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

Protein has long been celebrated as the cornerstone of muscle development, but its significance extends far beyond. From regulating metabolism and enhancing insulin sensitivity to preventing age-related conditions like type 2 diabetes and sarcopenia, protein plays a vital role in our health. However, questions persist: How much protein is optimal? Can too much, particularly from meat, be harmful? Let’s dive into the science, exploring protein’s role in ageing, longevity, and disease prevention while addressing common concerns.

Why Muscle Matters: More Than Strength

Muscle isn’t just about aesthetics; it’s essential for metabolic health and longevity. As we age, we naturally lose muscle mass and strength—a condition called sarcopenia—unless mitigated by resistance training. Starting as early as age 30, this decline accelerates with inactivity, increasing the risk of falls, fractures, and metabolic disorders.

The Metabolic Benefits of Muscle

Muscle mass isn’t just a reserve for strength; it’s a critical regulator of glucose metabolism and insulin sensitivity. More muscle helps maintain metabolic health and reduces the risk of type 2 diabetes. In older adults, muscle mass can be the difference between thriving and experiencing life-threatening health events during illness or injury recovery and Resistance Training Help?

Yes, and it’s never too late to start. Older adults require more protein to stimulate muscle protein synthesis effectively. Combining resistance training with adequate protein intake can combat sarcopenia and reverse anabolic resistance—the diminished ability to build muscle from protein as we age. For example, a study on older adults found that higher protein intake improved muscle retention and physical performance (source).

How Much Do We Need?

The Recommended Dietary Allowance (RDA) for protein—0.8 g/kg of body weight daily—is too low for optimal health. Research suggests that active individuals and older adults benefit from higher intakes. Here are some updated guidelines (source) :

• For general health: 1.2–2.0 g/kg of body weight per day.
• For resistance training: Up to 2.2 g/kg can maximise lean muscle gains.
• For weight loss or recomposition: Higher protein supports satiety and spares muscle during calorie deficits .

For individuals with osculating protein needs based on lean body mass rather than total weight ensures accurate requirements.

Timing and Distribution of Protein

Does the timing of protein intake matter? While spreading protein intake evenly across meals is beneficial for stimulating muscle protein synthesis (source), total daily intake is more critical. However, there are nuances:

• Post-exercise: The “anabolic window” is less strict than once thought. Muscle protein synthesis remains elevated for hours after training, making immediate protein intake non-essential .
• Pre-sleep protein: Consumption of slow-digesting protein (like casein) before bed can improve muscle growth and recovery, especially in older adults .

Protein Sources: Quality Matters

Quality is determined by its digestibility and amino acid profile. Animal proteins, like meat, eggs, and dairy, are superior for building muscle because they contain all essential amino acids and are rich in leucine, a key trigger for muscle protein synthesis. Plant-based proteins, though beneficial for health, often require complementary sources to meet amino acid needs.(source)

Can You Meet Protein Needs on a Plant-Based Diet.

Strategies include:

• Pairing incomplete proteins (e.g., rice and beans) to achieve a complete amino acid profile.
• Using plant-based protein powders like pea or rice protein enriched with leucine.

Does High Protein Harm Health?

One of the most persistent myths is that high-protein diets damage kidneys. However, in healthy individuals, there is no evidence that higher protein intakes harm kidney function. This concern applies only to those with pre-existing kidney disease .

Protein, Ageing, and Cancer Risk

Some studies link high intake, particularly from animal sources, to elevated levels of insulin-like growth factor 1 (IGF-1), which may promote ageing and cancer. However, the context is crucial:

• Exercise mitigates risks by redirecting IGF-1 to muscle and the brain, where it supports repair and function.
• Physically active individuals consuming high-protein diets show no reduction in lifespan .

Key Takeaways

1. **Muscle is vital for longevity. Resistance training and adequate protein intake are powerful tools to maintain muscle and prevent age-related decline.
2. Protein needs vary. Aim for 1.2–2.2 g/kg of body weight, adjusting for activity levels and goals.
3. Distribution is helpful but not critical. Total daily protein matters most, with pre-sleep protein benefiting older adults and athletes.
4. Quality is king. Animal proteins are more effective for muscle synthesis, but plant-based diets can work with careful planning.
5. Higher protein is safe for healthy individuals. Myths about kidney damage and reduced longevity lack strong evidence, particularly in active people.

Protein is not just a muscle builder but a pillar of overall health, influencing everything from metabolism to disease prevention. Whether your goal is to age gracefully, optimise athletic performance, or prevent chronic illness, the right amount and type of protein, paired with resistance training, can make all the difference.

Sources:

1. Why Muscle Matters
2. How Much Protein to Consume
3. Does High Protein Accelerate Ageing?