Has the Marchioness of Worcester's 'alkaline diet" helped her beat cancer? Thousands of studies are carried out on foodstuffs to see if eating or avoiding them will have an effect on cancerous cells. We are assailed by well-researched accounts of the benefits of vegetables and fruits. However, we know the vast majority of cancer is due to environmental factors: researchers from the University of Texas put it at 90-95 per cent in a 2006 report in the journal Pharmaceutical Research. Their conclusions? Cancer prevention involves increased ingestion of fruits and vegetables, moderate intake of alcohol, caloric restriction, exercise, minimal meat consumption and use of whole grains. But the key is that this is preventive advice - not the basis of a curative regime. Jean Slocombe, Cancer Research UK's senior information nurse, says: "Many breast cancer patients feel better and more in control of their illness when they do something proactive such as following a certain diet. But there is no strong scientific evidence to suggest that eating organic foods and following alternative diets can treat breast cancer or reduce the risk of it coming back. Robin Pritchard, spokesman for the Dimbleby Cancer Care charity, says: "A lot of research we have funded has found that any kind of complementary therapy can have a really positive effect, improving the sense of wellbeing." Learning how to eat healthily may even help recovery, found a 2011 report in the British Journal of Cancer. Evidence suggests that a low-fat, high-fibre diet might be protective against cancer recurrence and progression. So might the Marchioness's akaline diet have had more than a placebo effect? While countless books suggest alkaline eating can make you slimmer and fitter, scientists point out that the body self-regulates so efficiently that it's virtually impossible to change the pH balance of its fluids. And the American Institute for Cancer Research warns that the idea that we can become "less acid" is a "myth." Interestingly, though, a 2011 Canadian review in the Journal of Environmental and Public Health of published scientific literature found an alkaline diet could have some benefits, including improved bone health, reduced muscle wasting, as well as mitigating chronic diseases such as hypertension and strokes. Lead researcher Dr Gerry Schwalfenberg said: "Alkalinity may result in added benefit for some chemotherapeutic agents that require a higher pH." Could the Marchioness's passion for organic food have improved the efficacy of her chemotherapy? More studies are called for. But, by eating lots of fruit and vegetables and no meat or processed food, she is improving the odds against recurrence of cancer, and enjoying their preventive effects against heart disease and diabetes.