found in
the body it's there for a good reason. So in fact this is
a very good example of the body's holistic and balanced
functioning, because although you need LDL to absorb and
carry beta-carotene around the body, that beta-carotene
will itself help to raise levels of High Density Lipids
(HDL), or so-called "good" cholesterol.
In addition to this role in combatting cardiovascular
problems, many research studies, have highlighted the
potential of beta-carotene as a weapon against cancer,
probably because of its general anti-oxidant function, but
also because of the part it plays in the biochemical
communication between cells. This is vital if the immune
system is to be able to kill off cancer cells in the early
stages of their development and before the disease takes a
hold.
Conventional medicine recognises the benefits of a diet
rich in carotenoids, but tends to be sceptical that the
very high supplementary doses advocated by many alternative
practitioners will provide any significant advantage. As
so often, it is a question of balancing the risks.
But where a substance appears to be almost entirely benign
in any realistically conceivable quantity of intake, and
may offer very substantial health benefits at little
expense, the question must be: why wouldn't you take it? .
----------------------------------------------------
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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