For the healthiest hair (and body) possible, you should eat a well-balanced diet that includes:
• fatty acids (found in flaxseed oil and cold-water fish like salmon);
• zinc and copper (found in fish, shellfish, meat, and poultry);
• B vitamins (found in eggs, dairy, meat, and whole grains);
• selenium (found in cruciferous vegetables).
Also, keep your hair expectations in check. Typically, healthy hair grows only a half-inch each month, and growth slows with age. In addition, each strand of hair has a life cycle--the length of time it takes to reach maturity, fall out, and be replaced by a new hair--which varies from person to person. If your hair's average life cycle is only two years, it's doubtful that you'll ever have waist-length hair, which would take about six years to grow from a short hair cut.