As a person who is passionate about the benefits of eating a healthy diet, it won't come as much of a surprise to learn that I'm a big fan of fruit. To my mind, fruit thoroughly deserves its wholesome reputation and is one foodstuff about which there seems to be very little contention: nutrition experts agree that fruit is healthy, and nearly all of us accept that eating more of it can only be a good thing. Even so, a recent survey found that only three out of 10 of us actually consume the recommended amounts of fresh produce each day. So while our faith in fruit is undoubted, it appears we're not overly keen on eating it in useful quantities.

All fruits contain a complex of nutritional elements, a key component of which is fibre. Fibre is important, as diets rich in it have been linked with a reduced risk of conditions as diverse as gallstones, heart disease and cancer. But while the fibre in fruit is likely to confer significant health benefits, it's only part of the story. Fruit is also rich in a range of nutrients that offer real disease-protection power. Most of us are aware of the almost ubiquitous presence of vitamin C in fruit, but we may not be familiar with other goodies such as beta-carotene (found in mango, apricots and kiwi fruit) and folic acid (found in strawberries and citrus fruits). Along with vitamin C, beta-carotene has the ability to combat ageing and disease-promoting molecules known as free radicals. And folic acid has been linked with a reduced risk of several cancers, and might possibly offer relative protection from heart disease, too.

Fruit also contains still more health-giving elements in the form of phytochemicals. These plant compounds are said to have significant protective effects against disease. Black grapes, for instance, have been found to contain the phytochemical resveratrol, which some are lauding as the critical heart-healthy factor in red wine. Hesperidin, a phytochemical found in citrus fruits, is also thought to help stave off heart disease. Strawberries and other berries, meanwhile, are rich in ellagic acid, which is thought to offer protection against cancer.

Fruit's veritable cornucopia of nutrients doesn't just promise a lot, it delivers, too. A stack of research suggests that eating more fruit offers real protection from the major killers, and appears to extend our lives, to boot. One study published last year in the Lancet estimated that the additional vitamin C gained by consuming just an extra 50g of fruit each day would reduce the risk of death from all causes by an impressive 20 per cent.

Significant benefits are to be had from eating three or four 100g servings of fruit each day. A serving or two with breakfast, and a piece mid-morning and mid-afternoon ensures a decent fruit intake for the day. Freshly squeezed fruit juices are another option, though fresh fruit itself is generally better as it contains higher levels of health-giving elements that juicing may leave behind.

Nutrition news

We've all heard that it's a good idea to keep cholesterol levels in check in the body. When cholesterol becomes damaged through a process known as oxidation, it has the propensity to deposit sediment on the inside of the body's arteries, which in turn makes one vulnerable to cardiovascular conditions such as heart diseases.

A recent study evaluated the effects of a daily dose of two tablespoons of extra virgin olive oil on cholesterol in the body. After just one week, olive oil appeared to offer significant protection against the oxidation of cholesterol. This may help explain why diets rich in olive oil, such as those of the Greeks, are associated with a reduced risk of heart disease.

Dear John...

I am a 33-year-old mother of two and have recently been diagnosed with a heart condition known as mitral-valve prolapse. Despite the fact that my doctor has told me this is not a serious problem, I think it makes me unduly tired. Is there any advice you can give me about natural remedies for this problem?
Anita Benson, Cheltenham

The mitral valve is sited between the upper and lower chambers of the heart and its function is to ensure that blood is only pumped out of the heart towards the body's tissues, and not vice versa. In mitral-valve prolapse (MVP), the valve is slightly deformed, and this may eventually lead to some leakiness. If the condition is severe, it may give rise to chest pains, palpitations and fatigue.

Certain nutrients may reduce the risk of symptoms. Studies have shown that the majority of MVP sufferers are deficient in magnesium, a nutrient well known for its essential role in heart function. What is more, studies show that magnesium supplements can help control the symptoms of MVP. I would advise you to take 250-350mg of magnesium, twice a day. Another nutrient which may help your symptoms is Co-enzyme Q10 - a nutrient which helps energy production in the body and that seems to be particularly beneficial for the heart. Take 30-50mg two or three times a day.

· If you have any issues you would like Dr John Briffa to address in this column, please contact him by email on john.briffa@observer.co.uk. Please note that Dr Briffa cannot enter into any personal correspondence