These Iron Supplements Are Least Likely to Upset Your Stomach, According to Experts

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Getting enough iron is essential for a functioning and healthy body. Those deficient in the mineral may need to try the best iron supplement to help maintain healthy muscles, stable energy levels, and a clear mind.

“Iron is a mineral that the body needs for growth and development,” explains Catherine Canadeo, board-certified holistic health coach and integrative nutritionist based in Westbury, New York. “Your body uses iron to make hemoglobin, a protein in red blood cells that carries oxygen from the lungs to all parts of the body, and myoglobin, a protein that provides oxygen to muscles.” She adds that iron also partially makes up proteins that support muscle metabolism, healthy connective tissue, neurological development, and overall cell function. Plus, iron supports the production of some hormones, she says.

Meet the Experts: Catherine Canadeo, board-certified holistic health coach and integrative nutritionist based in Westbury, New York, Chisom A. Ikeji, M.D., assistant professor of critical care medicine at University of Pittsburgh, and Mona Rosene, M.S., R.D., global director of scientific affairs at ChromaDex.

Iron is best absorbed through foods like meat, poultry, and seafood, but most Americans don’t get the daily recommended amount (8 milligrams for adult males, 18 mg for adult females, per the National Institutes of Health), adds Chisom A. Ikeji. M.D., assistant professor of critical care medicine at University of Pittsburgh and Nature Made wellness ambassador. That’s especially the case for plant-based eaters, who “need almost twice as much recommended iron,” Ikeji continues, because the body does not absorb the type of iron found in plants (non-heme) as easily as it absorbs the type found in meat (heme). That setback, however, may be partially counteracted by plant eaters’ intake of vitamin C, which has been found to improve the absorption of non-heme iron.

Although iron deficiency is an issue, so is getting too much, which is why it’s crucial to consult a doctor for blood work before adding a supplement to your regimen. “There is no regulated way to excrete iron from the body,” explains Ikeji—it’s only lost through bleeding. Therefore, excess iron “can cause severe harm to your cells and organs,” resulting in symptoms like constipation, nausea, vomiting, abdominal pain, and diarrhea, Dr. Ikeji adds.

Our top picks

Dietary supplements are products intended to supplement the diet. They are not medicines and are not intended to treat, diagnose, mitigate, prevent, or cure diseases. Be cautious about taking dietary supplements if you are pregnant or nursing. Also, be careful about giving supplements to a child, unless recommended by their healthcare provider.

So, if your doctor has given you the green light to hunt for an iron supplement, keep scrolling for expert-recommended picks.

Pure Encapsulations OptiFerin-C

Canadeo recommends this supplement because it “supports red blood cell function and energy production,” she says. Plus, the chelated formula is chemically modified to be easy on the digestive system, and it’s gluten-free, non-GMO, and hypoallergenic. Canadeo also likes that is was third party tested for quality and purity.

Iron 65 mg

Dr. Ikeji recommends this supplement “because it provides a high dose, which is good for those with iron deficiency anemia,” she explains. It contains ferrous sulfate, a non-heme iron. “Oral iron supplementation should be taken on an empty stomach, since food may inhibit iron absorption,” Ikeji adds.

Nature's Bounty Gentle Iron 28 mg 90 Capsules

Mona Rosene, M.S., R.D., global director of scientific affairs at ChromaDex prefers chelated iron supplements, or supplements that are chemically altered to prevent them from breaking down during digestion, which aids in absorption and is usually “easier on the stomach and doesn’t tend to cause constipation,” she says. This one is highly rated for its gentle effects (hence the name), and also contains ascorbic acid (vitamin C) to boost absorption, as well as vitamin B12.

Base Control Daily Women's Multivitamin + Iron

This multivitamin is meant to fill any nutrition gaps in your diet with 22 essential nutrients including iron and vitamins A, C, D3, and E, as well as calcium, magnesium, and zinc. The vegan formula is especially recommended for pre- and perimenopausal people, per the brand, as they’re prone to experiencing iron deficiency.

Iron Liquid

There is some thought that liquid iron is more easily absorbed than iron in capsule form, though more research is warranted to confirm that. Liquid also may be easier on the digestive system. If you’ve tried capsules without success and want to give liquid a try, this fruit-punch-flavored formula (sweetened with Stevia) is a reviewer favorite.

Iron Bisglycinate

Canadeo recommends this iron supplement for its minimal ingredients and gentle chelated iron. It’s also third-party tested and NSF-certified for sport, meaning it’s free of substances banned by some organized sports. With over 4,000 Amazon ratings it maintains a 4.6-star rank.

Blood Builder Iron

Another recommendation from Canadeo, this supplement was third-party tested and clinically shown to increase iron levels without side effects. It contains vitamin C for increased absorption, as well as vitamin B12 and folic acid to support red blood cell production. A blend of beetroot, organic orange, broccoli, and brown rice gives it a superfood boost.

Iron Supplement

Iron sourced from bovine makes this a natural pick, plus, the supplement contains added wild hake roe and plant and mushroom extracts to deliver extra nutrients and fatty acids for well-rounded support. It also contains vitamin C for boosted absorption and is gluten-free.

How to choose the best iron supplement

Because iron toxicity presents very real health risks, it’s vital to consult your doctor and get checked for an iron deficiency before taking an iron supplement. Then, together, you can narrow down the best pick for you based on dosage and ingredients.

Once you get the okay from your provider, consider the following:

• Liquid versus capsule form

• Additional vitamins and minerals in the supplement

• Price

• Strength

When should you take an iron supplement?

Your healthcare provider can help you determine if you have an iron deficiency. But in terms of when during the day, “Oral iron supplementation should be taken on an empty stomach, since food may inhibit iron absorption,” says Dr. Ikeji.

What is the best form of iron supplement to take?

In dietary form, heme iron, which is most commonly found in meat, poultry, and seafood, is most easily absorbed, says Dr. Ikeji. With that being said, most supplements contain non-heme iron, the type of iron found in plant-based foods, with added ingredients like vitamin C to boost absorption because it tends to be easier on the stomach.

“Even though heme iron is better absorbed, it is easy to take higher quantities of non-heme iron, so that the net amount of iron absorbed is about equal,” explains Canadeo. “In other words, if you take 3 mg of heme iron and 50 mg of non-heme iron, the net absorption for each will be the same.”

Who needs an iron supplement?

Those who may benefit from an iron supplement include pregnant people, people with heavy menstrual cycles, frequent blood donors, elderly people, and people on strict vegan or vegetarian diets, explains Rosene. Dr. Ikeji adds that people with digestive conditions Crohn’s disease, celiac disease, or irritable bowel syndrome may also need one.

“Signs of iron deficiency anemia include fatigue, weakness, and ice cravings,” Rosene adds. “Prior to supplementation, please consult with your healthcare provider.”

How much iron should I take?

“The amount of daily recommended iron varies based on age, sex, pregnancy status, current iron stores, and your diet, making it difficult to state an average,” says Dr. Ikeji. According to the National Institutes of Health, the daily recommended intake for adult men is 8 mg and 18 mg for adult women. The recommendation for women drops to 8 mg after age 50 (post-menopause), and goes up to 27 mg during pregnancy.

How we chose the best iron supplements

We consulted Catherine Canadeo, board-certified holistic health coach and integrative nutritionist based in Westbury, New York; Chisom A. Ikeji, M.D., assistant professor of critical care medicine at the University of Pittsburgh; and Mona Rosene, M.S., R.D., global director of scientific affairs at ChromaDex to narrow down the best options. We also reviewed scientific research and product reviews to inform our selections.

Why trust us

For more than 70 years, Prevention has been a leading provider of trustworthy health information, empowering readers with practical strategies to improve their physical, mental, and emotional well-being. Our editors interview medical experts to help guide our health-focused product selections. Additionally, Prevention also examines hundreds of reviews—and often conducts personal testing done by our staff—to help you make informed decisions.

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