Your hair, which grows about 0.35 millimeter per day, or a little over .01 inch, is genetically predestined to grow to a certain maximum length. However, while you can't change how long your hair will grow, your food choices play an important role in making your hair its healthiest, fullest and most break-resistant.
Plenty of high-quality protein in your diet will ensure that your hair follicles receive enough of the right amino acids -- the "building blocks" of proteins -- from which to produce the healthiest, thickest hair possible for you. Lean meats, fish and poultry are good animal sources of protein. Vegetarian protein sources include grains, beans and legumes. Aim for 50 grams of protein per day or 60 grams if you are pregnant or nursing.
In addition to forming the structure of your hair, certain amino acids, such as cysteine, help regulate the rate at which your hair grows and may promote faster and longer growth, according to Wishard Health Services. Foods that contain high levels of cysteine include poultry, dairy products and wheat germ. Avoid supplementing with any single amino acid, as this can cause a nitrogen imbalance and place stress on your kidneys.
Folic acid helps maintain healthy hair by ensuring proper growth and division of the cells that make up the 100,000 hair follicles in your scalp. Folic acid also contributes to the production of methionine, an amino acid building block of keratin. Biotin, a B-complex vitamin, also known as vitamin H, may help strengthen and thicken weak or brittle hair. Though scientific evidence for this benefit of biotin is weak, according to the University of Maryland Medical Center, a deficiency of biotin can cause hair loss.
Calcium and Magnesium
In addition to their contribution to healthy muscles, bones and nerves, calcium and magnesium are important for healthy hair growth. Magnesium citrate helps hair grow by assisting with absorption and utilization of calcium, which contributes to hair structure, according to Dr. Margaret Greenwood-Robinson, author of "Hair Savers for Women: A Complete Guide to Preventing and Treating Hair Loss." Include beet and turnip greens in your diet to help you reach your 280-milligrams-per-day recommended allowance for this mineral.
Prevent hair loss by eating plenty of iron-containing foods such as lean meats, pumpkin seeds and tofu. A study published in the 2003 issue of the "Journal of Investigative Dermatology" found that iron deficiency is a common factor in a variety of different types of hair loss. Additionally, if your iron levels are at the low end of normal, you may not be experiencing optimal hair growth. Researchers concluded that iron status may be helpful for scientists to consider when designing treatments to promote faster hair growth or reverse hair loss.
- University of Pennsylvania Health System: Decreased Serum Ferritin is Associated With Alopecia in Women
- Wishard Health: Cysteine
- University of Maryland Medical Center: Cysteine
- YOU: Being Beautiful: The Owner's Manual to Inner and Outer Beauty; Michael F. Roizen and Mehmet C. Oz
- University of Maryland Medical Center: Lysine
- Annual Review of Nutrition: Iron, Ferritin, and Nutrition
- Columbia University Health Center: What Foods Contain Folic Acid?
- Healthaliciousness.com: Nutrition Facts Comparison Tool
- University of Rochester: What is Human Hair？A Light and Scanning Electron Microscopy Study
- Hair Savers for Women: A Complete Guide to Preventing and Treating Hair Loss; Margaret Greenwood-Robinson
- Bennington College: Mutants: Genetic Variation in Human Development
- University of Maryland Medical Center: Vitamin H (Biotin)
- Harvard University Health Services: Iron Content of Common Foods
- Prescription for Nutritional Healing; Phyllis A. Balch
- University of North Carolina Chapel Hill: USFDA Daily Values
- University of California Santa Barbara ScienceLine: I Have Some Hairy Questions
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