Aminosyror och muskler
Kroppens proteiner är uppbyggda av aminosyror. När vi äter proteiner bryts dessa ner till aminosyror som sedan används av kroppen för ett återigen bygga upp proteiner som används i muskler och annan vävnad.
I den här artikeln redogör dr Mic McMullen för hur aminosyror kan användas för att optimera muskeltillväxt, vilket är viktigt för idrottare men kanske i ännu högre grad för äldre personer som vill behålla sin hälsa.
Sammanfattning, nedanför finns hela artikeln och referenser på engelska.
- MBAA (muscle building amino acids, muskelbyggande aminosyror) i ett specifikt förhållande, antingen som vasslepulver eller en blandning av individuella aminosyror, ökar mTORC1 (mammalian target of rapamycin complex 1, ett multiproteinkomplex som fungerar som en cellulär energisensor och regulator av proteinsyntes för celltillväxt och -proliferation). och aktiverar MPS (muscle protein synthesis, muskelproteinsyntes) som ökar muskelmassan, som består av aminosyror.
- MPB (muscle protein breakdown, muskelproteinnedbrytning): under den postabsorptiva fasen bryts muskeln ner för att för 1000-tals funktioner i kroppen ska få tillgång till aminosyror, och för att tillhandahålla energisubstratet glutamin och leverglukoneogenesprekursorer som används för att producera blodsocker.
- All träning, inklusive styrketräning, ökar MPB och minskar muskelmassan.
- Motståndsträning ökar mTORC1 som aktiverar MPS och bygger muskler när det finns MBAA tillgängligt..
- Kompletterande MBAA aktiverar MPS på ett dosrelaterat sätt även utan motståndsövning.
- Alternerandet mellan MPB och MPS leder till muskelproteinomsättning. Detta reparerar och förnyar muskelfibrerna, vilket resulterar i ökad kontraktionseffektivitet i muskelfibrerna, vilket återspeglas i ökad styrka, oberoende av muskelmassa.
- Proteinbehovet i kosten är större för äldre än för unga vuxna.
- Vuxna över 40 år behöver anpassa sin kost för att kompensera för anabol resistens av MBAA.
- Matsmältningen är långsammare hos äldre men upptaget från isolerade aminosyror, som används i MBAA-tillskott, påverkas inte av åldrandet.
- För att aktivera MPS behöver äldre vuxna mer leucin i sin MBAA-blandning än unga vuxna (20-40 år).
- För äldre ger träning före intag av MBAA postprandial MPS av liknande omfattning som hos unga vuxna.
- MPB ökar vid sjukdom vilket resulterar i minskad muskelmassa som leder till ökad sjuklighet och dödlighet.
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Dosering och tips
- MBAA absorberas bäst när det tas på fastande mage, vanligtvis före frukost.
- MBAA tas bäst i pulverform med en 10 ml skopa (≈ 6,5–7 g).
- MBAA är inte vattenlösliga men kan blandas med 1–2 dl yoghurt eller färska/frysta bär.
- MBAA-dosen är i allmänhet 2 skopor/dag men fördubblas för de som är intensivt fysiskt aktiva.
- 2 skopor varannan dag är bättre än 1 skopa varje dag
- Professionella idrottare kan ta 4 skopor/dag, 2 före frukost och 2 efter aktivitet.
- MBAA kan kombineras med glutamin för att minska MPB under aktivitet med 1 – 6 skopor per dag
- Under läkning kan man kombinera aminosyrorna med 2-4 skopor glutamin och 1 skopa glycin dagligen.
- För att uppnå optimala effekter på muskelmassa och styrka hos äldre vuxna, särskilt de som är överviktiga, rekommenderas proteintillskott i kombination med styrketräning, med en användning av minst 24 veckor för att öka muskelmassan.
- MBAA luktar svavel på grund av närvaron av metionin.
- Börja idag
Vill du veta mer om aminosyror rekommenderas kursen Aminosyraterapi som leds av dr Mic McMullen.
S2.2 MUSCLE BUILDING AMINO ACIDS
BCAA – branch chain amino acids
CVD – cardiovascular disease
EAA – essential amino acids
MBAA – muscle building amino acids
MPB – muscle protein breakdown
MPS – muscle protein synthesis
mTORC1 -mammalian target of rapamycin complex 1
NEAA – non-essential amino acids
PRI – population reference intake
RDA – recommended dietary allowance
- MBAA in a specific ratio, either as whey powder or a blending of individual amino acids, increases mTORC1 and activates MPS which increases muscle mass, a reservoir of amino acids.
- MPB: in the postabsorptive period muscle is broken down to provide amino acids for 1000s of body functions, such as providing the energy substrate glutamine and hepatic gluconeogenesis precursors that are used to produce blood glucose.
- All exercise, including resistance training, increases MPB and reduces muscle mass.
- Resistance training increases mTORC1 which activates MPS and builds muscle when MBAA are present.
- Supplementary MBAA activates MPS in a dose related manner even in the absence of resistance exercise.
- The alternating periods of MPB and MPS lead to muscle protein turnover. This repairs and renews the muscle fibres, resulting in increased efficiency of contraction at the single fibre level, which is reflected in increased strength, independent of muscle mass.
- Dietary protein requirements are greater for the elderly than young adults.
- Adults over 40 years need to adjust their diet to compensate for MBAA anabolic resistance.
- Digestion of food is slower in the elderly but the uptake from isolated amino acids, as used in MBAA supplements, is not affected by aging.
- To activate MPS elderly adults require more leucine with their MBAA blend than young adults 20-40 years old.
- For the elderly, exercise prior to MBAA ingestion, produces postprandial MPS of similar magnitude to that of young adults.
- MPB increases with illness resulting in a reduced muscle mass leading to increased morbidity and mortality
S2.2.1 Muscle protein synthesis (MPS) and muscle protein breakdown (MPB)
Muscles are made of protein and muscle protein is directly affected by protein intake in the diet. The amino acids absorbed following the digestion of protein promotes MPS in a dose-dependent manner. This metabolic response is reflected physiologically. For example, children given high protein intakes grow faster and have greater muscle mass. [1, 2] The anabolic effect of exercise is amplified by the intake of MBAA or protein rich food.
The MBAA are a group of amino acids that are the building blocks of muscle tissue. The MBAA group contains all the EAA except tryptophan. It includes the three BCAA, leucine, isoleucine and valine, plus histidine, lysine, methionine, phenylalanine and threonine.
During the digestion of food, the macronutrients carbohydrates and protein are broken down to molecules, glucose and amino acids respectively. Approximately 1/3 of the glucose is stored by the liver as glucagon, similarly 1/3 of the glucose is stored by the skeletal muscles as glucagon while the remainder is distributed in tissues using glucose for fuel. Like glucose, the MBAA are stored by skeletal muscle during the anabolic period, MPS, providing a reservoir that later can be utilised during the catabolic period, MPB. The net balance between these 2 processes determines whether muscle mass increases (positive protein balance), decreases (negative protein balance), or remains constant.
Muscle plays a central role in whole-body protein metabolism by serving as the principal reservoir for amino acids to maintain protein synthesis in all vital tissues and organs. In the absence of amino acid absorption from the gut, muscles provide hepatic gluconeogenic precursors. Furthermore, MPB plays a key role in proteogenesis and therefore the prevention of many common pathologic conditions and chronic diseases. The MBAA in the skeletal muscle play a central role in energy production in the muscles. Additionally, during the postabsorptive period the MBAA are metabolised to produce both the energy substrate glutamine and to provide the hepatic gluconeogenic precursors used to produce blood glucose. If protein levels in meals are not sufficient to stimulate MPS, then MPB continues till the next meal that has sufficient protein to stimulate MPS. The next meal may be in 3 or 4 hours or 3 or 4 weeks.
In healthy individuals between the ages of 20 and into their late 30s or early 40s, MPS usually equals MPB and muscle mass does not change. However, with resistance exercising such as weightlifting and cycling, MPS predominates, and an increase of muscle mass occurs termed muscle hypertrophy. On the hand, when MPB predominates, a decrease in muscle mass occurs, termed muscle atrophy. Muscle atrophy is accelerated during periods of immobilization, as when limbs are fractured, and more generally in the aging process. In extreme cases it is referred as sarcopenia.
To put it bluntly, with aging and catabolic pathologies, when there is a negatively imbalanced protein turnover, skeletal muscle proteins are often irreversibly lost. While muscle protein loss can occur as a result of increased MPB or reduced MPS (or by some combination of the two), it is believed that a desensitization of MPS to normal anabolic stimuli, such as feeding and exercise, may be the principal cause underpinning the age and disease-related decline in muscle quantity or quality. This desensitization of MPS with aging is referred to as anabolic resistance.
It is important to understand that only the MBAA are required for MPS and to produce muscular hypertrophy. The NEAA and tryptophan are not required for MPS, rather, if present, they may be integrated individually into other tissues or metabolised for energy or synthesised to either fat or urea. For MPS all MBAA must be present in a specific ratio, consequently MPS is limited by the lowest level of any of the MBAA. For example, lysine is relatively low in rice which limits MPS, any unused MBAA are treated as NEAA, typically being metabolised for energy or synthesised to fat or urea. Foods with a balanced MBAA ratio are referred to as complete proteins. This includes animal muscle, milk, egg and soja beans. Grains and pulses are incomplete proteins and are low in lysine or sulphur amino acids, respectively.
The anabolic muscle phase starts 30-60 minutes into postprandial period after the completion of a protein rich meal. It is characterised by MPS and depending on meal size etc. may continue for 4 – 5 hours. Once the extraction process of the MBAA from the plasma is complete (MPS), the catabolic phase starts (MPB). Basal MPB provides amino acids for hundreds of activities in parts of the body, for example BCAA from the muscles are converted into glutamine. The catabolic phase with a basal MPB continues till the next protein meal. During the MPS phase there is also a degree of MPB as glutamine is produced to maintain glutamine plasma levels.
The alternating periods of MPB and MPS lead to muscle protein turnover. This repairs and renews the muscle fibres causing increased efficiency of contraction at the single fibre level, which is reflected in increased strength, independent of muscle mass.
The signal to start MPS comes from the protein complex mTORC1. Production of mTORC1 is stimulated by both resistance exercise and the of presence of adequate amounts MBAA in the plasma, particularly leucine. Resistance exercise raises plasma mTORC1 but for MPS to occur the building material, the MBAA must be available. On the hand, just the presence in the plasma of MBAA derived either from food or supplementation, raises mTORC1 and provides the MBAA allowing MPS to proceed. The higher the level of MBAA in plasma, the greater the level of mTORC1 and subsequently the greater the magnitude of MPS.
Exercise, both resistance and endurance, increases MPB above the basal level, causing a net loss of muscle protein. However, resistance exercise also increases mTORC1, which leads to increased MPS when MBAA are present. When MBAA are ingested following resistance exercise there is a synergistic effect resulting in a greater increase in MPS than either stimulus would induce and completely abolishing the increase in MPB. Over time this leads to muscle hypertrophy and gains in lean body mass and strength for both younger and older adults. While it thought that there may be an anabolic window for protein intake, within 60 minutes before or after training, total daily intake of protein is also important. The exercise-induced increase in anabolic sensitivity to dietary MBAAs has been shown to be sustained for up to 24 hours after exercise. Without adequate intake of MBA, whether via food or supplements, exercise leads to a decrease of muscle mass due to MPB.
Although tryptophan is an EEA it is not found in muscle tissue, so it is not a MBAA. Yet, tryptophan may play a role in muscle growth as it has been noted that children with greater levels of tryptophan develop to be taller than those with lower levels of tryptophan. Moreover, deficiencies of tryptophan in young children’s diet, leads to stunted growth.[1, 9]
S2.2.2 Sources of MBAA
There are various ways to provide MBAA:
- food with high levels of EEA;
- food extracts such as whey, soy, rice or hemp powder; or
- blends of pure synthetically produced MBAA.
The food approach avoids the use of supplements but provides a large amount of energy that may not always be an advantage or practical. A meat-based meal will provide a similar amount of MBAA and NEAA, and some fat. Furthermore, the meal must be palatable and so may include sauces, fats fruits and vegetables. So, a large volume of non-MBAA food needs to be ingested to supply the MBAA, with 60 – 90% of the energy in food coming from something other than MBAA. In addition, the food must be accessible, either prepared or purchased by the consumer. A further complication is that protein induces satiety, more than either carbohydrates or fats, and increasing protein intake via food may mean eating meals when there is no appetite, essentially “forced feeding”.
The simplest supplement approach is to use blends of synthetic MBAA. Synthetic refers to a production method which is typically quite natural, the fermentation of either rice or corn with specially developed bacteria. So, it is not much different to the production of yoghurt. Producing each MBAA separately allows for the content of each of the eight MBAA to be independently manipulated to produce an optimal combination. It is also devoid of the additional 12 amino acids, fibre, carbohydrates and lipids that prolong digestion and slow the uptake of the MBAA, which reduces the MBAA plasma peak resulting in reduced levels of mTORC1.
Protein powders are food extracts from foods containing medium to high levels of protein. To produce the extract varying amounts of carbohydrates, fats, fibre etc. need to be removed. Importantly, although the amino acid level is increased as % volume, the amino acid profile of the original material remains. Consequently, animal derived protein powders have relatively balanced MBAA profile whereas protein powders derived from grains and pulses are relatively deficient in either lysine or methionine respectively. Additionally, plant-based protein powders have low levels of leucine.
Milk has protein profile designed to produce rapid growth in a calf. Milk contains two types of proteins, casein and whey. During cheese making the casein and whey proteins separate into cheese, the casein proteins, and whey, the whey proteins left in the fluid after milk curdling. Until recently, when powdered whey became a popular nutritional supplement, whey was deemed a waste by the dairy industry.
Although whey and casein are both derived from milk, their proteins have different effects. Casein proteins prolong digestion by coagulating in the stomach, whereas whey proteins pass through the stomach quickly. After whey protein ingestion, the plasma appearance of dietary amino acids is fast, high, and transient. This amino acid pattern is associated with an increased MPS and oxidation but no change in MPB. By contrast, the plasma appearance of dietary amino acids after casein ingestion is slower, lower, and prolonged with a different whole body metabolic response: MPS slightly increases, oxidation is moderately stimulated, but MPB is markedly inhibited. Due to their digestive characteristics whey and casein are referred to as fast and slow proteins respectively.
An alternative form of casein is produced by combining calcium hydroxide and fresh skimmed milk to produce calcium caseinate. Calcium caseinate is much more soluble than micellar casein and does not clot in the stomach. As sports supplements, casein and calcium caseinate are designed to be consumed before bed, in order to provide a more sustained release of amino acids. Whey, casein and calcium caseinate all contain approximately 40% MBAA.[4, 13]
In some areas there is a trend towards a more plant-based diet which entails a reduction in animal protein. There are substantial differences between animal and plant protein:
- differences in amounts of MBAA.
- differences in composition of MBAA.
As food, plant protein, apart from soya protein, contains only 60 – 80 % of the volume of MBAA found in meat or whey. The availability of MBAA is further reduced as plant proteins are often low in one of the MBAA. Additionally, plants proteins are poorly absorbed compared to animal proteins. Protein from chicken, egg and egg white have an absorption of 85-95% whereas protein from chickpeas, mung beans and yellow peas have an absorption of 50 – 75%. However, after anti-nutritional factors, such as fibre and tannins, are removed during the production of plant protein powders absorption rates are comparable with animal protein.
Whey powder is widely recognised as being superior to other protein powders, both animal-based and plant-based, as a supplement because it contains all the MBAA in a balanced ratio and with adequate leucine. Hence, it has become the reference to which other protein powders can be compared. A serving of 25 g whey contains 2.7 g leucine and 10.9 g EAA. In contrast, 25 g of rice protein powder contains 0.8 g leucine and 7.5 g EEA and green pea protein powder 1.8 g leucine and 7.5 EAA. The amount of various protein powders necessary to match whey protein are listed in table below.
Table. S2.2.1 Representative amount of protein powder to match required leucine and Total EAA
|Protein powder||Amount of protein (g)||Amount of powder (g)|
The table indicates that compared to whey, much larger amounts of plant-based protein powders are required to produce MPS. For example, 3.3 measures of hemp powder is the equivalent of 1 measure of whey. The amino acids not used for MPS may be integrated individually into other tissues or metabolised for energy or synthesised to either fat or urea. Moreover, while a green vegan pea may be attractive image, the processing procedures utilised to produce plant-based protein powders free of fibre and tannins may not be so attractive, even if vegan. Today synthetically produced amino acids are usually vegan, with the starting material being either rice or corn, but prior to 2000 many were produced from human hair (!!) or duck feathers. If in doubt, read the label or contact the supplier.
Strategies to augment the anabolic properties on plant-based protein powders
- consumption of greater amounts of plant-based protein sources;
- combining multiple protein sources to provide a more balanced amino acid profile;
- fortification of plant-based protein sources with the amino acids methionine, lysine, and/or leucine;
- selective breeding of plant sources to improve amino acid profiles.
S2.2.3 MBAA for sport and exercise
A single exercise session increases MPS rates and to a lesser extent MPB rates however, net muscle protein balance only becomes positive when exogenous amino acids are provided. Ingestion of dietary protein increases MPS rates at rest as well as increasing MPS muscle protein synthesis rates during recovery from exercise. The MPS response is influenced by
- the amount of protein,
- the digestion and absorption kinetics,
- the amino acid composition of a protein
The MPS response to feeding is largely dependent on the post-prandial rise in plasma MBAA concentrations, with plasma leucine concentrations being of particular importance. Most research have focused on assessing the post-prandial MPS response to dairy protein and meat ingestion. There is a fundamental difference in MPS response between adults under 40 years and over 40 years. This will be covered in the next section, S2.2.4.
Muscle protein turnover is vitally important for sport and exercise. The alternating periods of MPB and MPS leads to muscle protein turnover. This repairs and renews the muscle fibres, resulting in increased efficiency of contraction at the single fibre level, which is reflected in increased strength, independent of muscle mass.
Supplements of leucine or all three BCAA are popular amongst amino acid users in sport and exercise. The initial research in the 1980s involved infusions of BCAA with rats and increases in MPS were reported. However, the results were not repeatable for dietary supplementation with humans. A recent review concluded that the claim consumption of dietary BCAAs stimulates muscle protein synthesis or produces an anabolic response in human subjects is unwarranted. Furthermore, the intake of only leucine may lead to oxidation of all three BCAA and thus reduce plasma levels of isoleucine and valine. This leads to a decreased MPS and an increased MPB as an attempt is made to adjust the ratio of MBAA in the plasma. On the hand when BCAAs (5 g) is combined with whey powder it produces much larger increases in MPS than whey alone. To gain a significant benefit from leucine either BCAA, the other MBAA must be present in physiologically proven ratio.
In health the consumption of protein or amino acids stimulates an increase of MPS in a dose-response manner. This is the body’s method of storing amino acids as well as producing muscle hypertrophy. Excess dietary amino acids and those not utilised by MPS are catabolized. The plateau of this dose-response curve, per meal, has been shown to occur at 0.25 g/kg protein in healthy young adults. 
Daily intake will depend on the extent of physical activity. A simple recommended dosage of plant-based proteins is difficult because there is wide variation in their MBAA levels and even in the protein concentration of an extract. For example, hemp protein powder is produced at protein levels of 50% and 75%. For those keen on plant-based protein it is worth remembering that just like plant-based diets, plant-based protein powders have a relatively low nutritional density and a disproportionate load of ‘empty calories’ made up of carbohydrates and fats.
Table S2.2.3. Dosage of MBAA and whey for sports and excerise
|Protein powder||Occasional||Regular||Intense and professional|
|MBAA||2 scoops* every other day||2 scoops everyday||2 scoops twice daily|
|Whey||– 40 g every other day||30 – 40 g everyday||30 – 40 g twice daily|
*scoop size 10 ml = 6.5 – 7.0 g
Research in the 2020s indicate that women who engage in resistance exercise and consume sport supplements have higher percentages of skeletal muscle and lower percentages of body fat than women who did not take supplements.
S2.2.4 MBAA for 40+
Skeletal muscle mass is an integral body tissue playing key roles in strength and performance (both in sport and the activities of daily living). As we grow there is a corresponding increase in skeletal muscle mass; but once growth is complete there is usually no net increase in muscle mass. Then, starting as early as the 4th decade of life, anabolic resistance starts and skeletal muscle mass naturally starts to decline at a rate of approximately 0.8% per year, a process termed sarcopenia.
In essence, sarcopenia is defined as a reduction in muscle mass, strength and function, and is prevalent in older adults. Sarcopenia, as a consequence of malnutrition or anabolic resistance, is characterized by weight loss with concomitant muscular atrophy and increases in both basal energy expenditure and protein catabolism. Moreover, sarcopenia will reduce food intake, quality of life and raise morbidity and mortality rates. Sarcopenia has been variously estimated to occur in
- 30% of individuals over the age of 60  or
- 5–13% in the age group 60 – 70 and increasing to 11–50% in the over 80s.
Sarcopenia also underpins frailty and the decline in functional capacity that compromises quality of life, and is associated with a range of clinical disorders, such as osteoporosis and obesity. Although the aetiology of sarcopenia is clearly multifactorial and not fully understood, key underlying factors include morphological changes in skeletal muscle, the loss of motor units, physical inactivity as well as dietary protein and energy deficiencies.
Aging is associated with a progressive and general loss of skeletal muscle mass and muscle strength. The loss of muscle mass is estimated at approximately 35% – 40% between the ages of 20 and 80 years. The difference in muscle strength between young persons and healthy elderly persons ages 60 to 80 years is in the range of 20% – 40%, and this difference increases to more than 50% when compared with those older than 80 years. After the age of 60, the muscle mass decreases at a rate of 3% per year, while the grip strength and gait speed decrease at a rate of 1.9 – 5.0% and 2.0 – 2.3% per year, respectively.
Age-associated anabolic resistance is associated with an impaired postprandial release of dietary amino acids into the circulation and a reduced responsiveness of MPS. It is estimated that amino acid digestive uptake from food is reduced by about 10% in the elderly  Following a meal the peak levels of dietary plasma EAA were delayed from 1 hour to 3 hours for the elderly (60 – 75 years) compared a group of young adults (20 – 25 years). In contrast, uptake from isolated amino acids, as used in MBAA supplements, appears not to be affected by aging.
It should be recognised that there is a wide interindividual variation in the peak muscle mass and strength achieved during the life prior to the 4th decade and this will influence the rate of decline of muscle mass and strength in adult and older life. This explains the differences in the remaining amount of muscle mass and muscle strength between older individuals. However at some point the threshold of low muscle mass and strength will be reached predisposing elderly persons to physical disability, mobility limitations, falls, institutionalization, and death.
Given the instrumental role of muscle in locomotion, force production, glucose disposal and metabolic regulation, the loss, or low levels, of muscle mass increases the risk of chronic diseases. Because skeletal muscle also acts as the primary site for insulin-stimulated glucose uptake, muscle atrophy causes dysregulation of muscle function and contributes to the development of metabolic syndrome, type II diabetes and increased risk of CVD, as well as falls and reduced ability to perform activities of daily living, all of which decreases the quality of life. As such, optimizing muscle mass across the lifespan for optimal performance and overall health is of utmost importance. Fortunately, it has now been established that this loss of muscle mass during energy deficit and with aging can be attenuated by the consumption of a higher-protein diet. [4, 10]
Protein requirements for older adults are likely higher than the current RDA in the United States or PRI from the European Union, of 0.8 g/kg/d and will be closer to 1.2 g/kg/d (or higher), an increase of 50% or more. Additionally, reports indicate that the daily dietary leucine requirement for older adults is 78.5 mg/kg, which is more than double the RDA of 34 mg/kg.
Yet outside of clinical trials and on the home front, the implementation of a high protein diet for the elderly (and their carers) is challenging. Firstly, a change of eating habits is an obvious option, but this involves the reduction of carbohydrates, such as bread, pasta, rice, potatoes, and increasing animal and possibly plant proteins. Changing diet is difficult without sufficient motivation and perhaps completely impossible for the institutionalized elderly. Secondly, as protein is the most satiating of all macronutrients and many elderly have under functioning digestive systems, the increase in protein may lead to a decreased appetite or desire to eat. It is imperative that interventions targeted at increasing total dietary protein intake do not decrease energy intake and increase sarcopenia.
MBAA supplements can be used to avoid these problems, but supplements need to be reformulated to suit the elderly, particularly in respect to leucine. While a supplement of 6.7 g of MBAA, with the amino acids in the same ratio as in whey powder, increased MPB in young adults (≈30 years old), it failed to increase MPS in an elderly group (≈67 years old). Yet after the supplement was reformulated, increasing the leucine content from 26% to 41%, MPS occurred in both groups. The initial supplement provided 1.7 g leucine and the reformulated supplement 2.7 g leucine.  Similarly, in a group of 70 years old men, the addition of leucine (52 mg/kg; 70 kg = 3.6 g) to casein powder (0.4 g/kg; 70 kg = 28 g) markedly increased leucine plasma levels between 60 and 300 minutes post ingestion and increased MPS. Yet leucine on its own is not enough, a recent metanalysis concluded that supplementation with only leucine (≥ 5 g), but without supplementary protein or MBAA, had no effect on lean muscle mass.
When a group of healthy elderly (≈ 70 years), who did not exercise and had a history of falls, were given either 18 g MBAA or 18 g MBAA + 22 g NEAA, both products contained 3.2 g leucine. Results were the same for both groups, MPS increased while MPB was unchanged. These findings demonstrate that
- the ingestion of MBAA, with a high level of leucine, can increase MPS without the need of exercise in the elderly; and
- that NEAA are not necessary for MPS to occur.
Nevertheless, when possible better results will be achieved combining resistance exercise with MBAA supplementation. Timing is important and for the elderly, exercise prior to the ingestion of supplements results in postprandial MPS of similar magnitude to that of young adults.
When considering how to preserve, and possibly improve, the muscle mass in the 40+ group it is necessary to accept that the diet developed in the early adult years, prior to 40, needs to be modified as the body processes have changed. In the later stages of life, we need to increase our protein intake. This may include moving from plant-based proteins to animal-based proteins. As far as supplements are concerned a 2000 – 5000 mg leucine is required to be included in the dose. This may be taken as capsules, usually 500 mg, or blended in powder. The latter is preferrable and much cheaper. Special blends of MBAA are available with high levels of leucine.
S2.2.5 IMMOBILISATION AND BED REST
There are times when exercise is not an option such as during immobilisation and bed rest. Different models of disuse (i.e. knee immobilization or bed rest for 10 to 28 d) have shown a down regulation of MPS. It appears that longer periods of disuse are associated with a progressive reduction in MPS, as a study in healthy elderly showed that the total mean nitrogen balance was significantly lower in the second half of a 10 d period of bed rest. Although disuse primarily affects MPS, there is also a reduction in MPB, indicating that fewer amino acids are available for the body’s processes and leading to a general slowing of metabolic activity.
Without use muscle strength and function is lost and muscle atrophy becomes an issue that is central to the recovery process. The extent and duration of the debilitation resulting from critical illness is dramatic. One report noted <50% of individuals employed before entering an intensive care unit return to work in the first year after discharge. Extensive losses of muscle mass, strength, and function during acute hospitalization causing sustained physical impairment were likely contributors to the prolonged recovery. If there is a pre-existing deficiency of muscle mass before trauma, the acute loss of muscle mass and function may push an individual over a threshold that makes recovery of normal function unlikely to ever occur. For example, in 1997 it was reported that <50% of women older than 65 years who break a hip in a fall never walk again.
In the last 25 years the problem of protein deficiencies, in elderly populations, has not gone away. Markers of malnutrition such as low albumin (a protein derived from MBAA) and low body mass index (BMI) increase mortality and complication rates in illness. Recently it was reported that low albumin (≤35 g/L) is prevalent in elderly hip fracture patients and is associated with slower recovery of function and quality of life after surgery. In other recent studies it has been reported that
- 20 – 50% of patients do not regain their pre-fracture mobility after hip fracture;
- 42% of elderly hip fracture patients could not regain pre-fracture mobility, and 35% could not walk unaided after the fracture;
- only 57% of the patients returned to their pre-fracture functional state and 13% became immobile in the first year after fracture;
- 34% of patients had a long-term deterioration in their daily activities after a fracture;
- 20% of patients were immobilized after hip fracture surgery.
AS stated previously, the alternating periods of MPB and MPS lead to muscle protein turnover. This repairs and renews the muscle fibres and results in increased efficiency of contraction at the single fibre level, which is reflected in increased strength, independent of muscle mass. Fortunately it is possible to stimulate MPS by the use of MBAA even in the absence of physical activity. When a group of healthy elderly (≈ 70 years) who did not exercise and had a history of falls received 18 g MBAA, MPS increased without changing MPB. This study clearly demonstrates that the ingestion of MBAA can increase MPS without the need of exercise.
Due to the serious risk to long term health caused by immobilisation and bedrest, the use of a MBAA supplementation is preferrable to either dietary changes or whey protein + leucine at least in the shortrun.
Dosage is 2 scoops before breakfast and perhaps an additional 2 scoops in the late afternoon.
Illness, such as sepsis, advanced cancer, and traumatic injury, imposes greater demands for amino acids from MPS. Physiologic responses necessary for recovery may include the accelerated synthesis of acute phase proteins in the liver, synthesis of proteins involved in immune function, and synthesis of proteins involved in wound healing. The demands for precursor amino acids for the synthesis of these proteins are significant. It is estimated that for wound healing a daily protein intake of 3 g/kg (= 210 g/70kg) is required to provide the necessary precursors for the synthesis of proteins required for normal healing of a burn injury to 50% of the body.
Loss of muscle mass is also known to be detrimental to survival from cancer. For example, in patients with lung cancer receiving radiation therapy, the amount of body protein predicted recurrence. In those in whom body protein decreased, recurrence and, ultimately, survival was worse than in patients who were able to maintain or increase muscle mass.
It is recognized that cancer patients are more vulnerable to malnutrition, due to tumour growth, with the activation of systemic inflammation via cancer-induced cachexia (weakness, wasting and loss of lean tissue). Cancer-induced cachexia is similar but distinctly different from sarcopenia and higher in elderly patients than in their younger counterparts depending on the type, location and/or stage of cancer. Tumor cells and activated immunologic cells release inflammatory mediators that are directly involved in the cancer cachexia-anorexia syndrome leading to weight loss and muscle mass atrophy
A study in 2022 showed a strong correlation between muscle strength and mobility and brain volume, including in the hippocampus that underlies memory function, in adults with Alzheimer’s disease. Investigators found statistically significant relationships between better handgrip strength and mobility and hippocampal and lobar brain volumes in 38 cognitively impaired adults with biomarker evidence of Alzheimer’s disease. ”The implication is that muscular strength and mobility influence brain health and can potentially be modified to improve outcomes in persons with Alzheimer’s.
S2.2.7 DOSAGE & TIPS
- MBAA are best absorbed when taken on an empty stomach, generally before breakfast.
- MBAA are best taken in powder form with a 10 ml scoop (≈ 6.5 – 7 g).
- MBAA are not water soluble but can be mixed with 1 – 2 dl of yoghurt or fresh/frozen berries.
- MBAA dosage is generally 2 scoops/day but doubles for the intensely physically active.
- 2 scoops/day every 2nd day is better than 1 scoop every day
- Professional sports people can take 4 scoops/day, 2 before breakfast and 2 after activity.
- MBAA can be combined with glutamine to reduce MPB during activity at 1 – 6 scoops per day
- In cases where healing is ongoing combine with 2-4 scoops glutamine and 1 scoop glycine daily.
- To achieve optimal effects on muscle mass and strength in older adults, particularly those who are obese, protein supplementation is recommended in combination with resistance training, with a usage of a minimum duration of 24 weeks to increase muscle mass.
- MBAA smell sulphur due to presence of methionine.
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