Bio Zinc

With zinc, the right answer is usually a sensible dose taken with food. These are the questions our naturopaths ask in store before you choose a brand.

A good fit if

• You eat little or no meat, fish or shellfish, so you need more zinc than most
• You want a modest everyday dose and can reliably take it with a meal
• You'd rather have zinc on its own than a combination that adds vitamin A or high-dose B6 you didn't ask for
• You find tablets hard to swallow. Chewables, liquids and powders come in ordinary doses
• You're happy to review a high-strength dose after a few months rather than stay on it for good

Check with us first if

• You take a quinolone or tetracycline antibiotic. Zinc binds to them and both are absorbed less, so space the doses two to six hours apart.
• You take penicillamine. Take zinc at least an hour apart from it.
• You take a thiazide diuretic (water tablet). These make you lose more zinc in your urine.
• You've been taking 50 mg a day for months. It's worth checking your copper, because copper is what the Australian Upper Level was set to protect.
• You're pregnant or breastfeeding. You need more zinc, and many zinc products also contain vitamin A, which carries its own required pregnancy warning in Australia.
• A zinc dose has made you feel sick before. The form, timing and amount can all be changed, so it's worth a chat rather than giving up.
• You're giving zinc to a child. Children's Upper Levels are a fraction of most adult doses on the shelf.
• You use a denture adhesive cream that contains zinc. Heavy long-term use has caused zinc toxicity, and it counts towards your daily total.
• You take prescription medicines. Check with your doctor, pharmacist or our naturopaths before starting.

• Zinc amino acid chelate / bisglycinate. Best known for: The standard form on Australian shelves. A label reads something like 'zinc amino acid chelate 125 mg (equiv. zinc 25 mg)', which is where most of the confusion about dose starts. Absorption: Zinc bound to glycine. Schedule 1 caps the zinc at no more than 30 per cent of the chelate, and Australian labels usually sit near 20 per cent. Typical use: Once-a-day tablets and powders across the whole range. Usually the easiest on a sensitive stomach, though every label still says to take it with food.
• Zinc citrate. Best known for: A neutral taste, which is why it is the main form in chewables, liquids and children's formulas. Absorption: About 61 per cent is absorbed in young adults. That is level with gluconate and better than oxide. Typical use: Chewable tablets, drops and practitioner-range single-ingredient products.
• Zinc gluconate. Best known for: The standard for lozenges and cold formulas, and it carries relatively little zinc: one Australian label uses 114.85 mg of zinc gluconate to give 15 mg of zinc. Absorption: About 61 per cent is absorbed, the same as citrate. Typical use: Lozenges and plain tablets. Gluconate forms bitter compounds with sweet carbohydrates, which makes lozenges taste worse and harder to finish.
• Zinc sulfate. Best known for: The research standard, used in many of the older clinical trials. Absorption: Well absorbed, but the form here most likely to cause nausea, especially on an empty stomach. Typical use: Basic tablets and oral solutions rather than premium retail formulas. Schedule 1 also caps it at 5 per cent for use on the skin.
• Zinc picolinate. Best known for: Popular in clinics overseas, and the one oral form here with no item of its own in Schedule 1. Absorption: Bound to picolinic acid. There is little human data comparing its absorption with citrate or gluconate. Typical use: Mostly imported and practitioner-range products. Because there is no ZINC PICOLINATE item in Schedule 1, it cannot be an ingredient in an Australian listed medicine. Check what the label and AUST L number actually say.
• Zinc oxide. Best known for: The white mineral in sunscreens and barrier creams. Used on skin far more often than swallowed. Absorption: About 50 per cent is absorbed by mouth, the lowest of the common forms, even though it carries the most zinc per milligram of compound. Typical use: Primary sunscreens and nappy creams, where Schedule 1 requires sun-exposure warnings. Occasionally the zinc source inside a multivitamin.
• Zinc acetate. Best known for: The salt used in the lozenge trials that reported the biggest cuts in how long colds lasted. Absorption: Made to dissolve slowly in the mouth rather than be swallowed, releasing free zinc where the cold virus is. Typical use: Not available in an Australian listed medicine. There is no ZINC ACETATE item in Schedule 1, so the best-studied lozenge salt is the one you cannot buy here in a listed product.

Reference values. These are the NHMRC Recommended Dietary Intakes, unless noted otherwise. Infants 0 to 6 months need 2.0 mg a day (an Adequate Intake), 1 to 3 years 3 mg, 4 to 8 years 4 mg, and 9 to 13 years 6 mg. Boys 14 to 18 years need 13 mg and girls 14 to 18 years 7 mg. Men 19 and over need 14 mg and women 19 and over 8 mg. In pregnancy it's 10 mg at 14 to 18 years and 11 mg at 19 to 50 years, and while breastfeeding it's 11 mg at 14 to 18 years and 12 mg at 19 to 50 years. We haven't listed the 7 to 12 month figure because we couldn't confirm it from the source, and we'd rather leave it out than guess.

Typical supplemental range. Australian labels range from about 15 mg to 50 mg of elemental zinc (the actual zinc) in a single daily dose. Plain zinc-only tablets usually sit at 15 to 25 mg, while combination and high-strength products come in at 30, 40 and 50 mg. 50 mg is the most Australia's permitted ingredients list (Schedule 1) allows a listed medicine to recommend. Anything above 25 mg must carry the zinc warning statement, so seeing that warning on the box is a handy clue that it's a higher dose.

Upper level. The NHMRC Upper Level of Intake covers all the zinc you get from food, water and supplements, including fortified food. It's 4 mg a day at 0 to 6 months, 5 mg at 7 to 12 months, 7 mg at 1 to 3 years, 12 mg at 4 to 8 years, 25 mg at 9 to 13 years, 35 mg at 14 to 18 years and 40 mg for adults 19 and over. In pregnancy and breastfeeding it's 35 mg at 14 to 18 years and 40 mg at 19 to 50 years. There are two different limits to keep in mind. The 50 mg ceiling in Schedule 1 is the most a single listed medicine may recommend, while the 40 mg adult Upper Level is a nutrition guide for everything you swallow in a day. The product limit sits above the nutrition limit, and both are correct.

Worth knowing. Look for the elemental zinc figure, not the weight of the compound, just as you would with iron. Two Australian labels show why: 114.85 mg of zinc gluconate gives you 15 mg of zinc, and 125 mg of zinc amino acid chelate gives you 25 mg. The big number on the ingredient line can be about five times the zinc you actually get, so look for the line starting 'equiv. zinc'. Take zinc with food unless your practitioner says otherwise. What you need depends on your age, diet and health, so talk to one of our naturopaths.

Food first, where the diet allows it.

• Oysters, farmed, raw: about 32 mg per 85 g
• Pacific oysters, cooked: about 28.2 mg per 85 g
• Beef, bottom sirloin, roasted: about 3.8 mg per 85 g
• Blue crab, cooked: about 3.2 mg per 85 g
• Rolled oats, cooked: about 2.3 mg per cup
• Pumpkin seeds, roasted: about 2.2 mg per 28 g

If any of these sound like you, talk to one of our naturopaths or your doctor before you start.

• You take quinolone or tetracycline antibiotics. Zinc binds to them, so take the doses two to six hours apart.
• You take penicillamine. Take zinc at least one hour apart from it.
• You take thiazide diuretics (water tablets). They make you lose more zinc in your urine.
• Long-term doses of 50 mg or more. These get in the way of copper absorption, and low copper can cause anaemia and nerve problems (neurological disease).
• Your total intake is above the NHMRC Upper Level of 40 mg/day for adults, counting food, water, fortified foods and supplements together.
• Babies and children. Their Upper Levels are much lower: 4 mg (0 to 6 months), 5 mg (7 to 12 months), 7 mg (1 to 3 years), 12 mg (4 to 8 years), 25 mg (9 to 13 years), 35 mg (14 to 18 years).
• Taking it on an empty stomach, or a dose above 25 mg. Nausea, vomiting, stomach upset, headache, dizziness and loss of appetite are the known effects of too much zinc or badly timed zinc.
• Pregnancy and breastfeeding. Your needs go up, and many zinc products also contain vitamin A, which must carry a pregnancy warning on Australian labels.
• You use denture adhesive creams that contain zinc. Long-term overuse has caused zinc toxicity and copper deficiency, and some creams contain 17 to 34 mg of zinc in every gram.
• Combination zinc formulas. These often contain vitamin A and vitamin B6, each with its own mandatory Australian label warning. Read the whole label, not just the zinc line.
• Products sold as zinc picolinate. There is no ZINC PICOLINATE item in Schedule 1, so check whether what you are buying is an Australian listed medicine.
• Zinc lozenges. Schedule 1 does not include zinc acetate, the salt used in the trials that showed the biggest effect, so an Australian lozenge is not the same product that was studied.
• If you take prescription medicines, check with your doctor, pharmacist or our naturopaths before you start.