Autism is a neurodevelopmental disorder usually beginning by the age of three years.  Altered levels of neurotransmitters, especially elevated serotonin levels, are often seen in autism.  Monoamine neurotransmitters (serotonin, dopamine, epinephrine and norepinephrine) can be elevated and function in the gastrointestinal and immune systems and, perhaps, in development of the nervous system.

Metabolism of neurotransmitters depends on the presence of methyl groups (-CH3) and sulfate (-SO4), so their levels don’t go too high.  If methyl and sulfate are not available, metabolism of the neurotransmitters can continue by the monoamine oxidase (MAO) enzyme.  This enzyme is often reduced in males as compared to females.  (Autism is four times as common in males as in females.)  The degradation of foreign chemicals from the body also requires the presence of methyl and sulfate groups and can deplete them.  Any increased need by the body to detoxify can impair the body’s ability to control the levels of monoamine neurotransmitters and result in elevation of those levels.

The U.S. Infant Formula Act of 1980 set a lower limit for vitamins for infants, but did not set an upper limit.  In 1988, an advertising campaign was initiated by U.S. baby formula companies. There was a sudden increase in autism in babies born in 1987-1992.  Before 1985, the prevalence rate for autism had been 4 to 5 per 10,000 children.  Babies born in 1992 had an autism rate of 19.1 per 10,000.  Studies have shown that premature weaning of babies is a risk factor for autism.  Studies often show that some formula-fed babies have excessively high levels of some vitamins.

Vitamins increase the body’s production of monoamine neurotransmitters and compete for methyl groups and sulfate (from the amino acids methionine and cysteine).  It is possible that the use of excess multivitamins in infancy may be partly responsible for increased monoamine levels and subsequently responsible for the increased frequency of autism.  Vitamins show increasing benefits up to a point, and above that point they begin to have negative effects, such as toxicity to the nervous system.  “The neurological effects of vitamin deficiency and vitamin excess may be similar.”  The detoxification systems of human infants up to about six months are immature and that may contribute to a lower tolerance to higher doses of vitamins.

CONCLUSION:  The authors postulate that autism may be due to excessive vitamin exposure causing neurological deficits in early infancy.  Breastfeeding may be best.

NOTE:  It should be noted that, although multivitamins can impair the body’s supply of methyl groups, folic acid is an excellent source of methyl groups and is important in pregnancy for preventing neurological birth defects of the spine of the fetus.

PMID:  23533752.

Summary 537.