Which Zinc Supplements Are Third-Party Tested?

Our recommendation

Buy Nature Made Zinc 30 mg

The lowest-cost zinc on a testing list. USP checks the dose on the label, contaminants and that the tablet breaks down. Each tablet has 30 mg of zinc as gluconate, which was about 61% absorbed in the study NIH cites. Take it with a meal.

Buy on Amazon · $4.99

• Drug-tested in sport? Thorne Zinc Picolinate 30 mg is NSF Certified for Sport, which also screens for banned drugs ($0.33 a day).
• Want a smaller dose? Momentous Zinc has 15 mg a capsule and Klean Zinc 10 mg a chewable tablet. Both are NSF Certified for Sport.
• Want bisglycinate? Thorne Zinc Bisglycinate 30 mg is on NSF/ANSI 173 ($0.33 a day).

30 mg is close to the limit. Adults should not go over 40 mg of zinc a day, counting food and any multivitamin. Weeks at 50 mg or more can lower your copper (NIH).

✓ On a testing list (5)

An outside program checked each of these and lists it by name. USP Verified and NSF/ANSI 173 check that the bottle holds what the label says. NSF Certified for Sport also screens for drugs banned in sport. More on each list

1. 

   Our pick · lowest cost on a list

   Nature Made Zinc 30 mg

   ✓ USP Verified

   30 mg zinc a tablet as gluconate · 100 in the bottle

   $0.05 a day

   Buy on Amazon · $4.99
2. 

   Klean Athlete Klean Zinc

   ✓ NSF Certified for Sport✓ NSF/ANSI 173

   10 mg zinc a chewable tablet as citrate · 100 in the bottle

   $0.22 a day

   Buy on Amazon · $22.00
3. 

   Momentous Zinc Picolinate 15 mg

   ✓ NSF Certified for Sport✓ NSF/ANSI 173

   15 mg zinc a capsule as picolinate · 60 in the bottle

   $0.32 a day

   Buy on Amazon · $18.99
4. 

   Also screened for drugs banned in sport

   Thorne Zinc Picolinate 30 mg

   ✓ NSF Certified for Sport✓ NSF/ANSI 173

   30 mg zinc a capsule as picolinate · 60 in the bottle

   $0.33 a day

   Buy on Amazon · $20.00
5. 

   Thorne Zinc Bisglycinate 30 mg

   ✓ NSF/ANSI 173

   30 mg zinc a capsule as bisglycinate · 60 in the bottle

   $0.33 a day

   Buy on Amazon · $20.00

Not on any testing list (3)

Well-known zinc brands on Amazon. None of these products is on a public list. Here is what each listing says about testing, and what that means.

1. 

   NOW Zinc Glycinate 30 mg

   Not on a public list

   30 mg zinc a softgel as glycinate · 120 in the bottle

   Its listing says its factory has an “A-rated, third-party certification” and its own labs test products. That covers how NOW makes products. This product is not on a public list.

   $0.10 a day

   Check price
2. 

   Solgar Zinc Citrate 30 mg

   Not on a public list

   30 mg zinc a capsule as citrate · 100 in the bottle

   Its listing says nothing about outside testing. It calls itself “The Gold Standard” but names no program.

   $0.10 a day

   Check price
3. 

   Garden of Life Raw Zinc

   Not on a public list

   30 mg zinc a capsule as whole-food blend · 60 in the bottle

   Its listing says “NSF Gluten Free”. That checks for gluten only. It is not NSF’s test of what is in the bottle, and this product is not on that list.

   $0.19 a day

   Check price

A day is one serving on the label at the Amazon price on October 11, 2026, the same way our best zinc guide prices them. The doses differ: 10 to 30 mg a day.

Gluconate, citrate, picolinate or glycinate?

Gluconate and citrate are absorbed about the same. In the tracer study NIH cites, zinc citrate and zinc gluconate were each about 61% absorbed in young adults, and zinc oxide 50%.

“Best absorbed” claims for picolinate and glycinate are not backed by that study. It did not test them. Pick on the testing list, the dose and the price. Every zinc form compared.

How much zinc, and when to be careful

• Most adults need 11 mg (men) or 8 mg (women) a day, from food and pills together. The upper limit is 40 mg a day.
• Too much for too long lowers copper. Weeks at 50 mg or more can cause low copper, weaker immune function and lower HDL cholesterol. High doses can also cause nausea.
• Antibiotics: take quinolones (such as Cipro) or tetracyclines at least 2 hours before or 4 to 6 hours after zinc.
• Other medicines: take penicillamine at least 1 hour apart from zinc. Thiazide water pills make you lose more zinc in urine.
• Iron: 25 mg or more of iron taken at the same time can lower how much zinc you absorb.
• Colds: the cold studies used zinc lozenges or syrup started early, not daily pills. This page covers daily zinc pills only.

Source for this section: NIH Office of Dietary Supplements, Zinc fact sheet (updated January 6, 2026). Not medical advice; ask your doctor or pharmacist.

What “third-party tested” means

A company outside the brand checks the product and lists it by name, so you can look it up yourself. There are two kinds. A contents program checks that the bottle holds what the label says, without harmful contaminants. A banned-substance program screens for drugs banned in sport, which matters only if you are drug-tested. “Third-party tested” printed on a label, with no program named, is the brand’s word.

How to check your bottle

1. Find the mark. Look for an NSF or USP mark on the product. “Third-party tested” with no program named is a claim.
2. Read which NSF mark it is. “NSF Gluten Free” checks for gluten only. It is not NSF’s test of what is in the bottle.
3. Open the program’s own list. USP Verified, NSF/ANSI 173, NSF Certified for Sport, Informed Choice, Informed Sport. Or search all five on our testing-list index.
4. Check the strength. Thorne sells its zinc in 15 mg and 30 mg. Make sure the listing matches the bottle you buy.

Questions

The best zinc supplement · picolinate vs glycinate · zinc guide.

Where each answer comes from

For the listed products, the entry as each program’s own list shows it. For the others, what we searched.

NSF/ANSI 173 lists Klean Zinc with a serving of 3 tablets; the label says 1. NSF found no listings at all under NOW Foods, Solgar or Nature Made, and Garden of Life’s listings include no zinc. The brand claims quoted above are from each product’s Amazon listing, read October 11, 2026.

Sources

1. NSF/ANSI 173 (info.nsf.org) searched by company, and NSF Certified for Sport listings 1211643, 1612942 and 1340980 read, October 11, 2026. NSF Certified for Sport full list from our copy of October 1, 2026. USP Verified, Informed Choice and Informed Sport from our copies of September 22, 2026 (USP’s site blocks automated reads).
2. Labels: NIH Dietary Supplement Label Database and each brand’s page or listing (linked above). Amazon prices: October 11, 2026. Amazon listing text: October 11, 2026.
3. NIH Office of Dietary Supplements. Zinc fact sheet for health professionals. Updated January 6, 2026; read October 11, 2026.