Making the case for the projected growth is one study out of UPMC Children's Hospital of Pittsburgh, which suggests the vitamin is beneficial for the hearts of larger children. Those who are overweight and obese also have a higher risk of vitamin D deficiency, as well as developing diabetes and heart disease.
Overweight and obese children who were deficient in Vitamin D were found to have improved cardiovascular health after taking a relatively high dose of vitamin D every day for six months. Lower blood pressure and improved insulin sensitivity resulted in the children who took a higher dose when compared to their peers who took a lower dose.
Researchers at UPMC Children's Hospital of Pittsburgh conducted a clinical trial with healthy, but vitamin D-deficient, 10 to 18-year-olds who were overweight or obese. Of the 225 children enrolled in the study, 211 of them were black. Those with darker skin are more likely to be vitamin D-deficient since they have more melanin pigment in their skin, which acts as a natural sunscreen and inhibits vitamin D production.
The children were divided into three groups and given different amounts of vitamin D.
One group received a 600 IU tablet daily, the current recommended daily dietary allowance. The other two groups received either a 1,000 IU or 2,000 IU tablet daily, which is still well below the 4,000 IU daily maximum considered safe for children in this age range.
Over the six month period, no one was aware of the dosage, including the participants’ doctors.
After six months, the children receiving the daily 2,000 IU vitamin D supplement had a reduced fasting blood glucose level and improved insulin sensitivity, which reduces the risk of diabetes and improves heart health. Also at the end of the trial, the children receiving 1,000 IUs of vitamin D daily had lower blood pressure.
"Current recommendations for taking vitamin D are pegged to optimal bone health," said lead author Kumaravel Rajakumar, M.D., M.S., professor of pediatrics at the University of Pittsburgh School of Medicine. "But we know vitamin D is involved in more than building healthy bones. It can turn on and off genes that direct our cells to regulate blood glucose levels, and immune and vascular function."
Blood tests indicated that the higher the daily intake of vitamin D, the greater the improvement in the participants' blood concentration of vitamin D. When the trial ended, none of the groups were considered vitamin D deficient.
A 2019 study published in the American Heart Association's journal Hypertension found that children born with low levels of Vitamin D had about a 60% higher risk of elevated systolic blood pressure between ages 6 and 18, when compared to children born with adequate vitamin D levels. The study also found that children with continuously low levels of vitamin D through early childhood had a double risk of elevated systolic blood pressure between ages 3 and 18.
Vitamin D alone may not be enough
However, the study did not show improvements in other cardiovascular and metabolic health markers, which suggests vitamin D supplementation alone may not be the cure-all for improving the heart health of children at highest risk for diabetes and heart disease.
Source: The American Journal of Clinical Nutrition
17 January 2020 DOI: 10.1093/ajcn/nqz340
“Effect of vitamin D3 supplementation on vascular and metabolic health of vitamin D–deficient overweight and obese children: a randomized clinical trial”
Authors: K. Rajakumar et al