Autism Therapy: vitamin C (ascorbic acid)

What is it?

Vitamin C (ascorbic acid) is an essential water-soluble vitamin that is found naturally in many foods. Vitamin C is important for many biological processes including the production of neurotransmitters. Vitamin C also acts as an anti-oxidant, protecting the body against damage from free radicals ⁽¹⁾.

What's it like?

Vitamin C is found naturally in many foods, particularly citrus fruits such as oranges, tangerines, and grapefruits. Vitamin C can be purchased over-the-counter, online, or at grocery, drug, or health-food stores. It can be taken every day. Unfortunately, it is not clear what the proper dose for children with autism should be. One published research report on treatment of children with autism used a dose of 8 grams/70 kg/day (or about 2 grams daily for a 40-pound child) divided into two or three doses ⁽²⁾. If you choose vitamin C as an alternative therapy, ask your child's pediatrician what dose is appropriate for your child.

What is the theory behind it?

Some children with autism may have a vitamin C deficiency. One study demonstrated normal vitamin C levels among children with autism ⁽³⁾, while another reported low levels ⁽⁴⁾. Some investigators believe, however, that supplementation with vitamin C can be helpful even for children with normal levels of vitamin C ⁽³⁾.

Vitamin C has been shown to have a calming effect on behavior in humans ⁽⁵⁾. In animals, stereotyped behavior, one of the characteristics of autism ⁽³⁾, was reduced by treatment with vitamin C ⁽⁶⁾. Scientists hypothesize that vitamin C has these effects because it affects the brain signaling system called the glutamatergic system ⁽⁷⁾ and/or the brain’s response to an important neurotransmitter called dopamine ⁽⁶⁾.

Another explanation for the effectiveness of vitamin C is its anti-oxidant properties ⁽¹⁾. Some researchers have theorized that children with autism may have more trouble managing free radicals than other children do ^{(8, 9)}. Free radicals are naturally-occurring chemicals that play important roles in normal functions in the body, but also can cause damage in the brain, immune system, and other tissues or organs in the body. The body has systems to protect tissues from free radical damage, and anti-oxidants are important for this protection. Because it is an anti-oxidant, vitamin C can protect the body against the damaging effects of free radicals.

Does it work?

So far, only one controlled study has shown that vitamin C can help treat behavioral problems associated with autism ⁽²⁾. This double-blind experiment showed that high doses of vitamin C in children with autism had significant positive effects on behavior, compared against their own behavior scores when they were taking a placebo. However, this study was very small (only 18 children), and has not been replicated ⁽¹⁰⁾.

Another research report (uncontrolled study) showed that high doses of vitamin C may help sleep and gastrointestinal problems in children with autism ⁽⁴⁾. In this study, vitamin C was taken along with other vitamins, so it's not clear which vitamin was responsible for the positive outcomes.

Is it harmful?

For most people, vitamin C is thought to be harmless. However, tolerance for vitamin C can vary. Therefore, you should watch your child carefully for signs of an upset stomach or diarrhea ⁽¹⁾. The U.S. FDA Recommended Daily Intakes are 15-75 mg/day for children, and 75-90 mg/day for adults ⁽¹¹⁾. Check with your child's pediatrician before starting treatment.

Cost

The cost of vitamin C treatment depends on the dosage selected. A bottle of 100 tablets at 1,000 mg (1 g) can cost anywhere from $5 to $20, depending on the quality of the ingredients and the store. The study showing positive effects on behavior used vitamin C donated from a pharmaceutical supply company (Hoffman-LaRoche). Vitamin C supplements may contain sodium, calcium, magnesium, potassium, or zinc ascorbates (salts) of ascorbic acid ⁽⁴⁾; ask your child's pediatrician which form is best for your child. Vitamin C supplements can also be found online, sometimes at a discount.

Resources

Healing Thresholds has partnered with Webvitamins. They have a large selection of top quality vitamins and supplements.

Vitamin C can also be purchased at most grocery stores and drug stores.

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References

1. Levy, S.E., and S.L. Hyman. 2005. "Novel Treatments for Autistic Spectrum Disorders." Ment Retard.Dev Disabil.Res Rev. 11(2):131-142.
2. Dolske, M.C., et al. 1993. "A Preliminary Trial of Ascorbic Acid as Supplemental Therapy for Autism." Prog.Neuropsychopharmacol.Biol.Psychiatry 17(5):765-774.
3. Sankar, D. 1979. "Plasma Levels of Folates, Riboflavin, Vitamin B6, and Ascorbate in Severely Disturbed Children." Journal of Autism and Developmental Disorders 9:73-82.
4. Adams, J.B., and C. Holloway. 2004. "Pilot Study of a Moderate Dose Multivitamin/Mineral Supplement for Children with Autistic Spectrum Disorder." J Altern.Complement Med. 10(6):1033-1039.
5. Pierce, R.C., et al. 1991. "Chronic Ascorbate Potentiates the Effects of Chronic Haloperidol on Behavioral Supersensitivity but not D2 Dopamine Receptor Binding." Neuroscience 45(2):373-378.
6. Deshpande, C., et al. 2006. "Antagonistic Activity of Ascorbic Acid (Vitamin C) on Dopaminergic Modulation: Apomorphine-Induced Stereotypic Behavior in Mice." Pharmacology 77(1):38-45.
7. Blaylock, R.L., and A. Strunecka. 2009. "Immune-Glutamatergic Dysfunction as a Central Mechanism of the Autism Spectrum Disorders." Curr Med Chem. 16(2):157-170.
8. Ming, X., et al. 2005. "Increased Excretion of a Lipid Peroxidation Biomarker in Autism." Prostaglandins Leukot.Essent.Fatty Acids 73(5):379-384.
9. Yao, Y., et al. 2006. "Altered Vascular Phenotype in Autism: Correlation with Oxidative Stress." Arch.Neurol. 63(8):1161-1164.
10. Hyman S.L., and S.E. Levy. 2000. "Autism Spectrum Disorders: When Traditional Medicine is not Enough." Contemporary Pediatrics 10:101-113.
11. U.S. Department of Agriculture. 2009. "Food and Nutrition Information Center: Dietary Guidance." USDA National Agricultural Library.