Milk alternatives are growing in popularity for adults, but a new study finds non-cow's milks can inhibit height growth in children.
Children who drink non-cow's milk such as goat, soy, rice, and/or almond varieties are shorter than those who are fed cow's milk, the observational study in the American Journal of Clinical Nutrition stated.
Researchers looked at more than 5,000 children at age 3 and found that those who had three cups of cow's milk per day were 1.5 centimeters (just over a half-inch) taller than those who drank alternative milks. It may not sound like much, but it could make a huge difference in growth chart percentiles, meaning that drinking non-cow's milk could move a child from the 50th percentile down to the 15th percentile, study authors said.
"Wherever you are as a child on the growth curve, you tend to stay [there]," Jonathon Maguire, M.D., a pediatrician at St. Michael's Hospital in Toronto, told Parents.com. Researchers didn't look at how alternative milks may impair height or if solely drinking alternative milks could hamper other areas of a child's development. The alternative milks were grouped together and it wasn't a randomized trial, so they do not know if one type of alternative milk studied would lead to the same conclusion.
They do know that kids who drank a combination of cow's milk and alternative milks were shorter than average—so even adding some cow's milk to a child's diet can't reverse the height deficiency.
The U.S. and Canada both regulate the nutritional content in cow's milk, but most non-cow's milks are not subject to regulation so protein and fat contents can vary widely, the study reported.
"It's a bit of a wild West in terms of the [alternative milk] marketplace," Dr. Maguire said.
Two cups of cow's milk have 16 grams of protein, or 100 percent of the daily protein requirement for a 3-year-old child. On the flip side, two cups of almond milk typically include 4 grams of protein—just 25 percent of the daily requirement.
"Many children just aren't getting as much fuel," Dr. Maguire said. His previous research has found that kids who drink non-cow's milk have lower vitamin D levels, too.
Parents who aren't giving their children cow's milk without good reason may want to reconsider their choice, according to Tammy Lakatos Shames and Lyssie Lakatos, registered dietitian nutritionists from New York.
But what if your child can't drink cow's milk, or just plain doesn't like it? Sharon Palmer, a California-based registered dietitian nutritionist, said fortified soy and cow's milk are very similar in nutritional content. They both have similar amounts of calcium, vitamin D, and protein, though cow's milk doesn't contain the fiber found in soy milk.
"It is completely fine to substitute soy milk for children (not infants—they should be on breast milk or formula) instead of dairy milk," Palmer advised. "However, it is a concern when children are consuming low-nutrient plant milks." (Think almond, rice, and oat milk.) Pea milk is another protein-rich option.
Kids who drink alternative milks should choose one with at least 7 grams of protein, 300 mg of calcium, and 100 IU of vitamin D per serving.
Some experts have a slightly different perspective, which focuses less on the type of milk your child is drinking and more on their diet as a whole. Andy Bellatti, a Las Vegas-based nutritionist, said alternative milks can be just as healthful as cow's milk because children can get protein, vitamin D, and calcium from other food. The key is to choose fortified milks without added sugar—and to limit highly processed foods.
Children who drink cow's milk but eat an imbalanced diet can also suffer from health-related consequences. Being taller doesn't mean a child is healthier, Palmer added.
"The absence—or presence—of cow's milk does not in and of itself make a child's diet healthy or unhealthy," Bellatti added. "The totality of the diet matters."