While many believe the practice of nutritional
supplementation to be a strictly contemporary phenomenon, this is
actually far from the truth. Cod liver oil, for instance, has been
advocated for its bone-building and joint-feeding effects for more
than a hundred years and some of us may even remember being plied
with a daily spoonful of this stuff when we were young. However,
the oil has been less popular of late, largely as the result of the
stiff competition it has faced from a growing number of nutritional
supplements that cram the shelves of health food stores and
pharmacies. It seems that cod liver oil’s reputation as a
stalwart supplement has been somewhat diluted by the vast range of
natural remedies that vie for our patronage and pound.
Despite its sinking competition, I believe there is much about
cod liver oil that is worthy of our attention. Its chief
ingredients are the so-called omega-3 fats, specifically
docosohexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Within
the body, DHA and EPA have the ability to thin the blood, reduce
the level of unhealthy blood fats known as triglycerides, raise
levels of ‘healthy’ high-density lipoprotein (HDL)
cholesterol and help reduce blood pressure. With such a plethora of
beneficial effects on the blood vessels and circulation, it comes
as no surprise that studies have linked goodly omega-3 consumption
(either from fish or fish oil supplementation) with a reduced risk
of both heart disease and stroke. One piece of research combining
the results of several studies found that eating more oily fish or
supplementing with omega-3 fats reduced the risk of suffering from
a fatal heart attack by 30 per cent.
Another effect the omega-3 oils have is to quell inflammation in
the body. Interestingly, there is mounting evidence that
inflammation is an important underlying mechanism in heart disease
and stroke. There is some thought, therefore, that the natural
anti-inflammatory effect of the omega-3 fats plays some part in
their apparent ability to keep heart disease and stroke at bay -
increasing research indicates that inflammation is an important
underlying process in these conditions. Also, its potential to
dampen inflammation means cod liver oil may also offer considerable
benefits as an anti-arthritic agent too. In one study, daily cod
liver oil supplementation for three months brought about
significant reductions in the stiffness and pain caused by the
inflammatory joint condition known as rheumatoid arthritis.
There is also evidence the oil may be useful in the treatment of
osteoarthritis - a condition characterised by ‘wear and
tear’ in the cartilage that lines and cushions the joints. In
addition to its rich catch of omega-3 fats, the oil offers useful
quantities of vitamin D which plays an important role in the health
of the bones and joints. Research shows that those individuals with
the highest intake of vitamin D have the lowest risk of suffering
from degeneration in their joints. Vitamin D has also been linked
with some protection from other conditions as well, including
cancers of the breast, colon and prostate. Most of our needs for
vitamin D are met by the action of sunlight on our skin. However,
as the days shorten and our need to wrap up increases, the
opportunity to make sufficient rom the sun declines. For this
reason, cod liver oil is a good supplement for ensuring that we get
enough vitamin D, especially from the autumn until the spring.
Another of cod liver oil’s beneficial elements is vitamin
A. Like vitamin D, this nutrient has been implicated in a wide
variety of health benefits, including a reduced risk of heart
disease and a number of cancers. Vitamin A also seems to stimulate
the immune system and appears to help protect against infections
including colds and flu. Its vitamin A content give even more
significance to the supplementation of cod liver oil during the
winter.
While vitamin A is an important nutrient, there is some evidence
that doses of around 3000mcg a day or more during pregnancy may
increase the risk of birth defects in several body parts, including
the heart, skull and face. However, this association is far from
clear-cut. More recent evidence suggests that vitamin A can be
taken in higher doses quite safely. Nevertheless, it seems the most
sensible thing to do is err on the side of caution. For this
reason, I recommend that women who are pregnant or planning
pregnancy should not supplement with vitamin A at doses exceeding
3000mcg (10,000 iu) per day (this is equivalent to about three
teaspoons of cod liver oil per day, though the content of any other
vitamin A-containing supplements that may be being consumed will
also need to be taken into consideration).
While cod liver oil offers a rich store of health-giving
nutrients, it is also known to contain cholesterol - a high level
in the diet is often said to be a risk factor for cardiovascular
disease. However, despite this conventional wisdom, the link
between dietary cholesterol and disease is far from clear. For
instance, there are several studies in the scientific literature
that show no significant difference in the levels of cholesterol
consumption between healthy individuals and those suffering from
heart disease. Also, there are other studies that show that there
is little or no relationship between the amount of cholesterol in
the diet and the levels of cholesterol in the bloodstream. This may
be due, at least in part, to the fact that the majority of
cholesterol in the bloodstream does not come from the diet, but is
made by the liver.
The evidence suggests that it is very unlikely that the
cholesterol in cod liver oil (or any other source in the diet) will
have any adverse effect on health. The scientific evidence suggests
that supplementation with the oil is likely to bring quite a catch
in terms of health benefits in the long term.
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