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While many people monitor their cholesterol levels, few will have heard of a substance that is a much better indicator of the risk of heart disease. Homocysteine, an amino acid and a normal by-product of the metabolism of protein, is 40 times more accurate than cholesterol in predicting heart problems, yet doctors are unlikely to offer you a test. Even more extraordinary, the research that first put homocysteine on the agenda is more than 30 years old. Raised homocysteine levels have been found in the blood of 40 per cent of patients suffering from heart disease, yet the work of a Harvard scientist, Dr Kilmer McCully, who first made the link in the 1960s, is only now filtering through to mainstream medicine. There is growing evidence to suggest that this link between raised levels of homocysteine and an increased risk of heart disease is independent of other risk factors such as raised cholesterol and high blood pressure. Around 80 per cent of fatal heart attacks, for example, occur in men who do not have high cholesterol levels. One explanation is that homocysteine promotes atherosclerosis - hardening of the arteries with plaque deposits of cholesterol and calcium - which can trigger a heart attack by restricting blood and oxygen flow to the heart. Smoking and high coffee consumption are linked to an increased risk of heart disease. What is less well known is that they have also been associated with high levels of homocysteine. In good health, the body detoxifies homocysteine by converting it back to methionine, from which it was produced, or by breaking it down further to form a more harmless substance called cystathionine. Factors that can interfere with this process include a genetic fault in one of the enzymes nutrients needed to activate these enzymes. Several of the B vitamins, including folic acid, can lower levels of homocysteine. If you have high homocysteine you should take B6 and B12, which act as cofactors for the enzymes that keep levels low. Where there has been an increase due to a nutritional deficiency, you need take only 400mcg of folic acid, 10mg of vitamin B6 and 50mcg of vitamin B12 a day. If a genetic defect is suspected, you will need to step up this supplementation and, since blood tests can determine the level of homocysteine, your doctor should be able to advise on the right amount to take. The point about taking all three is that one does not work without the other. Tests on men with high levels of homocysteine revealed suboptimal levels of all three B vitamins. The reported revalences were a 56.8 per cent suboptimal level of vitamin B12, 59.1 per cent for folic acid and 25 per cent for vitamin B6. If the lower dose is not working, the nutrients choline (2g per day), which is found in the B vitamins, and betaine (6g a day) may be more effective. In animal studies, intravenous choline was found to reduce damage to the arteries supplying the heart in rabbits which had been fed high-cholesterol diets. Betaine or trimethylglycine (TMG) occurs naturally in broccoli and spinach and deactivates harmful homocysteine molecules. A study by the Agriculture Research Service of the US Department of Agriculture found a strong correlation between high homocysteine levels and the loss of memory that is frequently linked to depression in the elderly. Choline can improve brain function and memory. It is used by the brain to make acetylcholine and is believed to help to keep the nerve cell membranes, including the synapses or communication points between them, intact so that cells can "talk" and share information. Since homocysteine is made from methionine, and if your levels are high, it makes sense to avoid foods that are a natural source of this substance. These include meat, fish, chicken and eggs. Beans and dark leafy greens such as spinach can help to keep keep homocysteine levels low. Walnuts, an excellent source of the heart-protecting omega-3 fatty acids, prevent blood clots and lower homocysteine. Higher levels of homocysteine have also been found in postmenopausal women and the substance is now believed to play a role in osteoporosis by interfering with the production of collagen. Supplementation with B vitamins will help but you need to take all three types together. Avoid processed foods and eat more fruit and vegetables.
Where to get it
Solgar sells homocysteine modulators. They contain betaine, plus vitamins B6, B12 and folic acid. 60 capsules cost £8.15. Take two a day. For stockists, call 01442 890355. Susan Clark (health journalist of the year) is the author of The Vitality Cookbook, HarperCollins, £19.99, which explains how diet can help to lower homocysteine levels. Orders: call 0870-900 2050 quoting Dept 235X. (Copyright 2000 Times Newspapers Ltd.) |
