What Vitamin Stops Age Related Muscle Mass?

Overview

As we age, an involuntary loss of skeletal muscle tissue, strength or function occurs, also termed as ‘sarcopenia’. Muscles’ degenerate nearly 3–8% per decade after the age of 30 and this rate increases after the age of 60.¹ Furthermore, after the age of 50, sarcopenia affects nearly 10% of the population.² This muscle loss is usually the contributing factor to disabilities and the subsequent increases in the risk of falls amongst the elderly.

How does age affect muscle mass? (sarcopenia)

The regulation of muscle mass is a combination of cell growth signals called anabolism and signals that break down cells called catabolism. During these processes, muscle growth factors work alongside enzymes that destroy proteins to keep muscle growth regulated during cycles of growth, stress or injury. Sarcopenia is the result of this balance being disrupted, and happens when the body becomes resistant to the growth signals, in turn causing catabolism and muscle loss. The decrease in muscle mass is also accompanied with an increase in fat mass and insulin resistance. Additionally, bone density and joint stiffness increases, this may lead to problems with posture, such as curvature of the spine (kyphosis). 

Other causes of muscle loss

Sarcopenia is a multifactorial disease where both genetic and epigenetic factors contribute to its pathogenicity. Some of these factors include:

• Environmental Factors: It is difficult to pinpoint whether a sedentary lifestyle is directly linked to the cause of sarcopenia due to its multi factorial nature. However, the lack of physical activity has been shown to reduce muscle mass and strength in individuals.¹ On the contrary, resistance exercises involving weights or resistance bands actively increases the production of muscle mass in both younger and older adults.³ Although aerobic exercises do not induce quick muscle growth like resistance exercises, it can to a certain degree grow the muscles.⁴ Therefore, it is important to understand that leading an active lifestyle can reduce the risk of sarcopenia

Like exercise, nutrition also plays a role in the progression of sarcopenia. Studies have suggested that older adults need to have a protein intake of approximately 1 gram per kilogram of body weight per day, which is higher than the recommended 0.8 gram per kilogram of body weight per day.⁵  Often in a bid to reduce fat and cholesterol in their diets, elder people simultaneously neglect their protein intake as well. Amino acids from the protein play a vital role in muscle synthesis.⁶ Therefore, it is important to have a balanced diet alongside adequate exercise inorder to reduce the effects of sarcopenia.

• Genetic Factors: There are several constituents of the cellular signalling pathways responsible for muscle synthesis. These signals gradually decline as we age and the effects of this decline are inevitable. Some of them include:
  • A progressive decline in the number of nerves that innervate the muscles. As a result, the muscles receive a lower rate of growth signals which subsequently causes muscle death (atrophy).⁷ Other muscular structures such as the muscle cell number and the structure of the muscle fibres become disrupted
  • A gradual decrease in the hormones responsible for muscle maintenance e.g. insulin-like growth factor, dehydroepiandrosterone sulphate (DHEA Sulphate), testosterone, and oestrogen, which contribute to sarcopenia⁸
  • An activation of the inflammation pathway due to other age-related diseases. This pathway increases the number of cell death signals, which subsequently causes muscle loss⁹  
  • A loss of the body’s ability to recover from muscle death. Skeletal muscle stem cells, also known as satellite cells, have the regenerative ability to produce new muscle cells. However, due to increasing age, there is a lack of these circulating stem cells and as a result they are slow to heal muscle damage¹⁰ 

Signs of muscle loss

Sarcopenia is characterised by the reduction of strength over a period of time. An individual may notice a loss in strength when they struggle to cope with daily activities such as:

• A diminished ability to conduct simple tasks such as walking, standing up or sitting down, or lifting familiar objects
• A loss of independence due to increased physical disabilities

Some other symptoms may include:

• An unexplained loss of muscle mass
• Feeling fatigued
• Falling down, due to having a lack of strength
• Muscle or joint stiffness

However, it is important to note that these symptoms may overlap with other diseases, therefore it is important to seek professional advice.

Vitamins to help prevent muscle loss

Currently, the methods to treat sarcopenia are limited, therefore, most of the research conducted has focused on how to slow down the rate of sarcopenia through appropriate nutritional intake. 

Vitamin C

Around two-thirds of the body’s vitamin C is found in skeletal muscles and plays an important role in improving bone health, as well as the maintenance of muscle mass.¹¹ It contributes to the production of carnitine, which is a chemical that provides energy for the muscles to function. Vitamin C is also responsible for the production of collagen, which is a structural protein found in the muscle fibres. Alternatively, vitamin C reduces the inflammatory effects of other age-related diseases. Studies have shown that increasing the intake of vitamin C can directly contribute to the gain of muscle mass.^12,13 Furthermore, vitamin C is an easily accessible dietary supplement to slow down sarcopenia, as it is readily available in the majority of fruits and vegetables such as citrus fruits, peppers, strawberries, blackcurrants, broccoli, Brussels sprouts, and potatoes.

Vitamin D

Vitamin D plays various roles in the muscle growth cycle, these include: the generation of stem cells, protein synthesis, and energy production.¹⁴ Studies have shown that a lack of vitamin D in the diet contributes to musco-skeletal diseases.¹⁵ Elder adults are at an even larger risk of vitamin D deficiency, due to a lowered ability to absorb it via digestion or sun exposure.¹⁶ Furthermore, studies have shown that upon increasing dietary intake of vitamin D, there is a lower incidence of both osteoporosis and sarcopenia in ageing people.¹⁷ Vitamin D can be found as supplements, however, foods that are rich in vitamin D include oily fish (salmon, sardines, herring and mackerel), red meat, liver, egg yolks, mushrooms and fortified foods (fat spreads and breakfast cereals). 

Protein

It is a well known fact that protein plays an important physiological role in muscle growth and maintenance. However, having a large amount of dietary protein may not necessarily contribute to optimal muscle growth. This depends of factors such as:

• Total Daily Protein: This is also known as the total amount of protein consumed in a day. Elder adults are more prone to anabolic resistance, which is when they do not respond to stimuli that promote muscle growth. Therefore, as previously mentioned, elder adults need to have a protein intake of approximately 1 gram per kilogram of body weight per day, which is much higher than the daily recommended dose.⁵ Studies had further shown that ≥1.0 g/kg/day of protein had decreased functional disability (inability to perform daily tasks) by 22%¹⁴

• Per-Meal Dose Protein: This is also known as the total amount of protein consumed in a meal. There is a common misconception that consuming above the recommended intake of dietary protein would mean more muscle growth. However, this isn’t the case, there is only a certain amount of protein that can be absorbed per meal, also known as a “threshold”. Surveys have indicated that adults over 65 years do not meet this threshold, and consume a very small amount (~0.4 g/meal), and only as two servings of protein in the day.¹⁸ It is recommended that elderly adults need to consume approximately 35 g/meal, translatable to 1.2 g/kg/day¹⁹

• Protein Distribution: This is also known as the way the amount of protein consumed is distributed throughout the meals of the day. Studies have shown that older adults often skewed their protein intake towards one meal, with dinner-time meals containing the most amount of protein.²⁰ Interestingly, studies have further shown that even though adults consumed a daily protein intake of approximately 1.2 g/kg/day, the rate at which the protein was absorbed for muscle development was much better (approximately 25% more) when intake was evenly distributed at meals during the day,  as opposed to one meal with a large portion of protein²¹ 

• Protein Quality: This is also known as the source or quality of protein ingested. Protein requires essential amino acids as they are important in building muscles. Animal-derived proteins such as dairy, eggs, and meat, are better protein sources when compared to most plant-derived proteins such as soy and wheat due to their high essential amino acid content.²² Particularly with animal-derived proteins, the quality of the protein plays a vital role. For example, hydrolyzed collagen protein when compared to whey protein, is a lower quality protein due to its lack of the essential amino acid, tryptophan²²

Similarly, some plant proteins naturally have a lower essential amino acid content. Furthermore, they have higher amounts of anti-nutritional factors, which impair protein digestibility.²³ When consuming vegan diets, it is important to incorporate high quality proteins such as potato protein isolate, which is known to have the highest leucine content of most commercially available plant-based proteins.²⁴

Omega 3

Omega-3 polyunsaturated fatty acids (n3-PUFA), are also known as fish oils. Although their role in reducing the effects of sarcopenia are not studied enough, they have many beneficial anti-inflammatory properties.²⁵ They play critical roles in building the structural components of cell membranes, and further aid in building skeletal muscle.²⁶ Studies have shown that some components of fish oil, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) can sensitise muscles to growth signals, thereby increasing muscle mass.²⁷ 

Others

Leucine is another type of essential amino acid that has been shown to play roles in protein synthesis and thereby increase muscle growth.²⁸ Leucine can be found in BCAA supplements, but can alternatively be incorporated in diet by consuming foods such as salmon, chickpeas, brown rice, eggs, soybeans, nuts, and beef.²⁹ 

Creatine predominantly exists in 95% of the body’s skeletal muscle.³⁰ It is used as an energy source during muscle movement. Studies have further shown that when adults had participated in resistance exercise, supplementing creatine into their diet increased strength and lean muscle mass.³¹ Since the muscles cannot synthesise creatinine themselves, it has to be obtained as a dietary supplement.

Other amino acids such as carnitine and glutamine have been shown to promote the growth of muscle mass.^32,33 Dietary sources of carnitine include beef, pork, whole milk, cod, chicken, and avocado.³⁴  Dietary sources of glutamine include chicken, fish, cabbage, spinach, dairy, tofu, lentils, beans, beets, and peas. However, they are both available as dietary supplements.

Summary

Skeletal muscle mass plays an important role in maintaining physical functionality and health. However, age-related muscle mass is inevitable due to its nature of being genetically acquired. Progression of sarcopenia can be slowed down by having a healthy diet and exercise regime. Since treating sarcopenia can be a difficult task, it is more feasible to slow down this muscle loss through prevention.