If you think osteoporosis is a geriatric disease, think again. New research shows that for girls as young as eight, getting too little calcium can increase the risk of brittle bones later in life.

The seven-year study, among the first to follow girls from childhood into early adulthood, showed that during girls’ growth spurts, taking calcium supplements is actually critical. The biggest spurt happens between age 11 and 15 but others begin around age 8.

The study followed more than 500 girls, ages 8 to 13 when the study began, for up to seven years. One group had an average daily calcium intake (from food) of 830 milligrams; the other got that amount plus about 670 mg from supplements. The girls who took the supplements wound up with about 4 percent higher bone density. That may not sound like much, but it brings a crucial advantage later in life, when bones begin to erode.

“Girls ages 8 to 11 should be sure to get 1,000 mg of calcium each day,” says Velimir Matkovic, lead researcher and a professor of physical medicine, rehabilitation, and nutrition at Ohio State University. “And teens should get up to 1,500 mg during the major growth phase from 11 to 15.”