Which foods?

Alcohol

Studies consistently show moderate drinkers (one to two drinks per day) have healthier hearts and live longer than either heavy drinkers or teetotallers.

The antioxidants in red wine were originally thought to make the difference, but it now seems a moderate amount of any alcohol will do the trick.

However, the benefits of alcohol come within a very narrow intake margin. A little too much can do more harm than good and the benefits do not apply to everyone. Small, regular amounts of alcohol seem to do some good for middle-aged and older men and postmenopausal women, but there are more risks than benefits for younger people.

Binge drinking at any age can do serious harm. Drinking during pregnancy is risky for the baby. It is also best to avoid alcohol while breastfeeding.

High alcohol intakes can cause cancers in the mouth, throat, oesophagus and liver. It has also been linked with breast and bowel cancers, though the evidence is not conclusive.

Beer contains B vitamins, especially folate. Links between low folate levels and heart disease are beginning to emerge. But a diet rich in folate, which seems to affect factors that reduce the likelihood of blood clotting, may help prevent heart attacks.

While foods like legumes, vegetables, nuts, cereals, fruit and fortified cereal products are richer and better sources of folate, there is no denying that beer can also add to your dose.

Chocolate

The prospect of chocolate being a health food might be the most exciting nutritional news ever. Cocoa beans contain flavonoids that seem to inhibit the effects of LDL - the bad cholesterol in the blood - and enhance the benefits of good cholesterol (HDL). The flavonoids may also have beneficial effects against cancer by stopping the oxidation of free radicals that can damage cells.

Dark chocolate has more of the flavonoids than milk chocolate, and white chocolate has none.

But chocolate also contains saturated fat and sugar. Small quantities as part of a good diet will do most people no harm, but there are better ways of getting antioxidants and flavonoids. Most fruit and vegetables contain rich quantities, without the disadvantages of saturated fat and so much sugar.

Tomatoes

Lycopene is a red beta-carotene present in tomatoes. Research suggests people who eat a lot of tomato-based foods have a reduced risk of cancer, especially prostate cancer. The association seems strongest with cooked and tinned tomatoes and tomato products. Lycopene has also been found in watermelon.

Soy

Soya beans contain protein and phytoestrogens called isoflavones that mimic oestrogen's effects on parts of the body and seem to lower blood cholesterol levels. It also seems that phytoestrogens may have a cancer-protective effect.

The effects come from soya beans, tofu, soy milk, yoghurt and flour, but not from soy sauce or soya oil.

The effects of soy are very controversial. Some research suggests the hormonal effects of soy are not always beneficial and there is increasing evidence it may affect the thyroid function in some people. Research into the benefits and risks of soy is ongoing. Until more is certain it is wise not to eat large quantities of soy-based foods.

Broccoli and sprouts

Brassicas include brussels sprouts, cabbage, broccoli, kale, cauliflower, bok choy and watercress. Research has shown people who eat a lot of brassicas appear to face lower risk of cancer, particularly lung, stomach, colon and rectal cancers.

Broccoli releases sulphoraphane, which seems to activate anti-cancer enzymes in the lung and colon. In lab tests, sinigrin released by brussels sprouts seems to makes colon cancer cells self-destruct.

Spinach

The antioxidant action of lutein and zeaxanthin, found in spinach, other dark green leafy vegetables and green beans, seems to reduce the risk of developing macular degeneration, a very common cause of blindness in older people. It is too early to recommend how much to eat but it seems the vegetables help.

Garlic

Sulphur compounds in garlic, onions, leeks and chives may inhibit blood clots, reduce blood cholesterol levels and blood pressure, and block the formation of some cancer-forming substances in the colon.

Observational studies of populations who eat a lot of onions and garlic show low rates of cancer and heart disease, but not enough large or long-term studies have been done to confirm any of these connections.

Fish

Omega 3 oils are found in fish such as salmon, tuna, warehou, dory, eel and sardines. They have possible protective roles in arthritis, hypertension, cancer and heart disease, and are thought to play a role in vision and brain development and function.

Observational studies have shown groups of people who regularly eat a lot of fatty fish have lower rates of cardiovascular disease and stroke. This is because omega 3 oils prevent blood platelets from sticking together and onto artery walls, and also boosts levels of HDL - the good cholesterol - in the blood. See our Omega-3 fish oil supplements report for more information.

Tea

Tea contains catechins. These are polyphenols which plants use to protect their cells from ultra-violet light.

Though all tea contains them, green tea has higher concentrations of catechins that are more readily available for the body to use than black tea. In Japan, where green tea is popular, many studies suggest tea drinking has a positive effect on the heart.

It is thought catechins may work by mopping up harmful free radicals. Another flavonoid present in tea, quercetin, is also found in red onions, apples and red wine and has been linked with an improvement in lung capacity. It may also help to protect lungs against atmospheric pollution.