Inadequate intake of dietary folates and folic acid has been strongly associated with the elevated levels of blood homocysteine which have been identified as a key risk factor for both cardiovascular disease and Alzheimer's disease. But folates and folic acid are also very important in protecting against certain cancers and birth defects and it is these functions which are considered here.



The term folic acid may be confusing to some, because it is in fact one of the most important and heavily researched of the B complex of vitamins and widely used in this form as a dietary supplement. In the form of folate compounds the vitamin is also found naturally in the body as well as in various common foods.

Folic acid is essential for a large number of biochemical reactions within the body, including the metabolism of energy from food, but is particularly important in ensuring that the continual process of cell division within the body proceeds normally. This is especially vital during the rapid development and production of new cells during the first weeks after conception. Inadequate intake of folates and/or folic acid in the early stages of pregnancy has been identified as a cause of what are known as "neural tube defects" which lead to inadequate or abnormal development of the foetal brain and spinal cord.

One of the most dreaded diseases which may result from these problems is spina bifida, but the incidence of this has been shown to be reduced by 75% when folic acid supplements of 400 mcg are taken during the first three months of pregnancy. Folic acid supplements are recommended because they are much more easily absorbed, "bioavailable" in the jargon, than folates from food.

It would in fact be difficult to obtain sufficient supplies of this nutrient from ordinary food sources. Supplementation is therefore recommended for all women of child bearing age because the need for this nutrient is at its most critical in the very early days of a pregnancy, possibly before the mother is even aware of her condition.

This is not to say, however, that a diet rich in folates should not still be followed, because amongst the best and most readily available sources of folates are leafy green vegetables, and orange juice which also provide a plentiful supply of valuable anti-oxidants and are extremely beneficial to general health.

A single cup of spinach or asparagus, for example, may provide as much as 130 or more micrograms (mcg) of folate; a small glass of orange juice perhaps 80 mcg. Pulses such as beans and lentils are also good sources, the latter providing around 180 mcg in just half a cup, beans between 80 and 140 mcg according to type.

Best of all, however, is fortified breakfast cereal, a single cup of which may yield between 200 and 400 mcg, reflecting the FDA's insistence on the addition of folic acid to refined grain foods, including bread.

Although this policy is driven mostly by a desire to protect the unborn, the more general advice to consume at least five servings of fruit and vegetables a day has also been put forward as a protector against cancer. Certainly such a diet would be rich in folates, and research suggests a strong association between folate deficiency and an increased incidence of certain of the more common cancers, including those of the cervix, colon and rectum, lung, oesophagus and breast. It is thought that the association may arise because of the role of folate in DNA repair within cells, DNA damage being regarded as a principal cause of cancer.

However, conventional medicine remains reluctant to accept folic acid supplementation as a possible weapon in the battle against cancer, even though one large scale study has reported a halving of breast cancer risk in women taking more than 600 mcg daily. For reasons which are not understood, however, this protective effect was only observed in the case of those women who also consumed at least one alcoholic drink per day. In general it can be said that the link between folic acid intake and cancer risk remains a matter of association rather than clear causation, but orthodox opinion is much less cautious in recommending a high intake of folates from food.

But not surprisingly, given the potential benefits, nutritional therapists are much less a cautious in recommending folic acid supplementation at levels far in excess of the officially Recommended Dietary Allowance (RDA) of 400 mcg (0.4 mg) a day; some suggesting as much as 10 mg (10,000 mcg). And in fact there appears little reason for concern over the ingestion of such apparently large amounts.

Although the US Food and Nutrition Board has recommended that folic acid intake should be limited to 1,000 mcg (1 mg) per day, this is not so much because of possible problems with such an intake of folic acid in itself, but rather because it may cure a particular type of anaemia which is one of the symptoms of an underlying deficiency of vitamin B12. Whilst you might think that such a cure would be beneficial, the problem is that it may mask the underlying vitamin B12 deficiency with potentially serious neurological consequences.

But the solution to the problem would seem straightforward. It is simply to ensure that a generous supply of vitamin B12 is obtained along with any folic acid taken. And this should not be difficult if the vitamins are taken as part of a supplement containing the entire B complex, as is always recommended. As with all vitamins supplements, they should for maximum effectiveness be taken in conjunction with a comprehensive multi-mineral.