It is estimated that around 1% of the population in the UK may have autism spectrum disorder, with a high health cost associated with the management of the disorder. So it is perhaps unsurprising that there is much interest in strategies for reducing autism risk, including nutrition. Researchers are exploring the idea that diet or certain nutrition supplements may play a role in either the development or treatment of autism.
Could a prenatal nutrition supplement be of benefit?
Recent research published in Cell Reports suggests a prenatal approach may protect against a certain type of autism. Prenatal prevention strategies in other areas are of course not new. Folic acid for example is an important supplement in women of childbearing age for the prevention of neural tube defects - defects in the baby’s developing brain and spinal cord such as spina bifida.
The new research hints that carnitine in the prenatal period may reduce autism risk. Carnitine, which is derived from an amino acid (the building blocks for protein) may be implicated in development of autism spectrum disorder as carnitine deficiency interferes with the normal processes by which neural cells promote brain development in the foetus. Carnitine can be obtained from the diet, but carnitine can also be made in the body.
Previous studies show that an inherited defect in the gene required for our bodies to make carnitine (TMLHE) is associated with increased risk of development of some (but not all) autism spectrum disorders. If we want to be strictly scientific, the TMLHE gene encodes the first enzyme in the carnitine biosynthesis pathway. Currently researchers hypothesise that this enzyme deficiency is associated with an increased risk for autism, and that this risk is modified by dietary intake of carnitine from birth through the first few years of life.
Carnitine intake of the pregnant or nursing mother could also be important. Pregnant women may be able to get enough carnitine from their diet to offset risk of carnitine deficiency and therefore reduce the likelihood of autism for their babies. A particularly rich source of carnitine in our diet is red meat, but it is also found in significant amounts in fish and milk, although consumption of these foods is decreasing in the UK. And the study authors suggest the possibility that screening for the genetic defect along with carnitine supplement before and during pregnancy could help as a preventative strategy in certain cases of autism spectrum disorder.
Supplementation is only likely to be helpful in a small number of cases
It is important to note though that there is a scientific understanding that carnitine deficiency will only be relevant in a small subset of autism cases. As many as 1000 genes may ultimately be found that relate to autism risk, and therefore even if this strategy works in some cases of carnitine deficiency (and there is no evidence currently that it would), other pathways are also in play.
More research is needed to understand the link between carnitine and autism risk. But it may be one piece of the autism and nutrition puzzle.
*All information is correct at the time of publishing