How do magnesium and other nutrients affect muscle and cellular energy?

Magnesium has a well-established biochemical role in cellular ATP use. By contrast, the broader proposition that low B12, zinc, selenium, vitamin D, and protein status collectively cause muscle and mitochondrial energy dysfunction is biologically credible but not directly established in humans.

Mechanistic and clinical evidence

• Magnesium: ATP in cells is predominantly present as the magnesium-bound MgATP complex. MgATP is the functional substrate for many ATP-dependent enzymes; magnesium also shields ATP phosphate charge and facilitates phosphoryl transfer and hydrolysis. Experimental systems show reversible reductions in MgATP and respiration during magnesium deprivation, although enzyme-specific magnesium requirements vary.
• Selenium and vitamin D: Selenium deficiency can cause myopathy. Severe vitamin D deficiency is associated with proximal muscle symptoms; in a small study of 12 adults with 25(OH)D <15 nmol/L, cholecalciferol was associated with improved muscle mitochondrial function.
• B12, zinc, and protein: Each has plausible links to neuromuscular or cellular energy biology. Protein inadequacy can compromise muscle maintenance, particularly with undernutrition. However, direct evidence that deficiency in B12, zinc, or protein measurably reduces skeletal-muscle mitochondrial respiration, ATP production, strength, or exercise capacity—and that repletion reverses these outcomes—is limited.

Limits and practical interpretation

• A 54-RCT meta-analysis found no overall benefit of vitamin D supplementation for muscle strength or physical performance, including most groups with low baseline vitamin D. Protein/essential-amino-acid trials likewise show small, inconclusive functional effects; low-risk-of-bias trials showed no significant benefit.
• No study establishes that these five inadequacies act as a combined or additive cause of mitochondrial-energy impairment, or that combined supplementation reliably improves fatigue or performance.

Bottom line

• Magnesium is fundamentally required for many ATP-dependent reactions. Individual nutrient inadequacies—especially severe selenium or vitamin D deficiency and protein malnutrition—can plausibly contribute to muscle dysfunction, but nonspecific fatigue or exercise intolerance should not be attributed to a combined “mitochondrial nutrient deficiency” without targeted assessment for confirmed deficiencies and other causes.