Muscle loss is a serious issue for men and women. Starting at about age 40, adults gradually lose muscle mass as they age, making it harder to maintain a healthy weight and affecting quality of life.
Sarcopenia, the age-related loss of muscle mass, is a slow, progressive condition that develops around the fourth decade of life. It often progresses unnoticed, until non-muscle weight starts creeping on, and daily tasks become progressively harder.
Muscle mass declines 3-8% each decade, while strength declines approximately 1.5% per year and accelerates to 3% per year after age 60. In addition to actual muscle loss, powerful, fast-acting muscle fibers convert to slower muscle fibers. There is a cascade effect that can accelerate the decline: As muscles become weaker, it becomes harder to exercise and energy declines, leading to further progression of the disease.
An aging population points to what can only be called an impending epidemic of muscle loss and weakness. Estimates compiled by the group Sarcopenia Awareness indicate as many as 45% of the US population has at least some level of age-related muscle loss.
With healthcare expenses for the condition racking up nearly $1,000 per person per year, it has been projected that reducing the numbers of persons with sarcopenia by only 10% could lead to savings across the population of more than $1 billion per year.
Sarcopenia also increases the risk of falling. Falling is a major cause of head injuries, broken bones, and hospitalization, most especially in the elderly.
While little can be done about some of the physiological changes in muscle, it is possible to slow the decline in muscle mass, strength and functioning. And while engaging in resistance training is a primary component, so is eating a well-balanced diet that includes the ingredients known to support the building and maintaining of muscle tissue.
Low protein intake leads to a reduction in muscle mass and strength throughout the life cycle. Seniors who consume more protein than their peers will lose less muscle mass as they advance in years. Older adults need between 1.1-1.5g of protein per kilogram body weight per day to support muscle and attenuate muscle loss.
While it’s a given that protein is the primary ingredient for creating muscle, and total daily protein intake is crucial for supporting muscle, studies have shown consumers should take advantage of timing protein intake when they are most catabolic—that is, during periods of muscle breakdown. This creates specific opportunities for product developers to focus on meals and snacks typically enjoyed at those times.
The body is usually in a catabolic state immediately after resistance training, as well as in the morning upon waking. After exercise, older adults can maximally stimulate acute muscle protein synthesis by consuming approximately 40g of high-quality protein. Elderly persons who do not habitually meet their protein needs will benefit the most from this strategy. However, there might be no additional benefit from post-exercise protein intake in those who regularly consume more than 1g protein per kg body weight per day.
Dairy proteins, particularly whey, have garnered a great deal of attention for their amino acid composition and ability to up-regulate acute muscle protein synthesis. In fact, studies have demonstrated that whey protein could perform in this manner to a greater extent than the same amount of soy protein. Whey also is highly popular due to its compliment of branched-chain amino acids (BCAAs), specifically leucine, isoleucine, and valine. Whey has been shown to help preserve lean muscle tissue between workouts or during dieting.
It must be qualified, however, that many of the studies comparing plant proteins to dairy proteins didn’t match protein based on total leucine content. Leucine is the key amino acid that triggers the initiation of muscle protein synthesis. More recent studies suggest proteins matched for total leucine content work as well as whey.
“Once you reach the ‘leucine threshold’—about 2g in healthy young adults and 3g in older adults—and if all other required amino acids are present, then there is no reason that an animal protein and a vegetable protein should differ in their ability to activate protein synthesis,” states Blake Rasmussen, PhD, professor and chair of the Department of Nutrition and Metabolism at the University of Texas Medical Branch at Galveston. “The key difference is that a person would have to eat a bit more protein from vegetable sources to achieve the leucine threshold, as compared to one eating animal protein sources.”
In addition to being cognizant of protein intake at breakfast and after exercise, acute studies conducted by the University of Texas Medical Branch suggest adults should consume approximately 30g of protein per meal, evenly spaced throughout the day, to decrease muscle loss. (Longer term studies are necessary to determine if consuming 30g protein boluses at each meal will translate to better long-term results compared to consuming the same amount of protein in an uneven pattern each throughout the day.) Also, some studies indicate some adults might benefit from consuming more than 30g of protein per meal.
Egg white is often used in sports formulations to enhance protein. As the most bioavailable protein food, it has the advantage of performing a panoply of textural functions throughout the food and beverage development industry.
Best of all, after a recent avian flu scare, prices have leveled off, and availability for processors is settling back to pre-flu capacity. (See, “Hard Boiled Crisis,” September 2015, http://bit.ly/1Q99nHU.)
Those who need to limit their protein intake due to specific medical conditions, they can boost acute muscle protein synthesis while keeping total nitrogen load low by consuming products with added leucine or branched-chain amino acids (BCAAs). However, it still is unclear if this strategy translates to longer term results. One study demonstrated that the addition of 2.5g of leucine to three daily meals over a period of three or six months did not improve muscle mass, strength, or muscle quality in elderly men who were healthy or diabetic.
Protein generation and turnover is a core metabolic function of the body and, thus, needs a comprehensive toolbox of biological cofactors and assistants to keep the machinery running smoothly. Of these, vitamins and minerals are primary participants. Magnesium has been gaining attention after recent surveys revealed that about half of American consumers are not getting enough of this nutrient in the diet.
Magnesium is needed for multiple enzymatic functions in the body, most importantly for generating energy and nervous system function. In muscle health, magnesium is needed for muscle contraction and glutathione production. Glutathione is an antioxidant. In addition to countering damage from free radicals, it suppresses muscle fatigue resulting from prolonged exercise. A deficiency in magnesium can disrupt muscle cell functioning, impair carbohydrate intake by muscle cells, and lead to muscle cramping and twitching; or spasms, fatigue, numbness, and tingling.
Although magnesium is abundant in an array of foods, food intake data consistently show that both men and women are falling far short on their magnesium needs. Single-tablet multivitamins typically contain less than one third of daily magnesium needs, but few processors have yet to employ a stronger focus on this important component of metabolic and muscle function.
Low zinc intake is a global issue, with some 15-30% of the worldwide population maintaining too little in the diet. NHANES data suggest that mean intakes of zinc in both men and women are on par with the RDI for this mineral; however, vegetarians, females, and adults on a reduced-calorie diet might not be consuming enough zinc. Also, with red meat and shellfish—two expensive ingredients—the primary dietary source of the metal, zinc deficiency hits less-affluent populations harder. On top of this, the body is less efficient at storing zinc than some other micronutrients.
Zinc deficiency leads to a decrease in muscle strength and reduced power output. Correcting this deficiency can improve both. Zinc’s strong metallic taste and insolubility can make it challenging to include the mineral in formulations, but in bars, cereals, baked goods and similar products, zinc forms are available that make it easy to incorporate. Also, microencapsulated forms of the mineral are available for use in beverages and such foods as dairy products, where off flavors from other forms of zinc would stand out.
Scrutiny of vitamin D has been strong in the past few years. More and more benefits of the fat-soluble, hormone-like vitamin have been revealed. Vitamin D has abilities to regulate blood pressure, protect against certain cancers, reduce risk of type 2 diabetes, protect the heart, and even mitigate depression. All this in addition to its well-known bone health role.
Supplementation with vitamin D—or any micronutrient—won’t turn a couch potato into a bodybuilder. However, the vitamin plays an important role in muscle strength and functioning. Vitamin D deficiency leads to muscle pain and weakness that is reversed when levels return to normal.
Correcting a vitamin D deficiency through supplementation in the elderly improves muscle strength and functioning, with no effect on muscle mass or power.
Additionally, vitamin D supplementation reduces risk of falling in the elderly who live on their own by 17 and 19%, respectively, with no adverse effects reported.
While the full palette of B vitamins merits consideration for any health-promoting formulation, one member of the B vitamin family often is ignored in healthy product formulation: choline. Choline is necessary for normal functioning of all cells and has a multifaceted, and often overlooked, role in muscle.
As part of the neurotransmitter acetylcholine, choline helps the brain communicate with muscle to facilitate muscle contraction. Milk, liver, eggs, and peanuts are rich in choline.
In addition to these foods, grain-based dishes contribute to approximately one quarter of our choline intake. (Grains also are a key contributor of multiple minerals and other needed micronutrients.) During intense and prolonged physical activity, plasma choline levels typically decrease. Significant decreases in circulating choline choline lead to a decline in exercise performance that can be attenuated by choline supplementation.
Although choline is in many commonly consumed foods, mean daily choline intake for both males and females in all age groups falls short of Dietary Reference Intakes (DRI). Choline intake is correlated with calorie intake and, therefore, males consume significantly more choline than females and come closer to meeting their dietary needs for this nutrient.
Creatine has been favored on the sports supplement circuit for many years. A byproduct of metabolism of the amino acids glycine and arginine, it is synthesized in the liver, pancreas, and kidneys and stored in skeletal muscle.
However, the primary source of the compound is meat, so vegetarians and flexitarians, especially those engaged in regular exercise and muscle-building programs such as resistance training, could benefit from supplementation.
Creatine helps in these activities by contributing to improved muscle strength and lean body mass. It also improves functional performance, as measured by the 30-second chair test, in the elderly.
Another amino acid metabolite, beta-hydroxy-beta-methylbutyrate (HMB), a byproduct of leucine metabolism, has been highlighted as a potential solution for slowing age-related loss of muscle mass. However, only 5% of leucine is converted to HMB. Studies have shown that a 3g dose of HMB, in the form of calcium HMB CaHMB, effectively increased strength and muscle quality compared with placebo in sedentary elderly adults.
Interestingly, there was no difference between CaHMB and placebo in resistance-training studies in the elderly. This could suggest the ingredient is only effective in those who are not active. More research is necessary, but should this ingredient prove to be an aid to muscle health in the sedentary, developers of muscle health products should take note.
Foods and beverages designed to support muscle mass include nutrients that can help build and repair muscle; support muscle functioning and balance; and assist the communication between brain, nervous system, and muscle. Adults who retain more muscle mass should theoretically reduce risk of falls, while also improving their quality of life.
Muscle Loss Facts and Figures
• Adults experience muscle mass loss of an average of 50% or greater by age 90.
• Roughly 45% of the US population is sarcopenic.
• A 10% reduction in the sarcopenic population would save $1.1 billion.
• Healthcare expenditures due to sarcopenia cost roughly $900/person/year.
• Lifestyle exercise programs cost about $200 per person per year.
• No race or ethnicity is protected from sarcopenia.
• In the US, an estimated 53% of men and 43% of women over the age of 80 are sarcopenic.
• Experts say sarcopenia affects about 10% of those over 60, with higher rates as age advances.
• One study estimated that disability caused by sarcopenia accounted for
$18.5 billion in direct medical costs in 2000, equivalent to 1.5% of the nation’s healthcare spending that year.
• An 80-year-old might have 30% less muscle mass than a 20-year-old. Strength declines even more than mass. Weight-lifting records for 60-year-old men are 30% lower than for 30-year-olds; for women the drop-off is 50%.
• Lean muscle mass generally contributes up to approximately 50% of total body weight in young adults but declines with aging to about 25% at
75-80 years old
• One study that tracked 3,000 people for 50 years found that only about 20 of them, now in their 80s, had not lost muscle mass.
• People who are physically inactive can lose as much as 3-5% of their muscle mass per decade after age 30.
• From 20-80 years of age, there is an approximate 30% reduction in muscle mass, and a decline in cross-sectional area of about 20%.
• Human muscle undergoes constant changes. After about age 50, muscle mass decreases at an annual rate of 1-2%. Muscle strength declines by
1.5% between ages 50-60 and by 3% thereafter.
• One in four adults either engage in a low level of activity (i.e., moderately active during usual daily activities and completely inactive during leisure time)
or are not active at all.
Source: Sarcopenia Awareness (www.sarcopeniacure.com) and multiple sources, including: NYTimes.com; Western Washington University; WebMD LLC. All rights reserved; National Institutes of Health; and others.)