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The Science of Protein: Its Role in Longevity, Cancer, Ageing and Building Muscle

Protein. It’s often considered the building block of muscle, but its importance extends far beyond fitness. Protein is vital for metabolic health, insulin sensitivity and the prevention of diseases such as type 2 diabetes and sarcopenia (age-related muscle loss).

The thing is, many questions surround protein intake: How much do we truly need? Could too much, particularly from animal sources, be harmful? And why is muscle health so crucial for ageing well?

Let’s dive into the science of protein and longevity — exploring its role in building muscle, preventing frailty and enhancing longevity while addressing misconceptions about its risks and optimal consumption strategies.

Jump there now:

• Why Muscle Matters
• Building and Maintaining Muscle
• How Protein Works
• How Much Protein Do You Need?
• Does Protein Harm Kidneys?
• How Does Protein Affect Ageing?
• Timing and Distribution of Protein
• Animal vs. Plant Proteins
• The Longevity Benefits of Muscle and Protein
• Practical Takeaways for a Frailty-Free Future

Why Muscle Matters

Muscle isn’t just about strength; it’s an indicator of overall health and longevity. Here’s a sobering fact: after age 50, the average person loses 1 per cent of muscle mass annually and strength declines even faster, by around 3 per cent each year. By age 75, without intervention, you could lose up to 4 per cent of your strength annually.

This loss is not just a cosmetic or mobility issue — it’s a life-threatening one. Muscle loss increases the risk of falls and fractures. Research shows that hip fractures double mortality risk, with 22–58 per cent of individuals dying within a year of the injury. So, for muscle and longevity, maintaining muscle mass and strength is, quite literally, a defence against ageing and frailty.

Building and Maintaining Muscle

Resistance training is the most effective way to preserve muscle mass and strength. Protein, however, intake plays a critical supporting role. A study found that people engaged in resistance training who consumed 1.6g of protein per kilogram of body weight daily gained 27 per cent more muscle mass and 10 per cent more strength compared to those consuming less protein.

Further Reading: The Different Types of Protein Powder

How Protein Works

Protein is broken down into amino acids, which the body uses to repair and grow muscle through a process called muscle protein synthesis (MPS). Key to this process is leucine, an amino acid that acts as a trigger for MPS. High-quality proteins — especially from animal sources — tend to be richer in leucine and are more effective at stimulating MPS.

Anabolic Resistance

As we age, muscles become less responsive to amino acids, a phenomenon known as anabolic resistance. This means older adults require higher doses of protein per meal to achieve the same MPS as younger individuals.

For example, while as much as 0.4g/kg of protein can stimulate MPS in younger adults, older adults may need as much as 0.6g/kg to do the same. Regular exercise, however, can offset this resistance, making muscles more responsive to protein intake.

How Much Protein Do You Need?

The Recommended Dietary Allowance (RDA) for protein is 0.8g/kg per kg of body weight per day— but many experts believe this is inadequate for optimal health. Based on newer research:

• General Health: 1.2–1.6g/kg of body weight per day (e.g., 84–112 grams daily for a 70 kg/154 lb person).
• Muscle Building: Up to 2g/kg per day.
• Weight Loss/Body Recomposition: 1.6–2.2g/kg per day to preserve muscle while losing fat.

These recommendations are particularly important for older adults, who benefit from protein intakes 30 per cent above the RDA to prevent frailty and muscle loss.

Further Reading: Is a Low-Protein Diet Worth It?

Does Protein Harm Kidneys?

In healthy individuals, higher protein intake does not harm kidney function or affect bone health. Studies on adults consuming 2.51–3.32g/kg per day had no harmful effects on kidney and liver function.

How Does Protein Affect Ageing?

Some researchers suggest that high protein diets, especially those heavy in animal protein, might increase the risk of cancer and age-related diseases. This is due to:

1. Increased IGF-1 Levels: While IGF-1 supports muscle and brain health, high levels may also promote the growth of precancerous cells.
2. MTOR Activation: MTOR is a pathway that drives muscle growth but may also play a role in conditions like atherosclerosis (artery hardening).

For active individuals, though, the story is different:

• IGF-1 Rebalancing: Exercise redirects IGF-1 to muscles and the brain for repair rather than fuelling cancerous growth, reducing the risks associated with high levels. Thus, an active lifestyle is key to mitigating potential risks as IGF-1 has been found not to change over time in response to exercise with protein.
• Protective Effects: Physical activity reduces inflammation, improves insulin sensitivity and strengthens the immune system — all of which counteract potential risks linked to high protein intake.

Timing and Distribution of Protein

Daily Distribution

While total daily protein intake is most important, spreading protein evenly across meals may optimise muscle protein synthesis. Aim for 20–40g per meal, depending on your age and activity level. The total amount of protein you eat throughout the day is far more important than the exact timing. Your body can still use larger protein meals effectively, so don’t stress if every meal isn’t perfectly balanced.

The Anabolic Window

The idea that protein must be consumed immediately after exercise for maximum benefit is outdated. Muscle protein synthesis remains elevated for up to 24 hours post-exercise, giving you flexibility in timing your intake. While it’s not necessary to rush for a protein shake immediately after exercising, having a protein-rich meal shortly after can be helpful, especially if you work out on an empty stomach.

Pre-Sleep Protein

Consuming 30g of protein before bed has been shown to improve overnight muscle repair and growth, especially on training days. It’s a simple strategy to boost total protein intake without negatively affecting morning appetite. Having protein before sleep can support muscle recovery and growth, particularly for athletes or older adults looking to maintain muscle mass. Casein protein, which digests slowly, is a great option.

Further Reading: Factors that Affect Longevity

Animal vs. Plant Proteins

Plant and animal protein; which is the best protein for longevity?

Animal proteins (e.g., meat, eggs, dairy) are complete, containing all essential amino acids and are highly effective at stimulating MPS. Plant proteins, while often incomplete, can be combined to provide all essential amino acids.

• Animal Protein: Offers higher protein density (more protein per gram of food), better digestibility and a complete amino acid profile. For example, 85g of chicken provides 27g of protein, while you’d need over a kilogram of potatoes for the same amount.
• Plant Protein: Often lacks one or more essential amino acids and is less digestible due to fibre content. But plant-based diets can meet protein needs with strategies like combining different protein sources (e.g., rice and beans) and using plant-based protein powders.

For vegetarians and vegans:

• Diversify Protein Sources: Combine grains, legumes and seeds.
• Use Plant-Based Protein Powders: These are rich in leucine and boost total intake.
• Increase Total Protein Intake: Since plant proteins are less bioavailable, aim for 10–20 per cent more protein overall.

Not all proteins are created equal. The best protein sources are easy to digest, contain all essential amino acids and include enough leucine—a critical amino acid for muscle growth. Leucine is a ‘trigger’ for muscle protein synthesis. Foods rich in leucine, like whey protein, are particularly effective at promoting muscle growth. To maximise this, aim for 2–3g of leucine per meal, which you’ll find in about 20–25g of whey protein.

The Longevity Benefits of Muscle and Protein

Improved Metabolism

Muscle improves insulin sensitivity, reducing the risk of type 2 diabetes. It also supports a healthier body composition, which decreases the risk of early death by 18 per cent.

Defence Against Frailty

Higher muscle mass reduces the likelihood of falls, fractures and disability in older adults. In one study, individuals over 90 years old increased muscle strength by 174 per cent after eight weeks of high-intensity resistance training.

Further Reading: Guide to Longevity Ingredients

Practical Takeaways for a Frailty-Free Future

1. Calculate Your Protein Needs: Aim for 1.2–1.6g/kg of body weight, adjusting for goals like muscle building or fat loss. Athletes, older adults and those aiming to lose fat while preserving muscle may need more.
2. Whole Foods First: Prioritise protein-rich foods like lean meats, eggs, dairy, legumes and tofu. Supplements like whey can help fill gaps if needed.
3. Exercise Regularly: If you’re exercising regularly, higher protein intake is not only safe but beneficial for health and longevity. Resistance training is essential to maintaining muscle and combating anabolic resistance.
4. Distribute Protein Intake: Spread protein evenly across meals to maximise muscle protein synthesis.
5. Consider Pre-Sleep Protein: A low-calorie protein shake before bed can support overnight recovery.
6. Diversify Sources: Combine plant proteins or include high-quality animal proteins for optimal results.

End Note

Protein is more than a muscle-building nutrient; it’s a cornerstone of longevity, metabolic health and resilience against ageing. Combined with exercise and a balanced diet, protein supports muscle growth, enhances recovery and can contribute to a longer, healthier life. Stay active, eat well and focus on the quality and variety of your protein sources for the best results.

Other than protein and ageing, are you looking for other ways to improve your longevity strategy? For brain and cognitive support as you age, try Xandro’s LPC Neuro and for a longevity ‘multivitamin,’ try Xandro’s Protocol X, full of scientifically-backed longevity ingredients.