I'm fortunate to live in a place where I have access to a very large black raspberry patch that yields several quarts of wild black raspberries every year. Black raspberries are not high on people's list of favorite berries because they have a lot more seeds than red raspberries and are not as sweet. Nonetheless, I enjoy them.
Most fruits and vegetables are good for us, and berries especially so, which is why they are a staple in my diet--and should be in yours too. Black raspberries contain phenols, phytosterols, vitamins, and minerals that individually are known to prevent cancer in animals. A recent study (link above) looked at freeze dried black raspberries and gene expression in rats when exposed to carcinogens. Scientists discovered that in the group of rats that ate the freeze dried black raspberry powder about one-fifth of the exposed genes showed near normal levels of activity meaning the cells they influenced would not develop into cancerous ones.
Freeze drying concentrates these substances making them 10 times more powerful than they would be otherwise. This type of "dosing up" with concentrated compounds like freeze dried black raspberry powder is referred to as cancer chemoprevention. For most of us, eating concentrated freeze dried berry powder is not an option; however, eating a cup of fresh or frozen berries every day certainly is.