IGF-1 is protein related to human growth hormone (HGH). Pharmaceutical HGH is now widely used as part of physician-assisted anti-aging hormone-replacement therapy, but is extremely expensive and requires a prescription. But since prescription-HGH users get such good results, there's growing interest in natural products that may deliver anti-aging support. NOW Foods has isolated IGF-1 from a naturally-occurring source. In fact the source of the IGF-1 - velvet shed from the antlers of a certain species of deer - has been used in Chinese medicine as a rejuvenating tonic herb for centuries. Natural lemon flavor and stevia give NOW IGF-1 LipoSpray a pleasant taste.