IRON DEFICIENCY VS IRON OVERLOAD
Iron is highly reactive and leads to oxidative damage in the body. Whilst iron is normally bound by ferritin to prevent this highly reactive element causing damage to the body, reactions with oxygen can lead to the relaease of iron into the tissues of the body and cell membranes. These factors combined can lead to a gradual loss of hair.
Most of the damage caused by hemochromatosis is thought to occur in the liver. Appropiate liver function is required for healthy hair growth and once liver function starts to decline, there will inevitably be a loss of hair.
Iron overload affects hair growth directly in a number of ways:
Itchy scalp – Pruritus or itch is defined as an unpleasant sensation of the skin that provokes the urge to scratch. It is a characteristic feature of many systemic diseases. Pruritus may be present in patients with hemochromatosis where the levels of iron in blood and tissues are elevated  or when the skin is dehydrated. Persistent scratching can break the skin or remove growing tissue.
Epidermal dehydration – As well as a lowered basal metabolic rate iron overload can also lead to dry, thickened skin. For normal hair growth, the hair follicle must be housed in a suitably hydrated epidermis. Water is essential for the normal functioning of the skin, especially its outer layer, the stratum corneum. Loss of water from the skin is normally carefully regulated, a function dependent on the complex nature of the stratum corneum (outermost layer of the epidermis). The retention of water in the stratum corneum is dependent on natural moisturising factors and intercellular lipids orderly arranged to form a barrier to prevent epidermal water loss. The water content of the stratum corneum is necessary for proper keratin cell development within the hair fibre.
Accumulation of iron in the sebaceous glands – When iron accumulates in a gland or organ it can have an inhibitory effect. When there are high levels of iron in sebaceous glands in can lead to a reduction of function.
The sebaceous glands are microscopic glands that secrete an oily matter onto the skin. They help with the removal of old skin cells on the scalp, they keep the scalp hydrated by providing a waterproof top layer on the stratum corneum and lubricates the hair fibre. The oily matter secreted onto the scalp is made up of wax esters and squalene and act as a barrier to microbes that might penetrated the skin and the hair follicle. The sebaceous glands also supply vitamin E to the scalp, clinical trials have shown this fatty vitamin is essential for hair growth.
Reduced blood circulation – Adequate blood flow is essential for the delivery of nutrients to the hair follicle. The keratin cells that make up the hair fibre are particularly dependant on blood flow the hyperactive hair follicle stem cells that drive hair growth will gradually slow their activity as blood flow declines.
Increased oxidative damage – Unbound iron is a highly reactive element and high levels of iron will lead to higher levels of oxidative damage to all tissue. This damage can occur to DNA, lipids and proteins. DNA provides the information that tells the cell when and how to produce keratin, if DNA is damaged this may lessen or completely prevent the manufacture of keratin within the hair fibre. Oxidative damage can also occur to the growing hair fibre that is still within the epidermal layer.
Decreased collagen production – Iron overload tends to reduce collagen production by interrupting the synthesis of proteoglycans. Type II collagen increases after iron depletion therapy in patients with hemochromatosis .