Reduced Dietary Protein Intake: A Path to Good Health and Longevity?

By Emily Mathew, BS student in Biology

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With the rise of products, such as creams and supplements, that claim to reduce the signs of aging, the question arises of whether human aging can be reversed or at least reduced. While there are still many unknowns within the field of aging, a point of interest has been dietary changes. For instance, research on animals, such as mice and nematodes (microscopic worms), has long shown that caloric restriction could lead to healthier and longer lives by delaying or even preventing age-related diseases such as diabetes, obesity, and cancer. Even so, is caloric restriction a reasonable change that people can make in their lives?

What is Caloric Restriction? 

Caloric restriction involves consuming fewer calories while maintaining proper nutrition. It has been associated with better health and an increased lifespan in animals. Caloric restriction may work by improving sensitivity to insulin (protects people from developing Type 2 Diabetes), changing energy-related body processes, or oxidative stress (chemicals in the body that can potentially cause aging when present at high levels).

While continuous caloric restriction has appeared to have beneficial effects on animals such as rhesus monkeys, which exhibit aging patterns similar to humans, concerns arise regarding the practicality of reducing calories in the long term. For example, 25% of human participants, following a five-day per month caloric restriction regimen, dropped out of the caloric restriction study, despite gaining significant health benefits. This included improved cholesterol and triglyceride levels that lasted for 3-months even after returning to their original diets. 

Another concern of long-term calorie restriction is developing eating disorders such as anorexia and binge-eating. While these concerns are valid, there appears to be no strong association between disordered eating and caloric restriction. However, some individuals may be more susceptible to developing disordered eating than others. Thus, careful monitoring of dietary behaviors may be necessary when following a calorie-restricted diet. 

Dietary Protein Restriction 

Relating to calorie restriction, researchers have found that reducing dietary protein intake, and maintaining intake of other nutrients such as fats and carbohydrates, could delay age-related conditions and, in turn, improve health and longevity. 

A study conducted by a team led by Dr. Valter Longo from the University of Southern California found that adults (age 50 – 65) with a high protein intake had a 75% risk of mortality and 4-times greater chance of dying from cancer than the group of low-protein intake participants. Even the group that consumed moderate-protein levels was 3-times more likely than the low-protein group to die from cancer. Interestingly, those aged 65 and older had a 60% reduced risk of cancer mortality and 28% reduced risk of overall mortality with greater protein consumption. Hence, the benefits associated with dietary protein restriction may be age-dependent. It is important to note that these results were not based on differing responses to animal-based and plant-based proteins. 

However, we do know that all proteins are not equal. While animal-based proteins can offer all the nutrients you need, processed meats, such as red meats and smoked meats, can increase your risk of heart disease, stroke, or even death. On the other hand, plant-based proteins are a great source of protein with less harmful effects. Diets that rely on plant-based protein have been associated with a lower risk of cancers, Type-2 diabetes, and other age-related conditions. Despite this, plant-based proteins are unable to provide all the necessary nutrients like animal-based proteins and require the consumption of a variety of foods. 

Despite the need for further research on aspects, such as differential responses to dietary changes, and the long-term effects of dietary protein restriction, dietary modifications are a cost-effective and long-term solution to the current epidemic of age-related disorders, especially in the US.

Peer Edited by Ashley Aguillard, PhD Student in Nutrition

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