Its role as an anti-carcinogen was first studied in the 1990s by Gary Stoner, professor of internal medicine at Ohio State University, who was especially interested in its effects on colon and esophageal cancers.
He discovered that compounds called anthocyanins - which give the fruit its colour - play a crucial part in fighting cancer. They scavenge for free radicals and they inhibit inflammation, Stoner found.
Following on from his discoveries, others at the university developed a gel from black raspberry extract, which they tested on patients with oral and skin cancers. In one trial, they treated 20 patients with pre-cancerous lesions who were instructed to apply the gel on their lesions four times a day for 42 days. After the end of the study period, lesions in half of the patients had improved significantly, and in several cases had cleared up altogether.
The gel is going through the approval process, and it could be in stores in the USA in the next couple of years.
(Source: Townsend Letter, September 2007; 24).