Hormones are chemical messengers secreted by the glands of the endocrine system (the pituitary, pineal, thyroid and parathyroid, thymus, adrenal, pancreas, ovaries and testes) directly into the bloodstream. The endocrine system regulates the functioning of every tissue, organ and gland in the body and affects the way we think and feel. The master gland, the pituitary, is situated in the brain and is linked to the hypothalamus, which is the control centre for the autonomic nervous system.

Nerve impulses or chemical changes in the blood trigger the release of a cascade of hormones that carry messages to target cells throughout the body. This process is controlled by complicated feedback mechanisms that continually monitor and adjust levels of circulating hormones.

Hormones influence our physical, emotional and psychological health and vice versa. Major life events, such as serious illness, pregnancy and childbirth, divorce, a change of job or financial status, death of a loved one or retirement, often precipitate hormone imbalances. The mental and physical stresses caused by such events, as well as the inevitable aging process itself, can result in the body's sensitive regulating mechanisms being unable to maintain equilibrium.

There are two categories of hormone: those responsible for the building up of cellular structures (anabolic) and others responsible for the breaking down of matter (catabolic). Thereby, hormones control the body's metabolism - the vital functions of continual tissue turnover, energy production and regeneration.

To maintain good health the body must always strive to keep a balance between anabolic and catabolic processes. If there is too much or too little of one type of hormone, production of others will be adjusted to compensate. An over or under supply in any one part of the endocrine system has a knock-on effect, causing a chain reaction. This may become apparent in numerous ways as is evidenced by the diversity of health problems associated with thyroid disorders, adrenal fatigue and insufficiencies in sex hormone production.

Consistently high insulin output, which occurs in response to excess carbohydrate in the diet, provides a common example of the far-reaching influence of hormonal imbalance. Chronic high insulin levels result in a decrease in other anabolic hormones particularly human growth hormone, controlling growth, maintenance and repair of the body and DHEA – an important precursor from which testosterone, progesterone and estrogen are derived. It also causes an increase in the catabolic hormone cortisol, normally produced in response to emotional and physical stress. This accelerates the aging process and inhibits production of eicosanoids, the short-lived chemical messengers that actually implement the orders from hormones. In turn excess cortisol causes a further decrease in the production of DHEA, low levels of which are linked to impaired immunity, chronic fatigue syndrome, osteoporosis and coronary artery disease.

Clearly, restoring optimal hormone balance is key to the treatment of many health issues and central to the holistic approach of Integrated Medicine.