Obesity is associated with a marked increase in colorectal cancer, and some hormone-dependent cancers, such as breast and endometrial cancers.

At least five portions of fruit and vegetables a day can reduce the risk of many different types of cancer. The exact reason for this is unknown, but it may be related to their fibre content, vitamins and minerals, other plant chemicals such as flavonoids, or the combination of all these nutrients. Vitamin and mineral supplements may be a useful addition to the diet for some people, but they aren't a substitute for fresh fruit and vegetables.

On average, most people need to eat about 50 per cent more fibre than they currently do to meet the recommended intake of 18g per day. Fibre is important to increase stool weight, which enables waste to pass easily from the body. Cancer of the large bowel is the second most prevalent cancer in the UK, affecting one in eight people. By increasing stool weight by 25 per cent, the incidence of this disease could be reduced by up to 15 per cent in Britain.

A high-fat diet is linked to an increased risk of colorectal cancer. (See the advice on fat intake in the cardiovascular section).

Excessive intake of alcohol has been linked with an increased risk of cancer of the mouth, liver and throat. Women should limit their intake to no more than two to three units a day, men to no more than three to four units a day, and try to have two or three alcohol-free days each week.

Cancer lies dormant in all of us. Like all living organisms, our bodies are making defective cells all the time. That’s how tumours are born. But our bodies are also equipped with a number of mechanisms which detect and keep such cells in check.Cancer cells do not behave like normal cells. They refuse to die after a certain number of divisions, and they poison the tissues around them with chemical substances, creating inflammation, which they need to sustain their growth.

The pharmaceutical industry is looking for drugs that will inhibit the chemical secreted by cancer cells which causes inflammation. But there are already a number of natural ways we can boost our immunity and reduce inflammation to help keep those cancer cells in check. It’s simply a matter of eliminating certain toxins from our environment, adopting an anti-cancer diet, seeking emotional balance and taking enough exercise.

Green tea is a top antioxidant.Rich in polyphenols that reduce the growth of the new blood vessels needed for tumour growth, green tea is also a powerful antioxidant and activates mechanisms in the liver which help to eliminate cancerous toxins from the body more rapidly. In mice it has been shown to block the effects of chemical carcinogens responsible for breast, lung, oesophageal, stomach and colon cancer.

The most powerful natural anti-inflammatory identified today. In the laboratory it enhances the effectiveness of chemotherapy and reduces tumour growth. To be assimilated by the body tumeric needs to be mixed with black pepper and, ideally, it should be dissolved in oil.

These all help to regulate blood sugar levels, which in turn reduces insulin secretion and thus the growth of cancer cells. They promote the death of cancer cells in colon, breast, lung and prostate cancer.

Shiitake, crimini, portabello and oyster mushrooms stimulate the reproduction and activity of immune cells.They are often used as a complement to chemotherapy to support the immune system.

Cabbages, sprouts, broccoli and cauliflower contain powerful anti-cancer molecules. But boiling will destroy them — steam briefly or stir-fry rapidly in a little olive oil.

Carrots, yams, sweet potatoes, squash, tomatoes, apricots, beets and all the brightly coloured fruits and vegetables contain vitamin A and lycopene, which have the proven capacity to inhibit the growth of particularly aggressive cancers.

Herbs can help reduce the spread of cancer cells. Rosemary, thyme, oregano, basil and mint are rich in essential oils of the tarpene family which reduce the spread of cancer cells by blocking the enzymes they need to invade neighbouring tissues.

Oranges, tangerines, lemons and grapefruit contain anti-infammatory flavonoids which are also present in the skin. So buy organic, unwaxed citrus fruit and add the zest to salad dressing or steep the skins in hot water or tea.