Mechanisms of Action
Hair Growth Cycle
The three-phase cycle (anagen, catagen, telogen) of human hair follicle growth.
The hair growth cycle consists of three phases: anagen (active growth, 2-7 years on scalp), catagen (regression, 2-3 weeks), and telogen (resting, 2-4 months). At any time, approximately 85-90% of scalp hairs are in anagen, 1-2% in catagen, and 10-15% in telogen. Factors that shorten anagen or increase the proportion of hairs in telogen (nutritional deficiencies, hormonal imbalances, stress) result in hair loss. Many supplements aim to prolong anagen duration, support follicle matrix cell proliferation during anagen, or reduce premature transition to catagen.