Two men who sought to boost their sexual performance and grow bigger muscles ended up with advanced prostate cancer instead after taking "herbal" supplements.
Many supplements that are marketed as "safe" and "natural" actually contain unknown and potentially dangerous ingredients.
The product the men took contained the hormones testosterone and estradiol, and laboratory tests proved the supplement fueled the growth of prostate cancer cells more potently than testosterone alone.
The two men have both survived, but have extensive cancer that has spread throughout their bodies.
* Reuters January 15, 2008