“This finding provides novel insights into the existing literature, indicating that the combined intake of different types of prebiotics may play a pivotal role in improving bone health among Japanese female athletes,” wrote researchers from Waseda University, the Waseda Institute of Sports Nutrition, and the Japan Institute of Sports Sciences in the journal Sports.
Prebiotics and bone health
The potential bone health benefits of prebiotics were first reported many years ago and are linked to the induced changes in the microbiota that result in the production of short chain fatty acids. These SCFAs decrease the pH within the colon, improving the solubility of the calcium present. The calcium is then better absorbed into the body. In recent years, data has emerged supporting a gut-bone axis.
Two main approaches to boost bone health for women have been explored over the years: The first is to optimize bone mass acquisition during adolescence (about 35% of a mature adult's peak bone mass is built-up during puberty), and the second is to minimize bone loss after the menopause. Much of the focus has been on females because osteoporosis is many times more common in women than in men.
The studies to date have focused on established prebiotics like inulin, fructo-oligosaccharides (FOS), galacto-oligosaccharides, and lactulose.
The new study is the said to be the first to investigate if a combination of inulin and lactulose affects bone health in female athletes.
Twenty-nine female athletes between 18 and 25 were recruited to participate in the pilot study. The women were gymnasts, soccer players, middle- and long-distance runners, and figure skaters. All the women were asked to supplement their habitual diet with one pack of the prebiotic food every day. The prebiotic food was manufactured by Morinaga Milk Industry Co., and each pack provided 2.5 grams of inulin and 1.0 gram of lactulose.
As was seen in other prebiotic-bone studies, levels of Bifidobacterium spp. significantly increased in response to prebiotic consumption, with levels significantly elevated compared to baseline by week three.
The researchers focused on a marker of bone resorption called TRACP 5b (Tartrate-resistant acid phosphatase), which is an enzyme that is expressed in high amounts by bone resorbing cells called osteoclasts. The results indicated that serum TRACP-5b levels were significantly reduced at the end of the 12 weeks compared to levels at the start of the study.
“The finding of reduced bone resorption marker in this study may prove beneficial for preventing issues related to bone health among female athletes,” wrote the authors.
Importantly, no significant changes to body composition measures, including body weight and fat mass, were detected in the women.
“The rate of bone turnover varies with age; therefore, it was unclear whether prebiotic intake in female athletes would prove beneficial for bone health,” wrote the researcher. “Thus, the present findings can be used as a nutritional strategy in sports fields.
“Future athletes’ studies using probiotics or synbiotics are needed, as probiotic intake has reported to have a protective effect on bone parameter in rats.”
The study was funded by a grant from the Japan Sports Agency.
2021, 9(6), 82; doi: 10.3390/sports9060082
“Prebiotic Food Intake May Improve Bone Resorption in Japanese Female Athletes: A Pilot Study”
Authors: T. Ishizu et al.