Plant-based diets are healthy. Plants are high in flavonoids. But the concentrated flavonoids in supplements can affect the body in unpredictable and potentially harmful ways, according to a new study in the journal Hormones & Cancer.
The researchers expressed special concern about the use of flavonoid supplements in children with autism spectrum disorder (ASD). This popular use comes on the heels of evidence that some individuals with autism may suffer from “oxidative stress.” Among their many biological actions, flavonoids can act as anti-oxidants.
"What we're saying is that flavonoids are active and not always in good or predictable ways," says study senior author Steven Nordeen, PhD, of the Colorado University Cancer Center. "[When] you're giving prepubescent kids a supplement that affects the endocrine system, that's dangerous." A recent report in The New England Journal of Medicine linked breast development in young boys to the use of shampoos and balms containing lavender or tea tree oils high in flavonoids, he notes.