Just two years ago the infant formula shortage in the US was making headlines around the world, with the US Food and Drug Administration (FDA) later announcing guidance outlining increased flexibilities regarding importation of certain infant formula products.

Now, researchers from the University of California Davis have looked into the impact of the infant formula shortage, carrying out a survey with US parents and caregivers.

The results of the study were published in the journal Nutrients and revealed that baby formula substitutions “led undesirable effects for babies, including vomiting”.

In an online survey of 178 parents whose infants were under six months of age during the May 2022 shortage, 81 percent of respondents switched formulas, and 87 percent of those switching because they “could not find the formula they typically used”.

“We have so many food choices as adults; you can eat anything. Infants have strict nutrient requirements; they can only eat two things: human milk and formula,” explained Jennifer Smilowitz, Assistant Professor of Cooperative Extension for the Department of Nutrition and corresponding author of the study.

Study authors also included Karla Damian-Medina, Karina Cernioglo and Maha Waheed with the Department of Nutrition, and researchers from New York Langone Medical Center and Yale University School of Medicine.

Back in 2021, Abbott Nutrition, a large US infant formula manufacturer, recalled multiple brands of its powdered formula products in 2022 due to bacterial contamination. According to the researchers, this move “exacerbated existing shortages caused by pandemic-related supply chain issues”.

In addition, the survey found that 60 percent of infants whose parents had to switch formulas had experienced “issues such as fussiness, gas, spit-up, constipation and diarrhoea”. Meanwhile infants who relied on specialty formulas due to a medical or metabolic condition, experienced these issues “more frequently than babies who had not required specialty formulas”.

What’s more, the study found that about 30 percent of parents switched formulas three to five times during the shortage and also visited “more than four stores in a 24-hour period” to find baby formula, travelling more than 20 miles in a 24-hour period to purchase formula.

Previously in 2023, Smilowitz and researchers conducted an initial study on this topic. In the paper published last year, they found that 48.5 percent of individuals used at least one unsafe feeding practice during the shortage, up from 8 percent before.

In order to navigate the infant formula shortage, parents were found to rely on several resources including social media (51 percent) and healthcare providers (48 percent), followed by relatives or friends (43 percent), and lactation consultant or lactation counsellor (30 percent), according to the latest survey.

Going forward, Smilowitz has said that she hopes the results of the study will “spur changes to healthcare policies and programmes to improve the resiliency of the infant food system and hopefully prevent infant-feeding crises in the future”.

In addition, Smilowitz highlighted the importance of informing mothers about their options and resources during and immediately after their pregnancies, claiming this would be a “step in the right direction.

“We see there’s a systematic problem in the infant feeding supply and that is a result of a lack of lactation education and support and priority in human milk feeding,” she said. “We need to improve infants’ food supply and it starts with supporting mothers and babies.”