Zinc: when should you suspect a deficiency, and when are supplements useful?

Zinc: when should you suspect a deficiency, and when are supplements useful?

Zinc plays a role in our immune system, wound healing, skin and sense of taste. Our body needs only small amounts of it. Even so, a deficiency can cause symptoms. When is a blood test useful? And why is simply taking a zinc supplement not always a good idea?

What does zinc do in the body?

Zinc is an essential trace element: we have to get it from our diet. It supports the function of numerous enzymes and the production and repair of cells. Among other things, we need it for normal immune function, wound healing and a good sense of taste. Zinc is also important during growth and development.

Which foods contain zinc?

Zinc is found in meat, shellfish, dairy products and eggs, among others. Legumes, nuts, seeds and wholegrain products also provide zinc.

If you follow a fully plant-based diet, your zinc intake deserves extra attention. Wholegrains, legumes, nuts and seeds in particular also contain phytates, substances that can reduce the absorption of zinc in the gut. Soaking, sprouting or fermenting, as in sourdough bread, lowers the phytate content. This does not mean that vegetarians or vegans automatically have a deficiency. A varied, well-balanced diet remains the starting point.

Which symptoms may point to a deficiency?

A zinc deficiency can show up in different ways, for example:

wounds that heal poorly;

skin inflammation or a rash;

hair loss;

a reduced sense of taste or smell;

persistent diarrhoea;

in children: delayed growth.

None of these symptoms proves a zinc deficiency on its own. Hair loss, skin problems and changes in taste often have other causes. Taking a supplement without looking for the cause can therefore delay the right treatment.

A deficiency becomes more likely when such symptoms occur together with a limited food intake, chronic bowel problems or other risk factors.

Who is at higher risk?

Some people absorb too little zinc or lose more of it. This can happen with malnutrition, a very one-sided diet, chronic excessive alcohol use, or bowel diseases such as coeliac disease and Crohn’s disease. Absorption can also be reduced after certain types of weight-loss surgery. Older people with a poor appetite, people with chronic kidney or liver disease, and people taking certain medicines, such as some diuretics, are also at higher risk.

In these situations, we look not only at possible deficiencies but also at the underlying cause.

When is a blood test useful?

Measuring zinc can help when symptoms and risk factors suggest a deficiency. In someone without symptoms or particular risk factors, it is usually not part of a standard blood test.

Interpreting the result requires care. A low zinc level does not always mean the body is truly deficient. During an infection or inflammation, the concentration in the blood can drop temporarily. A low level of albumin, a protein that carries zinc in the blood, can also affect the result. Conversely, a normal level does not always rule out a mild deficiency.

That is why we assess the zinc level together with your symptoms, diet, medication and, where needed, other blood values such as CRP and albumin. The reference values of the laboratory performing the test are the starting point.

To make the measurement as comparable as possible, blood is preferably taken in the morning on an empty stomach, following the instructions of your doctor or the laboratory. Please also mention any supplements you take.

Are zinc supplements useful?

If a deficiency has been confirmed or is strongly suspected, a supplement may be appropriate. The dose and duration of treatment depend on the cause and severity of the deficiency. A follow-up check is sometimes needed.

The fact that zinc is essential for the immune system does not mean that everyone needs extra zinc. Taking high doses for a long time can be harmful. Too much zinc can cause stomach and bowel complaints and interfere with the absorption of copper. A copper deficiency can in turn lead to anaemia and nerve problems.

Zinc can also reduce the absorption of some antibiotics. Do not take a zinc supplement at the same time as an antibiotic, and ask your doctor or pharmacist how far apart to take them.

The European upper limit for long-term total intake in adults is 25 mg of zinc per day, from food and supplements combined. This is a safety limit, not a recommended daily dose. If you have a deficiency, a doctor may prescribe a different dose for a limited period.

Discuss persistent symptoms with your GP

Do you have persistent changes in taste, slow-healing wounds, skin problems or hair loss? At HAP.GENT, we will look at the possible causes and whether a targeted blood test makes sense.

Please also bring up any dietary supplements you take. That way, we can check whether you are getting enough zinc and avoid different products together adding up to too high a dose.