What safe and legal supplements can a generally healthy adult use to support muscle building?

Safe and Legal Supplements for Muscle Building

For healthy adults seeking to build muscle, protein supplementation (1.2-1.8 g/kg/day total intake), creatine (3-5 g/day), and caffeine (3-6 mg/kg body weight) have the strongest evidence for safety and efficacy, while most other popular supplements lack robust support. 1, 2

Evidence-Based Supplements with Strong Support

Protein Supplementation

• Adequate total protein intake is the foundation: Target 1.2-1.8 g/kg/day for those engaged in resistance training, distributed throughout the day to optimize muscle protein synthesis 3, 4
• Protein supplements accelerate gains in muscle mass and strength when training stimulus is adequate (sufficient frequency, volume, and duration) and dietary intake is consistent 5
• Animal-based proteins (whey, casein) contain higher amounts of leucine and essential amino acids critical for protein synthesis compared to plant proteins 6, 7
• For plant-based protein users: increase total doses, mix multiple plant sources, or add leucine supplementation (2.5g with meals) to overcome inferior anabolic properties 6, 3

Creatine

• One of the most studied and effective ergogenic aids: Increases phosphocreatine stores in skeletal muscle, improving ATP production during high-intensity exercise 2
• Dosing: 3-5 g per day is safe for long-term use 2
• Consistently increases muscle mass, strength/power, and muscular endurance with Level A evidence 1
• The weight gain includes both water retention in muscle and new muscle protein 8

Caffeine

• Acute performance enhancer: Reduces perceived pain while enhancing focus and alertness during training 2
• Dosing: 3-6 mg/kg body weight, consumed approximately one hour before exercise 2
• Sufficient evidence (Level A) supporting acute beneficial effects on muscle strength 1

Supplements with Mixed or Limited Evidence

Beta-Alanine

• Elevates intramuscular carnosine, which buffers hydrogen ions and delays fatigue during high-intensity exercise 2
• Dosing: 2-6 g daily in divided doses to minimize paresthesia (tingling sensation) 2
• Most effective for activities lasting 1-4 minutes 2

Nitrates (Beetroot Juice)

• Enhances aerobic performance by increasing oxygen delivery to muscles 2
• Dosing: Approximately 500 mg taken 2-3 hours before exercise 2
• Primarily benefits endurance rather than muscle building directly 2

Beta-Hydroxy-Beta-Methylbutyrate (HMB)

• May reduce muscle loss during periods of immobilization or bedrest 6
• Mixed evidence (Level B) for muscle building in healthy adults 1
• Limited human studies available 8

Leucine Supplementation

• Adding 2.5g crystalline leucine to suboptimal protein doses optimizes anabolic response, particularly relevant for older individuals 6
• Can overcome anabolic resistance when proportion of leucine to mixed amino acids is increased 6

Supplements with Weak or No Evidence

Branched-Chain Amino Acids (BCAAs)

• Mixed or unclear evidence (Level B) for muscle building 1
• Unnecessary if total protein intake is adequate, as complete proteins already contain BCAAs 1

Supplements Lacking Evidence

• Conjugated linoleic acid: Weak evidence (Level C) 1
• Glutamine: Weak evidence (Level C) 1
• Tribulus terrestris: Weak evidence (Level C), with potential adverse events reported 1
• Ornithine and α-ketoglutarate: No evidence (Level D), with adverse events reported for α-ketoglutarate 1

Critical Pitfalls to Avoid

Quality Control and Safety Concerns

• Nutritional supplements can be marketed without FDA approval of safety or effectiveness, raising concerns about unsubstantiated claims and questionable quality control 8
• Some supplements have reported adverse events after large intakes (caffeine, vitamins, α-ketoglutarate, tribulus terrestris, arginine) 1
• Insufficient evidence exists to determine the safety of many frequently used supplements 1

Common Mistakes

• Protein supplements are unnecessary if dietary protein intake already meets requirements (1.2-1.8 g/kg/day for active adults) 3, 5
• Focusing solely on supplements without adequate training stimulus (frequency, volume, duration) provides minimal benefit 5
• Increasing protein without sufficient total calorie intake provides no benefit and may be counterproductive 7
• Neglecting protein quality when using plant-based sources without proper amino acid balancing 6

Practical Implementation Algorithm

1. Calculate current protein intake in g/kg/day and compare to target of 1.2-1.8 g/kg/day 3, 4
2. If dietary protein is insufficient, add protein supplementation distributed throughout the day 3
3. Add creatine (3-5 g/day) as the second-line supplement with strongest evidence 2
4. Consider caffeine (3-6 mg/kg) pre-workout for acute performance enhancement 2
5. For plant-based diets, ensure variety of protein sources or add leucine (2.5g with meals) 6, 3
6. Avoid wasting money on supplements with weak or no evidence (BCAAs if protein adequate, glutamine, tribulus terrestris, ornithine) 1