Many widely available dietary supplements are marketed to support prostate health. African Cherry (pygeum africanum) and beta-sitosterol are two related supplements that have been studied as possible prostate cancer treatments.
African Cherry / P. africanum
African cherry or Pygeum africanum is a tree that grows in tropical climates. It is found in a number of African countries including Kenya, Madagascar, Uganda, and Nigeria. Bark from the P. africanum tree was used by African tribes to relieve urinary symptoms and stomach pain. In the 18th century, European travelers learned from South African tribes that P. africanum could treat bladder discomfort and "old man's disease" (enlarged prostate).
Since 1969, bark extracts from P. africanum have been available as prescription drugs in Europe and have been widely used to treat benign prostatic hyperplasia (BPH). The bark contains a number of compounds including fatty acids and phytosterols (e.g., beta-sitosterol). The bark is processed and purified as an extract.
Laboratory studies and animal studies have shown that two substances in bark extract from P. africanum are active in blocking cells from taking up androgen. The antiandrogen activity found in P. africanum is at a markedly lower concentration than the antiandrogen activity found in flutamide (an anticancer drug).
Beta-sitosterol is a plant substance found in P. africanum, saw palmetto, and various nuts, beans, and seeds. It is a type of phytosterol (plant sterol) and has a chemical structure similar to cholesterol. Phytosterols, including beta-sitosterol, limit the amount of cholesterol that can be absorbed from the diet and they are being studied for their potential to protect against cardiovascular disease.
Studies suggest that phytosterols may have anticancer activity, but their exact actions are unknown. Phytosterols may affect immune and hormonal systems or may directly target cell cycles and cause cell death in tumors.
Laboratory studies have shown that certain concentrations of beta-sitosterol markedly slow the growth of human prostate cancer cells and cause cancer cell death.