On Christmas morning of 2017, the Leitao’s house filled with the delicious scent of holiday cookies. For Zach Leitao, 8, this was a special occasion – he was about to try his first Christmas cookie. After they cooled, he took a bite and tears of joy came down his face. In the past, Zach, who has severe food allergies, typically had his own special plate of sweets. Just a few days prior to his first bite, he was declared free of three serious food allergies.


When he was 6 months old, Zach Leitao’s mother, Tiffany Prout-Leitao, fed him strawberry yogurt. Minutes later, Zach’s face, hands and forearms were covered in hives. His pediatrician suspected a food allergy to strawberries, so Tiffany switched to vanilla yogurt. But Zach’s skin still erupted in hives. He was diagnosed with a dairy allergy shortly after.

That wasn’t Zach’s only allergic reaction to food. Just after his first birthday, Zach went into anaphylactic shock – a severe, life-threatening reaction - after eating scrambled eggs with breakfast. Three years later, at age 4, he broke out in hives again after eating trail mix with tree nuts.

The gold standard of testing whether a person is allergic to a particular food is a food challenge. During a food challenge, a person will eat small samples of a certain foods in the safety of a doctor’s office in case they have a reaction. If they do not react, they pass the food challenge. Since the fall of 2017, Zach has completed food challenges for dairy, egg and hazelnut - and passed all three.

“About 50-70 percent of kids will outgrow milk and egg allergies by school age, but the likelihood of outgrowing a tree nut allergy is much lower – about 20 percent,” said Yamini Virkud, MD, MA, MPH, a physician in the Food Allergy Center at Mass General for Children (MGfC). “What’s amazing about Zach is that he outgrew three food allergies in about a year. In most kids, it takes much longer than that.”

With three of Zach’s food allergies no longer causing concern, new precious childhood memories await. “Food is such a cultural and emotional experience, especially around holidays. When you ask someone what their favorite holiday memories are, they very often center around food,” said Virkud. “For Zach, this means he gets to create a whole new set of childhood memories.”

This year, Zach is taking the opportunity to make memories outside of the holiday season – especially at the ice cream stand this summer. “Having allergies made me feel left out a lot, but now I am excited because I can eat lots of new stuff. I don’t have to worry or constantly check everything,” he said. “I can also eat at my friends’ houses and at restaurants and parties. I love being able to go out for ice cream too!”

For the Leitaos, that sense of fear that is common in families with food allergies no longer lurks in the background. “For us and for Zach, we don’t have to worry when we go to a family member’s house or a friend’s house,” said Tiffany. “He doesn’t have to pack special food when he goes to school or goes out somewhere. It gives us and him a sense of normalcy.”