From the Guidelines
The best iron tablet for most adults is ferrous sulfate taken once a day, as it is the least expensive and has no advantages over other formulations in terms of effectiveness or tolerance. For optimal absorption, take iron on an empty stomach with vitamin C (like orange juice) and avoid taking it with calcium, dairy, coffee, tea, or antacids which can reduce absorption 1. If stomach upset occurs, taking it with food is acceptable though less effective. Alternatively, ferrous gluconate or ferrous fumarate are gentler options that may cause fewer gastrointestinal side effects. Some key points to consider when taking iron supplements include:
- Taking iron more than once a day will not improve absorption but will increase side effects 1
- Taking iron every other day may improve tolerance, but further study is needed to confirm this 1
- Certain dietary manipulations, such as taking iron with vitamin C, may improve iron absorption, but evidence is mixed and further study is needed 1
- Tea and coffee should not be consumed within an hour after taking iron, as they are powerful inhibitors of iron absorption 1 Iron supplements should be taken for 3-6 months to replenish stores, even after symptoms improve. Iron is essential for hemoglobin production and oxygen transport throughout the body, and deficiency can cause fatigue, weakness, and anemia. Common side effects include constipation and black stools, which can be managed with increased fluid intake, dietary fiber, and stool softeners if needed. Always consult with a healthcare provider before starting iron supplements to confirm deficiency and determine the appropriate dosage for your specific needs. According to the British Society of Gastroenterology, the initial treatment of iron deficiency anemia should be with one tablet per day of ferrous sulphate, fumarate or gluconate, and if not tolerated, a reduced dose of one tablet every other day, alternative oral preparations or parenteral iron should be considered 2. The American Gastroenterological Association also recommends giving oral iron once a day at most, and considering every-other-day iron dosing for patients who may be better tolerated 3.
From the FDA Drug Label
DIRECTIONS FOR USE: Do not crush or chew tablets. Adult Serving Size: 1 tablet two to three times daily. CONTAINS: Each tablet contains 324 mg of ferrous sulfate, equivalent to 65 mg of elemental iron, providing 362% of the U.S. recommended daily intake (RDI) of iron for adults and children 4 and older. DESCRIPTION Each tablet contains 324 mg of ferrous gluconate, equivalent to 38 mg of elemental iron, providing 211% of the U.S. recommended daily intake (RDI) of iron for adults and children 4 and older. Directions for Use Do not crush or chew tablets. Adult Serving Size: 1 tablet three to four times daily.
The best iron tablet is ferrous sulfate with 65 mg of elemental iron per tablet, as it provides a higher percentage of the U.S. recommended daily intake (RDI) of iron for adults and children 4 and older 4, 5. The recommended frequency for ferrous sulfate is 1 tablet two to three times daily for adults 4. For ferrous gluconate, the recommended frequency is 1 tablet three to four times daily for adults 6.
From the Research
Best Iron Tablet
- Ferrous sulfate is considered one of the best iron tablets for treating iron deficiency anemia, as it has been shown to be effective in increasing hemoglobin concentration and improving iron status 7, 8, 9.
- Ferrous glycinate chelate is another option, but it may not be as effective as ferrous sulfate in treating iron deficiency anemia, especially in gastrectomized patients 8.
- Ferrous gluconate is also effective in preventing iron deficiency anemia in toddlers, and may be more effective than ferrous sulfate in improving hemoglobin and ferritin levels 9.
- Lactoferrin is a milk-derived iron-binding glycoprotein that has been shown to be superior to ferrous sulfate in improving serum iron parameters and hemoglobin levels, with fewer gastrointestinal side effects 10.
Frequency of Iron Supplementation
- The frequency of iron supplementation depends on the individual's iron status and the severity of their iron deficiency anemia.
- For infants and children with nutritional iron-deficiency anemia, once daily low-dose ferrous sulfate is recommended 7.
- For toddlers, daily supplementation with ferrous gluconate or ferrous sulfate is recommended to prevent iron deficiency anemia 9.
- For adults with iron deficiency anemia, the frequency of iron supplementation will depend on the severity of their anemia and their individual iron needs, but typically involves taking iron supplements 2-3 times a day 11.