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CL Answer

Which supplements and foods help relieve constipation and which can cause constipation?

Find out which supplements can cause constipation, including iron, calcium, protein powders and drinks and others.'s answer explains.

Which supplements can cause constipation? -- Woman with gastrointestinal pain

CL Answer

Can zuPOO and its primary ingredient, cascara sagrada, cleanse the gut, improve digestion and help with weight management?

zuPOO is marketed for gut support and as a colon cleanser for weight management. Find out if research supports these claims and if ingredients in zuPOO are safe.

zuPOO supplement bottle with white background

Product Review

Iron Supplements Review (Iron Pills, Liquids and Chews)

See Which Iron Supplements Are CL's Top Picks for Different Needs

CL Answer

Can turmeric or curcumin with black pepper extract cause constipation? I had this problem, but it resolved when I switched to a curcumin supplement without piperine (black pepper extract).

Learn more about black pepper extract, why it is added to turmeric/curcumin supplements, and if it can cause gastrointestinal effects.

Turmeric or Curcumin

Product Review

Probiotic Supplements Review (Including Pet Probiotics)

Probiotics: See What They Really Contain and Our Top Picks

CL Answer

What are the benefits of Daily Synbiotic by Seed Health? Does it do what it claims, and is it better than other probiotics and prebiotics?

Review of Daily Synbiotic by Seed, including information about the prebiotic and probiotic strains in the supplement, and whether there is evidence of benefit for the synbiotic.

Person pouring Daily Synbiotic capsules from container into other hand

Product Review

Psyllium Fiber Supplements Review

Most Psyllium Supplements Failed Our Tests Due to Lead Contamination. Find Out Which Passed or Failed and Which Is Our Top Pick.

Psyllium Supplements Reviewed by

CL Answer

Is magnesium citrate safe? I heard that it might cause damage to the esophagus.

Find out if magnesium citrate is safe to use or if it causes damage to the esophagus.

Magnesium citrate in a spoon over a glass of water

CL Answer

After taking a curcumin supplement, I started getting chronic diarrhea which went away when I stopped taking it. Can curcumin supplements cause diarrhea?

Learn more about the side effects of curcumin supplements, including diarrhea and other gastrointestinal discomfort.

Turmeric and Diarrhea

Product Review

Prebiotic Supplements Review

You Can't Tell How Much Fiber Is Really In Most Prebiotics Without Testing

Clinical Update


Kiwi for Constipation?

Can eating kiwifruit reduce constipation as well as psyllium fiber? Find out what a recent study showed in our updated answer to the question: Which supplements and foods help relieve constipation and which can cause constipation?

CL Answer

What are the side effects of magnesium supplements?

Info on magnesium supplement side effects, such as stomach upset, nausea and diarrhea. Learn about magnesium dosage, safety and drug interactions. answer explains.

Magnesium Side Effects -- Magnesium supplements

CL Answer

Are there supplements I should take, or take differently, when intermittent fasting?

Supplements that may help when intermittent fasting. Information about whey protein, CoQ10, magnesium and others, plus coffee, fiber and more.

CL Answer

As vitamin D is a fat-soluble vitamin, why is it necessary to take it every day?

Find out how best to take vitamin D supplements, including cautions on overdoses.

Do I need to take vitamin D daily

CL Answer

What are the health benefits of manuka honey, and is it safe?

Manuka honey health benefits, how it differs from common, store-bought honey, safety, evidence for using manuka honey for wounds, sore throat and cough, constipation and more.

Health Benefits of Manuka Honey -- jar of manuka honey

CL Answer

Does magnesium cause diarrhea? Are some forms less likely to cause loose stools than others?

Could your magnesium supplement be causing diarrhea? Find out why the dose of magnesium in your supplement matters, and which forms of magnesium are less likely to cause diarrhea's answer explains.

Product Review

Whole, Ground, Milled, and Cracker Flaxseed Review

High Levels of Cadmium Found in Flaxseed Products – Testing Expanded

CL Answer

Are there side effects from collagen supplements?

Find out if there are collagen side effects from supplements (collagen hydrolysate, collagen peptides, etc.) such as nausea, constipation, skin rash and others.'s answer explains.

Collagen Supplement Side Effects -- woman with stomach pain

CL Answer

I have IBS and don't want to take medication if I can help it. I've heard that peppermint works for IBS, but is there good research to support this?

Information about using peppermint oil for irritable bowel syndrome (IBS), including clinical evidence, dosage, safety and more.

Peppermint Oil for IBS? -- Bottle of peppermint oil and capsules and peppermint leaf

CL Answer

Can taking too much fish oil be dangerous?

Find out if too much fish oil can be dangerous, and if taking too much fish oil can cause effects such as suppressing the immune system, thinning the blood (increasing the risk of bleeding), increasing levels of LDL cholesterol and liver enzymes or increasing the frequency in episodes atrial fibrillation.'s answer explains.

Taking Too Much Fish Oil -- bottle of fish oil and fish oil capsules

CL Answer

Do any supplements help for irritable bowel syndrome (IBS)?

IBS supplements may help reduce irritable bowel symptoms such as pain, diarrhea and constipation. Supplements include probiotics, melatonin, and flaxseed.

Supplements for IBS? -- Women With Stomach Pain

Clinical Update


Inulin for Constipation

A small study among men and women with constipation found that inulin, a type of prebiotic, was able to modestly increase the frequency of bowel movements in men and women with constipation. For details, evidence for other uses of prebiotics and our tests of products, see the Probiotics Supplements Review >>

Clinical Update


Inulin for Constipation?

Can inulin increase bowel movements in people with constipation? Find out in our updated CL Answer about supplements for constipation.

Clinical Update


Sodium Bicarbonate or Marshmallow Root for Constipation?

Does supplementing with sodium bicarbonate (baking soda or bicarbonate of soda) or marshmallow root help treat constipation? See the answers in our updated article about supplements for constipation.

CL Answer

Is drinking coffee good or bad for heart health?

Learn more about coffee and caffeine, its safety, if it's good for you, how much coffee is too much and its impact on your heart.

CL Answer

What is lunasin and does it really reduce cholesterol?

Lunasin supplement information, whether lunasin can lower cholesterol, safety and side effects, foods that contain lunasin, like soy.

Clinical Update


Supplements and Foods for Constipation

Which supplements and foods are best for relieving constipation? We’ve updated our answer to include more information about fruits.

Clinical Update


Synbiotic for Constipation?

Can supplementing with a synbiotic (probiotic + prebiotic) increase bowel movements in children with constipation? Find out what research showed in our CL Answer about this brand of synbiotics.

Clinical Update


Best Fiber Supplement for Constipation?

Which type of fiber supplement is best for treating mild, chronic constipation? See what experts recommend, and why, in the What It Does section of our Psyllium Supplements Review.

Clinical Update


Probiotic Helps with Constipation

A recent study found that taking a particular probiotic twice a day after meals significantly increased the number of bowel movements in people with chronic constipation. For details about the probiotic and dose, see the Probiotic Supplements Review >>

CL Answer

Does taking a laxative interfere with the absorption of vitamins or minerals?

Information on laxative interactions with other medications and supplements such as Maalox, antibiotics, and statins and diabetes medications.

Laxatives and vitamin and mineral absorption

CL Answer

Risks of Too Many Vitamins & Supplements

Taking too many vitamin supplements -- or taking too much of a particular supplement -- can have short and long-term adverse effects.

Too Many Vitamins

CL Answer

Butyrate Supplements for Gut Health: Does butyric acid really work and is it safe?

Can butyrate supplements improve gut health or help reduce symptoms of irritable bowel syndrome (IBS) or Crohn's disease? Find out what the clinical evidence shows, learn about the different forms of butyrate, including sodium butyrate, calcium-magnesium butyrate, and tributyrate, and get details about products such as BodyBio Sodium Butyrate and Healus Complete Biotic Tributyrin, dosage, safety and cost.

Butyrate Supplements

CL Answer

What are the health benefits of andrographis? Can it treat colds, help with joint pain, or other conditions, and is it safe?

Learn about the health benefits of andrographis, whether it can help relieve cold symptoms, reduce pain and stiffness of osteoarthritis or rheumatoid arthritis, decrease symptoms of ulcerative colitis, or slow the growth of cancer. See the clinical evidence for the branded andrographis extract ParActin. Plus, learn about dosage, side effects and drug interactions with andrographis.


CL Answer

What are the health benefits of bovine colostrum and is it safe?

Bovine colostrum is promoted for boosting immunity, preventing and treating diarrhea, and improving gut health, but does it really work? See the clinical evidence for bovine colostrum, including doses that have been used, as well as safety concerns, cost considerations, and the difference between regular bovine colostrum and hyperimmune bovine colostrum.

Bovine colostrum powder and capsule supplements

CL Answer

Does Restore (Bionic Sciences LLC) really improve gut health? What is in Restore?

Learn more about Restore, including clinical studies on gut health, dosage, cost, and safety.

CL Answer

What is Prelief? Does it really help for heartburn and/or bladder pain from acidic foods?

Prelief information, including what it has been claimed to do (such as helping with painful bladder, frequent urination, heartburn or indigestion from acidic foods), clinical evidence, and safety.

CL Answer

Which supplements have been shown to be helpful for autism?

Find out which supplements may help reduce symptoms of autism, including multivitamins, probiotics, and melatonin.

Bottle and Pills Spread Out on Blue Background

CL Answer

Is it possible to get too much vitamin D?

Too much vitamin D can lead to adverse effects, including hypercalcemia (excess calcium in the blood).

Too Much Vitamin D? -- bottle of vitamin D and vitamin D tablets in the shape of the letter D

Clinical Update


Precaution When Taking Iron

Supplementing with iron can cause constipation and even bowel obstruction. Find how to reduce these risks when taking iron in the ConsumerTips section of the Iron Supplements Review. Also see our Top Picks for iron.

Clinical Update


Caution With Too Much Magnesium

Magnesium can be an effective laxative, but taking too much magnesium can be very dangerous, as was recently reported. Get the details in the Concerns and Cautions section of our Magnesium Supplements Review.

Also see our answer to the question: Which supplements can help treat constipation?

Clinical Update


Curcumin for Indigestion?

How well does curcumin (from turmeric) improve digestive symptoms such as indigestion, diarrhea or constipation? See what a new study found in the What It Does section of our Turmeric and Curcumin Supplements & Spices Review. Also see our Top Picks among turmeric and curcumin products.

Product Review

Fruits, Veggies, and Other Greens Supplements Review (Including Spirulina and Chlorella)

Fruit and Veggie Supplements -- Find Out If They Are Worthwhile and See Our Test Findings

Product Review

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

Find Out What Magnesium Does, Who Needs It, and Our Top Picks Among Supplements

Product Review

Berberine and Goldenseal Supplements Review

Choose the Best Berberine & Goldenseal Supplements. CL Tests Reveal Problems With 25% of Berberine and 67% of Goldenseal Supplements.

Berberine and goldenseal supplements reviewed by

CL Answer

I take omeprazole (Prilosec), a proton pump inhibitor, to reduce stomach acid. Are there supplements I should avoid, or be taking, due to this drug?

Supplement interactions with proton pump inhibitor (PPI) drugs like omeprazole (Prilosec) and Nexium.

Product Review

Aloe Juices, Gels, and Supplements Review

How Much Aloe is Really in Aloe Products? Find Out and See Our Top Picks.

CL Answer

Does Z-Stack multivitamin work to boost the immune system, and is it safe?

Find out about Z-Stack, including if it can help boost the immune system and if it is safe to use at the suggested dose.

A bottle of Z-Stack capsules

CL Answer

Do any supplements naturally suppress appetite and help with weight loss?

Learn which natural ingredients can suppress appetite and find if these natural appetite suppressants help with weight loss.

Container of natural appetite suppressant supplement with measuring tape and scale in background

CL Answer

Is it safe to drink coffee regularly? Does drinking coffee increase or decrease the risk of cancer?

Learn more about coffee, its safety, if it's good for you, and if it impacts your risk of cancer.

CL Answer

Does OsteoMD improve calcium absorption and increase bone density?

ConsumerLab reviews the evidence for OsteoMD by 1MD, a bone health supplement promoted to slow bone loss and reduce the risk of osteoporosis.

OsteoMD by 1MD

CL Answer

What are the health benefits of grapefruit seed extract (GSE)? Is it safe?

Learn more about grapefruit seed extract health benefits, including its possible antifungal and antibacterial effects and its safety.

Grapefruit with Extract and Spoon

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

CL Answer

Do diamine oxidase (DAO) supplements for histamine intolerance really work?

DAO supplement info for histamine intolerance, including diamine oxidase safety, evidence from clinical studies, and dosage.

Person in Pink Shirt Scratching Arm

CL Answer

What is lactoferrin and will it really strengthen my immune system?

Info about lactoferrin supplements, clinical evidence for strengthening the immune system, preventing or treating colds, gut health and treating H.

What is Lactoferrin? -- lactoferrin capsules and bottle

News Release


Best Probiotic Supplements Identified by ConsumerLab Tests

  White Plains, New York, November 10, 2022 — Probiotic supplements can be helpful in preventing or treating constipation, diarrhea, flatulence, vaginal infections, and other conditions, but with so many different products on the market, choosing the best one is no easy task.

Recalls & Warnings


Senna Laxative Recalled Due to Microbial Contamination

On January 11, 2022, Lohxa LLC issued a voluntary recall of one lot of Senna Syrup 8.

CL Answer

10 Supplements That May Help Reduce Nighttime Urination (And 5 That May Not)

Waking up more than once during the night to use the bathroom? Learn more about the 9 supplements that may help and 5 others that don't.

A toilet in an empty bathroom at night

CL Answer

Top 8 Supplements for Vegetarians and Vegans

Find out which 8 supplements may be needed by vegetarians or vegans to meet all their daily nutrient requirements and learn ways to find supplements that do not contain ingredients objectionable to people following vegetarian or vegan diets.

Woman pouring supplements into her hand while sitting in front of a table on which vegetables are placed

CL Answer

Does Prevagen really improve memory?

Learn more about Prevagen, including clinical studies on Prevagen's impact on memory & cognition, safety, pricing, and an FDA warning letter. ConsumerLab explores the efficacy of Prevagen.

Prevagen for Memory? -- bottle of Prevagen

CL Answer

Is there a risk of liver toxicity with certain supplements?

Find out if there is risk of liver damage from supplements such as green tea, niacin, red yeast rice and vitamin A.

Liver Shape Made From Paper with Pills and Bottle Against Blue Background

CL Answer

What are trace minerals and do I need them?

Trace minerals include boron, chromium, copper, iodine, iron, manganese, molybdenum, nickel, zinc, and others. Find out what they do, how much of each trace mineral you should be getting, and who's most likely to be deficient in these minerals.

Trace Minerals - What are they and do you need them?

Product Review

Calcium and Bone Health Supplements Review (Including Vitamins D & K, Magnesium and Boron)

See Which Bone Health Supplements Are Top Picks and Which Fail

Product Review

Turmeric and Curcumin Supplements and Spices Review

Find the Best Turmeric and Curcumin Supplements & Spices. Big Differences Discovered Among Brands -- Little Curcumin In Some.

Turmeric and Curcumin Supplements and Spices Reviewed by

Recalls & Warnings


Prune & Senna Softgels Recalled Due to Undeclared Peanuts

On March 26, 2022, Indiana Botanic Gardens Inc. issued a voluntary recall of one lot of Botanic Choice brand Prune & Senna Softgels because the product contained undeclared peanuts.

News Release


Labels on Prebiotic Supplements Are Often Unreliable, Tests Show

  White Plains, New York, October 28, 2022 — Prebiotic supplements provide fiber that feed beneficial bacteria in the gut. However, recent ConsumerLab tests show that consumers often can’t rely on labels to know how much prebiotic fiber is really in products.

Recalls & Warnings


CVS, Target, Walgreens, and Other Oral Magnesium Citrate Laxatives Recalled Due to Bacterial Contamination

On July 14, 2022, Magnesium Citrate Laxative Oral Solution Lemon Flavor products manufactured by Vi-Jon, LLC and sold under various store brand names were recalled after testing identified the presence of the bacteria Gluconacetobacter liquefaciens.

News Release


Best Iron Supplements for Different Needs? ConsumerLab Selects Its Top Picks

White Plains, New York, February 10, 2022 — With so many different forms and doses of iron available from supplements, it can be difficult for consumers to know which best suits their needs.

Recalls & Warnings


Canadian Creatine Recalled for Dangerous Levels of Vitamin D

On February 21, 2021, the Canadian company Genex Nutraceuticals recalled one lot of Perfect Sports Core Series Pure Creatine (also known as Creatine Powder) because it "contains vitamin D that is not listed on the label, at dangerous levels.

Recalls & Warnings


Clover Leaf Sardines Recalled Due to Risk of Botulism

On January 22, 2021, Clover Leaf Seafoods Corp.

News Release


ConsumerLab Tests Reveal Best Probiotic Supplements and Those With Quality Issues

White Plains, New York, April 14, 2020 — Probiotic supplements may be helpful for conditions including antibiotic-associated diarrhea, irritable bowel syndrome, and respiratory infections.

Recalls & Warnings


Company Failed to Report Adverse Events Associated With Its Nutrition Shakes

On February 12, 2020, the FDA sent a warning letter to Market America Inc for failure to submit serious adverse event reports about two of its products, as required by federal regulation. The company received two reports following serious adverse events but did not submit the proper forms:

Recalls & Warnings


CBD Oil Recalled, Risk of High Lead Exposure

On May 15, 2020, Summitt Labs issued a recall of one batch of KORE ORGANIC Watermelon CBD Oil Tincture due to contamination with lead. A random sample of this product tested by the Florida Department of Agriculture and Consumer Services found it to contain lead levels at 4.7 ppm.

Recalls & Warnings


Alaskan Smoked Silver Salmon in Jars and Cans Recalled Due to Risk of Botulism

On February 15, 2019, Smoked Alaska Seafoods, Inc. recalled all jars and cans of Smoked Silver Salmon because it has the potential to be contaminated with Clostridium botulinum, a bacterium which can cause life-threatening illness or death.

Recalls & Warnings


Homeopathic Teething Tablets and Gels May Pose Danger, FDA Warns

On September 30, 2016, the FDA warned consumers that homeopathic teething tablets and gels may be dangerous for infants and children. The agency has received adverse events reports, including seizures, associated with the use of these products.

Recalls & Warnings


51 CBD Products Recalled Due to Lead Contamination

On June 23, 2020, InHe Manufacturing, LLC and MHR Brands issued a recall of fifty-one CBD products due to contamination and/or potential with lead. Thirty-six of the products are marketed for people and fifteen of the products are marketed for pets.

Recalls & Warnings


Herbal Teas Recalled Due To Botulism Risk

On May 1, 2017, U.S. Deer Antler Ex. & Imp. of Los Angeles, California, issued a recall of various herbal teas because they have the potential to be contaminated with Clostridium botulinum. This bacterium can cause botulism, a potentially fatal form of food poisoning.

Recalls & Warnings


FDA Testing Confirms Elevated Levels of Belladonna in Some Homeopathic Teething Products

On January 27, 2017, the FDA announced that its laboratory analysis found "inconsistent amounts of belladonna, a toxic substance, in certain homeopathic teething tablets, sometimes far exceeding the amount claimed on the label.

Recalls & Warnings


U.S. Marshals Seize $150,00 Worth of Kratom

On August 4, 2016, the FDA announced that U.S. Marshals seized approximately $150,000 worth of dietary supplements labeled as containing kratom from Nature Therapeutics (dba Kratum Therapy). The action was taken at the request of the FDA.

Recalls & Warnings


FDA Warns Parents to Be Careful Giving Vitamin D Drops to Infants

On June 15, 2010, the U.S. FDA (Food and Drug Administration) alerted parents and caregivers that some liquid Vitamin D supplement products are sold with droppers that could allow excessive dosing of Vitamin D to infants.

News Release


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


Seller of Aloe, Moringa Supplements Warned for Manufacturing Violations, Drug Claims

On January 13, 2016, the FDA issued a warning letter to Alkebulan International Services, LLC, following a facility inspection which found the company's products,Aloe Ferox and Moringa Oleifera Capsule to be adulterated because they prepared, packed, or held under conditions that ...

Recalls & Warnings


Over $400,000 Worth of Kratom Supplements Seized by U.S. Marshals

On January 6, 2016, U.S. Marshals seized nearly 90,000 bottles of dietary supplements labeled as containing kratom (brand name RelaKzpro) valued at over $400,000, from Dordoniz Natural Products LLC in South Beloit, Illinois. The action was taken at the request of the FDA.

Recalls & Warnings


Children and Adult Gummy Vitamins Recalled in Canada Due to Excessive Vitamin D

On August 6, 2015, Health Canada (the Canadian equivalent of the U.S. FDA) announced Church & Dwight Canada Corp. is recalling the following supplements because they contain more vitamin D than claimed on the label (identified in Canada by their assigned natural product number (NPN):

Recalls & Warnings


U.S. Marshals Seize $5 Million Worth of Kratom

On September 25, 2014, U.S. Marshals seized more than 25,000 pounds of raw kratom valued at over $5 million from Rosefield Management, Inc. in Van Nuys, California. The action was taken at the request of the FDA.

Recalls & Warnings


Seller of Flaxseed, Ginkgo and More Warned for Manufacturing Violations and Drug Claims

On April 18, 2014, the FDA issued a warning letter to Iowa Select Herbs, LLC, following a facility inspection which found the company's products, including Flax Seed, Holy Basil, Papaya Leaf Extract, and Ginkgo Leaf Extract products, to be adulterated because they were prepared, packed, or held ...

Recalls & Warnings


Products Containing Kratom Recalled Following FDA Import Alert

On March 14, 2014, SNI National issued a voluntary recall of all kratom supplements, including kratom XL 4 Pack, Maeng Da Kratom 10 Pack, Max Kratom 20 Pack, and Bali Kratom 40 pack, following an FDA-issued import alert on all products containing this ingredient.

Recalls & Warnings


Teas Recalled Due To Potential Botulism Contamination

One June 28, 2013, Harmony Chai issued a voluntary recall of its Concentrated Black Spiced Chai and Decaffeinated Rooibos Chai bottled tea drinks, because they have the potential to be contaminated with Clostridium botulinum.

Recalls & Warnings


Glucomannan May Cause Choking if Not Taken with Fluid

On January 29, 2010, the Canadian health department, Health Canada, adised that natural health products containing the ingredient glucomannan in tablet, capsule or powder form have a potential for harm if taken without at least 8 ounces of water or other fluid.

News Release

6/10/2015 Tests Reveal Best and Worst Magnesium Supplements

White Plains, New York, June 10, 2015 — Magnesium supplements have become extremely popular, surpassing even calcium among frequent users of supplements. However, recent tests by ConsumerLab.

News Release

3/13/2006 reports on supplements for bone health containing calcium and vitamin D— Results posted for 32 supplements for adults and children; One found contaminated with lead

WESTCHESTER COUNTY, NEW YORK — MARCH 13, 2006 — announced test results today from its new Product Review of Supplements for Bone Health covering 32 adult and children's products containing calcium and vitamin D. Sales of calcium supplements in the U.S.

Recalls & Warnings


Recall of Calcium & Magnesium Softgels Containing Excessive and Potentially Toxic Amounts of Vitamin D

On or about June 7, 2011, NOW Foods announced the following recall to retailers. was subsequently made aware of the recall by a member.

Recalls & Warnings


Seller of "NaturalDoctor" Vitamin C, Echinacea and More Warned for Manufacturing Violations

On October 16, 2015, the FDA issued a warning letter Sound Healing Arts, PC, dba Grounds for Tea, LLC, following a facility inspection which found the company's products, including  NaturalDoctor Vitamins C & K3, NaturalDoctor Goldenseal & Echinacea Plus, NaturalDoctor Centella ...