Women in the US who are of childbearing age are being warned to avoid taking a synthetic ingredient named vinpocetine, which is commonly sold in the form of 'memory enhancing' supplements.
A statement published earlier this week on the US Food and Drug Administration website cautions consumers of the supplement that they could be putting their unborn child at risk of serious harm.
Citing a recent National Institute of Health and National Toxicology Program report containing evidence of vinpocetine toxicity in animal studies, the FDA is concerned the supplement could cause spontaneous miscarriages.
"That's why today we're advising pregnant women and women who could become pregnant not to take vinpocetine," the statement reads.
"We are also advising firms marketing dietary supplements containing vinpocetine to evaluate their product labelling to ensure that it provides safety warnings against use by pregnant women and women who could become pregnant."
The caution comes as the FDA continues to crack down on the dietary supplement industry, which has been accused of peddling products that don't do what they claim, and sometimes contain hidden surprises that put our health at risk.
Legally speaking, a dietary supplement contains dietary ingredients, such as vitamins, minerals, amino acids, or materials extracted from something we could eat.
Given vinpocetine is a synthetic derivative of a chemical found in extracts of lesser periwinkles, it's really stretches the definition's limits to breaking point. Which is one reason why the FDA refuses to call it a dietary ingredient for the time being.
Still, this doesn't stop people from buying the compound under the impression that it boosts memory and potentially helps prevent strokes and impede the onset of dementia by increasing blood flow to the brain. In countries such as Germany and Russia, these characteristics make the compound a drug only available via a prescription.
Regardless of whether it's considered a drug or a supplement, it's vital that consumers know what they're putting into their bodies.
Unfortunately, this isn't necessarily the case.
A 2015 study on 23 claimed vinpocetine supplements bought over the counter revealed alarmingly varied concentrations, from nothing at all to 32 milligrams per suggested daily dose.
Prescribed doses tend to vary from 5 to 40 milligrams. That might not make the pills seem particularly toxic, but the lack of information does leave plenty of room for unnecessary risks.
Inaccurate labelling becomes a truly serious concern in light of investigations suggesting there's potential for serious harm.
The report referred to by the FDA describes assessments conducted on groups of pregnant rats and rabbits that conclude dosages of the supplement could be responsible for decreased foetal weight and increased chances of miscarriage.
Of course, rats and rabbits aren't people. Without clear evidence of a similarly adverse effect in a human population, we can only be left to draw our own conclusions.
The FDA isn't waiting around for further studies before acting.
"The blood levels of vinpocetine measured in the pregnant animals were similar to those reported in people after taking a single dose of vinpocetine, indicating that pregnant women may experience adverse effects from vinpocetine similar to those seen in the pregnant animals," says the administration.
Further research is always welcome. None of this should imply vinpocetine has no place in our medical arsenal. But it does mean companies marketing supplements have a responsibility to provide clear information for consumers, outlining risks and providing accurate details on ingredients.