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Measuring zinc and magnesium levels

A Mineral analyses are usually requested by therapists for clients with chronic fatigue, irritable bowel, osteoporosis, PMS, ADHD, autism or migraine (for magnesium), or poor wound healing, skin disorders, or perceived compromised immunity (for zinc).

Magnesium plays a key role in cellular metabolism, cardiac contractility, skeletal muscle excitability and neuromuscular transmission. Magnesium deficiency is implicated in insulin resistance and hypertension. It is essential for PTH production and vitamin D biosynthesis.

Plasma zinc is more useful than serum zinc to identify marked deficiency, but is insensitive to moderate deficit. Zinc is primarily albumin-bound, so circulating levels are lower if CRP or other inflammatory markers are raised. Levels are lower in OC users but this has no clinical significance. The use of a pressure cuff while sampling can falsely elevate levels.

Zinc deficiency is rarely due to dietary lack, but rather to clinical conditions such as chronic liver or renal disease, sickle cell disease, malabsorption (secondary to small bowel problems, acrodermatitis enteropathica, or high intake of phytate-rich unleavened wholegrain breads), which can all compromise zinc status.

One in 10 of the population have potentially deficient diets, although deficiency is more associated with CVS, CNS and chronic malabsorption problems (Crohn's disease, pancreatic insufficiency, high output ileostomy or prolonged diarrhoea).

Catherine Collins is

chief dietitian at

St George's Hospital,


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