(More in the series on Lack of Protein Drives Hunger, Part 1 and Part 2, and Supplements) If you are looking for information regarding Protein Requirements and Age you are in luck! Look no further than this article!
About Scott V Watkins, MD
“As we age” is one of the phrases commonly used in medicine.
For instance, you may have heard:
- CoQ10 production decreases “as we age.”
- Testosterone production decreases “as we age.”
- Mitochondrial function and repair decrease “as we age.”
Our ability to digest, absorb, synthesize and utilize protein also tends to be affected as we get older, as Muscle Protein Synthesis (MPS) declines and Muscle Protein Breakdown (MPB) increases.
The list goes on, and I’m certain each of you can add to it!
A major question for me, however, is at what AGE do we begin to age? Is it at 65, the long-standard age of retirement? Is it when you become a nursing home resident who uses a walker? The answer may surprise you.
There are two additional factors that make this concept so important:
- The population is aging, especially in developed, Western countries.
- Our diets and sedentary lifestyles age us and make us less resilient.
Collagen synthesis actually begins to decline in our early 20s. Production of testosterone (a hormone that regulates sexual development, muscle mass and red blood cell production) can begin to decline in our late 20s to early 30s and is often significant by age 35. An article published in the Journal of Neurologic Sciences in 1988 evaluated muscle fibers from the thigh, in a study group of men 15-83 years old. There’s a gradual decline in the third decade (this is from age 20-29!) with a 30% to 50% loss after age 40.
Physiologically, the aging process actually begins when most of us still feel we are well within our “prime” years — and what we see in the nursing home resident using a walker is the end result, not the start of the process.
A study published in the journal Nutrients in 2018 focuses on this issue regarding the protein requirements for an “aging population, defined in the article as 40 years of age or older.” To paraphrase an American advertising campaign from some years ago, “This is not your grandfather’s protein requirement.” Chances are, this is YOUR protein requirement.
As we age, our protein intake declines (for a variety of reasons). We have a decreased ability to digest and absorb protein, and a decreased ability to synthesize amino acids into protein. We also have increased degradation of proteins and increased transcription errors from DNA to protein, and therefore faulty protein synthesis. All of these mechanisms point toward an even higher probable protein requirement than we discussed in my recent article.
The International PROT-AGE Study Group and the European Society for Clinical Nutrition and Metabolism (ESPEN) have made the following recommendations:
- Over age 65: Increase protein requirements to 1.0 to 1.2 grams (gm) of protein per kilogram (kg) of body weight.
- Acute or chronic illness: Increase protein requirements to 1.2 to 1.5 gm/kg.
- Serious illness, injuries, and malnutrition: Increase protein to 2.0 gm/kg.
An additional study — published in 2009 in the Journal of Nutrition, Health, and Aging — documented skeletal muscle mass loss of 0.5%-1.0% per year starting at age 50.
The bottom line is: if you are over age 25 and want to maintain a healthy amount of skeletal muscle mass for optimum health, the current protein recommendations are probably inadequate, and are even worse “as we age.”
To learn more about some of the research on protein intake that’s been used in this article, click on the following:
“Age-related changes in the structure and function of skeletal muscles”: Faulkner, J. A. et al. (Clin. Exp. Pharmacol. Physiol. 2007, 34, 1091-1096.)
“Evidence-based recommendations for optimal dietary protein intake in older people: A position paper from the PROT-AGE Study Group”: Bauer, J./ Biolo,G.; Cederholm, T.; Cesari, M.; Cruz-jentoft, A.J.; Morley, J.E.; Phillips, S.; Sieber, C.; Stehle, P.;Teta, D.; et al. J. (Am. Med. Dir. Assoc. 2013, 14, 542-559.)
“Protein intake and exercise for optimal muscle function with aging: Recommendations from the ESPEN Expert Group”: Deutz. N.E.; Bauer, J.M.; Barazzoni, R.; Biolo, G.; Boirie, Y.; Bosy-Wstphal, A.; Cederholm, T.; Cruz-Jentoft, A.; Drznaric, Z.; Nair, K.S.; et al. (Clin. Nutr. 2014, 33, 929-936.)
