As kids return to school, avoiding playground and sports injuries are on many parents’ minds. But, a new study questions whether nutrition has more to do with breaking a bone than the accident itself.

Researchers looked at 150 children and found that those with forearm fractures were more likely to have thinner bones and lower levels of vitamin D.

“Many of the children that I treated were simply tripping and falling and breaking their forearms,” says Dr. Leticia Ryan, pediatric emergency medicine physician at George Washington University School of Medicine and Health Sciences.

“[Those types of injuries] typically happen to older people with osteoporosis, not in children. They should tolerate tripping and falling without sustaining a bone fracture.”

Childhood forearm fractures have increased steadily since 1969. They commonly occur from falling from monkey bars or breaking a fall with outstretched arms.

“A lot of kids growing up get forearm fractures,” said Dr. Abigail Allen, pediatric orthopedic surgeon at Mount Sinai School of Medicine. “They’re so common.”

However, Ryan finds this increase peculiar because the rates of other childhood injuries are decreasing.

The children studied were African-American, a population that she says is at higher risk for these fractures. She names vitamin D deficiency, obesity — African-American teens have more obesity than other groups — and low intake of calcium as important risk factors. There were no differences based on the parents’ levels of education.

Some experts report that milk intolerance among people of African descent plays a role in low calcium and low vitamin D intake. However, Allen reminds that milk doesn’t naturally have vitamin D — it’s added artificially. Therefore, milk-intolerant children can consume other fortified foods, like children’s cereals, instead.

“Being outside and being in the sunlight also increases your vitamin D,” Allen says. “[Unfortunately] we are a more indoor population now.”

Both Allen and Ryan agree that vitamin D deficiency and thinner bones in childhood have long lasting effects, such as leading to osteoporosis.

“You only have so long to build up your bone density,” says Allen. “So, I always tell parents it’s like putting money in the bank. You have to invest early. At age 25, it’s going downhill from there. You can’t play catch up later in life.”

She adds that the easiest tactic is to give the child a multivitamin supplement daily, but an overall healthy diet should be encouraged.

Ryan suggests using a forearm fracture to start a conversation with the doctor about the child’s nutrition and have a vitamin D level checked.

Dr. Tyeese Gaines is a physician-journalist with over 10 years of print and broadcast experience, now serving as health editor for theGrio.com. Dr. Ty is also a practicing emergency medicine physician in New Jersey. Follow her on twitter at @doctorty.