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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