A Guide To Iron Supplementation

Just like getting too little iron isn’t ideal for optimal health, having excessive iron levels can also pose potential risks (1). Conditions like hereditary hemochromatosis cause the body to absorb too much iron. Frequent blood transfusions may also cause iron overload. It is possible to over-supplement with iron to the extent of causing toxicity or iron overload (9, 10). Normal dietary iron intake alone is not generally regarded as a way to cause iron overload.

Potential symptoms of iron overload may include joint pain, fatigue, skin discoloration, and in severe cases liver damage (1).

The recommended daily intake of iron varies by age, gender, and life stage. Below are the guidelines from the National Institutes of Health (NIH) (1):

• Birth to 6 months: 0.27 mg
• Infants 7–12 months: 11 mg
• Children 1–3 years: 7 mg
• Children 4–8 years: 10 mg
• Children 9–13 years: 8 mg
• Teen boys 14–18 years: 11 mg
• Teen girls 14–18 years: 15 mg
• Adult men 19–50 years: 8 mg
• Adult women 19–50 years: 18 mg
• Adults 51 years and older: 8 mg
• Pregnant teens: 27 mg
• Pregnant women: 27 mg
• Breastfeeding teens: 10 mg
• Breastfeeding women: 9 mg

Iron needs are highest during infancy, adolescence, and pregnancy due to periods of rapid growth and increased blood volume. Women of reproductive age require more iron than men due to menstrual blood loss. After menopause, iron requirements for women decrease to the same amount as men.

Iron is found in food in two forms: heme iron and non-heme iron.

• Heme iron: Found in animal products like red meat, poultry, and fish, heme iron is more easily absorbed by the body.

• Non-heme iron: Found in plant-based foods like beans, lentils, tofu, fortified cereals, spinach, and seeds, non-heme iron requires specific conditions for optimal absorption.

According to the National Institutes of Health (NIH), vegetarians and vegans should aim to consume nearly twice the recommended daily intake of iron to account for the lower absorption rates of non-heme iron (1).

For references, below are a few common foods that are considered rich in iron, with their iron amount as per the USDA Food Data Central (11) listed in mg:

• Beef liver (4 oz): 5.4 mg

• Cooked spinach (½ cup): 0.6mg

• Lentils (1 cup, cooked): 6.5 mg

• Canned bone-in sardines (1 can): 2.7 mg

• Cooked quinoa (1 cup): 2.8 mg

• Firm tofu (3 oz): 1.4 mg

To maximize the absorption of iron, especially non-heme iron found in plant-based foods, it’s helpful to pair iron-rich meals with foods high in vitamin C, such as citrus fruits, bell peppers, or tomatoes, or with a vitamin C supplement.

It’s best to avoid consuming calcium-containing foods or supplements, coffee, or tea during iron-rich meals, as these can inhibit iron absorption.

Cooking with cast iron pans can slightly increase the iron content of foods.

If you struggle to meet your daily iron needs through dietary intake alone, iron supplements can help bridge the gap. There are several forms of iron supplements available, and it’s helpful to understand the potential pros and cons of each.

Iron bisglycinate is a chelated form of iron, meaning the iron is bound to glycine, an amino acid (12). This binding supports effective absorption and allows for a gentler effect on the digestive system compared to traditional iron salts like iron sulfate.

• Pros: Gentle on the stomach, less likely to cause constipation or nausea (13).

• Cons: Not as widely available. It is sometimes thought that this version of iron requires a longer duration or higher dose to correct iron deficiency due to lower elemental iron content, but that is not consistently demonstrated in research. In fact, some research shows that iron bisglycinate corrected mild iron deficiency in children quicker than iron sulfate did (14).

Iron sulfate, or ferrous sulfate, is one of the most prescribed forms of iron. It contains a high percentage of elemental iron, making it generally quite effective for correcting iron deficiency quickly (15). However, it’s also associated with potential gastrointestinal side effects (16).

• Pros: Affordable and widely available, high elemental iron content, well-regarded as being generally effective for iron deficiency.

• Cons: More likely to cause gastrointestinal side effects like constipation and nausea.

Desiccated beef liver supplements are made from grass-fed, dried, and powdered beef liver. They provide a natural source of heme iron, which is more easily absorbed by the body than non-heme iron found in plant-based foods. In addition to iron, beef liver is rich in essential nutrients like vitamin A, B12, and folate, making it a nutrient-dense option for overall health.

• Pros: A natural, nutrient-dense source of heme iron, also rich in other vitamins and minerals like vitamin A and B12.

• Cons: May not be suitable for vegans or vegetarians and is less suitable for when a very precise dose is desired.

To learn more about beef liver, read these articles: 

• Beef Liver Capsules Are A Great First Food For Babies
• The Benefits of Beef Liver Capsules for Kids + Three Family Friendly Recipes!

Choosing the right iron supplement depends on factors such as your deficiency level, tolerance, life stage, and specific health needs. Below is a guide to help you decide:

For those looking to maintain healthy iron levels or prevent mild deficiency, good supplement options include:

• Beef liver capsules: A natural, whole-food source of heme iron, plus additional nutrients like vitamin A and B12.

• Iron bisglycinate: A gentle, well-tolerated form of iron that’s less likely to cause digestive discomfort.

• Herbal teas and/or herbal supplements: Certain herbal supplements and teas can provide a boost in daily iron intake.

In cases of moderate to severe iron deficiency, correcting iron levels quickly is key. Recommended iron supplement options include:

• Iron bisglycinate: Absorbable and gentle on the stomach, making it ideal for consistent daily use.

• Beef liver capsules:  A nutrient-dense, whole food source of heme iron.

• Tips: Alternating between iron bisglycinate and beef liver supplements is a method preferred by some to combine the benefits of both. To get the most from your iron supplements, take them with vitamin C to enhance absorption. Remember to take iron supplements away from calcium-containing supplements, as calcium inhibits iron absorption (17).

• IV Iron: For severe deficiencies or when iron absorption through the digestive tract is impaired, medical providers may recommend an IV iron infusion (18). This treatment bypasses the digestive system and delivers iron directly into the bloodstream. Your doctor will assess whether this option is appropriate for your situation.

Iron needs during infancy are high due to rapid growth. The AAP recommends that starting at four months of age infants who are partially or completely breastfed be supplemented with 1 mg/kg per day of oral iron until appropriate iron-containing complementary foods are introduced in their diet (2). For supplementing iron in infants, look for:

• Liquid iron supplements: These provide precise dosing and are easy to administer. Iron bisglycinate can be a gentler option for little bellies.

When choosing an iron supplement for kids, it’s important to choose an option they’ll take consistently. Look for liquid or chewable supplements with natural flavors and without colorants or filler ingredients.

• Iron bisglycinate: This form may be especially preferred for kids who experience occasional constipation, as it’s gentle on the stomach and less likely to cause digestive discomfort.

• Beef liver capsules: These can be opened and mixed into foods, offering a natural, whole-food source of heme iron along with essential nutrients like B12 and vitamin A.

For kid-friendly recipes that include beef liver, read this article: The Benefits of Beef Liver Capsules for Kids + Three Family Friendly Recipes!

During pregnancy, iron needs increase significantly to support both mother and baby (1). While most prenatal vitamins contain iron, some mothers may have higher intake requirements, especially since calcium in prenatals can reduce iron absorption. A separate iron supplement, taken separately from the prenatal, may help ensure adequate intake. Options suitable for pregnancy include:

• Prenatal vitamins: A prenatal vitamin is foundational during preconception, pregnancy, lactation and postpartum. To learn more, read this article: What To Look For In A Prenatal Vitamin.

• Additional iron supplementation: If blood tests show low iron levels, adding an iron supplement can help increase iron levels. Many times, expectant mothers prefer iron bisglycinate for its digestibility. Note: If you’re supplementing with an iron supplement in addition to your prenatal, it is best to separate it from your prenatal by a few hours.

• Beef liver supplements: A natural, whole-food source of heme iron plus additional bioavailable nutrients.

For more information on choosing the right supplement, read these articles:

• Choosing A Supplement Delivery Method For Your Family
• Is Getting Nutrients From Food Better Than Taking a Supplement?

Iron is an essential mineral important for oxygen transport, energy production, and overall health. Despite being present in many foods, iron deficiency remains common, particularly in infants, children, pregnant women, and those following vegetarian or vegan diets. If dietary iron intake isn’t sufficient to meet daily requirements, iron supplements such as iron bisglycinate, iron sulfate, and beef liver capsules can help bridge the gap. Iron absorption can be enhanced by pairing iron-rich foods or supplements with a source of vitamin C and by taking iron separately from calcium-containing foods or supplements. Blood testing is the most reliable way to determine if iron levels are adequate and whether supplementation is needed.