The Best Iron Supplement: The Complete Guide (Research Based)

The best types of iron supplements help to address symptoms of iron deficiency or iron deficiency anemia. Iron is an essential nutrient that helps the body to function properly and keeps red blood cells healthy. Proper levels of iron in the body also help to maintain healthy skin, hair, nails, and cells.

Iron is contained in foods that we eat. Meat, poultry, and seafood are the richest sources of available iron. Although there are plant-based sources of iron, these are poorly absorbed by the body.

You may need to take iron supplements if your diet lacks nutrients or you have digestive problems that restrict the absorption of nutrients. Very often, women are at more risk than men from iron deficiency anemia because or pregnancy or heavy menstrual bleeding.

The best iron supplement has high dose of elemental iron per tablet, is relatively inexpensive and is easily absorbed by your body. The best iron pill for anemia or iron deficiency also has minimal side effects such as constipation.

In this guide I will look at what medical research reveals as to the best types of iron supplements on the market. You will also find out if you really need an iron supplement to increase your iron levels.

What is Iron?

Iron is a mineral and it’s one of the essential nutrients in the body. Researchers from the National Institutes of Health report that iron is stored in the liver, bone marrow, and spleen as a compound called ferritin. Some traces or iron are also stored in muscle tissue.¹

Why Do We Need Iron?

One of the main reasons that we need iron is that it is an essential component of hemoglobin and it’s required to prevent iron deficiency anemia.

According to Dr. Brunilda Nazario on WebMD, hemoglobin carries oxygen throughout our bodies to every cell and tissue. Because a lack of iron affects levels of oxygen in the blood, iron deficiency anemia can impact on organ function and brain function. Iron is also essential to keep your immune system healthy.²

Dr. Nazario says that women, pregnant women, and infants especially need iron. For example, adequate levels of iron help maintain healthy pregnancies and ensure babies grow properly.

Foods That Contain Iron

It should be possible to obtain enough iron from your diet without having to resort to iron supplementation. There are many foods that are rich in iron where iron is easily absorbed and metabolized by the body.

The Journal of Research in Medical Sciences reports that the best sources of iron from your diet include meat, poultry, fish, and seafood. This type of iron is called heme iron and has the highest bioavailability. This means that more of the iron in food can be absorbed by the body.³

Other sources of iron in food also come from vegetable and plants. Some of the best plant-based sources of iron are green leafy vegetables, fruits, cereals, beans, and legumes. However, iron in organic sources is nonheme iron and have relatively poor bioavailability (it does not absorbed well).

Heme iron vs. nonheme iron

What is the difference between heme iron and nonheme iron? The World Journal of Gastroenterology reports that the heme protein is found in muscle and hemoglobin. This type of iron makes up about two-thirds of iron stores in the body. The presence of the heme protein makes it easier for your body to absorb heme iron during digestion.⁴

Nonheme iron is found in plant foods and, as its name suggests, doesn’t contain the heme protein. Your body absorbs nonheme iron at a slower rate than heme iron. This means that eating a vegan or vegetarian diet can cause iron deficiency and may cause these signs of an iron deficiency.

If you enjoy a meat-free and dairy-free diet, please read my article on important things to remember in a vegan diet.

How to increase iron absorption

One way to increase iron bioavailability from plant-based iron sources is to take vitamin C. Research published in the journal Folia Medica found that vitamin C (ascorbic acid) helps to increase iron absorption in the small intestine. This happens because the antioxidant properties of vitamin C change how the body absorbs iron.⁵

Including more green leafy vegetables in your diet along with taking vitamin C has many health benefits. You can find out how to detox your body with leafy greens and boost your immunity with vitamin C.

Symptoms of Iron Deficiency or Iron Deficiency Anemia

Your doctor may recommend that you take iron supplements if blood test results show an iron deficiency or that you have iron deficiency anemia.

Iron deficiency anemia is when you have a low hemoglobin or red blood cell count that is due to low iron levels. Some people show signs of iron deficiency without anemia and it’s called nonanemic iron deficiency. The journal Swiss Medical Weekly reports that in many cases the symptoms of nonanemic iron deficiency and iron deficiency anemia are similar.⁶

According to doctors from the Mayo Clinic, some of the symptoms accompanying iron deficiency anemia can include:⁷

• General fatigue and a lack of energy
• Pale skin due to lack of oxygen-rich blood circulating
• Unexplained pain in your chest and a rapid heartbeat
• Lightheadedness or shortness of breath
• Cold and clammy feet and hands due to poor circulation
• Lack of appetite

Why You Might Need to Take Iron Tablets

Many researchers report that iron deficiency and iron deficiency anemia is a widespread medical concern. A report from 2013 on the problems related to iron deficiencies found that as many as 10 million people in the U.S. are iron deficient. About half of these have signs of iron deficiency anemia.⁸

Doctors from the National Institutes of Health report that you may need to take iron supplements in the following circumstances:¹

• Your diet is lacking in essential nutrients, vitamins, and minerals
• You suffer from a digestive disorder that causes malabsorption
• You have blood loss because of heavy menstrual periods or chronic internal bleeding (for example, if you have a stomach ulcer)

However, certain groups of people are at an increased risk of iron deficiency or iron deficiency anemia.

Iron deficiency in women

Iron supplements for women are sometimes necessary if you suffer from heavy bleeding during your period.

The journal Haemophilia reports that iron deficiency and fatigue are common if you have heavy menstrual bleeding. Studies show that nearly 90% of adolescent females have iron deficiency due to menstruation.⁹

Pregnancy is another reason for having to take iron supplements to boost your iron levels. The journal Obstetric Medicine says that iron supplements during pregnancy giving a daily dose of 40 mg should prevent anemia in pregnancy. However, with a healthy, nutritional diet, it should be possible to meet iron needs during pregnancy without taking supplements.¹⁰

Iron deficiency in infants and toddlers

Adequate levels of iron are important for infants and toddlers. The journal Nutrients reports that low iron levels in newborns may be due to iron deficiencies in mothers. Sometimes, iron supplementation of 10 – 12 mg is recommended for children to address iron deficiencies.¹¹

How Much Iron Should You Take?

Before looking for the best iron supplements to take, it’s important to know if you need to take iron tablets. Too much iron in your body can be just as detrimental to your health as having an iron deficiency.

Knowing how much iron to take depends on how your body absorbs nutrients and if you suffer from chronic or heavy blood loss.

How much iron should you take? Doctors from the National Health Service say that the daily iron requirements for adults are as follows:¹²

• Iron requirements for adult males: 8.7 mg per day
• Iron requirements for adult females: 14.8 mg per day
• Iron requirements of women over 50 years old: 7 mg per day

Doctors from the Mayo Clinic say that the recommended dosage of iron supplementation to prevent iron deficiency is as follows (daily amounts):²⁰

• Adult males: 10 mg
• Adult females (including if you are breastfeeding): 10 to 15 mg
• Iron supplementation during pregnancy: 30 mg
• Children aged 4-10 yrs. old: 10 mg
• Newborns to age 3: 6 to 10 mg per day

Type of Iron Supplements: The Best Iron Supplement for You

It can be confusing to know which is the best type of iron supplement for you to take. Here is an overview of some of the most popular iron supplements and their reported benefits.

Ferrous sulfate supplement (iron sulfate)

Ferrous sulfate, or ferrous iron, is one of the most popular forms of iron supplements. Generally, ferrous iron sulfate supplements contain high levels of elemental iron and they are generally very cost-effective.

The Scientific World Journal reports that ferrous iron supplements are usually effective in treating anemia and iron deficiency symptoms. Researchers found that the benefits of ferrous sulfate iron tablets are that they are cheap, tolerable for most people, and very effective.¹⁴

Some studies report that ferrous sulfate supplementation does cause gastrointestinal upset such as constipation, diarrhea, nausea, flatulence and abdominal pain .¹³ However, other research has shown that slow-release ferrous iron supplements are better tolerated.¹⁵

Carbonyl iron supplement (Feosol, Icar)

Carbonyl iron supplements are another effective iron supplement to address symptoms of iron deficiency anemia.

Research published in the journal Blood reported that carbonyl iron tablets or powder have some benefits over ferrous sulfate supplements. For example, most people can tolerate higher doses of carbonyl iron supplements without gastrointestinal upset.¹⁶

The research showed that carbonyl iron helped treat women who had anemia due to heavy menstruation. Taking up to 3,000 mg carbonyl iron daily cured anemia in the majority of patients after 12 weeks.

Researchers found that the benefits of carbonyl iron were that they are relatively inexpensive, are effective for iron deficiency anemia, and cause fewer symptoms of digestive upset. There is also less risk of iron poisoning in cases of overdose.

Ferric citrate supplement (iron citrate)

For some people, ferric citrate supplements are the preferred option of iron tablets because they cause fewer gastrointestinal side effects.

The Scientific World Journal (quoted earlier) compared ferrous iron supplement with oral ferric iron. Researchers found that, although ferric iron supplements are better tolerated, they are less effective than ferrous sulfate.¹⁴

A study using iron-fortified Thai fish sauce found that ferric citrate isn’t as well absorbed in the body as ferrous sulfate. The study also found that using citric acid increases iron absorption rates in both ferrous sulfate and ferric citrate.¹⁷

Iron amino acid chelates supplement

Iron amino acid chelate supplements are some of the best iron supplements for treating symptoms of anemia.

The Journal of Dietary Supplementation published a randomized, double-blind clinical trial on the effectiveness of iron amino acid chelates. It compared ferrous sulfate with iron multi-amino acid chelate.

Both supplements contained 25 mg of elemental iron (this is the amount of iron that can be absorbed by the body). The results of the study showed that iron amino acid chelates were just as effective as ferrous sulfate iron supplements. However, there were fewer gastrointestinal adverse effects reported by people taking iron amino acid chelate.¹⁸ 

Iron amino acid chelates may be an excellent choice as an iron supplement for anemia without causing constipation.

Ferrous bisglycinate iron supplement for pregnancy

Pregnancy causes a number of gastrointestinal side effects like constipation and hemorrhoids. Symptoms of anemia may mean that doctors recommend an iron supplement during pregnancy. However, taking iron supplements may make it even more difficult to pass stool.

The Journal of Perinatal Medicine published results of a randomized trial comparing the effects of taking ferrous bisglycinate and ferrous sulfate during pregnancy. 40 women were given ferrous bisglycinate (25 mg elemental iron) and 40 were given ferrous sulfate (50 mg elemental iron).

The women taking ferrous bisglycinate reported fewer instances of digestive complaints. Blood test results showed that both types of iron supplement were just as effective at treating iron deficiency anemia in both groups.¹⁹

Researchers concluded that a low dose of ferrous bisglycinate should be enough to prevent iron deficiency in pregnancy in up to 95% of women.

Best Time to Take Iron Supplements for Best Absorption

Iron absorption depends on getting the best iron supplements and knowing the optimal time to take them. The best way to take iron supplements for optimal absorption is to take them 1 hour before meals or 2 hours after eating.

There are also certain foods and drinks that you shouldn’t take with iron. Doctors from the Mayo Clinic explain that certain foods can result in only little amounts of iron being absorbed. Things not to take with iron include:²¹

• Dairy products like cheese, yogurt, or milk (because they contain calcium)
• Spinach
• Tea or coffee
• Whole grain foods

You should also avoid taking calcium supplements or antacids at the same time as iron supplements.

Precautions When Taking Iron Pills or Supplements

Iron supplements can be an essential way to prevent complications of an iron deficiency or iron deficiency anemia. If your healthcare provider recommends or prescribes iron pills, there are a few things you should remember.

First, blood tests will confirm levels of iron in your body and if you are deficient in iron or have signs of iron deficiency anemia.

What else is important to consider when taking iron deficiency supplements? Dr. Melinda Ratini on WebMD gives the following advice:²²

• Expect changes to your stool and digestive system. In fact, black stools are a sign that your body is properly absorbing iron from supplements.²¹
• Iron can interact with antacids for heartburn, proton pump inhibitors, and some antibiotics.
• Iron poisoning is a medical emergency and can be fatal. Signs of an iron overdose are severe vomiting, cramping, diarrhea, and bluish skin.
• Long-term use of iron supplements with vitamin C can cause gastrointestinal inflammation that results in ulcers.²³

What Is the Best Iron Supplement?

When looking for the best iron supplements to address your health needs, it’s important to consider elemental iron levels. Elemental iron is the amount of iron that is available for absorption by your body.

Ideally, iron supplements should contain vitamin C to improve absorption rates in your body.

When it comes to choosing the best iron supplement that you should take, there is no consensus of opinion. If you tolerate ferrous sulfate supplements, then these can be a cheap and effective way to address iron deficiencies.

If ferrous sulfate iron supplements result in unpleasant gastrointestinal side effects, then you could try lowering the dose and slowly increase it over time.

In some cases, switching to an iron multi-amino acid supplement could help to increase your iron levels without causing any digestive complaints.

The Risks or Side Effects of Taking Iron Supplements

Taking iron supplements for anemia or to address an iron deficiency is necessary to keep your body functioning properly. However, iron supplementation can cause some side effects.

Research published in the journal PLoS One found that many people suffer from gastrointestinal upset when taking iron pills. Some side effects of iron supplements can include:¹³

• Abdominal pain and cramping
• Diarrhea or constipation
• Excess gas
• Passing black tarry stools
• Metallic taste in your mouth
• Some types of liquid iron supplements may blacken your teeth

It is recommended to take iron supplements on an empty stomach for optimal absorption. However, if you have adverse side effects, you should take them with a little food.

When to See a Doctor

You should see your doctor immediately or go to the emergency room if you or your child show signs of iron poisoning.

If iron supplements are making your constipated or giving you stomach cramps, your doctor could recommend other forms of OTC iron supplements or prescribe a better iron tablet.

Of course, even if you aren’t taking iron pills, you should visit your doctor if you have any symptoms of anemia.

Related articles:

• Top Signs of Iron Deficiency and How To Increase Iron Levels In Your Blood
• 5 Essential Nutrients You May Be Missing From Your Diet
• Warning Symptoms of Vitamin B12 Deficiency and How to Fix It