What's Hair Made Of?
Think of your hair like a strong rope made of tiny building blocks. The main building block is a protein called keratin. This protein is like the glue that holds your hair together, making it strong and flexible.
Your hair also gets its colour from pigments called melanin. There are two types: eumelanin, which gives hair dark colours like brown and black, and pheomelanin, which gives hair red and yellow tones. How much of each type you have determines your hair colour.
Structure of Hair:
Hair Follicle: Anchors hair beneath the skin, akin to a plant's seed in soil.
Hair Shaft: Visible part of hair consisting of:
- Cuticle: Outer layer akin to fish scales; smooth cuticles yield shiny hair.
- Cortex: Main structure with tightly packed keratin for strength and elasticity.
- Medulla: Optional core resembling a straw's centre; less impactful on hair strength or appearance.
Three Phases of Hair Growth:
- Anagen Phase (Growth Phase): This is the active growth phase when your hair follicles are busy producing new hair. Your hair can stay in this phase for several years, which is why some people have longer hair than others. About 80-90% of your hair is usually in this phase at any given time.
- Catagen Phase (Transitional Phase): After the anagen phase, your hair enters a transitional phase that lasts for a few weeks. During this time, the hair follicle shrinks, and the hair stops growing. This phase is like a short break before the next growth phase begins.
- Telogen Phase (Resting Phase): In this phase, your hair takes a well-deserved rest. It stays in the follicle but doesn't grow anymore. After a few months, the old hair falls out to make way for new hair during the next anagen phase. Around 10-15% of your hair is in the telogen phase at any given time.
Hair Texture and Curl Pattern
Understanding Hair Texture:
- Straight Hair: Smooth texture, round shaft, easy oil flow for moisture and sleek appearance.
- Wavy Hair: Falls between straight and curly, with gentle waves or loose curls, adding volume and texture; slightly oval-shaped shaft contributes to the pattern.
- Curly Hair: Forms tight curls or coils, bouncy and textured look; often elliptical or flat shaft, prone to dryness but can retain moisture effectively.
Hair Colour Genetics
Hair colour is determined by pigments called melanin, which are produced by cells called melanocytes in the hair follicles. There are two main types of melanin that contribute to hair colour:
- Eumelanin: This pigment comes in two forms—black/brown (producing darker hair colours) and yellow/red (contributing to lighter hair colours).
- Pheomelanin: This pigment adds red and yellow tones to hair, creating shades like strawberry blonde or copper.
Factors Affecting Hair Growth
Genetics
Your genetic makeup plays a significant role in determining your hair growth rate, thickness, and pattern. Traits inherited from your parents can influence how quickly your hair grows and its overall quality.
Hormonal Changes
Hormones have a profound impact on hair growth. Changes in hormone levels, such as during puberty, pregnancy, menopause, or hormonal disorders, can affect the hair growth cycle. For example, increased levels of androgens (male hormones) can lead to excessive hair growth in certain areas (hirsutism) or hair loss (androgenetic alopecia).
Age
Ageing can affect hair growth, with hair typically growing slower and becoming thinner as you get older. This is due to changes in hormone levels, decreased blood flow to the scalp, and reduced activity of hair follicles over time.
Nutritional Factors
A balanced diet rich in essential nutrients like vitamins (especially biotin, vitamin D, and vitamin E), minerals (such as iron and zinc), and protein is crucial for healthy hair growth. Nutritional deficiencies can hinder hair growth and lead to hair thinning or loss.
Stress and Lifestyle
Stress, both physical and emotional, can disrupt the hair growth cycle and contribute to hair loss. Adopting a healthy lifestyle with regular exercise, adequate sleep, and stress management techniques can support optimal hair growth.
Medical Conditions and Medications
Certain medical conditions, such as thyroid disorders, autoimmune diseases, and scalp infections, can impact hair growth. Additionally, medications like chemotherapy drugs, hormonal medications, and some antidepressants may cause temporary or permanent hair loss.
Scalp Health and Care Practices
Maintaining a healthy scalp environment is essential for promoting hair growth. Regular washing, gentle scalp massage to improve circulation, and using suitable hair care products can support a healthy scalp and hair growth.
Environmental Factors
Environmental factors such as exposure to harsh chemicals, pollutants, UV radiation, and extreme weather conditions can damage the hair and scalp, leading to hair thinning or breakage. Protecting your hair from environmental stressors can help maintain healthy growth.
Effects of Hormones on Hair
Androgens and Hair Growth
Androgens are a group of hormones, including testosterone and dihydrotestosterone (DHT), that have a significant impact on hair growth. While androgens stimulate hair growth on the body, they can also affect hair growth on the scalp. In individuals with androgenetic alopecia (male or female pattern baldness), hair follicles become sensitive to DHT over time. This sensitivity can lead to miniaturization of hair follicles, resulting in thinner and shorter hair strands.
Estrogens and Hair Health
Estrogens, primarily produced in higher levels in females, contribute to maintaining healthy hair. During pregnancy, increased estrogen levels can prolong the anagen (growth) phase of the hair growth cycle, leading to thicker, fuller hair. However, hormonal changes post-pregnancy or during menopause, when estrogen levels decline, can result in hair shedding or thinning in some individuals.
Thyroid Hormones and Hair Growth
Thyroid hormones, including thyroxine (T4) and triiodothyronine (T3), play a crucial role in regulating metabolism and energy production. Imbalances in thyroid hormones, such as hypothyroidism (low thyroid function) or hyperthyroidism (excessive thyroid activity), can impact hair growth and texture. Hypothyroidism may lead to dry, brittle hair and hair loss, while hyperthyroidism can cause rapid hair growth and thinning.
Cortisol and Stress-Related Hair Changes
Cortisol, often referred to as the stress hormone, can influence hair health. Chronic stress and elevated cortisol levels may disrupt the hair growth cycle, leading to increased shedding or hair loss. Stress-related hair conditions, such as telogen effluvium, can result in temporary hair thinning due to a shift in hair follicles from the growing phase to the resting phas
Hormonal Changes During Puberty and Aging
Puberty is a time of hormonal changes, with increased androgen production contributing to the development of secondary sexual characteristics, including changes in body hair growth patterns. As individuals age, hormonal fluctuations, especially during menopause in females, can affect hair texture, thickness, and growth patterns. Declining estrogen levels may contribute to hair thinning or loss in some cases.
