BALTIMORE — A new Johns Hopkins study found children exposed to higher levels of manganese and selenium during their mother's pregnancy had a lower risk of high blood pressure.
Researchers analyzed the levels of toxic metals and trace minerals in blood samples drawn from nearly 1,200 women in the Boston area who gave birth between 2002 and 2013. Of the mothers, 61 percent were African American and 20 percent were Hispanic.
The blood pressure readings were taken from children during clinic visits 3 to 15 years later.
Researchers concluded that manganese had a stronger inverse relationship with childhood blood pressure when higher maternal blood levels of cadmium, a toxic heavy metal that can cause hypertension, were detected.
That finding hints that manganese can specifically protect against the hypertension-promoting effect of cadmium, and may even mask cadmium’s hypertension-promoting effect in normal populations.
“People often assume that exposures to heavy metals such as cadmium occur only in occupational settings, but in fact these metals are all around us—for example, cadmium is found in ordinary cigarette smoke,” says study first author Mingyu Zhang, a PhD candidate in Mueller’s research group.
Underscoring the apparent cadmium link, the researchers observed that manganese was associated much more strongly with lower blood pressure in children whose mothers had smoked during pregnancy.
For every doubling of maternal selenium levels, children’s systolic blood pressure was found on average to be 6.23 points lower. Manganese showed a similar albeit weaker relationship to blood pressure: A doubling of exposure was associated with 2.62 points lower systolic blood pressure on average.
Manganese and selenium have antioxidant properties and are found in a variety of foods including nuts and grains, leafy vegetables, fish and shellfish.