Protein: its under-appreciated role in Optimal-Active Aging (Part I)
by Joseph Jimenez, M.D., MBA, CSCS, and Hector Lopez, M.D., CSCS, CFT.
Sarcopenia is the unintentional and involuntary loss of lean body mass (muscle and bone mass), functional strength and power as a person ages. Typically, age-related decreases in muscle mass may begin as early as age 25. Between 30 to 60 years of age, muscle mass decreases at a rate of 0.3– 0.8 percent per year, and by age 80 a substantial loss of muscle mass of up to 25–40 percent would have accrued because the rate of loss accelerates after age 60. The prevalence is in
the range of 8.8 percent in women in their 60s to as high as 18 percent in men in their 80s. The muscle wasting correlates with a substantial loss of functional strength necessary to competently and confidently perform ADL (activities of daily living, such as regular housework or lifting tasks in the home, etc.) This often leads to decreases in weight-bearing physical activities and hence energy expenditure. From this perspective, one can see how sarcopenia is intimately linked to osteoporosis, increased risk of falls, fractures, hospitalizations, and,
as a consequence, expensive orthopedic procedures, which pose unique challenges in the rehabilitation setting either in the pre-surgical or post-surgical period.
This loss of muscle tissue can also be accompanied by an increase in body fat, particularly in the visceral area.
The negative change in body composition has implications
for increased risk in cardiovascular disease, insulin
resistance, and type II diabetes. Hence, you have the
emergence of the “fat-frail” population, characterized by
sarcopenia and obesity (this could be termed “diabesity”).
The “fat-frail” syndrome is really part of the spectrum of
dysfunctional metabolic syndromes including diabetes,
hypertension, hypercholesterolemia, and gout. Consequently,
this population of obese-sarcopenics is prone to
worse medical outcomes than their non-obese and frail
counterparts. The cumulative impact on the health care
costs related to sarcopenia is 1.5 percent of the total health
care costs for the year 2000 alone. Interestingly, reducing
the prevalence of sarcopenia by 10 percent would yield a
staggering $1.1 billion in savings per year for the U.S. It is
important to note that these are direct costs of the disability,
which means that the study did not account for many
other medical complications associated with sarcopenia
and dysfunctional metabolic syndrome, such as increased
risks of metabolic, renal and cardiovascular conditions.
In this article, we will discuss strategies to help prevent
sarcopenia and slow its progression. The following
strategies build on each other and are by no means
an answer to sarcopenia and age-related dysfunctional
metabolic syndrome in isolation. We will provide a rationale
for using a comprehensive, integrative approach as
the optimal strategy for attenuating and/or preventing
sarcopenia.
A High Protein Meal a Day Keeps Sarcopenia Away
Sarcopenia, in the classic non-obese, frail elderly population,
is a consequence and manifestation of chronic
energy deficit and malnourishment. The question is, if
this population is not eating enough, what macronutrients
(carbohydrates, fats, protein) are preferred as
the source of calories? Can nutritional interventions
be recommended to prevent sarcopenia? What is clear
from the studies is that diets high in carbohydrates and
low in protein (i.e., protein intake as recommended by
the RDA) consistently fail to prevent muscle wasting,
and providing enough calories to theoretically maintain
bodyweight still often results in negative nitrogen balance
(a marker of protein/muscle breakdown). In contrast,
higher protein intake in the elderly tends to result
in more positive nitrogen balance (a marker of muscle
anabolism or preservation). Preliminary studies suggest
that seniors need higher protein daily intake in the range
of 0.8–1.2 grams/kg per day. So if you weigh 150 lbs,
this equals 68 kg (to calculate your weight in kg, divide
your weight in pounds by 2.2, so 150/2.2 = 68). This
translates to about 70 grams of protein per day to 105
grams per day in this example. Increasing protein intake
however, is only a starting point, and, as we will see, the
source of protein, timing and possibly frequency of protein
intake are often underappreciated, yet critical factors
in this population.
Sarcopenia in the “frail and obese” population or in
the context of the aforementioned dyfunctional metabolic
syndrome, may benefit from increasing protein
intake for reasons mentioned above and realize the
added advantage of fat loss and body composition
improvements. Studies show that the higher protein
diets promote greater weight loss/fat loss and improved
markers of lipid and carbohydrate metabolism relative
to low protein diets. Therefore, for this population of
dysfunctional metabolic patients, strategic protein intake can not only help preserve lean body mass, but also decrease
body fat. Some of the attributes of protein that may explain the
results of improved overall body composition and metabolic
health include:
- increased sensation of fullness with protein
- improved insulin sensitivity and more stable blood sugars throughout the day
- improved nitrogen balance
- increased metabolism secondary to the thermic effects of protein
Here Are Some Useful Points With Regard To Protein:
- Before you start on a higher protein diet, ask your physician first if you have a chronic liver or kidney condition related to diabetes and/or high blood pressure. Higher protein diets may be a contraindication. Otherwise, increasing protein intake can be done safely, particularly when using strategic nutrient timing, supplementation with specific amino acid profiles, and protein of high quality. There are also other strategies to enhance the impact and anabolic efficiency of a protein meal that involves “fortification” with certain amino acids.
- Increase your protein intake to the above recommendations of 0.8 grams to 1.2 grams protein/kg of bodyweight and increase your caloric intake to help prevent progression of sarcopenia, but this is only a starting point. There will be certain situation where more than 1.2 grams protein/kg of bodyweight is clinically beneficial.
- Diets with moderate carbohydrate and moderate protein intake (40–55 percent of calories from carbohydrates, 20–30 percent of calories from protein, and 15–25 percent of calories “healthy fats”) are a great start to decreasing body fat and maintain lean body mass.
- If you are currently on a high carbohydrate/low protein diet, replace your mid-day meal or snack with a high protein meal containing 20–35 grams of protein. Protein rich meals once a day have been shown to benefit whole body protein status, prevent muscle protein catabolism, and stimulate muscle protein synthesis.
To recap, sarcopenia and dysfunctional metabolic syndrome
exist in a vicious cycle of interdependent factors, all the while
increasing the risk for developing multiple medical complications
and co-morbidities. The vicious sarcopenic cycle, which
comes full circle involves: loss of metabolically active skeletal
muscle mass > decreased physical activity > decreased
responsiveness of skeletal muscle to nutritional and hormonal
stimuli > further decrement in skeletal muscle mass >
further decline in physical activity, functional capacity, and
mobility, etc. Since the elderly already have limited reserves
of muscle mass, strength and function, it follows that even a
modest catabolic response from acute or chronic disease could
have a devastating impact on activities of daily living, quality of
life, and wellness.
In part 1 of this two-part article, we have explored the
importance of establishing a sound nutritional foundation to
develop metabolic momentum toward “breaking the vicious
sarcopenic cycle.” The second installment will focus on exercise,
strategic protein supplementation, and integrating several
modalities to optimize a sarcopenic prevention and management
regimen. Click Here to read Part II
| Sarcopenia is the unintentional and involuntary loss of lean body mass (muscle and bone mass),
functional strength and power as a person ages. . . . The negative change in body composition has
implications for increased risk in cardiovascular disease, insulin resistance, and type II diabetes. Hence, you have the emergence of the “fat-frail” population, characterized by sarcopenia and obesity ( this could be termed “diabesity” ). |
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References:
- Acheson, Kevin J. Carbohydrate and weight control: where do we stand? Current Opinion in Clinical Nutrition and Metabolic Care 2004; 7: 485–492.
- Short K, Nair K, The effect of age on protein metabolism. Current Opinion in Clinical Nutrition and Metabolic Care 2000; 3: 39–44.
- Janssen I, Shepard D, Katzmarzyk P, Roubenoff R. The Healthcare Costs of Sarcopenia in the United States. JAGS 2004; 52: 80–85.
- Kinney J. Nutritional frailty, sarcopenia and falls in the elderly. Current Opinion in Clinical Nutrition and Metabolic Care 2004; 7: 1–20.
- Manninen A. High-Protein weight loss diets and purported adverse effects: Where is the evidence? Sports Nutrition Review Journal 2004: 1(1): 45–51.
- Morley J, Baumgartner R., Roubenoff R., Mayer J, Nair K. Sarcopenia. J Lab Clin Med 2001; 137–143.
- Volpi E, Nazemi R, Fujita, S. Muscle tissue changes with aging. Current Opinion in Clinical Nutrition and Metabolic Care 2004; 7: 405–410.
- Warland S, Boirie Y. Optimizing protein intake in aging. Current Opinion in Clinical Nutrition and Metabolic Care 2005; 8: 89–94.
- Westerterp-Plantenga, M. The significance of protein in food intake and body weight regulation. Current Opinion in Clinical Nutrition and Metabolic Care 2003; 6:635–638.
Joseph Jimenez, MD, MBA, CSCS, and Hector Lopez, MD, CSCS, CFT are physicians training in the specialty of Physical Medicine and Rehabilitation. They are co-founders of Physicians Pioneering Performance, LLC. PPP, LLC, is a multi-specialty group of like-minded physicians who seek to seamlessly integrate the disciplines of musculoskeletal, spine and sports medicine, with rehabilitation, medical and performance nutrition, athletic performance, fitness, and optimal aging. We are sensitive to the varied and complex needs of diverse populations, from athletes, activehealthy individuals, to patients afflicted with illness, disability, and medical co-morbidities. The organization seeks to participate in applied and clinical research related to nutritional science, medicine, and human performance to accommodate the needs of this diverse population.
PPP, LLC, is collaborating with MyoTrend Nutritional Technologies to educate and empower countless consumers with regard to adequate
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