Fiber helps your gut — new research shows it may also help your bones

Scroll through TikTok for long enough and you’ll soon stumble across people putting chia seeds into almost everything imaginable — water, oatmeal and yes, even ice cream — or piling their plates with lentils and beans. They certainly do not play around about their fiber intake. They’re fibermaxxing, of course.

Dietitians have gotten behind this viral trend for good reason: High-fiber diets lower the risk of heart disease, stroke, type 2 diabetes and certain types of cancer.

Cristina Palacios, a nutrition researcher at FIU, understands the hype. Long before the powerhouse nutrient was getting the level of attention it is today, she was compiling evidence of its other benefits. Palacios has most recently led the NIH-funded MetA-Bone clinical trial to test whether a prebiotic fiber supplement help growing bones get more of the mineral they need during a critical period of childhood.

The results, published in The American Journal of Clinical Nutrition, suggest it can.

“People think about osteoporosis as something that affects their grandparents,” said Palacios, professor and chair of the department of dietetics and nutrition at FIU’s Robert Stempel College of Public Health & Social Work. "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 we'll carry for life. That’s why kids need more calcium during these years. Think of it like a savings account: the more calcium that’s deposited when you're young, the more you have to draw on as you age.

Current guidelines recommend adolescents get 1,300 milligrams of calcium daily. That’s the equivalent of about 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.

“We wanted to find out how to make calcium absorption more efficient, so that whatever little calcium you are consuming, as much of it as possible is getting absorbed," said Palacios.

Calcium gets into the body through the walls of the small intestine. How efficiently that happens, though, depends on the bacteria living in the gut. Certain prebiotics, like soluble fiber, feed the beneficial microbes. And 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 DEXA (dual-energy X-ray absorptiometry) scans.

Fiber made the biggest difference for girls. Their bone mineral content increased by 18.8%, compared to 12.9% in the placebo group.

“That 6% may sound like a small difference, but this is a significant, clinically relevant number for just adding this powder to the diet,” Palacios said. “That 6% could possibly mean not getting an osteoporotic fracture as you age.”

The same effect, however, was not seen in boys. One possible explanation 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 get more from the calcium they already consume.

“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.”