It’s a well-accepted tenet in fitness circles that protein reigns supreme when it comes to building muscle. Protein remains the cornerstone of muscle hypertrophy. However, a recent study from the University of Padova has shed light on an assortment of other nutrients that play critical roles in enhancing muscle response to resistance training. In this blog, I’ll delve deeper into how these nutrients support muscle growth and repair.

Protein: The Foundation of Muscle Synthesis

Protein is the most potent nutritional stimulus for building muscle. In scientific terms building muscle is described as muscle protein synthesis (MPS). The body uses the amino acids from dietary protein to repair and build muscle fibres. Current guidelines suggest varying levels of protein intake. A minimum of 0.8 g/kg of body weight has been suggested as being generally sufficient for non-active individuals. While as much as 2.4 g/kg is proposed for those engaged in rigorous strength training. However, the lower end of this spectrum is often considered inadequate for optimising muscle hypertrophy. This is particularly the case in those actively training. These levels of protein intake might not fully support the enhanced demands for muscle repair and growth in people who are training. And everyone who does not have an illness should be training. Studies suggest that people building muscle mass and strength need at least 1.7 g/kg of protein on non-training days to optimise muscle hypertrophic response. Even the need of protein to support muscle repair for an endurance athlete may be higher than it was previously thought. It should be (1.6–1.83 g/kg) and even higher the day following a training session.

Dietary protein supplementation stimulates MPS and is essential for hypertrophy. Key studies like those by Moore et al. (2009) highlight that protein intake after resistance training significantly enhances MPS. Optimal protein intake per meal is suggested around 20-25 grams to maximise muscle growth. Just this year a study by Trommelen and colleagues (2023) investigated consuming even higher doses of protein. They showed that the ingestion of 100 g of protein resulted in a greater and more prolonged (>12 h) anabolic response when compared to the ingestion of 25 g of protein. These findings suggest that the anabolic response to protein ingestion likely has no upper limit.

Carbohydrates: More Than Just Fuel

While their primary role is to replenish muscle glycogen, carbohydrates also enhance muscle recovery and growth. They do this by spiking insulin level. Yes, spikes in insulin are not all bad! Insulin is a potent anabolic hormone that improves glucose and amino acid uptake by muscles. Thus, facilitating muscle repair and growth after training.

Carbohydrates do not directly contribute to MPS but play a supportive role. Studies such as those by Glynn et al. (2013) indicate that consuming carbohydrates and protein post-exercise can enhance the insulin response. This likely increases MPS indirectly through improved nutrient delivery and anabolism.

Creatine: Enhancing Energy and Growth

Creatine supplementation increases phosphocreatine stores within the muscle. These are essential for ATP regeneration during short, intense bursts of activity such as lifting weights or sprinting. This increase in available energy can significantly enhance muscle strength, power, and size. Creatine also helps increase muscle cell volume. This plays a role in muscle growth signalling pathways.

Creatine supplementation has been very widely researched. Numerous studies have supported its efficacy in improving strength and muscle mass. For instance, research by Branch (2003) demonstrates that creatine enhances phosphocreatine recovery between sets. Therefore, creatine allows greater work output and training volume. These are both critical for stimulating MPS.

The International Society of Sport Nutrition (ISSN) and the IOC consensus statement have released updated position statements on creatine monohydrate (CM). These suggest that the most effective strategy for increasing creatine stores is splitting supplementing into different phases. The first phase is the so called “loading phase.” During this phase 20.9 ± 4.5 g/day should be divided into four equal daily doses (5 g/dose or ~0.3 g/kg body weight). The loading phase lasts for 5–7 consecutive days. The subsequent phase of the protocol requires a “maintenance phase.” In this phase, 3–5 g of CM is taken daily for the entire duration of the supplementation period. Consuming carbohydrates and proteins (~50 g of proteins and CHO) increases the retention of creating muscle. An effect that is mediated via insulin.

A second protocol involves the ingestion of 3 g/day of CM for 28 days. This is the approach that I take as it has fewer gastrointestinal side effects. But, until muscle creatine levels are completely saturated, it has lesser effects on exercise performance.

Long term use of creatine has shown no negative health effects. (around 4 years of consequent supplementation).

Omega-3 Fatty Acids: Anti-inflammatory Effects

Omega-3 fatty acids, particularly EPA and DHA, are known for their anti-inflammatory properties. They help modulate the inflammation induced by rigorous training. This attenuation of inflammation supports muscle recovery and growth. Omega-3s also enhance the insulin sensitivity of muscles. This can further support muscle health by improving muscle nutrient delivery and reducing muscle breakdown.

Omega-3s have been shown to not only reduce inflammation. It has been suggested that they increase MPS. Smith et al. (2011) found that omega-3 fatty acid supplementation effectively increased the mTOR pathway’s sensitivity to amino acids in humans. mTOR plays a vital role in muscle protein synthesis. Hence Omega-3 fatty acids stimulate muscle protein synthesis and may be useful for this purpose as a supplement.

Vitamin D: A Direct Role in Muscle Function

Vitamin D is crucial for more than just bone health. It directly influences muscle function and strength. It enhances the transcription of genes involved in muscle contraction and protein synthesis. Furthermore, vitamin D is involved in calcium regulation. Calcium is a key mineral in muscle contraction and signalling pathways related to muscle growth.

Vitamin D’s role in muscle health extends beyond bone metabolism. Studies like those by Girgis et al. (2013) suggest that adequate vitamin D levels are linked to improved muscle repair and function. This impacts MPS through enhanced muscle cell proliferation and differentiation.

Emerging and Supportive Roles in Muscle Health

The evidence for protein, carbohydrates, creatine, omega-3s, and vitamin D is robust. Yet, several other nutrients have been studied for their potential supportive roles in muscle health and hypertrophy:

1. Magnesium and Zinc: Both are essential for muscle function and protein synthesis. Magnesium plays a pivotal role in energy production and electrolyte balance. These are crucial during intense training sessions. Zinc is critical for hormone regulation, including testosterone. Of course testosterone significantly impacts muscle growth and repair. However, the evidence linking direct supplementation with enhanced muscle hypertrophy is less conclusive than for the primary nutrients.
2. Chromium: This mineral is known for enhancing insulin action. This potentially affects muscle protein synthesis by improving nutrient delivery to muscles. Still, direct impacts on muscle mass or strength are not well-supported by current research.
3. Polyphenols: Found in fruits, vegetables, and teas, polyphenols like resveratrol and quercetin have anti-inflammatory and antioxidant properties. They may help reduce oxidative stress and support muscle recovery post-exercise. However, their direct impact on muscle growth is less understood.
4. Prebiotics and Probiotics: These influence gut health. Our gut health can indirectly affect nutrient absorption and inflammation. Both of these factors are important for muscle health. While promising, the direct evidence linking these supplements with improved muscle hypertrophy is still emerging.

Conclusion

To truly optimise muscle growth and recovery, it’s crucial to consider a broad spectrum of nutrients beyond just protein. Protein, carbohydrates, creatine, omega-3s, and vitamin D form the backbone of a muscle-friendly diet. Yet, emerging evidence suggests that other nutrients like magnesium, zinc, chromium, polyphenols, and gut health supplements can also play supportive roles. Tailoring your diet to include a wide range of these nutrients can help maximise your training results. This will ensure that every workout brings you closer to your strength and muscle growth goals.

Dr Hugh Coyne

Private GP

Parsons Green