Black raspberries are rich in fibre, vitamins and phytochemicals, and in a recent study at Ohio State University in the US, they also inhibited the development of oral cancer in rats. Researchers also identified key cancer-related genes that may explain this effect. The results of the study were among the more than 140 posters presented at the American Institute for Cancer Research Conference in November.
Preclinical and clinical trials in human beings suggest that black raspberries may prevent or slow the development of oral cancers, though there has been little understanding of the molecular basis for their beneficial effects. Previous research has also identified key cancer-related genes in human beings that were switched on and off in response to eating black raspberries.
The researchers assigned rats with oral cancer to one of three dietary groups for 16 weeks: a standard diet, a diet that was 5% freeze-dried black raspberries, or a diet that was 10% black raspberries. A comparison group of rats was cancer free. At the end of the study period, the researchers analysed the animals’ tongues and blood for markers associated with inflammation and apoptosis, a type of programmed cell death.
Markers of apoptosis showed signs of promoting cancer cell death and markers of inflammation were reduced in the animals that ate the black raspberries, compared to the animals on the standard diet. Also, the tumours in the rats that ate diets that were 5% or 10% black raspberries were reduced by 39% and 29%, respectively, compared to the rats on the standard diet.