What it is
Zinc takes part in the activity of a large number of enzymes, in immune function, protein synthesis and wound repair. The recommended intake for adults is 11 mg per day for men and 8 mg for women. It is sold mostly for immunity, skin and the hormonal side.
What the label does not say
- The NIH specifies that the nutrition facts table declares elemental zinc, not the weight of the whole compound. A zinc gluconate listed at 50 mg of salt does not provide 50 mg of zinc.
- From about 50 mg per day for a few weeks, the NIH reports inhibited copper absorption, reduced immune function and lower HDL cholesterol. That is the opposite of the effect you are after.
- The upper limit of 40 mg per day applies to total intake. A dedicated supplement, a multivitamin and lozenges add up without the total appearing anywhere.
The forms on the shelf
- Gluconate and citrate: the NIH reports absorption of about 61% in young adults.
- Oxide: absorption of about 50% in the same NIH comparison.
- Picolinate: heavily promoted on store shelves, but the NIH fact sheet does not set it apart from the other salts on absorption.
Published reference values
- Recommended intake for adults: 11 mg per day for men, 8 mg for women.
- Upper limit: 40 mg per day for adults, all sources combined.
- Above that, the NIH reports nausea, dizziness, headaches, stomach discomfort, vomiting and loss of appetite.
When
Often taken with a meal to limit nausea. Spacing it from certain antibiotics matters more than the time of day.
Keep apart from
- Quinolones and tetracyclines: at least 2 hours before or 4 to 6 hours after.
- Penicillamine: at least 1 hour apart.
To mention to a professional
- Prolonged use above 40 mg per day and copper status, use of thiazide diuretics (which increase urinary zinc excretion), pregnancy and breastfeeding: check with a health care professional.
From the plate first
Oysters provide about 32 mg per 3 ounces according to the NIH. Beef, crab, pork, turkey, pumpkin seeds and fortified cereals provide it too. Zinc from legumes and whole grains is less well absorbed.
Sources
- NIH Office of Dietary Supplements, Zinc (Health Professional)
- Health Canada, Dietary Reference Intakes, reference values for elements
Educational information, drawn from the sources above. It does not replace the advice of a health professional, who remains the reference for your situation, your medications, pregnancy or breastfeeding.