B-12 Vitamin Supplements for Children

Most children get enough nutrients from their diet and don't need expensive supplements — you can save that money for the college fund. However, supplemental B12 for kids with restrictive diets or certain medical or genetic conditions may be necessary.

Always consult your pediatrician before giving your child a supplement.

The best way for children to get all the nutrients they need is from a healthy diet, including fruits, vegetables, whole grains, fortified dairy or dairy substitutes, meat and seafood. If your child is eating a varied diet, she's probably getting everything she needs, says Boston Children's Hospital pediatrician Dr. Claire McCarthy.

B12 is found in a variety of foods and added to others. The richest sources are meat, fish and dairy. Very few plant foods provide B12, but some are fortified with the nutrient.

One of the main reasons children and adults may become deficient in B12 is if they eat a vegetarian or vegan diet. It's not impossible for children to get all the B12 they need from a vegetarian diet; however, it is sometimes challenging to get kids to eat the plant-based foods that are highest in the vitamin.

For example, according to an article in the journal Nutrients in May 2014, one of the richest vegan sources of B12 is a type of seaweed — not exactly every child's favorite food.

Other children who are at risk of B12 deficiency include:

• Very picky eaters who refuse to eat all but a few foods.
• Children with malabsorption conditions, such as celiac and Crohn's diseases.
• Those who take medications for chronic conditions. Some medications, like isoniazid or methotrexate, may make it necessary to supplement with extra nutrients, advises McCarthy.

Read more: 43 Supplements Exposed: Which Ones to Consider

If you think your child's diet or another condition is causing a B12 deficiency, make an appointment with your pediatrician. B12 deficiency can lead to megaloblastic anemia, a condition in which blood cells become very large and not fully developed. This leads to stalled production of blood cells by the bone marrow. Fewer red blood cells mean that oxygen can't be delivered properly to tissues throughout the body.

Symptoms of B12 deficiency that your child might exhibit include:

• Pale skin
• Poor appetite
• Fatigue
• Diarrhea
• Irritability
• Muscle weakness
• Difficulty walking
• Numbness or tingling in the hands and feet
• A smooth and tender tongue

The long-term effects of low B12 in children can be serious and permanent, especially a deficiency in toddlers and infants. B12 is crucial for proper neurological and DNA development, and a lack of the vitamin can cause brain damage.

Although research is mixed, there is some evidence of a link between low B12 and autism and schizophrenia, according to a study published in the journal Plos One in January 2016.

The daily recommended intakes (DRI) for B12 for kids, established by the National Academy of Medicine, depend on age:

• 1 to 3 years: .9 micrograms
• 4 to 8 years: 1.2 mcg
• 9 to 13 years: 1.8 mcg

These amounts are not difficult to obtain through diet if your child is healthy and eats a wide range of foods. For example, 1.5 ounces of cooked salmon provide 2.4 mcg, and a serving of fortified breakfast cereal provides 1.5 mcg, according to the National Institutes of Health.

If your child needs a supplement, there are several options: liquid drops, pills or sublingual tablets. According to NIH, there is no difference in the bioavailability and efficacy between sublingual and oral formulations.

One important thing to note is the vitamin B12 dosage for a child. The DRI for a 4-year-old is 1.2 mcg, but children's B12 supplements often contain way more than that. One brand provides 1,200 mcg. One reason for this is that the body's ability to absorb supplemental B12 is limited. NIH reports that healthy people absorb only about 10 mcg of a 500-mcg supplement.

Even if only 2 percent of the B12 in a supplement is absorbed, a child will get 24 mcg from a 1,200 mcg supplement. That's 20 times the RDI for a 4-year-old.

However, that's not likely cause for concern. B12 is a water-soluble vitamin, meaning excess is excreted in urine, not stored in the body's tissues, as with the fat-soluble vitamins A, D, E and K. According to NIH, no upper intake limit (UL) has been established for B12 because no adverse effects of excess intakes from food or supplements have been found in healthy individuals.

That doesn't mean supplemental B12 is completely safe. According to Mayo Clinic, high-dose vitamin B12 used to treat a deficiency could possibly cause short-term effects such as dizziness, headache, anxiety, nausea and vomiting.

If you give your child a B12 supplement made for adults, that could be enough to cause problems, especially if your child is sensitive to the effects. Adult B12 supplements may contain 5,000 mcg — 4,167 times the RDI for a 4-year-old.

Read more: The 10 Best Supplements

If you're scanning the shelves of your local health food store, you might notice that B12 bottles are labeled with different names, such as methylcobalamin, adenosylcobalamin and hydroxocobalamin.

According to a study published in Integrative Medicine: A Clinician's Journal in February 2017, these are the natural forms of the vitamin available to consumers. A synthetic form of the nutrient called cyanocobalamin is used to fortify foods and is also available in supplement form.

After searching the PubMed database for human, animal and in vitro studies on the bioavailability and absorption of different forms of B12, the researchers concluded that supplementing with any of the natural forms of B12 is preferred because of their superior bioavailability and safety.

They report that for most people, all three forms of the nutrient likely have similar physiological effects and bioavailabilities. Thus, barring any specific recommendation from your pediatrician, it may make sense to go with the least expensive supplement, which is typically methylcobalamin.