A UK study of pregnant women that followed their babies into early childhood finds kids were likely to have stronger muscles if their mothers had higher levels of vitamin D during pregnancy.
The study, from the Medical Research Council Lifecourse Epidemiology Unit (MRC LEU) at the University of Southampton, is published in the Journal of Clinical Endocrinology and Metabolism.
Although previous studies have linked reduced muscle strength in children and adults to low levels of vitamin D in their own bodies, not much is known about links to levels in their mothers' bodies when they were carrying them before birth.
Of the nutrients our bodies require for health, vitamin D is unique. While we get it from foods like fish, cheese, beef liver, eggs and fortified cereals, our main source is our bodies making it from sunlight.
Vitamin D helps us absorb and metabolize calcium and phosphorous, keep our bones healthy and regulate the immune system. There have also been suggestions that it keeps the brain working later in life, and reduces the risk of many diseases such as asthma, rheumatoid arthritis, and cancer.
In 2011, a report from the National Center for Health Statistics in the US revealed inadequate vitamin D affects a third of Americans.
The researchers behind this new study say low levels of vitamin D are also fairly common among young women in the UK; and while pregnant women are urged to supplement their diets with an additional 10μg per day, not many do.
Higher vitamin D during pregnancy linked to higher offspring grip strength
For the study, lead investigator Dr. Nicholas Harvey, Senior Lecturer at the MRC LEU in the University of Southampton, examined data on 678 mothers taking part in the Southampton Women's Survey (SWS) and whose vitamin D levels were measured in late pregnancy.
The survey followed the mothers and their children, who at the age of four, underwent tests of grip strength and muscle mass, among others.
When they analyzed the results, the team found higher levels of vitamin D in the mother when pregnant was linked to higher grip strength in their children.
There was also a less pronounced link between vitamin D in pregnancy and children's muscle mass.
Dr. Harvey says the links between vitamin D in pregnancy and children's muscle strength may well affect health later in life, explaining that muscle strength peaks in young adulthood and wanes as we get older. Low grip strength in adults has been linked to diabetes, falls and fracture, he adds, and so the message from this study is:
"It is likely that the greater muscle strength observed at four years of age in children born to mothers with higher vitamin D levels will track into adulthood, and so potentially help to reduce the burden of illness associated with loss of muscle mass in old age."
Study supervisor Cyrus Cooper, professor of Rheumatology and director of the MRC LEU at Southampton, adds:
"This work should help us to design interventions aimed at optimising body composition in childhood and later adulthood and thus improve the health of future generations."
Meanwhile, another team in the US recently suggested low vitamin D may damage the brain. The leader of that study, Allan Butterfield, a professor at the University of Kentucky, says people need about 10 to 15 minutes of sunshine a day to make sure they have enough vitamin D.