Understanding about hair and hair follicle.

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Vaibhav Shah

                                Understanding about hair and hair follicle.

         The understanding about hair and hair follicle has improved tremendously in the last decade. But in terms of treatment options nothing much has changed apart from refinement of surgical techniques. As the percentage of men and women, who suffer from hair loss grows, proportionally, the number of products sold for hair loss also grows. These products (growth factors, stem cell preparation, vitamin pills, and peptides) are advertised widely in the media and on the net and by late night pitches via infomercials. They prey on those who may be concerned about recent or dramatic hair loss. We urge caution when considering these products and always maintain that be suspicious of treatments that offer a large benefit for very little in return. Usually these products do not have any scientific studies backing them.

           We practice evidence based hair restoration which integrates the best available research evidence with clinical expertise and patient values.

         As it is our endeavor to educate people affected by hair issues, this blog will have basic details about the biology of the hair follicle and how it undergoes changes to cause hair problems. We intend to do this through a series of question and answers.

WHAT IS HAIR?

Hair is a collective term for slender, threadlike outgrowths of the epidermis of mammals, forming a characteristic body covering.

WHAT IS A HAIR FOLLICLE?

The hair follicle represents a unique and complex biological system (a miniature factory), found only in mammals which is geared toward the production of hair. This is the part that is below the skin and is not visible in intact skin.

HOW MANY HAIRS DOES A HUMAN HEAD HAVE?

Each human typically has between 2 million to 5 million hairs on the body. A human head has anywhere between 100,000 and 150,000 hairs. The number, calibre and density per unit area varies with age, gender, and ethnicity. Oriental heads have most hairs and redheads have the least. Apart from the palms and soles almost all skin has follicles. But not all hair grows to the same length or at the same rate.

HOW DOES A HAIR FOLLICLE DEVELOP?

In humans, follicle formation begins on the head in the fourth fetal month of gestation, and then moves downward to the remainder of the body. Follicles first produce soft, short and fine hairs, which are called "lanugo" hairs.

WHAT ARE THE DIFFERENT PARTS OF THE HAIR FOLLICLE?

The follicles are slanted in epidermis and an oblique muscle the arrector pili runs from the middle of the follicle wall to the dermo epidermal junction, additionally one or more sebaceous glands open into the follicle.The follicle may be divided into vertical components : Infundibulum, Isthumus, Suprabulbar region and Bulb.

WHAT IS THE COMPOSITION OF HAIR?

The hair as we see it is a compact structure made up of dead cells. Individual hairs are composed chiefly of the horny scleroprotein known as keratin and contain neither blood vessels nor nerves. They usually contain pigment (except in the case of albinos). The shaft of the hair consists of modified epithelial cells arranged in columns (cortex) surrounding a central medulla (or core) and covered with thin, flat scales (cuticle).

WHAT IS THE DENSITY OF HAIR ON SCALP?

Accurate quantitative analysis of scalp hair density is difficult and time consuming. Scalp possesses the greatest density of hair fibers 300 – 500/cm2 (different figures are quoted by different specialists ranging from 130-280/sqcm2), Chest about 100/cm2, Thigh about 50/cm2. Clinically when we look at the hair follicles on the back of the head we have an average density of 160 hairs per cm2.

HOW DOES HAIR GROW?

The hair follicle bulb is like a minute factory which manufactures cells continuously. As new cells are formed the older ones are pushed into the follicle towards the surface. The cells on reaching a particular point undergo cell death and are converted into a scleroprotein called keratin, which is then compacted to form the hair. This continuous activity is responsible for the hair growth.

During anagen the follicle actively grows hair.

During catagen the follicle is almost entirely degraded.

During telogen the follicle rests prior to re-initiation of an anagen phase and the growth of a new hair shaft. On any given day, human beings lose about 50-100 scalp hairs due to exogen, these are the hairs we find in our comb, brush and shower drain. Shedding in excess of this may be due to an increase in the follicles of scalp hair in the telogen stage and should be addressed to contain hair loss.

          At any given time approximately 90% of our scalp hair are in the growing phase and about 10% in the resting phase, if the scalp is healthy and not affected by any condition that causes hair loss.

           Recently a fourth phase has been added based on the findings in patients of pattern hair loss. This is known as the Kenogen or the lag phase. This is the period after the hair has been shed and before the new hair formation begins. It is this phase that is prolonged in patients of Pattern Hair Loss.

          The normal growth rate of scalp hair is 0.3 - 0.4 mm per day or roughly 1cm per month. Hair growth has a cyclical pattern that can be affected by a number of genetic, disease, medication or other factors to cause hair loss.

WHY DO SOME PEOPLE HAVE VERY LONG HAIR? HOW LONG CAN YOUR SCALP HAIR GROW?

         If you do not cut your hair then you can grow it quite long, but there is an upper limit to the maximum length that you can grow your scalp hair.

       There are various papers that examine the time duration for scalp hair follicles are actively producing a hair fiber. The most frequently quoted time period is 1000 days (2-6 YEARS), but this figure is a rough approximation. The time duration of anagen growth, plus knowing what length of hair fiber a scalp hair follicle can produce per day, will enable a calculation of the average maximum length that scalp hair can grow to. Research on humans suggests that active hair fiber growth production from scalp hair follicles may last from 500 to 1800 days. The scalp hair fiber growth rate is between 0.3 to 0.4 mm a day. For the most part, the studies were done with male volunteers, but a few other studies indicate similar results for women too.

          If you put it all together in a calculation, the research would suggest that the maximum length scalp hair can grow to, is between 20 and 60 centimeters. However, from the picture below you can see that some people are able to grow their hair much longer. The upper limit to scalp hair length is determined by our genes. Some people have genes for short hair, others grow hair much longer.

HOW IS HAIR GROWTH REGULATED?

           The hormones called androgens are important control factors in hair growth and in inherited male and female patterns of hair loss. The androgen hormone testosterone and its metabolite dihydrotestosterone (DHT) are the key control factors:

        Testosterone is a key control factor in the growth of beard, underarm and pubic hair. Scalp hair loss is associated with presence of DHT in male and female pattern hair loss. DHT plus the presence and activity of hair loss gene(s) are the key factors underlying male and female pattern hair loss.

           The androgens mediate their effect by binding to the androgen receptors present in the follicle. The testosterone is converted to DHT by the action of the enzyme 5-Alpha reductase. The DHT then binds to the receptor and initiates its action.

WHAT ARE THE CAUSES OF HAIR LOSS?

        A detailed answer is given in Hair loss causes. However to answer briefly, the interaction between the triad of, hereditary factors, male hormones, and age plays an important role in causing baldness in males. In females it is the change in the hormone levels at menopause, stress (both physical and mental), poor nutrition and ill health, which are responsible for hair loss. Damage to the follicles caused by injury, burns etc, certain medications can also lead to hair loss.

IS DIET LINKED TO HAIR LOSS?

       Excess or deficiency of any kind will affect the system and thereby affect the hair follicle. Including fresh fruits, leafy vegetables, sprouts and cutting down oil and refined sugar will go a long way in tackling hair loss. Crash dieting is one of the major reasons for accelerated hair fall in females.

         Eating a balanced diet is essential for maintaining good hair health and also your overall body health. According to nutritionists, people who have nutritional deficiencies in their diet have dull and stringy hair and can at times even suffer from a temporary case of hair loss. Hair loss caused due to dietary deficiencies is usually temporary and different from the pattern hair loss which is progressive and permanent.

      A diet, which is very low in calories, can affect your hair. Eating too much of only certain food groups and eliminating others from your diet, can also cause hair loss. Studies have shown that a deficiency of Zinc can severely affect your hair and cause it to fall. Zinc is present in meat, seafood, and eggs; so you should try and incorporate these in your diet. For vegetarians, a zinc supplement may help.

          Hair, to remain healthy, needs essential fatty acids. The omega-3 fatty acids provide the hair follicles with the nutrients necessary for good health and to keep the hair and scalp from drying up. If the hair follicle will not get its share of these fatty acids, it becomes weak and this results in hair loss and thinning of hair. Thus a diet, which all but eliminates fat, is not good for the hair. Omega-3 fatty acids are present in mackerel, salmon, flaxseed oil, macadamia nuts, and walnuts.

           Another constituent of the Vitamin B complex, known as Biotin, is very essential for healthy hair. A deficiency of biotin is known to cause hair loss. Any foods which give you a good amount of protein such as meat, eggs etc, should take care of your biotin requirements for preventing temporary hair loss. Vegetarians can take milk products, cereals, cottage cheese, and tofu to increase their protein and biotin intake.

           Hence, from all the above, it can be seen that people who have a poor diet or eating disorders such as anorexia and bulimia, are at an increased risk of temporary hair loss due to nutritional deficiencies that weaken their hair shafts and follicles. Thus it is important to have a proper diet. A healthy and balanced diet will definitely help in improving your hair condition as well as stop it from falling due to any diet related deficiency.

             Nutritional deficiencies (or as you put it, restrictive diet) can cause hair loss. In addition, this may trigger a stress response and turn on a gene that may kick start your male pattern hair loss. Unfortunately, after the process has started it is difficult to stop the progression of hair loss.

IS THERE A LINK BETWEEN SMOKING AND HAIR LOSS?

Article in Brtish Medical Journal BMJ says that.

WHICH MEDICATIONS ARE RESPONSIBLE FOR HAIR LOSS?

The following is the list of drugs which may lead to hair loss usually with long-term use:

Cholesterol-lowering drug: clofibrate and gemfibrozil

Parkinson Medications: levodopa

Ulcer drugs: cimetidine, ranitidine and famotidine

Anticoagulents: Coumarin and Heparin

Agents for gout: Allopurinol

Antiarthritics: penicillamine, auranofin, indomethacin, naproxen, sulindac and methotrexate

Drugs derived from vitamin-A: isotretinoin and etretinate

Anticonvulsants for epilepsy: trimethadione

Antidepressants: tricyclics, amphetamines

Beta blocker drugs for high blood pressure: atenolol, metoprolol, nadolol, propranolol and timolol

Antithyroid agents: carbimazole, Iodine, thiocyanate, thiouracil

Others: Blood thinners, male hormones (anabolic steroids)

WHAT IS THE DIFFERENCE BETWEEN HAIR TRANSPLANT AND HAIR WEAVING, HAIR BONDING AND HAIR FUSION?

        Hair transplant is a surgical procedure in which permanent hair from the patient's own head is transferred to the bald areas. Hair weaving, bonding and fusion are temporary procedures in which, external hair bearing devices are attached to the existing hair or scalp using weaves, micro clips, adhesives to achieve cover of the bald area. Hair transplant is a permanent and natural method to correct baldness.

WHAT IS FOLLICULAR UNIT TRANSPLANT (FUT)?

       Hair grows in naturally occurring groups of 1, 2, 3 or 4 hair, a good transplant imitates nature and transfers these units as they occur giving a very natural and undetectable look. The older methods of hair transplant using punches, minigrafts (3-5 hair), micrografts (1-2 hair) that do not respect the follicular unit as a single entity, give a very unnatural look.

AM I A CANDIDATE FOR FOLLICULAR UNIT MICROGRAFTING?

          Age, grade of baldness, quality of your hair, a detailed medical history and physical examination will decide whether you can be a candidate for hair transplant. Being well informed regarding various aspects hair loss, restoration etc and having realistic expectations from the procedure, increase the chances you will be happy with the results.

HOW DO I DECIDE ABOUT THE LOCATION OF MY HAIRLINE AND NUMBER OF GRAFTS REQUIRED FOR ME?

   The placement and quality of the hairline are important factors in determining the success of a transplant. Patient's expectations, facial proportions, grade of baldness and generally accepted guidelines help in planning the hairline. In general it is advisable not to place a hairline too low, as it looks unnatural. Imitating the natural hairline in terms of density, direction of hair growth and gradual transition is as much a work of art as it is a science.

           The number of grafts required is directly proportional to the extent of the bald area and depends on the available donor area.

WHAT HAPPENS TO THE DONOR AREA?

          After single strip harvesting, the donor area is closed with stitches and every effort made to keep the ensuing scar, thin and flat. Keeping the surrounding hair at least one inch long helps in hiding it. After 8-12 months it is virtually undetectable, even to the hairdresser.

HOW PAINFUL IS HAIR TRANSPLANT?

         Usually the only pain (tiny, sharp) you would feel is during the injecting of local anesthetic. Some patients report a painful discomfort towards the end of the procedure which gets relieved by the pain relief medication. Many patients report no pain whatsoever.

WHEN WILL THE GRAFTS START TO GROW?

           Growth starts at about 3-6 months after the transplant. In the initial phase of growth the hair are fine but as time passes by (8-12 months), they gain length and diameter. By the end of one year, the "new" hair should be as robust as the surrounding non-transplanted terminal hair and growing at the same rate.

WHAT ARE THE SIDE EFFECTS / COMPLICATIONS OF HAIR TRANSPLANT?

         In the overwhelming majority of hair transplantation procedures there are no complications. However, a number of side effects, risks, and complications are mentioned in the medical literature and these are quite uncommon. For the purpose of putting these things in perspective, you may refer to PRE AND POST CARE. If you are worried about any particular complications you could contact Dr.Shah for detailed information on the same.

CAN BALDNESS BE PREVENTED OR CURED BY USING A FORM OF GENE THERAPY?

       Genes play a very important role in causing androgenetic alopecia. Hence manipulating the genes responsible for hair loss will cure baldness.

         Dr. Angela Christiano the founder of the gene responsible for a condition called Universal atrichia (total absence of body hair, usually at birth), is involved in ongoing search for the elusive gene causing baldness and feels that someday gene therapy will be used to treat hairloss.

WHAT ABOUT CLONING?

       Hair cloning is a slang term for engineered hair growth. It involves isolation of a group of cells at the base of the hair follicle. These follicular cells are multiplied in a laboratory and they divide to create new follicles and generate new hair, which are then implanted back into the bald area. Early results are promising, but it will take almost a decade of further study, clinical trials and meeting regulatory requirements before cloning is widely available. This would be a boon for patients with limited donor area whenever it is available.

ANY NEW TREATMENT OPTIONS?

        Researchers in Japan claim to have isolated two genes responsible for androgenetic alopecia. They also claim to have discovered a plant-derived ingredient called 6-benzyl aminopurine which could help revitalize the two genes and restore hair growth. It is difficult to verify this claim till large-scale studies are conducted.

WHAT ARE THE AVAILABLE REMEDIES FOR COMBATING HAIR LOSS? WHAT IS EFFICACY OF HERBAL REMEDIES?

        At present there are only two remedies approved for hairloss. In terms of topical applications we have Minoxidil or its derivatives and in the pill form we have Finesteride in 1mg strength, which are effective (either singly or jointly) in large number of patients.