Postmenopausal women who received a probiotic treatment of three Lactobacillus strains had significantly less lumbar spine bone loss, compared with women in a placebo group, according to recent research published in The Lancet Rheumatology.

“The menopausal and early postmenopausal lumbar spine bone loss is substantial in women, and by using a prevention therapy with bacteria naturally occurring in the human gut microbiota we observed a close to complete protection against lumbar spine bone loss in healthy postmenopausal women,” Per-Anders Jansson, MD, chief physician at the University of Gothenburg (Sweden), and colleagues wrote in their study.

Dr. Jansson and colleagues performed a double-blind trial at four centers in Sweden in which 249 postmenopausal women were randomized during April-November 2016 to receive probiotics consisting of three Lactobacillus strains or placebo once per day for 12 months. Participants were healthy women, neither underweight nor overweight, and were postmenopausal, which was defined as being 2-12 years or less from last menstruation. The Lactobacillus strains, L. paracasei 8700:2 (DSM 13434), L. plantarum Heal 9 (DSM 15312), and L. plantarum Heal 19 (DSM 15313), were equally represented in a capsule at a dose of 1 x 1010 colony-forming unit per capsule. The researchers measured the lumbar spine bone mineral density (LS-BMD) at baseline and at 12 months, and also evaluated the safety profile of participants in both the probiotic and placebo groups.

Overall, 234 participants (94%) had data available for analysis at the end of the study. There was a significant reduction in LS-BMD loss for participants who received the probiotic treatment, compared with women in the control group (mean difference, 0.71%; 95% confidence interval, 0.06%-1.35%), while there was a significant loss in LS-BMD for participants in the placebo group (percentage change, –0.72%; 95% CI, –1.22% to –0.22%) compared with loss in the probiotic group (percentage change, –0.01%; 95% CI, –0.50% to 0.48%). Using analysis of covariance, the researchers found the probiotic group had reduced LS-BMD loss after adjustment for factors such as study site, age at baseline, BMD at baseline, and number of years from menopause (mean difference, 7.44 mg/cm2; 95% CI, 0.38 to 14.50).

In a subgroup analysis of women above and below the median time since menopause at baseline (6 years), participants in the probiotic group who were below the median time saw a significant protective effect of Lactobacillus treatment (mean difference, 1.08%; 95% CI, 0.20%-1.96%), compared with women above the median time (mean difference, 0.31%; 95% CI, –0.62% to 1.23%).

Researchers also examined the effects of probiotic treatment on total hip and femoral neck BMD as secondary endpoints. Lactobacillus treatment did not appear to affect total hip (–1.01%; 95% CI, –1.65% to –0.37%) or trochanter BMD (–1.13%; 95% CI, –2.27% to 0.20%), but femoral neck BMD was reduced in the probiotic group (–1.34%; 95% CI, –2.09% to –0.58%), compared with the placebo group (–0.88%; 95% CI, –1.64% to –0.13%).

Limitations of the study included examining only one dose of Lactobacillus treatment and no analysis of the effect of short-chain fatty acids on LS-BMD. The researchers noted that “recent studies have shown that short-chain fatty acids, which are generated by fermentation of complex carbohydrates by the gut microbiota, are important regulators of both bone formation and resorption.”

The researchers also acknowledged that the LS-BMD effect size for the probiotic treatment over the 12 months was a lower magnitude, compared with first-line treatments for osteoporosis in postmenopausal women using bisphosphonates. “Further long-term studies should be done to evaluate if the bone-protective effect becomes more pronounced with prolonged treatment with the Lactobacillus strains used in the present study,” they said.

In a related editorial, Shivani Sahni, PhD, of Harvard Medical School, Boston, and Connie M. Weaver, PhD, of Purdue University, West Lafayette, Ind., reiterated that the effect size of probiotics is “of far less magnitude” than such treatments as bisphosphonates and expressed concern about the reduction of femoral neck BMD in the probiotic group, which was not explained in the study (Lancet Rheumatol. 2019 Nov;1[3]:e135-e137. doi: 10.1016/S2665-9913(19)30073-6). There is a need to learn the optimum dose of probiotics as well as which Lactobacillus strains should be used in future studies, as the strains chosen by Jansson et al. were based on results in mice.

In the meantime, patients might be better off choosing dietary interventions with proven bone protection and no documented negative effects on the hip, such as prebiotics like soluble corn fiber and dried prunes, in tandem with drug therapies, Dr. Sahni and Dr. Weaver said.

“Although Jansson and colleagues’ results are important, more work is needed before such probiotics are ready for consumers,” they concluded.

This study was funded by Probi, which employs two of the study’s authors. Three authors reported being coinventors of a patent involving the effects of probiotics in osteoporosis treatment, and one author is listed as an inventor on a pending patent application on probiotic compositions and uses. Dr. Sahni reported receiving grants from Dairy Management. Dr. Weaver reported no relevant conflicts of interest.

SOURCE: Jansson P-A et al. Lancet Rheumatol. 2019 Nov;1(3):e154-e162. doi: 10.1016/S2665-9913(19)30068-2