The top 20 foods to help you beat cancer

We all know that fruit and vegetables are good for us. But some have astonishing powers to protect us from deadly disease, experts now say

Cancer and cookery may seem unlikely bedfellows. The first drains the appetite, while the second seduces it. Yet they are also closely linked. Up to one-third of cancers are thought to be associated with diet, and modifying the food we eat is one of the best defences against it.

Cancer and cookery may seem unlikely bedfellows. The first drains the appetite, while the second seduces it. Yet they are also closely linked. Up to one-third of cancers are thought to be associated with diet, and modifying the food we eat is one of the best defences against it.

But the road to a healthy diet is littered with false trails and blind alleys. Which is the greater threat - fat or cholesterol? Should we go high carb or low? Are there risks associated with eating more protein?

Two cancer organisations are separately trying to cut a path through this confusing jungle. The World Cancer Research Fund (WCRF), a charity committed to cancer prevention, has published a list of the 20 best foods to prevent cancer. It is a distillation of the findings of its immense report "Food Nutrition and the Prevention of Cancer", based on thousands of studies, which is being updated for publication in 2006.

It declares that eating more vegetables and fruits is the second-most effective way to reduce the risk of cancer, after not smoking. In a survey, more than half of people questioned said they were unaware that diet could influence their risk of cancer

The 20 superfoods it identifies are vegetables, fruits, nuts, oily fish and whole grains - the familiar foods that it says "stand out in the nutritional crowd" because of their health-giving properties. They contain the highest levels of antioxidants, the vitamins and minerals that help protect the body from the damaging effects of oxygen-free radicals, the unstable molecules created by the body and produced by toxins, such as tobacco, that can be carcinogenic.

Meanwhile, the Royal Marsden Hospital in London is entering the fray with a book to be published next year called Cancer: The Power of Food. It's the first time that Britain's premier cancer-healing institution has offered advice to the public on cancer prevention, and the first time it has tried to cash in on the cookery-book market.

Written by the hospital's chief dietician, Clare Shaw, the book contains recipes for dishes such as "one-pot beef", with tips on the need to cook the beef slowly to "avoid the formation of heterocyclic aromatic amines". Cheesy lentil and vegetable pie is a "high fibre supper dish that is a good source of caretonids, folate and calcium".

There's useful advice on weight-loss regimes. Coyly avoiding any mention of the Atkins diet, the book asks whether a "high protein, low carbohydrate weight-reducing diet" will affect cancer risk. "Yes, it might," it says: "All the evidence for diet being protective indicates that it should contain plenty of starchy foods, fruit and vegetables, with small portions of animal protein."

There are other valuable nuggets. Although it is assumed that raw fruit and veg are better than cooked, as some vitamins are destroyed in cooking, this isn't necessarily true. The body absorbs beta carotene, which is converted in the body into Vitamin A, better from cooked carrots than raw.

Both the WCRF and the Royal Marsden try, in different ways, to refine the research evidence into advice that people can act on. Certain facts are established - such as the dramatic decline in stomach cancer in the West in the past century, thought to be linked with the advent of the fridge.

Refrigeration meant a switch in the diet to consumption of more fresh food and less preserved meat - salted or smoked - which is known to increase the risk. Stomach cancer remains high in countries where salty foods occupy a prominent place in the diet, such as Japan.

Bowel cancer is commoner in countries of the West, where more refined, processed food is eaten, and rare in the developing world where the diet is high in whole-grain cereals, pulses and root vegetables. A high-fat diet also appears to increase cancers of the bowel, breast, prostate and lung.

But there is one problem with their thesis that has arisen too late for either organisation to address. The single most consistent piece of advice from the cancer epidemiologists in the past decade has been to eat more fruit and vegetables. Southern Europe, where more fruit and vegetables are consumed, has lower rates of cancer of the mouth, throat, lung and stomach than northern Europe.

Now, the "five portions of fruit and veg a day" strategy, which has been adopted as a central pillar of the healthy lifestyle, has been severely shaken. Earlier this month, a major study was published suggesting it might not protect against cancer after all.

American researchers who analysed results from two large US studies involving 100,000 people found that those who ate the most fruit and vegetables had lower rates of heart disease, but their "healthy" diets had no effect on cancer incidence.

The findings, published in the Journal of the National Cancer Institute, were based on results from 71,000 female participants in the Nurses' Health Study, established in 1976, and 37,000 male participants in the Health Professionals' Study, launched in 1986. Overall, those who ate at least five portions of fruit and vegetables a day had a 12 per cent lower risk of a heart attack or stroke, compared with those who ate less than 1.5 portions a day. But there was no effect on overall cancer incidence.

The researchers, led by Walter Willett, wrote in the journal: "The protective effect of fruit and vegetable intake may have been overstated." An editorial in the journal went further, adding: "The evidence is simply inadequate at this time to determine whether fruit and vegetable intake confers modest protection against cancer."

As shibboleths go, there are none greater than the protective power of fruit and vegetables on health. But if this belief did turn out to be false, it would raise doubts about the reliability of all other medical advice.

Cancer organisations have remained defiant, pointing out that this is only one study and it is contradicted by the vast bulk of research. Steven Heggie of the WCRF says: "Our first expert report into cancer prevention brought together thousands of studies from all over the world, which showed that we can reduce our risk of developing cancer by up to 40 per cent by eating a plant-based diet with lots of fruit and vegetables, taking regular exercise and watching our weight."

But the truth is that hard evidence of the right kind for the cancer-protective effect of fruit and vegetables is lacking. Cancer experts are pinning their hopes on the most detailed examination yet of the link between diet and cancer: the European Prospective Investigation into Cancer and Nutrition. The study, of 500,000 recruits in 10 countries, has been running for 10 years. Participants keep daily food diaries and contribute regular blood and urine samples.

According to Cancer Research UK, which is supporting the study, it will provide the most accurate picture yet of the links between food and cancer. Early findings are already challenging the conclusions of some large studies in the past.

But what should we eat today? Those who have to cook tonight cannot wait for tomorrow's research. The only sensible answer is that a diet based on the WCRF's 20 superfoods and the Royal Marsden's recipes is unlikely to do harm, and probably offers the current generation the best chance of outliving their parents.