Green diet may not beat cancer
November 3
A large study has cast doubt on the protection offered by fruit and vegetables against cancer. Researchers from the Harvard School of Public Health in Boston, USA noted that previous work has focused on specific diseases. So they decided to look at overall risk by analysing data from more than 100,000 study participants. Current advice in the UK and US is to eat at least five servings of fruit and vegetables daily to reduce risk of cardiovascular disease and cancer, leading causes of death in the developed world. The team, led by Dr Walter Willett, found that increased intake of fruit and vegetables is associated with a lower risk of cardiovascular disease, but not cancer. Results are published in this week’s issue of the Journal of the National Cancer Institute. The 100,000 participants were members of two large US cohort studies – the Nurses’ Health Study and the Health Professionals’ Follow-up Study. When looking at different groups of fruits and vegetables, the team found that green leafy vegetables had the strongest link to reduced cardiovascular disease. They write: “Consumption of five or more servings of fruits and vegetables per day has been recommended, but the protective effect may have been overstated.” “Our findings for cardiovascular disease still support the recommendations of the American Heart Association of consuming at least five servings of fruits and vegetables per day,” they add. However, in an editorial, Dr Arthur Schatzkin and others from the US National Cancer Institute, point out the difficulty of this type of study. They write, “The evidence is simply inadequate at this time to determine whether fruit and vegetable intake confers modest protection against cancer.” J Natl Cancer Inst 2004;96:1564-65 & 1577-84