What is Ferrous Sulfate (Iron)?
This ingredient is one that many parents recognize. Let’s explore why this ingredient is added to infant formula and other common questions parents have about this ingredient.
Is Ferrous Sulfate the Same as Iron?
Ferrous sulfate is the most common form of the mineral iron with the the chemical formula FeSO4. There are many forms of iron. Other common forms of iron are ferrous gluconate, ferric citrate, and ferric sulfate. These forms of iron are not usually used in baby formulas
Ferrous sulfate is also added to some foods, like breakfast cereals, baby cereals, and breads. And, if you have ever taken iron pills, you most likely took iron sulfate.
Why is Ferrous Sulfate (Iron) Added to Baby Formula?
Iron plays several important roles in the body.
While many people have heard of iron’s role in carrying oxygen in the blood, it also helps remove carbon dioxide, the “waste” gas left over from metabolizing carbohydrates and lipids. About 70% of iron is found in hemoglobin (within your red blood cells) and myoglobin (within your muscles).
Iron is also important for brain development, although, as we’ll discuss, the science isn’t clear about the relationship between iron status (how much iron in the body).
Amount of Iron in Formula
Iron is absorbed better from breastmilk than it is from baby formula. To make up for this difference in absorption, infant formula contains higher amount of iron than breastmilk.
The optimal amount of iron that infant formula should contain is controversial and differences of opinion are clearly seen in the amount of formula found in US and European formulas. Most US formulas have 1.8 mg iron for every 5.3 ounces. European and European-styled formulas have about 33% less iron. They contain on average 1.2 mg per 5.3 ounces. Some have as low as 1.0 mg in the same volume.
Although US formulas typically contain 1.8 mg per 5.3 ounces (100 calories), only 1.0 mg is required per Federal infant formula nutrient regulations. These regulations have had minimal updates since they were developed in 1979-1980. I agree with others health providers who have called for a revision of these regulations.
Is Ferrous Sulfate (Iron) Safe in Baby Formula?
The risks and benefits of iron intake for healthy babies aren’t fully understood. Researchers and clinicians in the United States and Europe don’t agree on how much iron should be in infant formula because they interpret the current research differently. European regulators seem more concerned about babies being harmed by getting too much iron. US regulators seem more concerned about the health risks of iron deficiency.
Clinicians and researchers generally agree on the minimum levels of iron needed in formula. Setting the upper limit is challenging because, research has show both risk and benefits to including higher amounts of iron in formula. For example, growth can become impaired with too much iron. Research in the 1990s showed that more iron can be risky for infants who have good irons stores. European formulas have much lower amounts of iron than US infant formulas. Indeed, it is one of the main differences between European and US infant formulas.
Lastly and surprisingly, there is no research that specifically tests the health implications of formula containing 1.8 mg per 100 calories compared to one with lower levels. This is significant research gap that urgently needs addressed.
Regulations and Safety
The US FDA requires 0.15 – 3.0 mg iron per 100 calories prepared formula (~ 5 ounces), which is a wide range. Formulas containing less than 1.0 mg per 100 calories must be labeled as low iron. The European Food Safety Authority requires between 0.3 and 1.5 mg iron per 100 calories. Most US formulas contain well above this minimum amount. Almost all US infant formulas in the Formula Sense database, contain 1.8 mg per 100 calories prepared formula. The few that contain less than this amount are made by European producers
Both the European and North American medical societies agree that more study is needed to determine appropriate fortification levels in infant formula, particularly in those designed for infants over six months.
Iron Upper Limits for Infants
Iron is one of only eight micronutrients the FDA has set a maximum level for in infant formula. The upper limit for infant formula is 3.0 mg per 5.3 ounces formula (100 calories). An upper intake level is set for iron for two reasons.
First, unlike other nutrients, iron cannot be excreted by the body. In other words, humans don’t lose iron through urine (like water soluble vitamins) or body fluids (like zinc) or through poop (like vitamin D).
Second, as we’ve mentioned, too much iron is dangerous for infant growth and according to some studies, also to long-term infant cognition (cognition is all the processes involved in learning, remembering, and using knowledge).
Key Takeaways
Iron is necessary for infants to grow and thrive. All infant formula has iron added, almost always in the form of ferrous sulfate. However, the science supporting exactly how much iron formula isn’t clear. As a result, the United States and Europe have made different decisions about the amount of iron in formula. European regulators seem more concerned about babies being harmed by getting too much iron. US regulators seem more concerned about the health risks of iron deficiency.