Zinc deficiency stems from a combination of not getting enough zinc from food, not absorbing it well, or losing too much of it through urine or the gut. Roughly 20% of the global population is estimated to be zinc deficient, and the causes range from everyday dietary patterns to chronic diseases, medications, and even the quality of the soil where food is grown. Most cases involve more than one contributing factor at the same time.
Low Dietary Intake
The most straightforward cause is simply not eating enough zinc-rich food. Adult men need about 11 mg of zinc per day, while adult women need 8 mg. During pregnancy that jumps to 11 mg, and during breastfeeding it rises to 12 mg. Oysters, red meat, poultry, and crab are among the richest sources. Beans, nuts, whole grains, and fortified cereals contain zinc too, but your body absorbs far less of it from those foods.
That absorption gap matters a lot if you eat a vegetarian or vegan diet. Plant-based foods are high in compounds called phytates, which bind tightly to zinc in the digestive tract and prevent your body from taking it in. When you remove meat and rely more heavily on legumes and whole grains, zinc absorption drops measurably compared to a diet that includes animal protein. This doesn’t mean plant-based eaters will inevitably become deficient, but they need to be more intentional about their intake, through strategies like soaking beans and grains before cooking, which reduces phytate content.
Gut Conditions That Block Absorption
Even if your diet provides plenty of zinc, certain digestive diseases can prevent your small intestine from absorbing it. Celiac disease and Crohn’s disease are two of the most significant culprits.
In celiac disease, the immune reaction triggered by gluten destroys the tiny finger-like projections (villi) lining the small intestine. These villi are where zinc absorption happens. The more damage there is, the worse the deficiency: one study found that 60% of patients with partial villous damage were zinc deficient, 80% with more extensive damage, and 92% of those with total villous destruction. The relationship may also run in the other direction. When zinc levels drop in the intestinal lining, it can activate an enzyme that amplifies the immune response to gluten, potentially worsening the disease itself.
Crohn’s disease creates a similar problem through chronic inflammation. Even when the main absorptive section of the small intestine appears visually normal, zinc uptake can still be impaired. The inflammatory chemicals present in Crohn’s damage the tight seals between intestinal cells, making the gut lining leaky. Low zinc then makes this worse, because zinc is essential for maintaining those seals. People with Crohn’s also often follow restricted diets to manage symptoms, further limiting their zinc intake.
Chronic Alcohol Use
Heavy, long-term drinking attacks zinc status from multiple directions at once. Alcohol increases the amount of zinc your kidneys flush out in urine, and the effect worsens as liver damage progresses. People with more severe alcoholic liver disease lose the most zinc through urine. At the same time, alcohol impairs the intestine’s ability to absorb zinc and disrupts the transporter proteins responsible for moving zinc into and out of cells. On top of all that, heavy drinkers often eat poorly, so their dietary intake tends to be low to begin with. The combination of poor intake, reduced absorption, and increased excretion makes zinc deficiency extremely common in people with alcohol use disorder.
Medications That Increase Zinc Loss
Certain widely prescribed medications push zinc out of the body faster than normal. Thiazide diuretics, commonly used to treat high blood pressure, are a well-documented example. These drugs work in a specific part of the kidney’s filtration system and, as a side effect, significantly increase the amount of zinc excreted in urine. The risk of deficiency is especially high when someone taking these medications also has another risk factor like heavy alcohol use, kidney problems, or pregnancy.
Interestingly, not all diuretics have this effect. Some potassium-sparing diuretics actually reduce urinary zinc loss. The type of diuretic matters, which is why zinc status can vary considerably among people on different blood pressure medications.
Pregnancy and Breastfeeding
Pregnancy increases zinc demand because the mineral is critical for cell division and fetal development. The recommended intake rises by about 38% compared to non-pregnant women. Breastfeeding pushes it even higher, to 12 mg per day, since zinc passes into breast milk. Women who enter pregnancy with borderline zinc levels or who have morning sickness severe enough to limit food intake are at particular risk. This is compounded if they’re also taking prenatal supplements that contain high doses of iron, which can compete with zinc for absorption.
Zinc-Depleted Soils
The zinc content of food depends partly on the zinc content of the soil it was grown in, and not all soils are equal. In India, roughly 38 to 39% of agricultural soils are considered zinc deficient for crop production. Research in Malawi found that maize grown in one soil type contained 30% more zinc than maize grown in other soils nearby, and that difference directly affected the dietary zinc supply of farming communities in those areas. Soil pH, organic carbon levels, and soil type all influence how much zinc a crop can pull from the ground. This means people who depend on locally grown staple grains in zinc-poor regions can be deficient even if they eat adequate quantities of food.
A Rare Genetic Cause
A small number of people are born with a condition called acrodermatitis enteropathica, caused by mutations in the gene that produces a zinc transporter protein in the small intestine. This transporter sits on the surface of intestinal cells and is responsible for pulling zinc from digested food into the body. When it’s missing or dysfunctional, zinc absorption essentially fails regardless of diet. The condition typically appears in infancy and produces a recognizable triad of symptoms: a distinctive rash around the mouth and on the hands and feet, hair loss, and chronic diarrhea. Genetic testing confirms the diagnosis. Lifelong zinc supplementation resolves the symptoms, but without it the deficiency can be severe.
How Multiple Causes Overlap
In practice, zinc deficiency rarely has a single, clean explanation. A person with Crohn’s disease who avoids many foods and takes a diuretic for blood pressure is being hit from three directions simultaneously. An older adult eating a limited diet on a fixed income who also drinks heavily faces the same kind of overlap. This stacking effect is why certain populations, particularly older adults, people with chronic digestive conditions, heavy drinkers, and those eating plant-based diets in regions with zinc-poor soil, carry disproportionately high rates of deficiency. Recognizing the cause (or causes) is the first step toward correcting it, because the solution looks different depending on whether the problem is intake, absorption, or loss.