Garlic is one of the oldest known medicinal plants, and it's been credited with fighting heart disease, lowering blood pressure and helping to fight off colds. Michele Simmons reports

The therapeutic qualities of garlic are nothing new. Sanskrit records reveal that garlic remedies were pressed into service in India 5,000 years ago, while Chinese medicine has recognised garlic's powers for over 3,000 years. Even Louis Pasteur, who discovered penicillin, recognised the anti-bacterial powers of garlic back in 1858. And during World War One surgeons regularly used garlic juice to stop wounds turning septic.

So, what is it about garlic that makes it such a boon to our health? When cloves are chewed, crushed or cut, they release a sulphur-bearing compound called allicin - the chemical that gives garlic its pungent taste and smell. And it's the allicin that scientists have discovered is the magic ingredient thought to be responsible for garlic's therapeutic qualities.

Garlic - helping your health
Most of the modern research on garlic has concentrated on its ability to lower cholesterol and blood pressure as well as offering protection against strokes and heart disease. For example, when the Journal of the Royal College of Physicians reviewed data on cholesterol in 1993, it found that after just four weeks there was a 12 per cent reduction in cholesterol levels in the research groups that had taken garlic.

Scientists have also looked at the role garlic plays in helping prevent the formation of blood clots. A review of recent clinical trials, published in the Journal of Hypertension, showed that taking garlic tablets cut volunteers' blood pressure by between one and five per cent. These results led the report's authors to conclude that taking supplements could cut the incidence of stroke by anything from 30-40 per cent, while heart disease could be reduced by 20-25 percent.

While garlic is gathering a reputation for helping to maintain a healthy heart, regular amounts of garlic seems to also help the body fight off infections. These antibacterial effects were first discovered in the early 19th century during an outbreak of infectious fever - English priests caught the fever but the French priests, who ate garlic every day, remained healthy. However, you don't need to suffer with a fever to benefit from garlic's health enhancing properties.

Fighting off the common cold
A recently published study found that a daily garlic supplement reduced the risk of the volunteers catching a cold by half. The researchers also discovered that even when those taking the supplement did develop a cold they were more likely to make a speedier recovery than the non-garlic taking volunteers. And if that's not enough, just one clove a day will top up your body's supplies of vitamins A, B and C, as well as a vast array of minerals including selenium, iodine, potassium, iron, calcium, zinc and magnesium.

Research into the benefits of garlic are continuing all the time and some scientists have been reviewing evidence that suggests it may even help to protect against stomach cancer. The thinking behind this is that the allicin compounds, contained in garlic, may help prevent cancerous changes in the stomach wall. While more research is clearly needed there is little doubt that a little garlic, every day, can go a long way in helping to protect, as well as boost, your health.

Embarrassing side effects?
For some, garlic can be the cause of heartburn as well as flatulence. And then, of course, there is the smell that eating garlic leaves behind! For those who prefer their garlic odourless, a range of products, from chemists and health food shops, provide the recommended dose - between 600-900 mg a day.

Look our for Holland and Barrett Odourless Garlic, £4.99 for 100; Kwai Once a Day garlic tablets, £4.95 for 30; Hofels Odourless Garlic, £2.59 for 30; and Boots Odour Controlled Garlic Tablets, £4.90 for 30. If you'd prefer to stick to the real thing, a clove a day can help improve your overall health and two or three cloves a day can help to stem a cold. If the taste is too overpowering, try mixing with plain yoghurt or cottage cheese. Chew parsley after eating garlic to help neutralise your breath.

Cooking with garlic
When used in cooking, crush or cut the garlic finely, then leave for 10 minutes to allow the allicin to fully develop before adding to recipes. Add the garlic about five minutes before the end of cooking - this way you apply just enough heat to convert the allicin into medically active compounds.

Garlic can interact with anticoagulants, such as Warfarin, so if you take blood thinning medication or aspirin, talk to you doctor before taking supplements. It is also recommended that no garlic supplement is taken for two weeks before surgery, as they may interfere with blood clotting and increase risk of bleeding.