Zinc is a trace mineral involved in over 300 enzymatic reactions in the body. It supports immune defence, wound healing, skin integrity, protein synthesis, and the senses of taste and smell. Unlike iron or calcium, the body does not store zinc in large reserves, so ongoing dietary intake is needed to maintain adequate levels.
Serum zinc is the standard first-line test for assessing zinc status. It measures the amount of zinc circulating in blood plasma at the time of the draw. While it is a useful screening tool, serum zinc can fluctuate with food intake, time of day, and acute illness or inflammation. A morning fasting sample gives the most consistent result.
Deficiency is more common than many people realise, particularly in those following plant-based or restrictive diets, people with coeliac disease or Crohn's disease, older adults, and pregnant or breastfeeding women. Phytates in grains and legumes reduce zinc absorption, which is why plant-based eaters may need higher dietary intake to maintain adequate levels.
Common signs of low zinc include frequent infections, slow wound healing, skin conditions such as acne or dermatitis, hair thinning, and changes in taste or smell. These symptoms overlap with many other conditions, making a blood test a practical way to confirm whether zinc is a contributing factor.
If your serum zinc result comes back normal but symptoms persist, your practitioner may recommend a red blood cell zinc test, which measures zinc stored inside cells and provides a more detailed picture of intracellular zinc status over time.
Suited to people experiencing frequent infections, slow wound healing, skin conditions, hair thinning, loss of taste or smell, or those with dietary patterns or health conditions that increase the risk of zinc deficiency. Also relevant for people following plant-based diets, with coeliac disease, Crohn's disease, or who have had gastrointestinal surgery.
