Miami – October 14, 2026 -- Girls who added a prebiotic soluble corn fiber powder to their usual diets for 12 months built more bone than girls who took a placebo, according to a clinical trial led by Florida International University nutrition researcher Cristina Palacios. Bone mineral content rose 18.8% in the fiber group, versus 12.9% in the placebo group.
Boys did not see the same bone gain
The effect did not appear in boys. The researchers say one possible explanation is that boys were at a different stage of puberty and skeletal development. The study was not designed to detect differences between boys and girls, so larger trials need to confirm the finding.
The NIH-funded MetA-Bone trial was published in The American Journal of Clinical Nutrition. Palacios, professor and chair of dietetics and nutrition at FIU's Robert Stempel College of Public Health & Social Work, called the roughly 6% difference clinically relevant. She said it could possibly mean avoiding an osteoporotic fracture years later, after menopause.
Kids aged 9 to 14 took the powder twice a day
The trial enrolled children aged 9 to 14 who consumed too little calcium. They kept their usual diets and added a twice-daily powder. About half received soluble corn fiber, and the rest received a look-alike placebo. Dual-energy X-ray absorptiometry (DEXA) scans measured bone mineral content at the start, at six months and at 12 months.
Most adolescents miss the 1,300 mg calcium target
Early adolescence, around the onset of puberty, is when the body builds most of the bone mass it carries for life. Current guidelines call for 1,300 milligrams of calcium daily for adolescents, equal to about three to four servings of dairy. An estimated 90% of girls and 70% of boys fall short. Many kids also swap milk for sodas, which can pull calcium out of bone.
Gut bacteria turn fiber into better calcium absorption
Calcium enters the body through the walls of the small intestine, and gut bacteria influence how efficiently that happens. Soluble fiber feeds beneficial microbes. As they break it down, they produce compounds that help the body absorb more calcium. Short-term studies had already shown the fiber boosts calcium absorption, and this trial tested whether that translates into more bone.
Palacios sees potential in fortifying kid-friendly foods with soluble corn fiber so children absorb more of the calcium they already consume. High-fiber diets are already known to lower the risk of heart disease, stroke, type 2 diabetes and certain cancers.
Her advice applies to growing kids and adults alike: "just find a way to increase your intake of soluble fiber," whether through diet or over-the-counter fiber supplements.