Dietary Changes including nutritional supplements may have little influence on altering the course of cancer in patients, as was reported by major review of research on the subject.
The results of the research have been published in July 19 issue of the Journal of the National Cancer Institute.
British researchers have however stated that the limited number and quality of most of the trials studied make it tough to draw definitive conclusions on the effectiveness of such interventions.
According to Dr. John A. Baron, a Dartmouth Medical School professor, "The take-home point is that the field isn't mature enough for us to know if any intervention works."
Still, all news is not discouraging. The study's lead author, Dr. Steven Thomas of the University of Bristol added, "There are some promising findings particularly for breast cancer, which suggest a reduction in cancer-specific mortality with healthy diet interventions, although the reviewed studies were small."
A 'meta-analysis' of data from 59 studies which included 25 studies involving patients with cancer and 34 with patients with pre-cancerous lesions was conducted. Dietary interventions including supplements of Vitamins A, B6, C, fiber, folate, calcium and beta-carotene and also weight loss, exercise, and calorie-reduction was examined in these studies.
Some benefit was shown in some of the studies such as dietary changes reducing the risk for breast cancer recurrence and two studies which focused on increased calcium intake pointing to a reduced recurrence of colorectal polyps, which can lead to colon cancer.
Thomas also said, "Encouraging a healthy diet is certainly important for general well-being because many patients with cancer will live for along time with increasingly effective medical treatments."
Dr. Dimitrios Trichopoulos, a cancer specialist at Harvard School of Public Health in Boston said that although the UK report was a 'very good paper', he stressed on the inherent limitations that trials focusing on disease prevention, have inherent.
He also said, 'They can't last long enough [to obtain definitive answers].' It's also difficult to get study participants to comply with specific interventions over an extended period of time.
Trichopoulos said, "Diet still works," although its effect on cancer recurrence and prevention was probably not as high as experts once believed. He said, "My guess is, diet could reduce cancer by 10 to 15 percent." Trichopoulos suggested a diet containing little red meat and high amounts of fruits, vegetables and plant based foods.