Higher selenium and manganese levels during pregnancy may protect babies
from future high blood pressure
Manganese may also protect against the hypertensive effect of the heavy
metal cadmium

Date:
June 23, 2021
Source:
Johns Hopkins University Bloomberg School of Public Health
Summary:
Children who were exposed to higher levels of trace minerals
manganese and selenium during their mothers' pregnancy had a lower
risk of high blood pressure in childhood, according to a new study.



FULL STORY ========================================================================== Children who were exposed to higher levels of trace minerals manganese
and selenium during their mothers' pregnancy had a lower risk of high
blood pressure in childhood, according to a study led by researchers at
the Johns Hopkins Bloomberg School of Public Health.


==========================================================================
The 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. They found that higher levels of selenium
or manganese in the mothers' blood were associated with lower blood
pressure readings in their children at clinic visits 3 to 15 years later.

The researchers also observed that manganese had a stronger inverse relationship with childhood blood pressure when maternal blood levels
of cadmium, a toxic heavy metal, were higher -- hinting that manganese
lowers blood pressure in part by countering a blood pressure-raising
effect of cadmium.

The results appear online June 23 in Environmental Health Perspectives.

"These results suggest that healthy levels of selenium and manganese
in mothers' diets during pregnancy may protect their children against developing high blood pressure," says study senior author Noel Mueller,
PhD, assistant professor in the Bloomberg School's Department of
Epidemiology. "This work highlights the importance of nutrition
and environmental exposures in the womb for a child's cardiovascular
health and, as we continue research this further, could eventually lead
to updated nutritional guidance and environmental regulations aimed
at preventing disease." Hypertension is one of the major modifiable
risk factors for other debilitating and deadly diseases including heart disease, stroke, kidney failure, and Alzheimer's disease. It is also very common; the U.S. Centers for Disease Control and Prevention estimates
that about half of Americans over the age of 20 have hypertension --
defined as systolic blood pressure above 130 mm Hg or diastolic blood
pressure above 80 mm Hg -- or have been prescribed antihypertensive drugs.



========================================================================== Prior research suggests that the predisposition to hypertension can
start early in life, even in the womb, and that protection from that predisposition also can start early. The researchers examined these
questions in the study: They compared children's blood pressure readings
to levels of toxic metals and trace minerals in their mothers' blood;
they measured the toxic metals lead, mercury, and cadmium, which have
been linked to hypertension in adults; and they looked at levels of the
trace minerals manganese and selenium, which have been linked to lower
blood pressure.

The dataset used for the analysis covered 1,194 mother-child pairs from
a study known as the Boston Birth Cohort. Blood pressure readings in
the children were taken at ages ranging from 3-15 years. Most of the
mothers were Black (61 percent) or Hispanic (20 percent).

Although a preponderance of earlier evidence linked lead, mercury,
and cadmium to high blood pressure and heart diseases in adults,
the researchers did not find a link between these toxic metals with
childhood blood pressure in this study. They did, however, observe a
link between the mothers' levels of selenium and lower blood pressure in
their offspring during childhood. 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.

Although cadmium on its own was not linked to childhood blood pressure,
the researchers found that when maternal blood levels of cadmium were
higher, the inverse relationship between manganese and childhood blood
pressure was significantly stronger. 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.

Manganese and selenium have antioxidant properties and are found in
a variety of foods including nuts and grains, leafy vegetables, fish
and shellfish.

The researchers will aim to replicate their findings in studies based on
other birth cohorts. Johns Hopkins maintains a registry of birth cohort datasets under its Environmental influences on Child Health Outcomes
(ECHO) Program.

The researchers were supported by the American Heart Association (827990)
and the National Institutes of Health (K01HL141589, R01ES029531). The
Boston Birth Cohort is funded by the Health Resources and Services Administration's Human Maternal and Child Health Bureau (UJ2MC31074) and
NIH (R01HD086013, R01HD041702, R01HD098232, R01ES031272, and R01ES031521).

========================================================================== Story Source: Materials provided by Johns_Hopkins_University_Bloomberg_School_of_Public Health. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Mingyu Zhang, Tiange Liu, Guoying Wang, Jessie P. Buckley, Eliseo
Guallar, Xiumei Hong, Mei-Cheng Wang, Marsha Wills-Karp, Xiaobin
Wang, Noel T. Mueller. In Utero Exposure to Heavy Metals and Trace
Elements and Childhood Blood Pressure in a U.S. Urban, Low-Income,
Minority Birth Cohort. Environmental Health Perspectives, 2021;
129 (6): 067005 DOI: 10.1289/EHP8325 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/06/210623130640.htm

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