FIU study finds prebiotic fiber helped girls build more bone

MIAMI, Oct. 14, 2026 /PRNewswire/ -- Girls who added a prebiotic fiber supplement to their usual diets for a year built more bone than girls who took a placebo, according to a clinical trial led by Florida International University nutrition researcher Cristina Palacios. 

Over 12 months, bone mineral content in girls who took soluble corn fiber increased by 18.8%, compared to 12.9% in the placebo group. The same effect was not seen in boys. The results of the National Institutes of Health-funded MetA-Bone clinical trial were published in The American Journal of Clinical Nutrition. 

"That 6% may sound like a small difference, but this is a significant, clinically relevant number for just adding this powder to the diet," said Palacios, professor and chair of the department of dietetics and nutrition at FIU's Robert Stempel College of Public Health & Social Work. "That 6% could possibly mean not getting an osteoporotic fracture may years later, after menopause." 

The trial tested whether the fiber could help children build more bone mass, as short-term studies show that the fiber helps absorb more calcium, an essential mineral for bone growth, during a critical period of childhood. 

"People think about osteoporosis as something that affects their grandparents," Palacios said.  "But so much of what happens to our bones later is set in motion when we're young."  

Early adolescence, right around when puberty hits, is when the body builds most of the bone mass carried for life. That's why kids need more calcium during these years. The more calcium you deposit during childhood, the more you have to draw on when menopausal changes set in and affect your bones as you age. 

Current guidelines recommend adolescents get 1,300 milligrams of calcium daily. That's the equivalent of about three to four servings of dairy. Most kids fall short, however. An estimated 90% of girls and 70% of boys don't get enough. Many also swap calcium-rich milk for sodas, which can actually pull calcium out of bone. 

Calcium gets into the body through the walls of the small intestine. How efficiently that happens depends, in part, on the bacteria living in the gut. Certain prebiotics, like soluble fiber, feed the beneficial microbes. As those good bacteria break down the fiber, they produce compounds that help more calcium get absorbed.  

To find out whether that absorption boost would actually translate into more bone, Palacios and her colleagues ran a year-long trial in children age 9 to 14 who consumed too little calcium. They kept their usual diets and simply added a twice-daily powder. About half got a soluble corn fiber supplement; the rest, a look-alike placebo. The research team checked their bone mineral content three times — at the start of the study, six months in and again at 12 months — using special dual-energy X-ray absorptiometry (DEXA) scans. 

One possible explanation for why boys didn't see the same benefit is that they were at a different stage of puberty and skeletal development. The researchers cautioned the study wasn't designed to detect differences between the boys and girls, so the finding needs to be confirmed in larger trials. 

While more research is needed, Palacios says these early results are promising. She sees potential in fortifying kid-friendly foods with soluble corn fiber to help children absorb more calcium they already consume.  

High-fiber diets are already known to lower the risk of heart disease, stroke, type 2 diabetes and certain types of cancer. 

"My message is the same for everyone. For kids growing bone and for adults maintaining bone. This can be a small, easy addition to your diet," she said. "Whether it's through your diet or popular over-the-counter fiber supplements, just find a way to increase your intake of soluble fiber." 

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SOURCE Florida International University