Poor zinc absorption is caused by dietary inhibitors like phytates (in whole grains, beans) and high iron/calcium, gastrointestinal diseases (Crohn's, celiac), chronic illnesses (diabetes, kidney disease), alcoholism, certain medications (diuretics, proton pump inhibitors), and malnutrition, all reducing the zinc your body can utilize from food.
Zinc requires regular dietary intake. Deficiency is common in developing countries and high-risk groups, such as malnourished, alcoholics, and those with malabsorption syndromes. Phytates in grains and legumes inhibit zinc absorption.
What Blocks Zinc Absorption?
Adverse effects of high zinc intake include nausea, vomiting, loss of appetite, abdominal cramps, diarrhea, and headaches. Intakes of 150–450 mg of zinc per day have been associated with such chronic effects as low copper status, altered iron function and reduced immune function.
Side effects that you should report to your care team as soon as possible: Allergic reactions—skin rash, itching, hives, swelling of the face, lips, tongue, or throat.
The clinical manifestations of zinc deficiency are similar regardless of the cause. Erythematous, scaly, thin papules and coalescing plaques are distributed predominantly in acral locations, on the face and extremities, and, most prominently, around the oral, orbital, genital, and anal orfices.
Taking zinc supplements by mouth long-term and in high doses can lead to copper deficiency. People with low copper levels might have brain and nervous system issues. Those issues may include numbness and weakness in the arms and legs.
People who consume too much zinc may have nausea, vomiting, and diarrhea. Inhaling zinc oxide fumes can cause rapid breathing, sweating, fever, muscle aches, and a metallic taste in the mouth—a disorder called metal fume fever.
As the brain regenerates during sleep, a zinc deficiency can lead to a decrease in sleep quality. Like magnesium, zinc contributes to the transformation of tryptophan into serotonin and then into melatonin, the sleep hormone.
Given that zinc aids in the rapid division and proliferation of hair cells, it, therefore, promotes the growth of strong and resilient hair strands and contributes to overall hair health. It provides the building blocks needed for healthy follicle development and helps to fortify the foundation from which hair grows.
Zinc deficiency can result from many conditions, including diabetes mellitus, alcohol use disorder, and use of diuretics. People lose their appetite and hair and may feel sluggish and lose their sense of taste. Doctors measure the zinc level in blood and urine, but these tests may not accurately determine zinc status.
As is the case with iron, avoid taking zinc with calcium, magnesium, or copper. Take zinc 2–3 hours apart from these minerals as they reduce zinc absorption in the intestines. Do not take zinc with tetracycline or ciprofloxacin antibiotics. These also inhibit zinc absorption.
Dietary protein levels positively correlate with zinc uptake [77,154]. Human zinc absorption is substantially higher in the presence of protein from animal sources than plant-based protein [181] and the addition of animal protein to vegetable-based food significantly improved its zinc bioavailability in vivo [182].
Much of the zinc consumed in the diet is not absorbed. A diet high in fiber and phytate (present in whole-grain bread, bran, beans, soybeans, other legumes, and nuts) reduces zinc absorption.
Conditions that may cause zinc deficiency include:
Zinc deficiency can lead to depression, increased anxiety, irritability, emotional instability, and induced deficits in social behavior. Clinical studies have shown that low levels of zinc intake contributes to the symptoms of depression and patients suffering from depression have a lower serum zinc level.
Because zinc deficiency can lead to appetite changes, unexplained weight loss can be a symptom of zinc deficiency. This can also lead to mood changes, irritability, or depression.
Research indicates that magnesium helps regulate the parasympathetic nervous system, promoting feelings of calm and relaxation. Additionally, studies involving zinc supplementation in humans and animals suggest that higher blood zinc concentrations correlate with better sleep quality.
Zinc, which is an essential nutrient found in various plants, animal foods, and supplements, has been shown to be a potential nutrient in anxiety reduction by acting on γ-aminobutyric acid (GABA), glutamatergic, serotonergic, neurogenesis, and immune systems. It can also influence important receptors, such as GPR39.
If you are taking a supplement, avoid exceeding the upper safety limit of 40 mg per day. Risks of too much zinc include stomach pain, headaches, cramps, nausea, vomiting, and diarrhea.
While zinc is an essential trace element required for various physiological processes in the body, as mentioned above, excessive amounts of zinc intake can lead to zinc overdose or toxicity. This typically occurs from supplements or denture adhesive creams [51].
Although rare, some individuals, such as those with a history of stomach surgery or prolonged intravenous nutrition, may be at an increased risk for copper deficiency. If you fall into this category, you should avoid taking a zinc supplement because it could decrease your copper levels even more.
The food highest in zinc is oysters, which contain significantly more zinc per serving than any other food, followed by other shellfish like crab and lobster, and then red meats such as beef, lamb, and pork. Other excellent sources include poultry, nuts (cashews, pumpkin seeds), legumes (lentils, chickpeas), dairy products, eggs, and fortified cereals, though zinc from plant sources is less easily absorbed.
Those who take high doses of zinc supplements can experience a lack of anagen development, which causes hair loss, but at the same time, one form of zinc treatment can actually encourage hair growth.
Zinc bisglycinate and zinc picolinate are considered to have excellent bioavailability. Otherwise, organic zinc compounds such as zinc citrate or zinc gluconate are generally better absorbed than inorganic variants such as zinc oxide or zinc sulphate.