The 7 Best Iron Supplements of 2022, According to a Dietitian

Combat iron deficiency with the correct supplement

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Best Iron Supplements

Verywell / Sabrina Jiang

PLEASE NOTE: Dietary supplements are not regulated by the FDA, meaning there is no guarantee that they are safe. Food is the preferred source of nutrition, and most people can meet their nutritional needs from food alone. Supplements may be useful when there is a specific nutrient deficiency, but they are not treatments or cures for any conditions or diseases. It is important to check with your healthcare provider before beginning any supplement regime.

Iron is an essential mineral the body requires for growth, cell functioning, and brain development. The body also uses iron to make hemoglobin, a component of red blood cells that carries oxygen around the body, as well as myoglobin, which supplies oxygen to the muscles.

The amount of iron required daily depends on an individual’s age, sex, and overall diet. Not obtaining enough iron can result in feelings of fatigue, lack of energy, difficulty concentrating, irritability, and impaired immune function. Those at higher risk of iron deficiency include infants and young children, women of reproductive age, individuals who experience heavy menstrual bleeding, pregnant women, frequent blood donors, endurance athletes, those who follow a vegetarian or vegan diet, and people with cancer, kidney failure, gastrointestinal disorders, or heart failure.

It is preferable to obtain iron from food, as food provides additional benefits such as energy, fiber, other nutrients, and reduced risk of toxicity. However, if a healthcare professional confirms an iron deficiency or anemia via blood test and determines needs cannot be met through food alone, using an iron supplement may become necessary.

Supplemental iron comes in various forms including capsules, liquid, chewable tablets, and gummies. According to Jamie Gershel, MS, RD, “The best way to make sure your iron supplement is working for you is to take iron on an empty stomach with water. If that is not an option, pair your iron pill with vitamin C rich foods or a cup of orange juice.” It is also important to take iron supplements separately from calcium, tea, zinc, and antacids as these items can inhibit absorption.

When deciding which iron supplement is best for you, consider appropriate dose, budget, ingredients, and the form of iron that will be absorbed well but not cause you gastrointestinal discomfort. Iron supplementation should only be done under the recommendation and supervision of a healthcare professional.

Who May Not Benefit From Iron Supplements

Individuals who obtain adequate amounts of iron from their diets and do not have a confirmed deficiency should not utilize iron supplements as there is risk of toxicity. Certain individuals are at higher risk of iron overload. Healthy postmenopausal women and adult men should typically avoid iron supplements, as well as those with hemochromatosis, a hereditary condition that results in absorption of excessive amounts of dietary iron.

While many people with iron deficiency may benefit from iron supplements, this is not the case for everyone. Individuals with iron deficiency who also use proton pump inhibitors may not respond well to iron supplementation. This is because proton pump inhibitors reduce stomach acid, which is involved in iron absorption. Additionally, those with malabsorptive conditions such as celiac disease may not be able to absorb iron until the disorder is managed.

Individuals utilizing other medications or supplements that may interact with iron supplements should also be cautious. Iron supplements reduce absorption of levodopa, found in medications that treat Parkinson’s disease and restless leg syndrome. Iron can also reduce the effectiveness of levothyroxine, found in medications used to treat hypothyroidism, goiter, and thyroid cancer. It is best to consult with your healthcare provider to discuss any potential interactions before beginning iron supplementation.

Iron Supplement Efficacy

The efficacy of iron supplements will depend on the underlying cause of deficiency, which should be determined first, as well as an individual’s adherence to supplementation. If the cause of the deficiency is a malabsorptive gastrointestinal disorder, then supplementation will not be helpful without correcting the underlying issue.

Studies demonstrate that, among those without malabsorptive conditions, oral iron supplements are indeed effective in correcting iron deficiency and iron deficiency anemia. Every other day supplementation has been shown to mitigate gastrointestinal symptoms and be as effective at raising iron levels and reducing fatigue among iron deficient individuals when compared to daily dosing. However, in cases of severe deficit, daily supplementation may be required. For those who do not tolerate oral iron treatments, IV therapy may be necessary. Studies also demonstrate that iron supplementation among pregnant women can prevent iron deficiency anemia and reduce risk of anemia.

Endurance athletes, and females in particular, may be at greater risk of iron deficiency due to greater iron demands and iron losses in sweat, menstruation, and intestinal blood loss. Studies show iron supplementation among athletes with a known deficiency, or who are iron deficient but not anemic, may improve performance. For athletes that are not iron deficient, iron supplementation will not enhance performance and should be avoided.

What to Look For in an Iron Supplement

Third Party Testing

Supplements that are third-party tested are sent to a lab where they are tested to ensure they contain what they say they contain and are not contaminated with specific high-risk, common contaminants. However, it’s important to note:

  1. Third party testing does not test to see if a product is effective or safe for everyone, and it does not ensure the supplement will not interact with other supplements or medications.
  2. Not all third-party testing is created equal. It is not uncommon for supplement companies to pay labs for certificates after conducting minimal to no testing. 
  3. The third party certifications we can trust are: ConsumerLabs, NSF, and USP. However, these certifications are difficult to obtain and/or expensive, so many companies choose not to get their products tested by one of these three organizations. 
  4. Sometimes products tested by these three companies are more expensive to try to offset the cost they pay for certification.
  5. Just because a supplement is not tested by one of these three companies, it does not mean it’s a bad product. We recommend doing some research on the reputability of the manufacturer, and calling up the manufacturer and their testing lab to determine their protocols and decide if you feel comfortable consuming the supplement.

While not common, some iron supplements have been found to be contaminated with lead. As there is no single agency responsible for testing supplements, it is also possible that iron supplements do not contain the amount of iron listed on the label. It is therefore best to use iron supplements that have been third party tested and to use them while under the supervision of a licensed healthcare provider.


Dietary iron can be found in two forms, known as heme iron and non-heme iron. Heme iron can be found in foods such as poultry, seafood, and meat, while non-heme iron can be found in plant foods including nuts, beans, vegetables, and iron-fortified foods. While the body is able to more readily absorb heme-iron, pairing non-heme sources with vitamin C rich foods or heme sources can enhance absorption. 

Supplemental iron can be administered intravenously or taken orally via liquid, pills, or gummies. Iron in supplemental form typically comes as ferrous or ferric iron salts. Ferrous iron in supplements is more readily absorbed than ferric iron. It may be best to avoid slow-release capsules, as these are poorly absorbed. Additionally, the varying forms of iron in supplements contain different amounts of elemental iron, the amount of iron the body can absorb. The amount of elemental iron is listed on the supplement facts panel.  

Ingredients, Potential Interactions, & Contraindications

It is essential to carefully read the ingredient list and nutrition facts panel of a supplement to know which ingredients and how much of each ingredient is included, relative to the recommended daily value of that ingredient.

In addition to iron, some supplements may contain vitamin C to aid in absorption. They also may contain other vitamins, minerals, and herbs as well as flavors, colors, and preservatives. Please bring the supplement label to your healthcare provider to review the different ingredients contained in the supplement and any potential interactions between these ingredients and other supplements and medications you are taking.

Iron supplements can interact with medications containing levodopa or levothyroxine. Use of proton pump inhibitors or calcium supplements may lower the effect of iron supplements. 

Excess Iron Supplementation/Toxicity

Consuming excess supplemental iron can be dangerous. Acute intakes of over 20 mg/kg can result in gastric upset, constipation, vomiting, and faintness. Repeated high dose supplementation can lead to stomach pain, nausea, vomiting, and over time can result in damage to the liver or brain.

The Tolerable Upper Intake Level for iron, which refers to the maximum daily amount that can be safely taken, from birth until 13 years is 40 mg, and for 14 years and older, is 45 mg. Unless a deficiency is being treated, no more than 45 mg should be taken to avoid harmful side effects and iron overload.

What Experts Say

"For those who experience constipation during supplementation, I recommend focusing on good hydration and fiber intake. Aim for at least 2 liters of water daily. Fiber recommendations for the average adult range from approximately 25 to 35 grams per day.  When increasing fiber in your diet, make sure to go gradually and ensure that you are spreading it out throughout the day for optimal tolerance." — Arielle Leben, RD

Iron Dosage

Always speak with a healthcare professional before adding a supplement to your routine to ensure that the supplement is appropriate for your individual needs and to determine which dosage to take.

According to the National Institutes of Health, the Recommended Dietary Allowances for iron are as follows:

1-3 Years: 7 mg

4-8 years: 10 mg

9-13 years: 8 mg

14-18 years: Males - 11 mg, Females - 15 mg

19-50 years: Males - 8 mg, Females - 18 mg

51+ years: 8 mg

Note that iron needs for females are higher during menstruating years, due to iron loss in blood. Additionally, iron needs differ for infants and for people who are pregnant and lactating. Transgender individuals ages 14-50 should work with their healthcare provider to assess iron needs, which will vary based on menstruation status and other variables.

Frequently Asked Questions

  • When should I take iron supplements?

    Iron supplements should only be used if a medical professional has determined you have an iron deficiency or iron deficiency anemia. They will prescribe the proper dosage and regimen.

  • Can iron supplements cause constipation?

    Iron supplements may cause constipation, especially when taken in higher doses of 45 mg/day or more. Certain forms of iron such as heme iron polypeptides, carbonyl iron, iron amino-acid chelates, and polysaccharide-iron complexes may have fewer digestive effects when compared to ferrous or ferric salts. To help alleviate constipation, incorporate adequate dietary fiber, fluids, and daily movement or consider using a stool softener.

  • Can iron supplements cause diarrhea?

    Iron supplements can cause diarrhea in some people, especially when high doses are taken on an empty stomach. The risk may be reduced with certain forms of iron, such as iron bisglycinate, or by taking iron supplements with food.

  • How should I take iron supplements for best absorption?

    For best absorption, iron supplements should be taken with water on an empty stomach in the morning or taken with a vitamin C containing drink. If taking iron on an empty stomach causes adverse side effects, consider taking iron bisglycinate with a small amount of food. Taking iron as ferrous sulfate with food can reduce absorption, while other forms such as ferrous bisglycinate or ferrous glycinate are better absorbed with food. Avoid taking iron supplements with calcium, caffeine, tea, zinc, or antacids.

  • How soon after taking iron supplements will I feel better?

    Most people will feel better within a few days to about three weeks, although it can take longer depending on your needs and the cause of deficiency. It is important to continue with iron supplementation as prescribed until iron stores are restored.

How We Select Supplements

Our team works hard to be transparent about why we recommend certain supplements; you can read more about our dietary supplement methodology here

We support supplements that are evidence-based and rooted in science. We value certain product attributes that we find to be associated with the highest quality products. These attributes include non-GMO, Organic, and allergy-friendly products that are free of most artificial ingredients including colors, flavors, preservatives, and sweeteners. We prioritize products that are third-party tested and certified by one of three independent, third party certifiers: USP, NSF, or ConsumerLabs. 

It's important to note that the FDA does not review dietary supplements for safety and effectiveness before they go to market. Our team of experts has created a detailed, science-backed methodology to choose the supplements we recommend.

Here, the best iron supplements for people with iron deficiency.

Our Top Picks
This iron bisglycinate formula is readily absorbed and contains 139% of the recommended daily value.
Best GI Friendly:
NOW Supplements Iron at Amazon
Made with ferrous bisglycinate, it has a better absorption rate and is less likely to cause gastrointestinal distress.
This wallet-friendly supplement contains 361% of the required daily value for iron.
Best with Vitamin C:
Zahler Iron Complex at Amazon
It contains an additional 60 mg of vitamin C to ensure that the iron is thoroughly absorbed.
This liquid supplement contains 10 mg of iron from an organic food blend, along with vitamin C, vitamin B12, and vitamin B6.
It's certified gluten-free, kosher, non-GMO, and is free from artificial colors, sweeteners, and preservatives.
This chewable tablet also contains vitamins C and B12, folic acid, and a proprietary blend of other nutrients.

Best Overall: Thorne Research Iron Bisglycinate

Thorne Research Iron Bisglycinate
  • NSF Certified for Sport

  • Contains well tolerated iron bisglycinate

  • No artificial flavors

  • Expensive

Thorne Iron Bisglycinate contains 25 mg of iron bisglycinate per capsule, a form of iron that is readily absorbed and typically does not result in gastrointestinal side effects such as nausea and constipation. The amount contained in these capsules provides 139% of the Daily Value of iron needed. It is also free from gluten, dairy, and soy.

Thorne Iron Bisglycinate is NSF Certified for Sport, so it has been tested to ensure absence of substances prohibited by sports organizations and is safe for athletes to use. Thorne also has cGMP certification and an A rating from Australia’s Therapeutic Goods Administration. Despite these benefits, Thorne Iron Bisglycinate is a more expensive choice.

Form: Capsule | Type: Iron bisglycinate | Dose: 25 mg | Recommended Use: Once daily | Third Party Certified: Yes

Best GI Friendly: NOW Supplements Iron

NOW Supplements Iron
  • ConsumerLab tested and approved

  • Contains easily absorbed ferrous bisglycinate

  • May cause less gastrointestinal discomfort

  • Dose of iron may not correct deficiency

One of the greatest struggles many people face with iron supplements is potential gastrointestinal distress. In addition to general discomfort, this can result in lowered adherence and failure to correct the deficiency. NOW Iron contains ferrous bisglycinate, which when taken with food has been shown to be two to four times better absorbed when compared to ferrous sulfate. This product is also suitable for vegans and vegetarians and is non-GMO.

While it may be gentle on the stomach, NOW Iron contains 18 mg iron. This is the daily requirement for women aged 19-50, but it may not be enough to correct an iron deficiency. Your healthcare provider will recommend an appropriate dose based on your needs.

Form: Capsule | Type: Ferrous bisglycinate | Dose: 18 mg | Recommended Use: Once daily with food | Third Party Certified: Yes

Best Budget: Nature Made Iron

Nature Made Iron
  • USP certified and ConsumerLab tested and approved

  • Inexpensive

  • Contains ferrous sulfate which is absorbed well

  • Dose above the Upper Limit; may not be indicated for all consumers

Iron supplements vary in price, and the cost can add up over time. For those able to tolerate ferrous sulfate, Nature Made is an affordable option with 180 tablets per bottle. Iron in all forms is best absorbed when taken with only water, although this is more likely to cause stomach issues. For those who experience digestive upset, iron can be taken with food. The instructions for use with this supplement recommend taking it with water and a meal.

Nature Made provides a higher dose of iron at 65 mg, or 325 mg ferrous sulfate. This amount is equivalent to 361% of the Daily Value. This higher amount of iron may be necessary for those with a deficiency but should be used under a healthcare provider's recommendation and supervision.

Form: Tablet | Type: Ferrous sulfate | Dose: 65 mg | Recommended Use: Once daily with water and a meal | Third Party Certified: Yes

Best with Vitamin C: Zahler Iron Complex

Zahler Iron Complex
  • Contains vitamin C to enhance absorption

  • Easily absorbed form of iron

  • Not third party tested

Iron is unique in that the body does not have a method to eliminate excess, but rather levels are regulated only through absorption. Some studies show vitamin C may help enhance absorption of non-heme iron. Zahler contains 25 mg iron bisglycinate and 60 mg vitamin C to aid in absorption.

While Zahler Iron is not third party tested, their products are produced in a cGMP certified facility. Zaher Iron is also certified kosher, non-GMO, and is free from gluten, dairy, and soy.

Form: Capsule | Type: Iron bisglycinate | Dose: 25 mg iron bisglycinate & 60 mg vitamin C | Recommended Use: Once daily with food | Third Party Certified: No

Best Liquid: Garden of Life mykind Organics Plant Iron & Organic Herbs

  • ConsumerLab tested and approved

  • Contains vitamin C to aid absorption

  • Certified organic & vegan

  • Amount of iron may not correct deficiency

  • Extensive ingredient list

For those who dislike swallowing pills, iron supplements can also be found in liquid form. Liquid iron is convenient and easy to add to water or juice. Garden of Life mykind Organics Plant Iron & Organic Herbs contains iron from an organic food blend, along with vitamin C, vitamin B12, and vitamin B6. This liquid supplement contains 10 mg of iron, which is 55% of the Daily Value. The dose may not be adequate for those with iron deficiency or anemia, so it is always best to consult with your healthcare provider.

This supplement is made entirely from whole food ingredients. However, the ingredient list is extensive and includes herbs, so be sure to read the entire ingredient list with your healthcare provider to check for allergens and potential interactions with other medications or supplements.

Of note, this supplement is certified organic, gluten-free, and vegan and may be more palatable than other liquid options.

Form: Liquid | Type: Organic whole food blend | Dose: 10 mg | Recommended Use: 10 ml daily directly or mixed into water or juice | Third Party Certified: Yes

Best Vegan: Country Life Easy Iron

Country Life Easy Iron
  • ConsumerLab tested and approved

  • Suitable for vegans and vegetarians

  • Contains a gentle form of iron

  • Does not contain vitamin C for added absorption

For those who follow a vegan diet, Easy Iron Country Life is certified vegan by the American Vegetarian Association. It provides 25 mg of ferrous bisglycinate, a form of iron that is typically gentle on the stomach. Easy Iron Country Life is aso certified gluten-free, kosher, non-GMO, and is free from artificial colors, sweeteners, and preservatives.

Easy Iron Country Life contains minimal ingredients and does not include vitamin C for enhanced absorption. Country Life recommends taking the pill with food, and we recommend pairing it with a vitamin C-rich food or drink (like orange juice!) for enhanced absorption.

Form: Capsule | Type: Ferrochel ferrous bisglycinate | Dose: 25 mg | Recommended Use: Once daily (if possible, with food) | Third Party Certified: Yes

Best Chewable: VegLife Vegan Iron Chewable Tablets

VegLife Vegan Iron Chewable Tablets
  • ConsumerLab tested and approved

  • Suitable for vegans

  • Convenient chewable tablets

  • Dose may not correct iron deficiency

  • Contains sugar alcohols

  • Extensive ingredient list

People who dislike swallowing pills may prefer taking their iron supplements in chewable form. VegLife Iron Vegan Chewable Tablets provide 18 mg of iron as iron glycinate. In addition to iron, these chewables also contain vitamin C, folic acid, vitamin B12, and a proprietary blend that includes spinach, parsley, dandelion, alfalfa, and rose hips. They are suitable for vegans and are sugar free.

Vegans and some vegetarians need to supplement with B12, so check with your healthcare provider to see if this supplement may be able to also serve as your B12 supplement. Since this option contains other nutrients, herbs, and sugar alcohols, it is especially important to show the label to your healthcare provider so they can cross-check the ingredients with other supplements and medications you might be taking.

VegLife Vegan Chewable Tablets contain 18 mg of iron, the daily requirement for premenopausal women. This dose may not be high enough to correct a deficiency.

Form: Tablet | Type: Ferrous fumarate | Dose: 18 mg | Recommended Use: One chewable once daily | Third Party Certified: Yes

Final Verdict

The correct iron supplement for you will depend on the dose you need. However, Thorne Iron Bisglycinate (view on Amazon) is an excellent iron supplement. In addition to being less likely to cause gastrointestinal distress, this supplement is safe for athletes and has NSF Certified for Sport, cGMP, and TGA certifications. For a more affordable option, consider NOW Iron (view on Amazon), which provides a lower dose of iron in the form of ferrous bisglycinate.

Why Trust Verywell Health

Tamar Kane, MS, RD is a Registered Dietitian and marathon runner. Tamar has her masters degree in nutrition and exercise physiology from Teachers College and specializes in working with plant-based athletes, one of the populations at highest risk for iron deficiency. Her goal is to help people understand how to properly fuel their bodies (and supplement if needed!) to optimize performance and wellbeing.

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