The immune supplement that could weaken the body: Zinc enjoys an almost perfect image. It appears in lozenges, winter supplements, multivitamins, skin products and products promising "natural strengthening" of the immune system. For many, taking zinc at the start of every cold has become a reflex. But as in many cases in the world of dietary supplements, the dosage and duration of use are what separate reasonable nutritional supplementation from medical risk.
Zinc is a trace mineral, meaning the body needs it in small amounts only. It participates in the activity of hundreds of enzymes, is important for building proteins and nucleic acids, is involved in wound healing, the function of taste and smell, and the proper activity of immune cells. Zinc deficiency can indeed harm immune defense, cause wounds that do not heal well, hair loss, loss of appetite and skin issues. Therefore, for those suffering from a proven deficiency or at nutritional risk, a zinc supplement can be important.
When too much zinc becomes a problem
The problem begins when people take zinc in high doses over time, sometimes from several sources simultaneously: Lozenges, a multivitamin, a dedicated supplement and additional products. In the digestive system, zinc and copper compete for similar absorption mechanisms. Excess intake of zinc encourages the production of a protein called metallothionein in intestinal cells. This protein binds copper strongly, traps it in intestinal cells and prevents it from reaching the blood. When the cells are replaced and shed, the copper bound to them is lost in the stool.
Copper deficiency is not a theoretical matter. Copper is essential for the proper production of red blood cells and the function of the nervous system. A significant deficiency can cause anemia that does not respond as expected to iron, a drop in neutrophils – which are important white blood cells in fighting infections, and sometimes neuropathy – nerve damage manifested by tingling, weakness, difficulty walking or a burning sensation in the limbs. In other words, a supplement taken to "strengthen immunity" can, with excessive and prolonged use, harm the very components needed for immune defense.
It is important to be precise: Short-term use of zinc during a cold, at a reasonable dosage, is not equivalent to poisoning. Nor will every person taking zinc develop a copper deficiency. But the public is hardly aware that zinc has an upper limit, and that high doses do not mean "more health." Symptoms such as nausea, abdominal pain, metallic taste, diarrhea and headaches can appear even with excessive use, while copper deficiency develops quietly over time.
Who should be most careful?
Those at special risk are people taking zinc for months, teenagers using supplements for skin and acne, post-bariatric surgery patients, vegans with an unbalanced diet, the elderly and people already taking several products simultaneously. Also, those suffering from unexplained anemia, a drop in white blood cells or neurological symptoms should report any supplement they take to their doctor, even if it seems "harmless."
Zinc is an essential mineral, and in certain situations even beneficial. But it is not candy or a snack, nor is it a miracle cure. If deficiency is suspected, one can test, consult and treat for a defined period. Prolonged daily intake, especially at high doses, should only be done when there is a medical reason. The immune system is not strengthened by indiscriminately overloading it with minerals. Sometimes the way to protect it actually begins by stopping the unnecessary pill.
Dr. Itay Gal is a specialist in pediatrics, sports and aviation medicine, and the medical commentator for Maariv. For more articles click here