Zinc supplementation side effects
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Zinc Supplementation Side Effects: Key Findings
Adverse Effects in Infants and Young Children
Research shows that while zinc supplementation can reduce illness in young children, excessive intake may lead to negative health effects. In children aged 0-3 years, high doses of zinc (3 to 70 mg/day) have been linked to lower levels of important blood markers such as serum ferritin, plasma/serum copper, hemoglobin, and hematocrit, and an increased risk of anemia in some groups. However, the clinical importance of these changes is still unclear, and the overall certainty of the evidence is low to moderate. These findings suggest that current upper limits for zinc intake in young children may need to be updated to prevent possible side effects .
Side Effects in Adults
Most studies in adults focus on the benefits of zinc, such as its anti-inflammatory and antioxidant effects, rather than side effects. Zinc supplementation in adults has been shown to lower markers of inflammation and oxidative stress, with no significant harmful effects reported in these studies . In overweight or obese middle-aged women, 12 weeks of zinc supplementation improved cognitive scores and increased salivary zinc and IL-1β levels, but did not cause significant negative side effects or changes in mood .
Blood Pressure and Zinc Supplementation
A review of clinical trials found that zinc supplementation can slightly reduce systolic blood pressure in adults, but does not significantly affect diastolic blood pressure. No evidence was found that different dosages or durations of zinc supplementation led to harmful effects on blood pressure .
Zinc Supplementation in Cancer Patients
For cancer patients, especially those undergoing radiotherapy for head and neck cancer, zinc supplementation has been associated with reduced oral side effects like mucositis, dry mouth, and loss of taste. The risk of side effects from zinc in these patients appears to be small, and no significant negative impacts on weight, quality of life, fatigue, or survival were observed. However, zinc did not help with chemotherapy-induced side effects .
Conclusion
Zinc supplementation is generally safe for most adults and cancer patients, with few reported side effects. However, in infants and young children, excessive zinc intake can negatively affect blood markers related to iron and copper status and may increase the risk of anemia. The clinical significance of these findings is still uncertain, and more research is needed to determine safe upper limits for zinc intake in young children. For adults, zinc supplementation is mostly associated with health benefits and minimal risk of side effects.
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