With more families placing their children on vegetarian diets, the results from a Canadian longitudinal cohort study are reassuring: It found no clinically meaningful differences in height, growth, or biochemical measures of nutrition in young children on vegetarian and nonvegetarian diets.
While z scores (the standard deviation above or below the mean) were similar in both dietary groups, there was a weak association between a vegetarian diet and lower mean z height, as well as slightly higher odds of underweight.
No significant associations were identified between vegetarian and nonvegetarian diets for child z body mass index (BMI), serum ferritin, 25(OH)D, and serum lipids, according to Jonathon L. Maguire, MD. MSc, of St. Michael’s Hospital Pediatric Clinic in Toronto.
Moreover, the magnitude of the height and vegetarian diet association was small at just 0.3 cm for a 3-year-old child and unlikely to be clinically meaningful, Dr. Maguire and colleagues wrote online in Pediatrics.
In a secondary study outcome, cow’s milk consumption was associated with higher serum lipid levels for both diets. Serum lipids were similar among those who did or did not consume a vegetarian diet and consumed the recommended 2 cups of cow’s milk per day.
“The vast majority of children with vegetarian diets have similar growth and nutrition as children without vegetarian diets,” said Dr. Maguire, who is also a professor of pediatrics and nutritional sciences at the University of Toronto, in an interview. “But, I think we should be mindful to carefully plan vegetarian diets for children [who are] underweight.”
The study conclusion was based on 8,907 children, 6 months to 8 years of age, including 248 vegetarian and 25 vegan children, at baseline. They were part of theTARGet Kids! practice-based research network in Toronto.
The mean age of children at baseline was 2.2 years (standard deviation, 1.5), and 52.4% were male. Participants were followed for an average of 2.8 years (SD, 1.7).
Those with a vegetarian diet had longer breastfeeding duration: 12.6 months (SD, 9.5) versus 10.0 months (SD, 7.0). They were also more likely to be of Asian ethnicity: 33.8% versus 19.0%. Otherwise, children with and without a vegetarian diet were similar at baseline.
In study outcomes, vegetarian children had higher odds of underweight: body mass index z score less than –2 (odds ratio 1.87; 95% confidence interval, 1.19-2.96, P = .007), while no association with overweight or obesity was found.
In a secondary outcome, cow’s milk consumption was associated with higher levels of non–high-density lipoprotein cholesterol (P = .03), total cholesterol (P = .04), and low-density lipoprotein cholesterol (P = .02) in young children on a vegetarian diet. Levels were similar in children with and without a vegetarian diet who consumed the recommended 2 cups of cow’s milk per day.
Previous studies have found that vegetarian children have normal growth and development but tend to be leaner than their omnivore peers.
As for the potential effect of following a fully vegan diet on these nutritional measures, Dr. Maguire said, “Unfortunately, there were not enough children with vegan diets to make meaningful conclusions.”
Would results likely be similar in older children who have more independence and engage more with their peers?“ I don’t know, but we will be following these children for many years to come through the TARGet Kids! research network, Dr. Maguire said.
Studies such as this are timely as plant-based eating becomes more widespread in the United States. The 2007-2010 National Health and Nutrition Examination Surveys found that 2.1% of American adults followed a vegetarian diet, and that figure appears to have increased, with 5% of American adults self-identifying as vegetarian in a 2019 Gallup poll.
Offering her perspective on the Canadian study but not involved in it, Stephanie Di Figlia-Peck, MS, RDN, agreed the results indicate that “a vegetarian diet is not a negative thing for growth and development.” She is a lead registered dietitian in the division of adolescent medicine at Cohen Children’s Medical Center in New Hyde Park, N.Y. She noted, however, that the study looked only at very young children on average.
Stephanie DiFiglia-Peck
She stressed that vegetarian regimens require family commitment and agreed on the need for planning. “For these diets to work, a lot has to go into it. But if they’re carefully planned, there is adequate protein and micro- and macronutrients and there’s a nonnegative effect on growth and development.”
The study results mirror what she sees in clinical practice, with vegetarian children tending to weigh less. “Some obese and overweight children will adopt vegetarian diets to lose weight,” Ms. Di Figlia-Peck said.
And perseverance has rewards. “When people follow a vegetarian diet, they tend to have lower blood pressure and cholesterol. A plant-based diet can favorably impact diseases for an entire lifetime.”
This study was supported by the Canadian Institutes of Health Research and the St. Michael’s Hospital and SickKids Hospital foundations. Dr. Maguire received an unrestricted research grant for a previous investigator-initiated study from Dairy Farmers of Canada, and D drops provided nonfinancial support (vitamin D supplements) for a previous investigator-initiated study on vitamin D and respiratory tract infections. Coauthor David Jenkins, MD, PhD, DSc, reported research support from multiple private-sector and nonprivate organizations; several of his family members are involved in the promotion of vegetarian diets. Ms. Di Figlia-Peck had no competing interests to declare.