uses JavaScript to provide the best possible experience for our content, but your browser has it disabled. Learn how to enable it here.


Search term may appear only in full report available to members. Join now for full access.

Product Review

Astaxanthin Supplements Review

See Which Astaxanthin Products Passed or Failed CL's Tests

Astaxanthin supplements reviewed by

Product Review

Nattokinase Supplements Review

Choose the Best Nattokinase Supplement. CL Tests Reveal Which Nattokinase Suppplements Provide the Best Quality & Value.

Nattokinase Supplements Tested by

Product Review

B Vitamin Supplements Review (B Complexes, B6, B12, Biotin, Folate, Niacin, Riboflavin & More)

See Which B Vitamins Are ConsumerLab's Top Picks!

Review of B Vitamin Supplements

Product Review

Melatonin Supplements Review

Trouble Sleeping? See CL's Tests of Melatonin Supplements and Top Picks.

Melatonin Review 2024

Product Review

Vitamin D Supplements Review (Including Calcium, Magnesium, Boron, and Vitamin K)

Find the Best Vitamin D Supplement with the Right Dose

Product Review

Saffron Supplements Review

See How Saffron Supplements Compare and What They Do

Product Review

L-Theanine Supplements Review

Touted for Stress Relief, Do L-Theanine Supplements Work?

Product Review

St. John's Wort Supplements Review

Find the Best St. John's Wort Supplement. Only 40% of St. John's Wort Supplements Pass Tests & Strength Varies Widely.

St John's Wort Supplements Reviewed By

Product Review

Ginkgo (Ginkgo Biloba) Supplements Review

Choose the Best Ginkgo Biloba Supplement. Finding Real Ginkgo Isn't Easy — 60% Fail ConsumerLab's Tests of Quality.

Ginkgo Biloba Supplements Tested by

Product Review

Milk Thistle Supplements Review

Find the Best Milk Thistle Supplement. Tests and Reviews of Popular Milk Thistle Supplements & CL's Top Picks.

Milk Thistle and Liver Formula Supplements Reviewed by

Product Review

Zinc Supplements and Lozenges Review

Find the Best Zinc Supplements and Lozenges. Have a Cold? See CL's Top Picks Among Zinc Supplements and Lozenges.

Zinc Supplements and Lozenges Reviewed by

CL Answer

Does Alpha Brain really improve memory, focus and cognition?

Find out if Alpha Brain really improves memory, focus and cognition. See the clinical evidence and get details about Alpha Brain ingredients, as well as potential side effects and drug interactions.'s answer explains.

Bottle of Alpha Brain capsules

CL Answer

Does AHCC (active hexose correlated compound) have anticancer or antiviral benefits, and is it safe?

Learn about AHCC (active hexose correlated compound), including whether it is beneficial for liver, pancreatic, or prostate cancer, chemotherapy-related side effects, or the flu, and if it is safe.

Capsules of AHCC in wooden spoon in front of green leaf

CL Answer

I take levothyroxine (Synthroid), a thyroid hormone to treat hypothyroidism. Are there supplements or foods I should avoid, or be taking, due to this drug?

Is taking certain supplements and hypothyroidism medications bad? Learn which supplements can interact with thyroid hormone medications like levothyroxine (Synthroid), thyroid hormone levels, and laboratory tests.

Levothyroxine (Synthroid) Supplement Interactions

CL Answer

Do any supplements or lifestyle changes reduce the symptoms of tinnitus? Is it true that some supplements can cause tinnitus?

Learn which supplements can ease tinnitus, including melatonin and pine bark extract. Understand which may actually cause tinnitus.

Word blocks spelling out “tinnitus”

CL Answer

Does Bacopa extract improve memory, mood, or sleep? Is it safe?

Find out if bacopa improves memory and cognition, mood or sleep, and whether it's been shown to be helpful in people with Alzheimer's disease or dementia. Plus, learn about the safety and common side effects of bacopa.

Bacopa for Memory and Cognition -- Bacopa leaves and powder

CL Answer

Does Gynostemma pentaphyllum really work as an AMPK activator and help for diabetes, high cholesterol, or weight loss?

Find out if Gynostemma pentaphyllum ( jiaogulan) works as an AMPK activator and helps to lower blood sugar and treat diabetes.'s answer explains.

Jiaogulan (Gynostemma pentaphyllum) -- Gynostemma herb and capsules

CL Answer

What are the health effects of turkey tail mushroom and is it safe?

Learn about the possible health effects of turkey tail mushroom, including its use as adjuvant treatment for cancer and for boosting immune function, plus get information about possible side effects and find out why ConsumerLab has not yet tested turkey tail products.

Turkey tail mushrooms growing on the side of a tree

CL Answer

What is inositol hexaphosphate (IP6) and myo-inositol? Are they helpful in treating cancer or other conditions?

Inositol hexaphosphate (IP6): Find out if IP6 (also known as phytic acid) can prevent or treat cancer. Clinical evidence, dosage, safety and how IP6 differs from myo-inositol.'s answer explains.

Wooden spoon filled with white inositol capsules

CL Answer

Which supplements may help with PCOS (polycystic ovarian syndrome)?

Many supplements are promoted to help treat symptoms of PCOS (polycystic ovarian syndrome), but do they really work? See the clinical evidence for inositol (myo-inositol and D-chiro-inositol), alpha lipoic acid, vitamin B-12, folic acid, vitamin D and more.

Supplements for PCOS

CL Answer

Are supplements such as Thyroid Care Plus helpful for hypothyroidism? Can supplements worsen thyroid function? And what is nascent iodine?

Learn about supplement ingredients such as iodine, selenium, zinc, acetyl-l-carnitine, ashwagandha and guggul used for thyroid conditions and find out if they are beneficial. Also learn why ingredients such as alpha-lipoic acid, soy, resveratrol, quercetin may impair thyroid function.

Woman holding various vitamins and supplements in one hand and glass of water in the other

News Release

April 13, 2022

ConsumerLab Tests Vitamin D Supplements and Cautions About Dose

  White Plains, New York, May 12, 2022 — Getting sufficient vitamin D is essential for healthy bones and has a wide range of other health benefits. It's no wonder that it has been the #1 supplement in popularity year-after-year in ConsumerLab's survey of supplement users.

News Release

May 02, 2018

Best Probiotic Supplements and Kombuchas? -- ConsumerLab Tests 41 Popular Products, Reveals Problems and Top Picks

White Plains, New York, May 2, 2018 — With so many different probiotic supplements on the market, each providing different amounts and strains of beneficial bacteria or yeast, choosing the right one can be an overwhelming task.

Recalls & Warnings

September 09, 2018

Higenamine -- A Potentially Dangerous Stimulant -- Found in Some Supplements

A recent study found concerningly high doses of the stimulant higenamine in some weight loss, energy and sports supplements sold in the U.S. Higenamine is a naturally-occurring stimulant which is permitted to be sold as a dietary supplement ingredient in the U.S.