Novel Compound BSO Shows Promise for Anti-Obesity Benefits Without Bone Loss
A new research paper, published in Volume 18 of Aging-US on March 2, 2026, investigates the compound D, L-buthionine-(S, R)-sulfoximine (BSO) as a potential alternative to sulfur amino acid restriction (SAAR) for anti-obesity effects. Crucially, the study explores whether BSO can achieve these benefits without the bone loss associated with SAAR.
Study Objective
Led by Naidu B. Ommi and Sailendra N. Nichenametla from the Orentreich Foundation for the Advancement of Science, the study aimed to determine if BSO, a glutathione (GSH)-lowering compound, could replicate SAAR's anti-obesity benefits. A key focus was to assess if BSO could achieve this while avoiding the bone density reduction typically associated with SAAR diets.
Methodology
The research utilized male C57BL6/NTac mice, which were induced to obesity with high-fat diets. These mice were then divided into four distinct groups for intervention:
- Control group: Fed a methionine-replete diet.
- SAAR group: Received a low methionine, no cysteine diet.
- SAAR plus N-acetylcysteine (NAC) group: Supplemented with NAC, a glutathione precursor, alongside the SAAR diet.
- Control diet plus BSO group: Administered BSO via their drinking water while on a control diet.
Researchers employed a range of analytical techniques to assess the effects of these dietary interventions, including body-composition analysis, micro-CT scans, histomorphometry, and biomechanical testing.
Key Findings
The study confirmed prior observations that SAAR effectively reduced body fat. However, it also reiterated SAAR's detrimental effects on bone health, including decreased trabecular and cortical bone mineral density, increased marrow adiposity, lowered osteoblast numbers, and weakened bone biomechanical strength.
Significantly, NAC supplementation was found to reverse the bone defects observed with SAAR, suggesting that the restriction of cysteine and glutathione plays a role in SAAR-induced bone loss.
Crucially, BSO treatment reproduced the lean, anti-obesity phenotype without causing the detrimental bone effects seen in SAAR mice.
The authors specifically noted that BSO achieved the anti-obesity benefits of SAAR without inducing the same level of bone loss, presenting a compelling new avenue for research.
Future Implications
The researchers emphasized the critical need for further studies to fully understand and validate these findings. These include:
- Mechanistic investigations to understand precisely how GSH lowering drives fat loss while preserving bone under BSO treatment.
- Examinations of age-at-onset, tissue-specific, and sex-specific effects of BSO.
- Long-term safety studies of BSO before any consideration for clinical development.
The paper positions BSO as a promising tool for dissecting the beneficial versus deleterious aspects of sulfur amino acid biology, though it strongly highlights the requirement for extensive additional preclinical evaluation before any consideration for human therapy.