Analysis of 53 randomized controlled trials reveals that four distinct pro-anabolic modulators—vitamin D, leucine, omega-3 fatty acids, and probiotics—show measurable benefits for muscle mass and strength preservation. Daily vitamin D supplementation outperformed bolus dosing, while leucine proved most effective when paired with resistance training. Omega-3 interventions demonstrated consistent improvements in muscle strength, particularly in longer-duration studies, and probiotics showed near-universal positive effects across varied bacterial strains. This comprehensive evidence base represents a significant advancement in our understanding of nutritional interventions for sarcopenia, the age-related muscle wasting that affects up to 50% of adults over 80. The findings suggest these compounds may work through complementary anabolic pathways—vitamin D through calcium signaling and protein synthesis, leucine via mTOR activation, omega-3s through anti-inflammatory mechanisms, and probiotics potentially via gut-muscle axis modulation. However, the researchers' candid assessment of "low to very low certainty" evidence highlights persistent methodological limitations in this field. The most compelling insight is that combination approaches or pairing with exercise amplified benefits, suggesting these modulators work synergistically rather than independently. This points toward personalized, multi-modal interventions as the future of muscle preservation therapy.