Deficiency symptoms

Short answer

Symptoms of zinc deficiency vary by age and also occur with other causes; a diagnosis cannot be made from a single symptom. The serum zinc test is used, but it is affected by factors such as the time of blood draw, infection and albumin. Being in a risk group (bowel disease, vegan diet, alcohol use disorder, pregnancy) calls for evaluation; this does not automatically mean supplements. ^{[1] [2]}

What are the symptoms of zinc deficiency?

Because zinc has many functions, its deficiency affects many tissues and systems: the skin, bone, digestive, reproductive, nervous and immune systems. Symptoms look different by age. ^[1]

This table shows which findings are reported when deficiency is present; it does not show the reverse. Hair loss, taste change or delayed wound healing can be due to many other causes. Their presence does not prove zinc deficiency and is not a sufficient reason to start supplements on one’s own. ^[1]

Who is at high risk of zinc deficiency?

The risk groups described by NIH are below. What they all share is reduced intake, impaired absorption or increased loss. ^[1]

Digestive diseases and bariatric surgery. In people with inflammatory bowel disease (ulcerative colitis, Crohn’s) and after bariatric surgery that removes part of the digestive tract, zinc inadequacy is common because of insufficient intake, reduced absorption and urinary loss due to inflammation. NIH reports that zinc deficiency has been reported in about 15–40% of people with inflammatory bowel disease, in both active disease and remission. About half of newly diagnosed celiac patients are at high risk of zinc inadequacy or deficiency; deficiency can persist despite a gluten-free diet. ^[1]

Vegetarians and vegans. Because they eat more legumes and whole grains, their phytate intake is high; phytate binds zinc and reduces its absorption. Meat, on the other hand, is rich in absorbable zinc. For this reason, zinc intake and serum zinc are generally lower in vegetarians and vegans. It is noted that methods such as soaking legumes, grains and seeds in water for several hours before cooking, and the organic acids in fermented foods, can increase absorption. ^[1]

Pregnancy and breastfeeding. Zinc requirements increase in pregnancy: the US reference on which NIH relies provides for 3 mg more per day in pregnant women than in non-pregnant women, and 4 mg more in breastfeeding. In US data, 11% of pregnant women are below the estimated average requirement for total zinc intake. ^[1]

Exclusively breastfed infants older than 6 months. The zinc in breast milk falls rapidly after the first month; by the ninth month it drops by about 75%. For this reason, after 6 months breast milk alone does not meet an infant’s zinc requirement and suitable complementary foods are needed. ^[1]

Children with sickle cell anemia. There is a risk of zinc inadequacy that may be due to the chelation therapy used for iron accumulation; in children with low zinc levels, growth delay in height and weight, pain crises and a higher risk of hospitalization have been reported. ^[1]

People with alcohol use disorder. Low zinc status has been observed in 30–50% of these people; alcohol reduces intestinal absorption and increases urinary loss, and dietary variety may also be limited. ^[1]

Older adults. NIH notes that in the US some age groups, especially older adults, may have borderline intake. Delayed wound healing and cognitive changes are listed among the symptoms of deficiency in older adults. ^[1]

Being in a group is not a diagnosis on its own. Evaluation comes up in these groups; the physician decides which measure is needed.

How common is zinc deficiency worldwide and in Türkiye?

Based on the amount of absorbable zinc in national food supplies and data on childhood stunting, Wessells and Brown estimated that about 17.3% of the world’s population is at risk of inadequate zinc intake. Estimates were highest in Sub-Saharan Africa and South Asia. This is a modeling study; it is not a blood level measurement, and the authors note that direct biochemical measurement is needed for a definitive diagnosis. ^[4]

In 2011–2014 NHANES data in the US, the proportion below the serum zinc threshold was 3.8% in children under 10, 8.6% in males aged 10 and over, and 8.2% in females. ^[3] These rates belong to the US and cannot be transferred to Türkiye; no national rate based on blood measurement is given here for Türkiye.

How is zinc deficiency detected, and is a blood test enough?

In clinical practice, serum or plasma zinc is mostly used. According to NIH, serum or plasma zinc in healthy people is in the range of 80–120 µg/dL (12–18 µmol/L), and values below 70 µg/dL in women and 74 µg/dL in men indicate inadequate zinc status. However, the same source states clearly that serum and plasma measurements have important limitations. ^[1]

These 70 and 74 µg/dL thresholds are for samples taken in the morning fasting. The cutoffs reported by the BOND panel vary with the blood-draw condition: morning non-fasting 66 µg/dL in women and 70 µg/dL in men; afternoon 59 µg/dL in women and 61 µg/dL in men; in children under 10, 65 µg/dL morning non-fasting and 57 µg/dL afternoon. The time at which a sample is taken in the same person can change whether the result falls below or above the threshold. ^[2]

Why is the serum zinc test an imperfect measure?

• It does not always match the amount taken. The BOND zinc expert panel reports that blood zinc responds less to additional zinc from food than to a supplement taken between meals, that there is large variability between people, and that it is affected by the last meal, time of day, infection, some medications and hormones. ^[2]
• Time of day. In an analysis of 4,347 participants in the US, serum zinc was about 9.7 µg/dL lower in samples taken in the afternoon and about 15.3 µg/dL lower in samples taken in the evening than in samples taken in the morning (regression coefficients). ^[3]
• Other conditions. Low albumin (OR 11.2), anemia in women (OR 3.4) and pregnancy (OR 9.6) increased the likelihood of serum zinc falling below the cutoff. In the same analysis, zinc taken from food and supplements did not significantly affect serum zinc. ^[3]
• Infection and inflammation. NIH notes that serum zinc also changes with infection, steroid hormone changes, and muscle breakdown in illness or weight loss. ^[1]

The BOND panel recommends three measures for assessing zinc status: dietary zinc intake, plasma zinc, and height-for-age in growing infants and children. Hair, urine and nail zinc are not recommended because there are insufficient data. Functional indicators other than growth also lack enough information for routine use. ^[2]

In practice, risk factors, symptoms and intake are evaluated together rather than a single low or normal result. NIH also notes that clinicians consider risk factors such as inadequate calorie intake, chronic alcohol use and malabsorption, together with symptoms such as growth delay. ^[1]

What matters when deficiency is corrected?

The cause of the deficiency matters: inadequate intake, malabsorptive disease, loss or medication effect require different approaches. The supplement amount and duration for a person found to be deficient are determined by the physician. NIH’s upper limit values do not cover zinc used for medical treatment under physician monitoring; however, since long-term high amounts can lead to copper deficiency, monitoring is needed. ^[1]

Thiazide diuretics increase the urinary excretion of zinc and can lower serum zinc. In people who use these medications long term and have complaints, this is taken into account in the evaluation. ^[1]

When should a physician be consulted?

People with prolonged diarrhea, unexplained weight loss, growth delay in children, markedly delayed wound healing, loss of taste or smell, recurrent infections, or complaints while in one of the risk groups listed above should consult a health professional. Most of these symptoms can point to diseases unrelated to zinc; for this reason, the cause should be investigated first.

This guide does not recommend a personal dose. When zinc supplements are considered, the medications and other supplements used are evaluated together.

Detailed guideZinc: overview, deficiency and upper limit→ Detailed guideWhich foods contain zinc?→ Detailed guideZinc benefits: which effects are supported?→ Detailed guideWhen should zinc be taken?→