GROWTH HORMONE, GROWTH FACTORS AND THE HAIR GROWTH CYCLE

The normal hair growth cycle is dependent on several intrinsic factors.  Hair remains in growing phase (anagen) or regresses into resting phase (telogen) when signalled to do so by growth factors like insulin-like growth factor.

Growth factors are dependent on growth hormone, thus for hair to remain in growing phase for the optimal period, we require enough growth hormone to increase the growth factors that stimulate hair growth.

GROWTH HORMONE AND METABOLISM

Growth hormone (also known as somatotropin) is a peptide hormone produced in the pituitary gland and released into the blood for circulation around the body.  Growth hormone is necessary for the reproduction of cells and stimulation of growth processes in the body.  When levels of growth hormone are low, a person may experience thinning hair and hair loss.

Secretion of growth hormone from the hypothalamus is dependent on adequate nutrition, dehydroepiandrosterone (DHEA), vigorous exercise, sleeping patterns, niacin (vitamin B3) and hormones such as androgen and estrogen.  Growth hormone is inhibited by free fatty acids, stress, dihydrotestosterone (DHT), high blood sugar and cortisol.

Growth hormone also supports the action of vitamin D in that it aids calcium retention, increases the synthesis of proteins, maintains normal function of the immune system and supports the conversion of thyroid hormone for increased metabolism.

Growth hormone cannot penetrate cells, they rely on binding to receptors to activate certain pathways.  One pathway that growth hormone stimulates is the JAK-STAT signalling pathway.

Disturbances in JAK signalling is linked to hair loss conditions such as alopecia areata.  Growth hormone stimulates insulin-like growth factor stimulation in the liver.  Insulin-like growth factor is essential for the continuation of a normal hair growth cycle and the prevention of thinning hair.

Growth hormone and hair loss
Growth hormone diagram

THE EFFECT OF INSULIN-LIKE GROWTH FACTOR ON HAIR GROWTH

Insulin-like growth factor is expressed in the dermal papilla, at the base of the hair shaft.  Insulin-like growth factor affects follicular differentiation, follicle remodelling and initiation of the hair growth cycle.  In the presence of Insulin-like growth factor: blood vessels dilate allowing a higher level of nutrients to reach the hair follicle, sebaceous gland function is regulated and production of keratin within keratin cells is increased.

Insulin-like growth factor also supports the uptake of glucose into keratin cells and increases collagen gene expression to support the network surrounding the hair follicle niche.

IGF-1 and hair loss
IGF-1 and hair loss

INSULIN-LIKE GROWTH FACTOR DEFICIENCY AND OVERALL HEALTH

Insulin-like growth factor is important for hair health, but it also has many other roles in the body that indirectly contribute to hair health.  Evidence consistently links insulin-like growth factor deficiency with impaired lipid profile, insulin resistance, high glucose levels, obesity, malabsorption and cardiovascular disease.

Adequate levels of insulin-like growth factor are crucial for the metabolism of carbohydrates and fats.  It is also necessary for the uptake of amino acids in the intestines.  Low levels of insulin-like growth factor have a high association with abdominal obesity and an accumulation of evidence is shows increasing insulin-like growth factor is crucial in maintaining metabolic health and normal immune function.

6 WAYS TO INCREASE GROWTH HORMONE AND INSULIN-LIKE GROWTH FACTOR

Levels growth hormone and insulin-like growth factor are sensitive to many external influences.  To increase levels of growth hormone and insulin-like growth factor for healthier hair there are several lifestyle improvements that will help:

Get a blood test – Check if you may have an iron deficiency, low B12 or low levels of vitamin D.  Look at haemoglobin levels, folate and check your thyroid function.  Even if your blood test is ‘normal’ get it looked over by a hair loss expert who can pinpoint inadequacies in your nutritional profile.

Avoid refined foods that will spike your blood sugar – High levels of blood sugar will inhibit growth hormone.  Concentrate on high quality protein, fresh fruit and non-starchy vegetables for stable growth hormone levels.

Eat a high zinc diet or take a supplement – A high zinc diet or supplementing over 15 mg of zing per day supports growth hormone production.  Zinc lowers inflammation and indirectly increases vitamin D, preventing growth hormone inhibition.

Get pumped up – Exercise provides a strong physiological stimulus for the secretion of growth hormone.  Cardiovascular and strength exercises both acutely increase growth hormone secretion.

Sleep well and sleep deep – Growth hormone peaks when we sleep and getting an adequate amount of deep sleep is one of the best strategies for increasing growth hormone in the long term.

Supplement with sulphur – Low levels of sulphur containing amino acids (cysteine and methionine) inhibit growth hormone signalling.

THE FINAL WORD

Hormones have an intimate relationship with the hair follicle and the initiation and duration of the hair cycle.  Growth hormone and insulin-like growth factor are powerful mediators of hair growth.  With the right lifestyle changes you can naturally increase levels of growth hormone and insulin-like growth factor to encourage the growth of stronger and thicker hair.