February 2020 Issue

Children’s Nutrition: Milk Soy Protein Intolerance
By Diana K. Rice, RD, LD, CLEC
Today’s Dietitian
Vol. 22, No. 2, P. 12

Dietitians are poised to help identify and treat infants with this uncommon digestive disorder.

New moms certainly have plenty to manage. Between recovering from childbirth, sleep deprivation, and the overall adjustment to a new way of life, it’s fair to say that having a new baby may be among the most stressful times in a woman’s life.

But many women experience an additional stressor they weren’t expecting: managing their baby’s food intolerance. Milk soy protein intolerance (MSPI) is a condition that affects somewhere between 2% and 5% of infants, often presenting around the infant’s third or fourth week of life.1

Symptoms of MSPI may include mucus and/or blood in the infant’s stool, diarrhea, gas, reflux, and colic. Pediatricians may run a guaiac test to confirm the presence of blood in an infant’s stool, but there’s no specific diagnostic test to confirm the condition, so the diagnosis generally is believed to be determined once the suspected foods are removed from the infant’s diet and symptoms resolve. This requires either switching the infant to a special formula or having the breast-feeding mother eliminate the suspected foods from her diet, as the milk and soy proteins she consumes pass into her breastmilk. Fortunately, MSPI generally doesn’t last beyond a child’s third year of life and often resolves as early as 10 or 12 months of age.

Since cow’s milk protein intolerance alone is more common that the combined milk and soy protein intolerance, parents typically are advised to first eliminate cow’s milk from the mother and/or baby’s diet. If symptoms don’t fully resolve, the family may need to eliminate soy protein and other top allergens.

And although milk and soy are among the “top 8” food allergens (the others include wheat, eggs, fish, shellfish, peanuts, and tree nuts), and an infant’s condition may be referred to informally as an allergy, it’s important to recognize that MSPI isn’t an immunoglobulin E–mediated food allergy. It also differs from lactose intolerance. The intolerance in MSPI is to the protein component of the offending food (eg, casein in the case of milk), whereas lactose intolerance is characterized by a deficiency in lactase, the enzyme required to break down milk sugar.

Chrissy Carroll, MPH, RD, is a Massachusetts-based dietitian with firsthand experience managing MSPI in her breast-fed infant. “Within a few weeks of my son’s birth, we started noticing that he was very fussy and had mucus in his stool.” Carroll says. “When our guaiac test came back positive, we were told to cut dairy [from my diet]. After that didn’t completely alleviate symptoms, we realized we also needed to cut soy and eggs [from my diet].”

Carroll considered herself lucky to be working with a pediatrician who had knowledge of MSPI, because many women have a much different experience.

“For my first child, my pediatrician was not familiar with MSPI at all,” says Ann Dunaway Teh, MS, RD, owner of Dunaway Dietetics in Marietta, Georgia. “I did all of my own research and presented it to him as something to try rather than reflux medicine. He told me to try it if I wanted to but didn’t seem to be interested beyond that in the results.” Teh’s maternal instinct was right. She saw a dramatic improvement in her son’s reflux and colic after eliminating dairy from her diet.

Fortunately for both Carroll and Teh, they possessed the skills as dietitians to do their own research and learn about and understand their infants’ condition. But for the general public, access to medical professionals who are aware of MSPI can be hit-or-miss, leading many to turn to the internet for answers.

“A big problem is that moms are desperate and cling to inaccurate information shared in Facebook groups or blogs,” Carroll says. “This type of ‘research’ can be helpful, but it can also be dangerous because it can encourage additional restrictions that are not always necessary.”

Inspired by her own experience, Carroll founded a blog called Dairy-Free for Baby (dairyfreeforbaby.com), an evidence-based online resource for women breast-feeding infants with MSPI. There, she shares creative dairy-free recipes and credible information on managing the condition for women who are suddenly faced with going dairy-free.

Because management of MSPI comes during the chaotic time of having a new baby, families are sure to benefit from a supportive medical team that includes the care of a dietitian.

For new moms who want to breast-feed, RDs can help by guiding women through a diet free from dairy and possibly soy. A woman should learn not only alternative sources of protein and calcium to support her needs for lactation and postpartum recovery but also the many hidden sources of dairy and soy, such as supplements that contain lactose. Dietitians also can serve as integral members of the family’s medical support team, coordinating with pediatricians and gastroenterologists on when a family should consider eliminating additional allergens and advocating for families who suspect their infants have MSPI when others on the medical team are doubtful or uninformed about the condition.

Of course, not all new mothers choose to or can breast-feed. In these cases, special formula is indicated, as infant formula almost always contains either milk or soy proteins. “The initial intervention when a milk and/or soy protein intolerance or allergy is identified, and the baby is formula fed, is to change to a hydrolyzed infant formula,” says Nicole Lattanzio, RD, CNSC, CSP, a Phoenix-based dietitian who owns The Baby Dietitian, PLLC, and works with families to select the most appropriate infant formula. “These formulas are hypoallergenic and available over the counter. They’re appropriate for both milk and soy protein intolerances as well as other allergens such as eggs.”

However, not all babies respond well to a hydrolyzed formula. “If baby continues to have symptoms of intolerance or allergy with a hydrolyzed formula after about two weeks, the next line of treatment is an elemental infant formula,” Lattanzio says. “These formulas are made from 100% free amino acids and are hypoallergenic as well. Elemental formulas are significantly more expensive and require a prescription to obtain; therefore they should be used only when necessary.”

Dietitians also should support mothers who wish to continue breast-feeding despite pressure to switch to formula from friends, family, and other providers. Lattanzio often finds that providers sometimes see switching to formula as the preferred first line of treatment with MSPI. “I encourage moms to advocate for themselves and their breast-feeding goals. If mom is open to changing her diet and has the education to do so, that should be the first treatment. More times than not, changing mom’s diet leads to improved outcomes in babies with MSPI, and formula is not indicated.”

In some cases, formula may serve as a temporary intervention. “It really depends on the baby and if they’re thriving despite having MSPI,” Lattanzio says. “If baby is having issues with growth and possibly anemia related to MSPI, he or she may need some formula supplementation during the time mom is adjusting her diet.”

Since MSPI often resolves near the end of infancy and babies start solids around six months, it’s important for parents to start with solids their children haven’t reacted to and try only small amounts of the problematic foods under the guidance of a pediatric gastroenterologist and dietitian once other solids are well tolerated.

“I remained dairy-free for about 10 months with both children,” says Teh, whose second child experienced both milk and soy intolerance. “I reintroduced both foods very slowly. I started with foods that had dairy and soy as ‘hidden’ ingredients, and, when that was tolerated, I slowly advanced to foods that had more dairy or soy in [them]. Sometimes it would be through what I was eating, and other times it may have been in a food I was feeding directly to my baby.”

Carroll had a similar experience. “We started with one food category at a time when my son was a year old,” she says. “Luckily, he had outgrown everything!”

And though some women may discover that they enjoy having less dairy in their diets long-term, many are ecstatic to relax about reading labels and once again enjoy their favorite foods. “I can’t describe how wonderful it was to eat cheese again,” Carroll proclaims.

— Diana K. Rice, RD, LD, CLEC, is known as The Baby Steps Dietitian and is the founder of Diana K. Rice Nutrition, LLC, where she works with families to eat well and reduce the stress surrounding their food choices. She specializes in pre- and postnatal nutrition as well as feeding young children and is a strong advocate for cooking with kids, family meals, and body positivity.

1. Brill H. Approach to milk protein allergy in infants. Can Fam Physician. 2008;54(9):1258-1264.