Hair originates in a follicle, which is a cavity in the skin that holds and protects the active or living cells that become the nonliving strand of hair. Each hair follicle operates independently of the other hair follicles. Because of this, each individual hair may be in a different phase of growth.
There are three phases in the hair life cycle:
- active growth phase, or anagen phase
- transition phase, or catagen phase
- resting phase, or telogen phase
Hair shedding usually occurs in the transition phase, but can also occur in the resting phase.
Active-Growth Phase
The hair root produces the cells that form the living part of the hair. This pushes the cells that already exist up and out from the follicle. As the distance from the follicle increases, the hair loses its nuclear DNA and becomes a strand of cross-linked proteins. This protein strand (the hair you comb or brush) is not living tissue. The only living parts of hair are the cells within the hair follicle in the skin.
Transition Phase
After a definite period of growth, the hair follicle goes into a transitional phase. New cells are not created at this stage. Instead, the hair follicle actually shrinks about 82%. Part of the hair root is destroyed, and the active dermal papilla breaks off from the rest of the hair follicle. This transition phase (from growth to resting) is called catagen, and lasts one or two weeks.
Resting Phase
In the resting phase, telogen, like the transition phase, the protein hair strand remains connected to the hair follicle, but it doesn't grow. After five or six weeks, the dermal papilla reconnects to the base of the hair follicle and the bloodstream. The hair reenters the active-growth phase and a new hair begins to form.
The old hair strand is usually shed near the end of the resting phase. If it does not shed, the new active-growth phase pushes the old hair out (sheds it) to make room for the new strand of hair.
Normal Shedding of Hair
Hair is normally shed during the resting phase in the hair life cycle. When hair is shed, the protein hair strand is pushed out of the hair follicle to make room for a new hair. This is a part of a gradual replacement cycle. Normally, 50 to 100 scalp hairs are shed per day in the hair-growth cycle.
Different types of hair are shed after different periods of time. For example, eyebrow hairs lasts 3-5 months. Scalp hair lasts two to five years before being shed.
Baldness or alopecia results when replacement hair (new growth) fails to keep up with hair loss. Baldness or alopecia may be due to hereditary factors, pathological conditions, aging, or to radiation injury to the dermal papilli.
Source: http://www.hairless.net/hairbiol.html
1- Diet Considerations
Hair loss may also occur due to dieting. Franchised diet programs which are designed or administered under the direction of a physician with prescribed meals, dietary supplements and vitamin ingestion have become popular. Sometimes the client is told the vitamins are a necessary part of the program to prevent hair loss associated with dieting. From a dermatologist's standpoint, however, the vitamins cannot prevent hair loss associated with rapid, significant weight loss. Furthermore, many of these supplements are high in Vitamin A which can magnify hair loss.
2- Hormonal Consideration
Hormonal changes are a common cause of female hair loss. Many women do not realize that hair loss can occur after pregnancy or following discontinuation of birth control pills. It is important to remember that the hair loss may be delayed by three months following the hormonal change and another three months will be required for new growth to be fully achieved.
3- Inadequate Protein in Diet - Some people who go on crash diets that are low in protein, or have severely abnormal eating habits, may develop protein malnutrition. The body will save protein by shifting growing hairs into the resting phase. Massive hair shedding can occur two to three months later. Hair can then be pulled out by the roots fairly easily. This condition can be reversed and prevented by eating the proper amount of protein and, when dieting, maintaining adequate protein intake.
4- Childbirth - When a women is pregnant, more of her hairs will be growing. However, after a woman delivers her baby, many hairs enter the resting phase of the hair cycle. Within two to three months, some women will notice large amounts of hair coming out in their brushes and combs. This can last one to six months, but resolves completely in most cases.
5- Medications - Some prescription drugs may cause temporary hair shedding. Examples include some of the medicines used for the following: gout, arthritis, depression, heart problems, high blood pressure, or blood thinner. High doses of vitamin A may also cause hair shedding.
6- Low Serum Iron - Iron deficiency occasionally produces hair loss. Some people don't have enough iron in their diets or may not fully absorb iron. Women who have heavy menstrual periods may develop iron deficiency. Low iron can be detected by laboratory tests and can be corrected by taking iron pills.
7- Major Surgery/Chronic Illness - Anyone who has a major operation may notice increased hair shedding within one to three months afterwards. The condition reverses itself within a few months but people who have a severe chronic illness may shed hair indefinitely.
Sources: (items 1-3) http://www.aad.org/pamphlets/hairloss.html
And (items 4-8) http://www.ahlc.org/female.htm
1) Fad diets can cause hair loss by putting stress on the body similar to emotional stress which causes the hair cells to quit reproducing.
2) Diets or rapid changes in eating habits can cause hair loss even if the diets are high in protein
3) Low protein or vegetarian diets can cause hair problems including hair loss.
It is important to note that once malnutrition is handled the body handles the hair loss as well. Results vary but are typically good when caught early enough.
We have also noticed that there are certain things that you can do for your body to reduce your susceptibility to hair loss regarding diet and stress.
Understanding how your diet affects your hair:
Low protein diets simply starve your hair since your hair is made up of proteins. The proteins are made up of amino acid chains many of which contain the amino cystine. For various reasons the proteins and aminos may not make it to your hair whether it be from lack of proteins or cystine or from lack of circulation to the vessels that feed the hair which is often seen in people with hormone related hair loss because the dht hormone derivative destroys the blood vessels that feed the hair.
Solving protein malnutrition hair problems is not as difficult however people should be aware that your hair is often the barometer of your body meaning that your body may be deficient and this should be addressed.
Solving hair problems associated with protein malnutrition and amino acid malnutrition is done by adding proteins and aminos the hair with certain products and adding proteins and aminos to the to the body as well.
Source: http://www.mmtresearch.com/