Zinc is a crucial mineral involved in numerous bodily functions, from immune health and DNA synthesis to wound healing and taste perception. While most people get enough zinc from a balanced diet, supplementation can be necessary for certain populations. However, improper use can negate benefits or, worse, lead to health complications. Understanding what not to do is as important as knowing what to do.
Never Exceed the Recommended Dosage
One of the most significant mistakes is taking more zinc than recommended. The tolerable upper intake level (UL) for most adults is 40 mg per day. Chronic, high-dose zinc intake can lead to serious health issues.
Potential Dangers of Excessive Zinc Intake
- Copper Deficiency: Zinc and copper compete for absorption in the small intestine. Long-term high zinc intake can cause a copper deficiency, which may lead to neurological problems like numbness and weakness in the extremities, and anemia.
- Impaired Immune Function: Paradoxically, while zinc supports the immune system, excessive intake can suppress it.
- Gastrointestinal Distress: Acute zinc overdose, often from single high doses, can cause nausea, vomiting, diarrhea, stomach pain, and headaches.
- Reduced HDL Cholesterol: Some studies indicate that long-term intake of high doses (over 50 mg/day) can decrease levels of high-density lipoprotein (HDL), or 'good' cholesterol.
Do Not Use Intranasal Zinc Sprays
For a time, zinc was marketed in nasal spray form to combat the common cold. The US Food and Drug Administration (FDA) has since issued warnings against intranasal zinc products due to a confirmed link to permanent loss of the sense of smell (anosmia). The proper forms of zinc for oral consumption are tablets, capsules, or lozenges.
Avoid Taking Zinc with Certain Foods and Nutrients
Several dietary components can interfere with zinc absorption, forming insoluble complexes that the body cannot utilize effectively.
- High-Phytate Foods: Foods rich in phytates, or phytic acid, significantly inhibit zinc absorption. These include legumes (like chickpeas and kidney beans), whole grains, seeds, and nuts. If you follow a vegan or vegetarian diet, this is particularly important to note. Try to separate your zinc supplement from these foods by at least two hours.
- High-Calcium Foods and Supplements: Calcium can compete with zinc for absorption, especially at high doses. Avoid taking zinc supplements at the same time as large amounts of dairy products (milk, yogurt, cheese) or calcium supplements. Spacing them by at least two hours is recommended.
- Iron Supplements: Like calcium, iron competes with zinc for the same absorption pathways. Take iron and zinc supplements at separate times of the day to ensure both are properly absorbed.
- Coffee and Tea: The tannins and polyphenols in coffee and tea can bind to zinc and modestly reduce its absorption. It's best to take zinc supplements away from your coffee or tea break.
- Excessive Alcohol: Chronic and excessive alcohol consumption impairs the body's ability to absorb zinc and increases its excretion.
Steer Clear of Medication Interactions
Zinc can interact with several types of medications, reducing their effectiveness or absorption. Always inform your healthcare provider about all supplements you take.
Zinc and Medication Interactions
- Antibiotics: Zinc can hinder the body's absorption of quinolone (e.g., Cipro, Levaquin) and tetracycline (e.g., Achromycin, Sumycin) antibiotics. To minimize this, take the antibiotic two hours before or four to six hours after your zinc supplement.
- Penicillamine: Used for rheumatoid arthritis and Wilson's disease, penicillamine's efficacy can be lowered by zinc. Space them by at least one hour.
- Certain Diuretics: Thiazide diuretics, such as chlorthalidone and hydrochlorothiazide, can increase zinc loss in the urine over time. Conversely, the diuretic amiloride can increase zinc levels, so caution is advised.
- HIV/AIDS Medications: Zinc can reduce the absorption of integrase inhibitors like ritonavir and dolutegravir, potentially affecting treatment efficacy.
Zinc Supplement Comparison Table
Not all zinc supplements are created equal. Different forms offer varying levels of elemental zinc and absorption rates. Choosing the right form for your needs is important.
| Zinc Form | Typical Elemental Zinc % | Absorption Rate (Human Studies) | Notes |
|---|---|---|---|
| Zinc Citrate | ~31% | ~61% | High absorption, well-tolerated. |
| Zinc Gluconate | ~14% | ~61% | Similar absorption to citrate, common form for lozenges. |
| Zinc Picolinate | ~20% | Higher than gluconate/citrate (some studies) | Some evidence suggests higher absorption, but mixed results. |
| Zinc Oxide | ~78% | ~50% | Lower absorption due to poor solubility; often used in topical creams. |
| Zinc Glycinate | Varies | Possibly higher than gluconate | Some studies indicate superior plasma level increase. |
Conclusion: Practice Safe Supplementation
By avoiding these common mistakes, you can significantly enhance the safety and effectiveness of your zinc supplementation. Remember to stay within the safe daily dosage limits, avoid concurrent intake with certain foods and medications, and select an appropriate, bioavailable form. As always, consulting with a healthcare professional before beginning any new supplement regimen is the best way to ensure it is right for your specific health needs.
For more in-depth information, the National Institutes of Health Office of Dietary Supplements offers a comprehensive fact sheet for health professionals.
