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People with Down鈥檚 syndrome who take green tea supplements from infancy are less likely to develop the characteristic facial features of the condition. But researchers have warned that parents shouldn鈥檛 give these supplements to their children yet because mouse studies suggest that high doses can cause abnormalities.

Down鈥檚 syndrome arises from having all or part of an extra chromosome, which affects the growth of the brain and skeleton. This can lead to a range of characteristics including intellectual disability, short stature and facial differences. There is evidence that this altered growth is partly due to having too much of an enzyme called DYRK1A.

at the Centre for Genomic Regulation in Spain and her colleagues wondered if blocking this enzyme would reduce some of the characteristics of Down鈥檚 syndrome. They turned their attention to a compound in green tea called epigallocatechin-3-gallate (EGCG), which is known to inhibit DYRK1A.

Face reshaping

Even though EGCG hasn鈥檛 been approved as a treatment, some parents have already started giving the over-the-counter dietary supplement to children with Down鈥檚 syndrome, prompted by studies that suggest it may have some cognitive benefits.

The researchers recruited 13 children under the age of 19 who have been taking such supplements. They then compared their facial dimensions with other children with Down鈥檚 syndrome who weren鈥檛 taking EGCG, as well as children without the condition.

EGCG appeared to have little effect when children with Down鈥檚 syndrome started taking it after the age of 3. But six of the seven children who began taking it before they turned 3 had facial dimensions that matched or closely resembled those of children without the condition. The supplement probably had more of an effect in these younger children because their faces were still forming, says Dierssen.

This small study follows previous work by the team that found that young adults with Down鈥檚 syndrome who took EGCG supplements for a year in tests of memory and reasoning. The EGCG dose was equivalent to drinking eight cups of green tea per day. Experiments in a mouse model of Down鈥檚 syndrome have shown that early EGCG treatment does seem to change face, skull and limb bone development.

Warning to wait

Minimising facial variation could help to reduce stigma towards people with Down鈥檚 syndrome, says at the Queensland University of Technology in Australia. But there are ethical questions about whether we should be trying to 鈥渘ormalise鈥� people who look different, she says.

Different families have different attitudes to raising children with Down鈥檚 syndrome, says Gilmore. 鈥淪ome are keen to try anything that might make things easier cognitively and socially, even treatments and interventions that have not been established scientifically,鈥� she says.聽鈥淥thers feel strongly about not changing their child鈥檚 personality or appearance 鈥� not changing the person they are.鈥�

The study was small, and cannot draw clear conclusions because the children took supplements for different amounts of time. But at the Brain and Spine Institute in Paris, who worked with Dierssen on the earlier cognitive benefits study, says the findings are encouraging and warrant larger-scale studies in young children. But it is important to determine the optimum dose, he says, because mouse studies suggest that very high amounts of EGCG can cause severe facial and skeletal abnormalities.

For this reason, Delabar advises that parents don鈥檛 give EGCG to children with Down鈥檚 syndrome until more research has been done. 鈥淚t is very important to state that non-prescribed use of this compound 鈥� even if found in green tea 鈥� is risky at this stage.鈥�

at the Telethon Kids Institute in Australia agrees, but says it can be hard for families to wait for the outcomes of long-running clinical trials. 鈥淭hat means the earlier this research can be done, the better.鈥�

Related: Parents giving unproven IQ-boosting drugs to kids with Down鈥檚