Hair Club Journal
Hair Science
Evidence-based insights into how hair grows, why it thins, and what actually works to keep it healthy. We translate clinical research and dermatology into routines you can use every day.
The hair growth cycle
Every follicle moves through anagen (growth), catagen (transition), and telogen (rest). Understanding which phase your hair is in shapes the right intervention — from scalp stimulation to nutrient support.
Why hair thins
Genetics, hormones (especially DHT), stress, nutrition, and scalp health all play a role. Most thinning is multi-factor — which is why a single product rarely solves it.
Ingredients that earn their place
Look for clinically-supported actives: caffeine and peptides for follicle stimulation, niacinamide for scalp barrier, salicylic acid for buildup, and biotin paired with iron and zinc for structural support.