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Vegan Diet Can Lead to Nutrient Deficiency, Metabolism Changes in Young Kids, Study Shows

vegan bowl. plant based meal

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Key Takeaways

  • Young children who are following a vegan diet may be lacking in several vitamins and essential fatty acids, according to a recent study.
  • Without adequate levels of these nutrients, children may suffer from delayed growth and development.
  • If you want your child to follow a vegan diet, it's important to work with your pediatrician or a registered dietitian to ensure your child gets the dietary supplements they need to thrive.

The vegan diet is more popular than ever—582,538 people signed up for Veganuary this year, the global campaign that encourages giving up animal-derived food products for the whole month of January. For some people, it's the beginning of a lifetime commitment to veganism, and it might extend to their whole family. But is a vegan diet suitable for very young children?

A recent pilot study carried out by researchers from the University of Helsinki and published in the journal EMBO Molecular Medicine sought to find the answer.

The researchers carried out a comprehensive analysis of the nutritional profiles of 40 young children in Helsinki daycare centers. They found that young children on a full vegan diet have significantly altered metabolism compared to children who are not on any type of restricted diet. The children also had lower levels of vitamin A, vitamin D, and essential amino acids.

Tamar Samuels, RDN

Protein and essential amino acids in particular are especially important for children because they serve as the building blocks for all of our cells, tissues, neurotransmitters, hormones, and DNA.

— Tamar Samuels, RDN

A Closer Look at the Study

One of the study authors, University of Helsinki academy professor Anu Suomalainen-Wartiovaara, MD, PhD, says she was surprised that a vegan diet affects the metabolism of healthy children in such a remarkable way.

“The low values of vitamin A [and vitamin D] status [were] a surprise, as the food content was especially planned to be balanced and nutritious for daycare children,” Suomalainen-Wartiovaara says. The vegan group seemingly had the same vitamin A and vitamin D intake as their omnivore peers (thanks to diet and supplements), but the levels of vitamin A and D present in their blood were lower.

The study also found that despite normal protein content in the children's food, they had generally low levels of essential amino acids and an absence of docosahexaenoic acid (DHA), an omega-3 fatty acid that is a primary structural component of the human brain, cerebral cortex, skin, and retina.

This draws attention to the importance of having variable protein sources and vitamin supplementation, Suomalainen-Wartiovaara says.

The study also explored the values of vitamin B12—which is critical for nervous system health, red blood cell function, and brain health, among other things—and found these to be within normal range. "This indicates that parents know this risk well and supplement the children’s diet with B12," Suomalainen-Wartiovaara says. Iodine and zinc were also within normal range.

Tamar Samuels, RDN

Children who are vitamin D deficient are especially at risk for rickets, a condition that causes bone malformation. Supplementing with this vitamin is critical for children who eat vegan diets.

— Tamar Samuels, RDN

Why These Nutrients Matter 

“Protein and essential amino acids in particular are especially important for children because they serve as the building blocks for all of our cells, tissues, neurotransmitters, hormones, and DNA,” says Tamar Samuels, RDN, cofounder of Culina Health.

Without adequate levels of these essential amino acids, there is a risk for delayed growth and development of bodily functions, Samuels warns. You can get essential amino acids from plants, but certain plant-based proteins need to be paired and consumed regularly to meet needs because animal proteins are the only proteins that contain all 20 essential amino acids in a single food.

Vitamin A is an essential vitamin for vision, immunity, growth, and development of the reproductive system. Although it's found in plants, the most bioavailable form (retinol) is found exclusively in animal foods. You can supplement with this form of the vitamin to meet your needs, but Samuels warns that there is also a risk for toxicity, so levels must be closely monitored.

Anu Suomalainen-Wartiovaara, MD, PhD

In our study, the vegetarian group was mostly in normal ranges for the measured substances, even if they followed a vegan diet mostly and had only occasional portions of animal-derived food. Therefore, an egg or a portion of fish even once a week would provide the important vitamins in a natural form.

— Anu Suomalainen-Wartiovaara, MD, PhD

Vitamin D is an essential nutrient found in a few foods, but mostly in animal foods like egg yolks and fatty fish. It's critical for bone health and immunity. "Children who are vitamin D deficient are especially at risk for rickets, a condition that causes bone malformation," Samuels says. "Supplementing with this vitamin is critical for children who eat vegan diets."

Another concern is that the children who ate vegan diets had lower levels of the essential fatty acids EPA ad DHA—these are key fats in brain development that also help fight inflammation.

Should Young Kids Be on a Vegan Diet? 

Ultimately, it’s your choice, and expert opinion varies. Samuels recommends working with a dietitian or your pediatrician to get a good quality, kid-friendly multivitamin to supplement your child’s vegan diet.

She also recommends supplementing with vitamin D and fish oil supplements. “When cooking/creating menus, make sure you pair certain foods to meet needs for all essential amino acids,” Samuels says. “This includes eating rice with beans and eating more plants that include all of the essential amino acids, such as soy (always choose organic), quinoa, amaranth, buckwheat, and hemp seeds.”

Summer Yule, MS, RDN

If a child is refusing fruits and vegetables, dairy products become a more important source of vitamin A. Many dairy alternatives are not fortified with everything that dairy provides (vitamin A, vitamin B12, calcium, iodine, protein, etc.) and parents often don't know everything they should be looking for.

— Summer Yule, MS, RDN

Summer Yule, MS, RDN, doesn’t recommend that children be placed on caregiver-imposed dietary restrictions of healthy whole foods (fish, dairy yogurt, etc.) unless the restriction is medically necessary.

“Certain groups of children may be at a bigger risk for nutrient deficiencies from caregiver-imposed dietary restrictions than others,” Yule explains. “For example, it can become more complicated when the vegan diet is layered on top of medically necessary diet restrictions (such as due to food allergies)."

What This Means For You

Experts warn against cutting healthy whole foods out of your child's diet based on general nutrition information that you read online. If you want your child to follow a vegan diet, it's crucial that you consult a registered dietitian to ensure your child is receiving all the nutrients they need to thrive.

Yule points to “too many cases,” documented in scientific literature, where parent-imposed diet restrictions in combination with picky eating led to severe nutrient deficiencies in the child. “For example, if a child is refusing fruits and vegetables, dairy products become a more important source of vitamin A,” she says. “Many dairy alternatives are not fortified with everything that dairy provides (vitamin A, vitamin B12, calcium, iodine, protein, etc.) and parents often don't know everything they should be looking for.”

And that doesn’t mean feeding your child huge amounts of meat and dairy. “In our study, the vegetarian group was mostly in normal ranges for the measured substances, even if they followed a vegan diet mostly and had only occasional portions of animal-derived food,” says Suomalainen-Wartiovaara. “Therefore, an egg or a portion of fish even once a week would provide the important vitamins in a natural form.”

If this is not possible, she stresses the need to supplement with vitamin D and A and suggests having these values checked via blood tests administered by your primary care physician.

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6 Sources
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Calder PC. Docosahexaenoic acid. Ann Nutr Metab. 2016;69(suppl 1):8-21. doi:10.1159/000448262

  3. National Institutes of Health; Office of Dietary Supplements. Vitamin B12: Fact Sheet for Health Professionals. Updated March 30, 2020.

  4. Mariotti F, Gardner CF. Dietary protein and amino acids in vegetarian diets—a review. Nutrients. 2019;11(11):2661. doi:10.3390/nu11112661

  5. National Institutes of Health; Office of Dietary Supplements. Vitamin A: Fact Sheet for Health Professionals. Updated February 14, 2020.

  6. National Institutes of Health; Office of Dietary Supplements. Vitamin D: Fact Sheet for Health Professionals. Updated October 9, 2020.