(NBC) - A study in today's journal "Pediatrics" finds seven in 10 american children don't get enough vitamin D. One in ten have levels so low, they're deficient.
Milk and fish are big sources of vitamin D, but so is sunshine, and that's where researchers think American children fall short.
"Four hours a day of using computers, watching TV, or playing video games, they were 60% higher risk of having vitamin D deficiency," says Dr. Michal Melamed of the Albert Einstein College of Medicine.
Twelve year-old Jasmine Carter can't drink milk, so she looks for vitamin D elsewhere.
"I get it from yogurt, anything that has milk in it. I don't really drink milk, or sometimes I go out in the sun and I play around with my friends."
It's a big issue for people with dark skin, because their bodies can't absorb vitamin D as easily.
The "Pediatrics" study found six in ten African-American teenage girls are vitamin D deficient.
Later in life, that can lead to osteoporosis, cancer, and according to another new study out today, heart problems.
"Two times the risk of high blood pressure, two times the risk of having high blood sugar or blood glucose concentrations and about four times the risk of the metabolic syndrome," says Jared Reis, Ph.D., of the National Heart, Lung, and Blood Institute.
All of which are risk factors for heart disease, but they can be reduced for most people with just 10-15 minutes of sunshine every day.
That's exposure without sunscreen, which of course raises concerns about skin cancer.