ELIZABETH DAVID was the cookery guru of the postwar era. While subjected in Britain to rationing and a diet that included powdered milk and eggs, she reminded herself of the well-seasoned foods that she had enjoyed in the Mediterranean countries by recommending liberal portions of garlic.

Garlic and onions were not total strangers to British households. It wasn’t only in the kitchen that the onions and garlic — bought from the autumnal, itinerant French onion sellers with their trademark black berets and striped Brittany sweaters — were important. Both were used throughout the year to treat those with a wide variety of ailments. As a six-year-old boarding at a school in Norfolk I queued every evening for a tablespoon full of concentrated onion broth. Onion broth was supposed to prevent coughs and colds, and to ease the symptoms for those who had them.

In country lore garlic was effective against upper respiratory tract infections, coughs and colds. There is some evidence that it is an expectorant (it eases the dry cough) and has some antiseptic, bacteriostatic and antiviral qualities. It increases the white-cell count and so may strengthen the body’s immune system. Garlic wasn’t just used to treat or prevent chronic bronchitis, colds, influenza and even asthma. When I started in practice in Norfolk garlic was still prescribed by some parents as a means of ridding their children of worms, and was even used as a treatment for persistent leg ulcers. Useful as these treatments may have been in Victorian rural life, they have now been superseded.

In Germany seven million people take garlic tablets regularly, recommended either by doctors or chemists. Millions more enjoy garlic-enhanced food, realising that it improves their health as well as titivating their taste buds.

The belief that garlic is a useful anti-infective agent persists, but now the emphasis is on the cardiovascular system. Garlic is still used as a spice but it is also taken to treat hyperlipidaemia (raised cholesterol and other blood fats) and hence those conditions that are associated with atherosclerosis — a furring up of the blood vessels — including high blood pressure.

Modern placebo-controlled, double-blind trials have shown that it does have an effect on triglyceride and low density lipoprotein cholesterol (LDL) levels of fat in the blood. It is LDL that is the pernicious, dangerous form of cholesterol. High-density lipoprotein cholesterol (HDL) is cardioprotective.

Garlic also reduces platelet stickiness so that the blood is less likely to clot. The platelets are the small particles in the blood involved in the clotting mechanism. Garlic, in addition, influences fibrinolytic activity, which lessens the propensity of blood to clot. As well having an effect on the development of atherosclerosis, it has been shown to have an immediate effect on blood pressure by relaxing the smooth muscle and hence inducing dilation of blood vessels.

The medicinal qualities of garlic are beginning to take their place in medicine beyond the folklore of Norfolk and the pharmacies of Germany. Professor Gunter Siegel, of Berlin, recently presented his latest research into garlic at the annual conference on Arteriosclerosis, Thrombosis and Vascular Biology in Washington.

His work has been on the reduction of arteriosclerotic nanoplaque formation as the result of taking garlic extract. Siegel’s findings involve the first stage of the formation of the plaques of atheroma that in time may extend and block coronary or cerebral arteries. In an in vitro model, rather than in human or animal medicine, Siegel has investigated nanoplaques, the first stage of atherosclerotic plaque development. He has demonstrated both a reduction in their number and size.

Garlic contains allicin, which has potent antibiotic properties, but smells strongly. It is not without side-effects other than its effect on the breath. Garlic may occasionally increase tiredness, headaches and liability to sweat as the result of lowering the blood sugar. It may also give rise to tummy upsets and diarrhoea. An important adverse reaction that stems directly from its usually beneficial effect on blood clotting is the slight danger this can cause before surgery. Garlic shouldn ’t be used for at least seven days prior to surgery. It can increase the action of Warfarin.