Grandma of child with autism worries about B12 side effects

September 5, 2018
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“My grandson who has autism has been on methyl B12 for approximately 9 months. The day after he receives a shot, I notice that he lacks focus, is hyperactive and is mouthing objects a lot. I've encouraged my son to tell the pediatrician and discuss possibly reducing the dosage. Is there anything else I can suggest or share?”


Today’s Got Questions answer is by neurodevelopmental-behavioral pediatrician Susan Hyman, of the University of Rochester Medical Center. The Rochester Medical Center is one of 14 sites in the Autism Speaks Autism Treatment Network.

Over the last 10 years, Dr. Hyman and colleague Susan Levy have published a series of scientific review articles updating doctors on the growing scientific evidence on the effectiveness and use of complementary and alternative medicine (CAM) treatments for autism. The journal Child and Adolescent Psychiatric Clinics of North America has provided open access to their 2008 review here. (Their more recent reviews require a journal subscription.)

Editor’s note: The following information is not meant to diagnose or treat and should not take the place of personal consultation, as appropriate, with a qualified healthcare professional and/or behavioral therapist.

Thank you for your question. The behaviors you describe the day after your grandson’s B12 injections could well be side effects.

Vitamin B12 is required for proper red blood cell formation and brain function. Interest in using B-12 for treating autism grew out of studies suggesting some children who have autism have low blood levels of naturally occurring antioxidants associated with B12 deficiency. Antioxidants help protect the cells of our bodies and brains from damage. In addition, a number of parents had reported improvements in their children’s behavior after they received B12 injections.

Research on B12 for autism

In 2010, researchers with the University of California MIND Institute published the results of an Autism Speaks-funded study on the benefits of B-12 treatment on the behavior and blood chemistry of 30 children with autism. The study showed no improvements in autism behaviors or blood chemistry. However, a subgroup of the children did see small but significant improvements. On the worrisome side, the researchers reported hyperactivity and pica (a tendency to eat nonfood items) as side effects.

So it is entirely possible that the behaviors you see are in response to the injections. From my perspective as a neurodevelopmental-behavioral pediatrician, such side effects are further reason to discontinue a therapy for which there is no scientific evidence of benefit.

In particular, we as physicians are concerned by the possible ill effects of the high dosages of B12 being administered by injection since there is limited information on short- or long-term side effects at such doses. In the Autism Speaks-funded study, the researchers administered 64.5 micrograms of methyl B12 for every kilogram (2.2 pounds) of body weight every three days for 6 weeks. For a 45-pound child, this would be about 45 micrograms per day.

Dietary recommendations

By contrast, the recommended dietary allowances for vitamin B12 are around 1 microgram per day for children ages 1 to 8, about 2 micrograms per day for children 9 to 13 years and increasing to around 2.5 micrograms for teenagers and adults. Most of us get sufficient amounts through our diet. Foods rich in B12 include meats, eggs, fish, milk and cheese. In addition, many breakfast cereals are fortified with B12. (Check the nutritional labels.)

Bottom line: We have no scientific evidence to support the use of B12 injection in the absence of a significant B-12 deficiency. Oral supplementation (a vitamin pill) may be warranted for children with severely restricted diets – not uncommon among those who have autism and for vegans. Severe dietary restriction can indeed lead to neurologic symptoms and anemia due to B12 deficiency.

Checking for deficiency

The good news is that it’s a simple matter to check a child for B12 levels and related anemia with a blood test.

If your grandson does have a deficiency related to restricted diet, a registered dietitian or a behavioral specialist in autism feeding issues could provide guidance and therapy designed to expand his diet, and so, improve nutrition. In the absence of such a deficiency, supplementation isn’t warranted.

How much is too much?

Unfortunately, we simply don’t have good information on safe upper limits for B12. I am particularly concerned about the long-term use of high-dose injections. For this reason, I would strongly suggest that your grandson’s parents discuss the injections with a primary care pediatrician, developmental-behavioral pediatrician or pediatric neurologist.

I hope this information proves helpful in your discussions with your family.

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