Zinc is the second most abundant trace metal in humans after iron and is required for the function of over 300 enzymes.  In almost every human cell and tissue, zinc is vital to several biological functions, including hormone production, cellular growth and digestion.  Like other biomarkers, including hormones, free radicals, antioxidants and macro-or micronutrients, zinc can be measured with blood tests. Nutrient-poor food such as cereals and other processed foods that are consumed on a regular basis in the UK is an accepted contributor to micronutrient deficiency within the population.

Zinc is tightly regulated in the body, and concentration in the blood changes only slightly in cases of low zinc in the body. The triage theory predicts that essential proteins can resist low zinc levels for longer than non-essential proteins. The proteins that will not be protected are those required for sexual reproduction or any type of growth (including hair growth). The prioritised protection of some proteins, in comparison with others, explains the ability of the body to maintain blood zinc levels when zinc availability is low.

According to the World Health Organisation, phytates can lower zinc absorption to as little as 15%, a high phytate diet is a risk factor for zinc deficiency.  Other risk factors for low zinc include the consumption of alcohol, smoking, high-fat diets and excessive exercise.  In clinical practice, low zinc contributes to malnutrition, malabsorption, and chronic inflammation. Zinc absorption is influenced by phytate intake; this should be considered when evaluating zinc intake.  Phytates are found in grains, legumes, nuts and seeds.  Zinc deprivation equates to a sub-optimal intake of 3-5 grams per day.

The skin and hair are primarily affected by zinc deficiency or sub-optimal levels in the body.  Zinc supplementation at approximately 100mg (35 mg elemental) has been shown to support recovery from the most common causes of hair loss: telogen effluvium, alopecia areata and androgenic alopecia.