Table 1.

Mechanisms of action and outcome readouts for efficacy in preclinical and/or clinical studies, for dietary supplements most commonly used in DMD.

Compound	Claimed mechanism of action	Preclinical studies in mdx mice: assessed endpoints	Evidences from clinical trials in DMD patients
Branched-chain amino acids	Increase protein synthesis	Modulation of vascular function	↓ Protein degradation [50]
		Myofibre phenotype	No improvements [51]
		Motor function [206]
L-arginine	Enhance utrophin expression	Utrophin expression [62,63]	In combination with metformin (AMPK activator) [60]:
		Necrosis [63]	↑ Activity of mitochondrial electron transport chain
		Respiratory function [63]	↓ Oxidative stress
			↑ Clinical scores
Glutamine	Antioxidant activity	Oxidative stress	↑ Insulin secretion [83]
		Protein breakdown [207]	↓ Protein degradation [82]
			No effect on muscle function or strength [80,81]
Creatine	Enhance metabolism	Necrosis [86,87]	↑ (PCr)/inorganic phosphate (Pi) ratio [90]
	↑ Ca2+-ATPase (SERCA2) content	Energy metabolism [86,88]	↑ Muscle strength [90,919293]
		Muscle force [87,88,89]	↓ Markers of bone breakdown [92]
			↑ Fat free mass [92]
Taurine	Antioxidant and anti-inflammatory activity; restoration of Ca2+ homeostasis	Muscle damage [103]
		Oxidative stress [103]
		Muscle function [89]
		Membrane conductivity [89]
		Cardiac function [104]
		Muscle strength (in combination with prednisolone) [105]
Green tea extract	Antioxidant and anti-inflammatory activity	Muscle damage and CK plasma levels [110,111]	Clinical trial ended but data not available
		Necrosis [111,112113]
		Regeneration [110]
		Oxidative stress [111,112113] [208],
		Muscle force [111,113]
Protandim	Antioxidant and anti-inflammatory activity	Oxidative stress markers [114]
Omega-3 fatty acids	Anti-inflammatory activity	Necrosis [133]	↓ Insulin resistance
		Inflammation [133,134]	Trend towards a decrease of muscle loss [135]
Vitamin D	Restored insufficient 25-hydroxyvitamin D serum levels in DMD boys	Muscle force	In combination with calcium-rich diet [210]:
		Muscle damage [209]	↑ Bone mineral density
			↑ Bone mineral content
Resveratrol	Anti-inflammatory activity	Muscle damage (CK/LDH plasma levels) [103]
		Oxidative stress [103,150,151]
		Inflammation [211]
		Autophagy/mitophagy [150,212]
		Muscle force [103]
		Utrophin expression [211]
Curcumin	Anti-inflammatory activity	Muscle strength [152,153]
		Muscle damage [152,153]
		Inflammation markers [152,153]
		NF-kappaB activity [152,153]
N-Acetyl cysteine	Antioxidant activity	Muscle damage (CK plasma levels) [168,169]
		Necrosis [168,169]
		Inflammation [169,170]
		Oxidative stress [169,170]
		βdystroglycan and utrophin expression [172]
Coenzyme Q10	Antioxidant activity		↑ Muscle strength [179]
			No effect on echocardiographic parameters [182]
Melatonin	Antioxidant activity	Muscle damage (CK plasma levels)	↓ Oxidative stress [187]
		Oxidative stress	↓ Plasma pro-inflammatory cytokines [187]
		Muscle force [186]	↓ Hyperoxidative status in erythrocytes [213]