Zinc supplements: zinc picolinate vs other forms, how much zinc to take, and when it does harm

What zinc does and who needs a supplement

Zinc is part of hundreds of enzymes. Your immune cells need it, and so do cell division, wound healing, taste and smell. The body stores almost no zinc, so you need a steady supply from food.

Deficiency is more likely if you:

• are vegetarian or vegan;
• have a gut condition such as Crohn’s disease or coeliac disease;
• have had weight-loss (bariatric) surgery;
• drink heavily;
• are pregnant or breastfeeding.

Zinc in food

Oysters are far ahead of everything else. Red meat, crab and other seafood follow, then seeds, cheese and beans. Zinc from plant foods is absorbed less well, because phytates in grains and pulses bind it. Compare everyday portions with supplement strengths:

A mixed diet with meat, dairy and wholegrains usually gets close to the NHS figure. A plant-based diet needs more planning.

Zinc picolinate vs bisglycinate, gluconate and other forms

Labels usually show elemental zinc, with the form in brackets: “Zinc (as zinc picolinate) 22 mg”. If only the compound weight is given, use the table below.

Zinc picolinate vs gluconate: a small 1987 study found that picolinate raised zinc levels more. Larger comparisons are lacking. The gap between picolinate, bisglycinate, citrate and gluconate is small. Pick the one you tolerate best and that costs least per milligram of elemental zinc.

How much zinc to take

• The NHS puts daily need at 9.5 mg for men and 7 mg for women.
• If your diet is low in zinc, a sensible supplement is 10–15 mg of elemental zinc a day. Food already supplies roughly 8–12 mg, so this keeps the total near EFSA’s limit rather than over it.
• The NHS says not to take more than 25 mg a day from supplements unless a doctor advises it. EFSA’s 25 mg counts zinc from food too, and the US limit is 40 mg.
• Take it with a meal if it upsets your stomach, and away from antibiotics, iron and calcium.

Many bottles on iHerb hold 30 or 50 mg per capsule. That’s too much for daily use. Taking a 50 mg capsule every other day doesn’t fix it: the average is still 25 mg before you count food. Switch to a 10–15 mg product instead. To add up food, multivitamins and your capsule, use our daily zinc calculator.

A worked example. Say you eat meat a few times a week and get about 10 mg of zinc from food. A 15 mg capsule brings you to about 25 mg, right at the EFSA limit. A 50 mg capsule takes you to 60 mg, above every limit. And if your multivitamin already has 10–15 mg, you probably don’t need a separate zinc supplement.

Signs of low zinc

According to NIH ODS, zinc deficiency shows up as poor appetite and weaker immunity. More severe cases bring hair loss, diarrhoea, slow wound healing, changes in taste and weight loss. These signs aren’t specific, so on their own they’re no reason to take high-dose zinc.

Why excess zinc does harm

Zinc and copper compete for absorption. According to NIH ODS, 50 mg of zinc a day or more over weeks can block copper absorption. Low copper can show up as anaemia, low white blood cell counts and nerve damage, which isn’t always reversible. The NHS also mentions weaker bones.

If your doctor has you on high-dose zinc long-term, ask whether you need copper too. Some brands add a little copper to their zinc. Zinc taken with magnesium is fine at normal doses. Other pairs are shown in our vitamin compatibility chart.

How much zinc to take for a cold

In meta-analyses, zinc acetate or gluconate lozenges started within 24 hours of the first symptoms shortened colds in some trials. The trials that worked gave more than 75 mg of zinc a day (typically 80–92 mg), and only while symptoms lasted. That was usually no longer than 1–2 weeks. Results are inconsistent, and the lozenges taste strong.

Swallowed zinc capsules and tablets haven’t shown this effect. Don’t use zinc nasal sprays or gels. The US FDA has warned about long-lasting and even permanent loss of smell.

Interactions and who should be careful

• Antibiotics (tetracyclines, quinolones): zinc reduces their absorption. Take the antibiotic 2 hours before or 4–6 hours after zinc.
• Penicillamine (for rheumatoid arthritis and Wilson’s disease): separate the doses by at least 1 hour.
• Thiazide diuretics increase zinc loss in urine.
• High-dose iron and calcium may reduce zinc absorption when taken at the same time.

In pregnancy, kidney disease or if you take regular medicines, check with your GP or pharmacist before adding zinc. Zinc often sits in men’s multivitamins too, so read about supplements for men before doubling up.

How to choose a zinc supplement on iHerb

1. Check elemental zinc per capsule. For daily use, aim for 10–15 mg.
2. Pick a form: bisglycinate or picolinate for a sensitive stomach; citrate or gluconate if price matters.
3. Check whether your multivitamin already contains zinc, so you stay under 25 mg.
4. Take it with food.

Vitamin D is the one supplement the NHS advises for everyone in winter. Read our guide to vitamin D tablets.