High Protein Intake for Those Aged 66 and Older Reduces Cancer Mortality by 60% and Helps Prevent Aging

While protein is an essential element for muscle building, there are concerns that excessive intake may be harmful to the body. In particular, claims have been made that high-protein diets may strain the kidneys or liver, or accelerate aging by stimulating mTOR, a cell growth switch. According to a Doctor Dingyo video, these concerns must be interpreted differently depending on an individual's health status and age.

Healthy Kidneys and Liver: Is High Protein Intake Always Dangerous?

Many people worry that eating a lot of protein will damage their kidneys. However, the video explains, "Rather than saying the kidneys are damaged because you ate too much protein, it is that you should not eat too much protein because your kidneys are already damaged." In other words, declining kidney function is a limiting factor for protein intake, rather than protein itself being the main culprit that destroys healthy kidneys.

In fact, according to research by Jose Antonio, even when healthy individuals who exercise consumed ultra-high doses of up to 4.4g of protein per 1kg of body weight for two months, there were no significant abnormalities in kidney function. While a general healthy adult is recommended to consume about 0.8–0.9g per 1kg of body weight, it is known that consuming up to 1.6–2.0g is certainly not a problem if combined with exercise. However, patients with stage 4 chronic kidney disease or higher must consult their nephrologist to determine their protein intake, as maintaining a high-protein diet while kidney function is impaired can be dangerous.

Concerns regarding the liver also exist. While high-protein diets were previously known to strain the liver, the video points out that appropriate protein intake may actually be necessary for patients with liver cirrhosis. Patients with liver cirrhosis are susceptible to the effects of aromatic amino acids (AAA: tyrosine, tryptophan, phenylalanine) that cause ammonia toxicity; in such cases, consuming sufficient BCAA, such as isoleucine, valine, and leucine, helps offset this toxicity. In particular, since having more muscle mass helps the muscles assist the liver in processing ammonia, it is recommended that even liver cirrhosis patients consume whey or plant-based proteins rich in BCAA at a level of 1.2–1.5g per 1kg of body weight while performing muscle exercises.

The Correlation Between the mTOR Switch and Aging: Reversal of Results by Age

The 'mTOR' pathway is most frequently mentioned as the link between protein intake and aging. The amino acid 'leucine' found in protein stimulates mTOR to induce cell growth, and there are concerns that if this process is excessive, it can promote aging and inhibit Autophagy, the cell purification process. The logic is that mTOR acts as a nutrient-sensing switch that commands 'growth,' and this growth can lead directly to aging.

In fact, according to a 2014 study by Levine and Valter Longo, it caused great controversy because it showed that in the 50–65 age group, excessive protein intake without exercise increased total mortality by 75% and cancer mortality fourfold compared to those who did not. However, the video emphasizes that this formula is completely reversed depending on age. In the elderly population aged 66 and older, research shows that eating more protein actually reduces total mortality by 28% and even lowers cancer mortality by up to 60%. This is because the risks of sarcopenia and frailty caused by protein deficiency are far more fatal for the elderly than the risks caused by protein excess.

The Decisive Reason to Increase Protein Intake After Age 65

As we enter old age, our body's 'anabolic' ability (the process of synthesizing protein to create tissue) drops sharply. When young, the mTOR switch turns on easily even with a moderate amount of leucine, but as one ages, this switch does not function well, requiring a larger amount of leucine. The video advises that for the elderly, they should eat enough protein to be able to consume about 3g of leucine in a single meal.

In particular, during old age, once muscle begins to be lost, it is extremely difficult to recover. While it is possible to recover from muscle loss caused by hospitalization due to illness or accidents when young, as one ages, muscle loss does not occur linearly but decreases sharply in a 'step-like' fashion. Citing cases from nursing hospitals, the video warns that even just a few hospitalizations can lead to a rapid loss of muscle, creating a high risk of leading to a 'bedridden state' where one can never walk again. To prevent such sarcopenia and frailty, protein requirements should be increased to a level of 1.2–1.5g per 1kg of body weight after age 65, and choosing proteins rich in leucine, which is advantageous for muscle synthesis, is key to a healthy old age.