BSO mimics anti-obesity effects without causing bone loss in mice

A new research paper was published in Volume 18 of Aging-US on March 2, 2026, titled "D, L-Buthionine-(S, R)-sulfoximine recapitulates the anti-obesity effects of sulfur amino acid restriction without the associated deleterious effects on bone in male mice."

Led by Naidu B. Ommi from the Orentreich Foundation for the Advancement of Science - with corresponding author Sailendra N. Nichenametla from the same institution - the study tests whether the glutathione (GSH)-lowering compound D, L-buthionine-(S, R)-sulfoximine (BSO) reproduces the anti-obesity effects of sulfur amino acid restriction (SAAR) without causing the bone loss seen with SAAR diets. Using diet-induced obese male C57BL6/NTac mice fed high-fat diets, the authors compared: a control methionine-replete diet, a SAAR diet (low methionine, no cysteine), SAAR plus the GSH precursor N-acetylcysteine (NAC), and control diet plus BSO in drinking water. 

Using body-composition, micro-CT, histomorphometry, and biomechanical testing, the team confirmed prior work that SAAR reduces body fat but also lowers trabecular and cortical bone mineral density, increases marrow adiposity, reduces osteoblast numbers, and weakens bone biomechanical strength. Crucially, while NAC supplementation reversed the bone defects of SAAR (implicating cysteine/glutathione restriction in bone loss), BSO reproduced the lean, anti-obesity phenotype without producing the deleterious bone effects observed in SAAR mice. In short, BSO recapitulated the anti-obesity benefits of SAAR without causing the same bone loss - a finding with potential relevance to developing anti-obesity strategies that avoid skeletal harm.

"Despite its anti-obesity effects, BSO did not exert any detrimental effects on bones."

The authors emphasize next steps and caveats. They call for mechanistic studies to define how GSH lowering drives fat loss yet spares bone under BSO treatment, investigations of age-at-onset, tissue-specific, and sex-specific effects, and long-term safety studies to assess off-target or delayed adverse effects of BSO before any clinical development. The paper frames BSO as a promising tool compound to dissect the beneficial versus deleterious axes of sulfur amino acid biology, but not yet as a human therapy without further preclinical evaluation.