"The contribution of diet and nutrition to cancer risk, prevention and treatment have been a major focus of research in recent years because certain nutrients in vegetables and dietary agents appear to protect the body against diseases such as cancer," said Shivendra Singh, Ph.D., lead investigator and professor of pharmacology and urology at the University of Pittsburgh School of Medicine. "From epidemiologic data, we know that increased consumption of vegetables reduces the risk for certain types of cancer, but now we are beginning to understand the mechanisms by which certain edible vegetables like broccoli help our bodies fight cancer and other diseases."

Dr. Singh's study is based on phytochemicals found in several cruciferous vegetables called isothiocyanates (ITCs), which are generated when vegetables are either cut or chewed. His laboratory has found that phenethyl-ITC, or PEITC, is highly effective in suppressing the growth of human prostate cancer cells at concentrations achievable through dietary intake of cruciferous vegetables.

In seeking to further define the mechanisms by which PEITC induces apoptosis, or programmed cell death, mice were grafted with human prostate tumors and orally administered a small amount of PEITC daily. After 31 days of treatment, the average tumor volume in the control group that did not receive PEITC was 1.9 times higher than that of the treatment group. In addition, a pro-apoptotic protein called Bax appeared to play a role in bringing about apoptosis by PEITC.

"Our next step is to design clinical trials to determine the efficacy of PEITC for prostate cancer prevention in men," said Dr. Singh.

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Goals for the intervention groups included a 15 lb weight loss (95 percent of participants were overweight or obese), 3 hours per week of moderate physical activity, daily sodium intakes of no more than 2300 milligrams (1 tsp salt), and limits of one alcoholic drink per day for women, and two per day for men. Those also following the DASH diet were asked to increase their consumption of fruits and vegetables to 9-12 servings per day, consume 2-3 servings of low-fat dairy products, and keep total fat to no more than 25 percent of total daily calories. To keep track, participants kept food diaries, monitored calories and sodium intakes, and recorded minutes of physical activity.

More than one-third of participants had high blood pressure at the beginning of the study. Of these, 62 percent in the intervention group with DASH, and 60 percent in the intervention group without DASH successfully had their blood pressure under control after 18 months (that is, their blood pressure levels were no longer considered high). Comparatively, only 37 percent of the control group with hypertension at the study's start had their blood pressure under control at the end of the study.

"These rates of hypertension control produced by the two interventions are even better than the 50 percent control rates typically found when single drug therapy is used to control high blood pressure," said William M. Vollmer, Ph.D., a study investigator from Kaiser Permanente Center for Health Research.

Compared with the control group, one or both intervention groups had:

Greater weight loss: 5.9 lb in the DASH group and 4.8 lb in the group without DASH. Greater improvement in fitness: 2 beats per minute lower heart rate for the DASH group and 1 beat per minute lower heart rate for those without DASH. (The greater the reduction in heart rate, the greater the improvement in fitness.) Greater sodium reduction: 354 milligrams for those on the DASH eating plan and 384 milligrams without DASH (about 1/6 tsp less salt). Greater reductions in calorie intake: the intervention groups reduced their daily intake by 95 (DASH) and 130 calories (without DASH).

In addition, 25 percent of intervention group participants met the weight loss goal. The group following DASH also achieved increased fruit, vegetable, dairy, fiber and mineral intakes and decreased fat intake.

The 6-months results of PREMIER results were reported in April 2003 in the Journal of the American Medical Association.

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