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Diet,
Sunlight And Osteoporosis
Author: ©Steve P Smith
The term osteoporosis refers to the unfortunately very common
condition by which bones become de-mineralised and reduced in
strength. Also sometimes known as "brittle bones", it
is particularly common in the elderly population and a well established
contributory factor in the fractures, especially following falls,
which are a tragically frequent occurrence during this time of
life.
Although the symptoms and consequences of osteoporosis are at
their most readily apparent during old age, it is a condition
which may develop throughout life. But although some of principal
risk indicators for the development of osteoporosis, such as the
ageing process itself, cannot be avoided, the good news is that
a little attention to diet and nutrition, particularly the intake
of calcium and vitamin D, will go a long way towards delaying
or even avoiding the onset of this dangerous condition altogether.
And because the bones' nutritional demands are their greatest
during their growth phase, this attention cannot begin too early
in life.
The human body stores and requires more calcium than any other
mineral, and most of this is in the bones. Not surprisingly, then,
an adequate intake of dietary calcium is essential for bone health,
and a deficiency one of the principal risk factors for osteoporosis.
But although essential, a good intake of calcium is not enough
on its own. Dietary calcium is relatively easy to obtain through
milk, other dairy produce and green vegetables, but even lavish
supplies cannot be absorbed without sufficient vitamin D, and
as many as 80% of sufferers from fractures attributed to osteoporosis
have been found to be deficient in this vitamin.
Unfortunately vitamin D is less easily obtainable through commonly
consumed foods but a potentially, though not necessarily easily,
modifiable "lifestyle choice" which may have a dramatic
effect on levels of vitamin D in the body is the amount of sunlight
to which the skin is exposed. For years medical orthodoxy was
inclined to rely on the fact that vitamin D can be synthesised
within the body on exposure to sunlight as evidence for the relatively
low significance of dietary intake. And there may even have been
some force in this idea in those far away days when a significant
proportion of the population worked in outdoor occupations and
children were accustomed to outdoor play rather than TV, computer
and video games.
But nowadays most people not only work indoors but are strongly
advised to cover themselves liberally with sunblock on the rare
occasions when they do expose themselves to any natural sunlight.
For those of us living more than about 37 degrees north or south
of the Equator, where sunlight is in any case in very short supply
for six months of the year, this combination of circumstance makes
it doubtful that we will be able to obtain a sufficient supply
of vitamin D from sunlight. And this concern is even more marked
for the elderly, as the body's ability to synthesis vitamin D
from sunlight reduces with advancing years.
Moreover, it is unfortunately not particularly easy to obtain
a good supply of vitamin D from a conventional Western diet; oily
fish, liver, eggs and certain cereals being the most reliable,
if unpalatable, sources. And contrary to popular belief, dairy
produce in itself is not an especially rich source unless specifically
enriched with the vitamin.
But even when vitamin D rich foods are regularly consumed, there
are still other risk factors for osteoporosis which need to be
considered when considering the adequacy of vitamin D and calcium
intakes. Smoking and the immoderate consumption of alcohol are
perhaps amongst the more readily avoidable of these. Less obvious,
but perhaps at least as important, is the need for physical activity,
and in particular load bearing exercise or strength training.
Low secretions of the main sex hormones, testosterone in men and
oestrogen in women, are also important precursors of osteoporosis.
Declining levels of these hormones with advancing age is one reason
why older people are much more prone to this condition, a problem
which is particularly marked for women, given the dramatic drop
in oestrogen levels which follows the menopause.
But perhaps most important is the fact that the typical modern
Western diet, with its heavy reliance on processed foods, is known
to result in a high intake of sodium, which, as well as being
a cause of high blood pressure, also increases the urinary excretion
of calcium and other vital minerals with corresponding adverse
consequences for bone density. The simplest and best solution
to this problem, of course, is the consumption of a diet rich
in fresh fruit and vegetables, rather than highly processed foods,
which will in itself ensure a reduction in sodium consumption
and an increase in potassium and other minerals, ensuring the
maintenance of a healthy balance.
To ensure adequate good intakes of both vitamin D and calcium,
however, it appears in the light of all of the above to be wise
to take advantage of a comprehensive multi-vitamin and multi-mineral
supplement.
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