SCIENCE: 13 SECRETS TO LIVING TO BE 100

1) Choose your parents carefully. Though overall longevity is only partly inherited (estimates vary from 10 to 20 per cent), many of the diseases that lead to premature death tend to run in the family, for example cardiovascular disease and breast cancer.

2) Be female. In all Western countries, women outlive men by five to 10 years. If you go into any old people's home, you could be forgiven for assuming it was a single-sex establishment. It isn't, but the men just haven't made it that far. If you are male, console yourself with the somewhat paradoxical fact that while men die younger, they tend to live their short lives in a far better state of health than their sisters.

3) Don't smoke. At all. Ever. If you are addicted to nicotine, forget whatever else you are doing and cure your addiction. If you smoke, the positive health effects of anything else that you do, such as exercise, are completely negated.

4) If you are too fat, eat less food. Obesity is linked to a range of problems such as a higher incidence of cardiovascular disease (the biggest killer of both sexes) and diabetes. Exercise will help you lose weight, but the quickest and surest way to shed the pounds is to lower your calorie intake.

5) Live in a place that keeps poor birth and baptism records. Most of the people who live to fantastic ages - 150-plus - come from obscure Chinese mountain villages, remote areas of the Caucasus and isolated Andean valleys, where the registrar for Births and Deaths is an infrequent visitor.

6) Eat a well-balanced diet that is rich in fruit and vegetables. Fruit is especially full of goodies. Take food and diet scares and fads with a pinch of salt, but don't add it to your food. Excess salt has been linked to increased blood pressure, which increases the risk factor for cardiovascular disease, the biggest single killer.

7) Exercise, but don't go crazy. Understand that health and fitness are not the same thing. If they were, professional athletes would live longer than the rest of us (they don't). Regular, light exercise is almost certainly healthy, particularly where the risk factors of cardiovascular disease are high. Fanatical exercise could even be harmful, in raising metabolic rates, liberating oxidising molecules and causing irreparable skeletal, tendon and ligament damage.

8) Understand risk factors. Don't stop eating apples because you are worried about pesticides - the risk from these chemicals is massively outweighed by the risk from eating too little fruit and vegetables. Don't get overstressed worrying about overhead power cables, computer screens, radon gas, sick building syndrome and contaminated drinking water. These are trivial risks inflated by sections of the media interested in sensationalism, scaremongering and promotion of ignorance. Go for a walk instead.

9) But some things are risky. Cars and motorbikes are real life-shorteners, so belt up before taking to the road. Unprotected sex with an HIV positive partner is risky - 500 such encounters give you a two-in-three chance of picking up the virus. If you enjoy taking heroin, potholing, parachuting or hang-gliding, and accept the risks, fine. If you don't, avoid these activities.

10) Don't feed the ducks. The various elixirs of youth on the market serve only one purpose - to line the pockets of quacks. Rare algae, diced monkey testicles, royal jelly and expensive Chinese potions will not make you live any longer, but they will make you poorer. More respectable, perhaps, are the various "magic bullets'' which have been developed recently by food and pharmaceutical companies. There is little evidence that melatonin, DHEA or Deprenyl can increase the human lifespan.

11) Hormone Replacement Therapy won't make you live to 120, but it may make old age for women much more bearable. The slight increased risk of breast cancer from HRT (a recent study by the Imperial Cancer Research Fund found a 0.2 per cent extra risk in women on HRT for five years) pales into insignificance when compared to the hugely reduced risk of cardiovascular disease. This may not be the case if you have already had breast cancer, or have a family history of the disease.

12) Go easy on the booze. In the United States, the drinking of alcohol is linked to more deaths than any other single activity except smoking. Excess alcohol is responsible for several diseases, such as cirrhosis, and is also linked to violent behaviour and road deaths. Moderate consumption, however, is probably quite healthy.

13) Be Greek or Japanese. No one knows why the Japanese and Mediterranean peoples live longer than anyone else. It may be the diet (low fat, fish, plenty of vegetables, olive oil and so on), it may be the sunshine, it may be some completely unidentified factor. What is known is that people from these countries lose their longevity advantage when they emigrate to countries like the US which have a radically different diet.