Origin Story — History of Infant Feeding

Before the development of modern infant formula, infants who did not receive human milk from their mother or wet nurse were often fed a variety of foods (gruel, pap, cereal, animal milk) that were not safe, reliable, or nutritionally complete.^1,2 As a result, survival rates were poor. For example, in the early 1800s in London, around 10% of non-human milk fed infants survived to age 1.^3,4 After the introduction of pasteurization, the benefit of pasteurized milk inspired physicians and scientists to develop milk-based infant formulas that could better support infant growth and survival.¹ The first commercial infant formula/food was developed by German chemist Justus von Liebig and consisted of wheat flour, cow’s milk, malt flour, and potassium bicarbonate to correct pH.³ Following the success of von Liebig, others followed suit in the pursuit of producing formula for infants; however, all fell short of success as the nutritional composition was not suitable for infant growth and development. In 1915, synthetic milk adapted (SMA) was developed and was the first sole source formula based on human milk fat content.¹ However, there were still issues with micronutrient content that were present from the 1910s through the 1960s.^1,5,6 As scientific understanding of infant nutritional requirements and human milk composition has advanced alongside technological innovation, today’s infant formulas are vastly different from those available less than a century ago.

Designed to Meet Infant Needs: Human Milk as Inspiration

Human milk is the gold standard for infant feeding and is the inspiration for formula design. Formula designs and requirements evolve through advancements in knowledge of human milk and infant physiology and technology. Although all mammals produce milk, the composition of lipids, carbohydrates, and proteins varies considerably by species.⁷ The basis of early formula development focused on milk fat percentage.¹ Advances in our ability to characterize the full fatty acid profile of human milk has enabled manufacturers to use multiple fat sources to achieve fatty acid profiles that more closely replicate its composition.^8,9  

In replicating human milk fatty acid composition, various sources of lipids are used in infant formulas today. No single ingredient source can replicate human milk; thus, all formulas are a mixture of different lipid sources to achieve a composition closer to human milk (Table 1). As evidenced by fatty acid composition in Table 1, the vegetable oil blend is closer in composition to human milk than the bovine milk fat with corn oil blend. Currently, infant formulas contain vegetable oils in varying amounts with or without bovine milk fat, typically added as whole milk. There are several reasons for the use of vegetable oils in infant formulas. Vegetable oils increase the mono- and polyunsaturated fatty acid content,¹⁰ allowing closer patterning to breast milk. In addition, the lower cost and greater availability of vegetable oils allow for more continuous supply and lower cost to consumers.¹¹ As our knowledge of human milk composition has advanced, other lipid sources have been added to infant formulas to pattern after breast milk and better meet the nutritional needs of infants.

One such prominent example of the application of recent scientific discovery is the addition of oils containing docosahexaenoic acid (DHA) in combination with arachidonic acid (ARA) to infant formula in the early 2000s. DHA is naturally present in breast milk and is important for cognitive and visual development in infants.^12-14 Research-driven product innovation has also informed the protein and carbohydrates present in formula. Protein sources can be chosen to mimic the whey-to-casein ratio of human milk or more specialized ingredients found more prominently in human milk than cow’s milk, such as alpha-lactalbumin and milk fat globule membrane.^{15, 16} Formulas in the past 20 years have added carbohydrates beyond lactose and glucose polymers. These additional carbohydrates either mimic or are oligosaccharides found in human milk, which are important for gut microbiota, immunity, and stooling consistency and patterning.^17,18,19 Many of the above advances in infant formula composition have occurred in the last quarter of a century.

Table 1: Fatty Acid Composition of Human Milk and Milk Fat and Vegetable Oil Formulas (Prior to Addition of DHA and ARA)*

Safety of Infant Formula and Operation Stork Speed

Worldwide regulations for infant formulas have different contaminant, nutritional, and labeling requirements, which can lead to confusion when comparing formulas from different countries and regions.^20,21 Prior to the 1980s, the U.S. had no comprehensive federal regulations governing the nutritional quality or safety of infant formula. The Infant Formula Act, enacted in 1980 and strengthened through subsequent amendments, established requirements for formula manufacturing, safety, nutrient composition, quality control, labeling, and reporting.²⁰ Although additional amendments have been proposed, including legislation introduced on March 9, 2026 that remains under consideration,²² the Infant Formula Act continues to provide the regulatory framework for infant formula sold in the U.S. In addition, all infant formulas regardless of production location, must be registered with the FDA and meet federal safety and nutritional standards.²³

To introduce a new formula, a growth and tolerance trial is necessary to demonstrate its safety and nutritional suitability, in addition to providing other supporting data. The study follows strict criteria that includes enrollment of exclusively formula-fed infants younger than 2 weeks of age. Infants are followed for 15 weeks with three timepoints within the first month of the study, and once per month thereafter, to evaluate growth, feeding tolerance, and any adverse events.²³ Infant formulas introduced prior to 1980 did not necessarily undergo growth and tolerance trials that meet today’s standards, or in some cases, any such studies at all. Evidence of safety for these formulas relies on other supporting scientific evidence and safe history of use from post market surveillance.

Operation Stork Speed was announced in March 2025 to “expand options for safe, reliable, and nutritious infant formula for American families”²⁴ through the thorough review of infant formula nutrients, increased transparency in communication and labeling, increased testing of contaminants and microbiological contaminants in formula, and increased research on infant and maternal nutrition and health outcomes.²⁴ In May 2026, Operation Stork Speed released the results of testing for contaminants in infant formula and human milk.²⁵ This analysis was in conjunction with FDA’s Closer to Zero and FDA’s routine food surveillance work for safe, reliable, and nutritionally suitable infant formula.

In brief, more than 300 infant formula samples available in the U.S. market were tested for lead, mercury, cadmium, arsenic, pesticides, and polyfluoroalkyl substances and phthalates. The vast majority of samples had undetectable or very low levels of contaminants, with all samples having levels of lead, mercury, arsenic, and cadmium lower than EPA requirements for drinking water.²⁶ More than 100 human milk samples from a state milk bank were also tested for lead, arsenic, mercury, and cadmium. The vast majority contained either undetectable or very low levels of these contaminants. For detailed information on methods and outcomes, see FDA’s Infant Formula Product Testing Results.²⁵

Preventing bacterial contamination requires careful manufacturing and handling of both formula and human milk throughout the entire supply chain, from ingredient suppliers and manufacturers to distributors, transport, retailers, health professionals, and parents/guardians/caregivers. Safe infant feeding also depends on proper preparation and storage. Infant formula should always be prepared according to the manufacturer’s instructions or healthcare provider’s recommendations, and neither formula nor breast milk should be diluted.

Achieving contaminant levels that are as low as possible in formula will require coordinated efforts across academia, industry, government, and the public. Advances in testing methods and technology are also necessary to improve the detection of contaminants in both ingredients and finished formula products. Detecting specific contaminants in finished formulas is challenging because these products contain numerous ingredients, all bearing different compositions, matrices, and potential contaminants.²⁷ Additionally, all assays have limits of detection and limitations of sample composition/preparation, which can affect the ability to detect contaminants.

There are other factors beyond scientific evidence and safety regulations that must be met to ensure safe infant feeding and reduce contamination. Contaminants are present in our water, food/ingredients, and environment. Lowering contaminants in ingredients, formula, and human milk would require lower contaminants in the environment, food sources, and water. Infant formulas are evolving as science and technology advance. Together, we can improve the health and safety of nutrition for infants.