The Health Benefits of Iron Supplements

An Essential Mineral Used to Treat Anemia

Iron supplements, also known as "iron pills," are commonly used to treat anemia (a condition characterized by the lack of healthy red blood cells or hemoglobin).

Iron plays a key role in making red blood cells that transport oxygen molecules throughout the body. Iron is also needed to metabolize the nutrients we eat and convert them into energy. Moreover, it contributes to the transmission of nerve signals to and from the brain.

While you will generally get enough iron from the foods you eat, there may be times when you may experience an iron deficiency. This commonly occurs during pregnancy or heavy menstruation.

There are certain groups vulnerable to iron deficiency, including preterm infants, young children, teenage girls, and individuals with chronic heart failure, Crohn's disease, celiac disease, or ulcerative colitis. Iron supplements are also commonly prescribed to women of childbearing age to help prevent anemia.

Health Benefits

Iron supplements are used to treat iron deficiency and iron-deficiency anemia. They are not typically used to treat other types of anemia (such as vitamin-deficiency anemia, hemolytic anemia, aplastic anemia, or anemia of chronic disease) unless iron deficiency is diagnosed. The response to oral iron supplements can vary by the underlying cause.

Iron Deficiency

Iron deficiency, also known as sideropenia, is the state in which your body lacks the iron needed to maintain normal function. Iron deficiency is common in the developing world where more than a quarter of the population may be affected (mostly due to poverty and the lack of nutrition). While this is less common in the United States, it still does occur.

Iron deficiency can also occur due to physiological changes that leave you at a deficit. Iron deficiency can occur in children, for example, because their bodies grow so quickly. Starting at adolescence, a woman's iron need will increase due to her monthly menstrual cycle.

Whatever the cause, iron deficiency can lead to iron-deficiency anemia if left untreated. Iron supplements may not only be used to treat a deficiency but prevent it from occurring in the first place.

Iron supplements are often provided to people at high risk of a deficiency. These include pregnant women, people on dialysis, or those with inflammatory bowel disease or thyroid disease.

Doing so can help prevent or treat many of the common symptoms of iron deficiency, including:

  • Fatigue
  • Weakness
  • Dizziness
  • Rapid heartbeat
  • Pale skin
  • Hair loss
  • Brittle or grooved nails
  • Sores at the corner of the mouth
  • Sore tongue
  • Twitches
  • Irritability
  • Frequent infections
  • Restless leg syndrome

Iron-Deficiency Anemia

When used to treat iron-deficiency anemia, iron supplements are sometimes effective and well-tolerated and in other cases not.

According to a 2015 review of studies in the American Journal of Medicine, as many as 27% with people with iron-deficiency anemia will not respond to oral iron supplements.

Generally speaking, women with postpartum anemia respond best. Those with heavy menstrual bleeding or individuals with gastrointestinal-induced anemia tend to be moderate responders. All other cases are largely hit or miss in their response.

If iron supplements are unable to provide relief, intravenous (IV) iron therapy or a blood transfusion may be needed.

iron supplement side effects
Verywell / JR Bee

Possible Side Effects

Iron supplements are generally safe and well-tolerated if taken at the recommended dose. The supplement may cause side effects in some people, including upset stomach, nausea, diarrhea, faintness, and vomiting. Dark stools are also common.Taking the supplement with food can usually alleviate many of the symptoms.

Iron supplements can cause constipation during pregnancy. Adding fiber to your diet or using a stool softener can usually help manage the symptom. To reduce the risk of side effects, start with a lower dose and gradually increase the dose as tolerated.

Taking too much iron can lead to iron overload. Extra iron in your blood can be toxic the liver, heart, and pancreas and may cause damage to the joints, as well.

Excessive doses of iron can lead to iron poisoning. Even a single high dose (60 milligrams per kilogram of body weight or more) can lead to death. The symptoms of iron poisoning usually become apparent within six to 24 hours of a dose and may include severe vomiting, diarrhea, and abdominal pain, oftentimes with bloody vomit or stools (especially in children).

Drug Interactions

Taking iron supplements containing 25 milligrams or more of elemental iron can affect the absorption of zinc and lead to a zinc deficiency. (Elemental iron is not the same thing as the iron supplement dose. Check the product label or speak with your pharmacist who can show you the difference.)

Iron supplements may also interact with the following drugs:

In some cases, separating the doses by two hours may be all that is needed to avoid interactions. In other cases, a dose adjustment may be needed. Speak with your healthcare provider if you intend to use iron supplements and take these or any other chronic medication.

Dosage and Preparation

Iron supplements are typically formulated as tablets or capsules. The dose can vary based on the level of your deficiency as well as the underlying cause. Your healthcare provider will recommend a dose based largely on the Recommended Dietary Allowance (RDA) for iron for your age, sex, and pregnancy status, as follows:

  • Birth to six months: 0.27 mg
  • Seven to 12 months: 11 mg
  • One to three years: 7 mg
  • Four to eight years: 10 mg
  • Nine to 14 years: 8 mg
  • Boys 14 to 18 years: 11 mg
  • Girls 14 to 18: 15 mg
  • Men 19 to 50: 8 mg
  • Women 19 to 50: 18 mg
  • Pregnant women 14 to 18: 27 mg
  • Breastfeeding women 14 to 18: 10 mg
  • Pregnant women 19 to 50: 27 mg
  • Breastfeeding women 19 to 50: 9 mg

Drink a full glass of water or orange juice with each dose. The vitamin C in orange juice is said to boost absorption. The water helps disperse the iron for better absorption.

When used to treat iron-deficiency anemia, the duration of therapy may be as long as six months. This requires a commitment on your part. Once started, you would need to continue treatment even if you feel better and no longer have symptoms.

What to Look For

Vitamin and mineral supplements are not subject to rigorous testing in the United States and can vary from one brand to the next. To ensure quality and safety, opt for supplements that have been tested and approved by an independent certifying body like the U.S. Pharmacopeia (USP), ConsumerLab, or NSF International.

Iron supplements can degrade when exposed to excessive temperatures and UV radiation. To avoid this, keep the supplements in their original light-resistance container and store in a dry, cool room. Always check the use-by date and discard of any expired, discolored, or damaged supplements.

Other Questions

Which foods are highest in iron?

Most people do not need iron supplements if they maintain a healthy, balanced diet. Rather than reaching for a pill, start by adding iron-rich foods to your meal plan, the highest of which include:

  • Iron-fortified breakfast cereals: 18 mg per cup
  • Oysters: 8 mg per 3-ounce serving
  • White beans (canned): 8 mg per cup
  • Dark chocolate: 7 mg per 3-ounce serving
  • Beef liver: 5 mg per 3-ounce serving
  • Lentils (cooked): 3 mg per ½ cup serving
  • Spinach (cooked): 3 mg per ½ cup serving
  • Tofu: 3 mg per ½ cup serving
  • Kidney beans (canned): 2 mg per ½ cup serving
  • Canned sardines in oil: 2 mg per ½ cup serving
  • Chickpeas (canned): 2 mg per ½ cup serving
  • Stewed tomatoes: 2 mg per ½ cup serving
  • Braised bottom round beef: 2 mg per 3-ounce serving
  • Baked potatoes: 1 mg per medium-sized potato
  • Cashews: 1 mg per 1-ounce serving
  • Green beans (cooked): 1 mg per ½ cup serving
  • Roast chicken: 1 mg per 3-ounce serving

Frequently Asked Questions

  • Should iron supplements be taken at a certain time of day?

    No, but iron is best absorbed when taken on an empty stomach. If an iron supplement causes stomach upset, you can still take it with a small amount of food, but avoid taking it with high-fiber foods or caffeine.

  • How quickly do iron supplements correct a deficiency?

    Iron supplements start to absorb into the body immediately, especially when taken on an empty or near-empty stomach, and most people who are iron-deficient start to feel better within a few days.

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8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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