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.
The new study explored the effects of the flavonoids luteolin and quercetin on cell models of breast and endometrial cancer. Luteolin supplements, in particular, are marketed for use in children with ASD.
The researchers showed that luteolin partially blocks the naturally occurring hormone progesterone. This resulted in one anti-cancer effect and two cancer-promoting ones. The latter included directly stimulating cancer cells and disabling the “brakes” that progesterone puts on certain cancers.
"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.
Nutritional supplements including flavonoids aren't regulated by the Food and Drug Administration (FDA). As a result, they don’t have to be thoroughly tested for safety or effectiveness.
“While many people take nutritional supplements to address an unbalanced diet or treat a specific concern, caution is needed,” concurs Daniel Coury, M.D., medical director of Autism Speaks Autism Treatment Network. “It’s important to remember that too much of anything can cause health problems, and supplements can provide much larger amounts of active compounds than a person would receive in food.” Dr. Coury encourages individuals and families to consult with their physicians to weigh the pros and cons of any nutritional supplement.
Autism Speaks is currently funding a number of studies looking at the potential role of oxidative stress in ASD. You can explore these studies and all the research Autism Speaks is funding using this website’s grant search. This research is made possible by Autism Speaks’ passionate community of families, donors and volunteers.