Posted by ProPortion Foods Blog on Sep 14, 2017 in Muscle, Protein
Protein in a nutshell, is a nitrogen-containing macronutrient made up of smaller individual chemical chains known as amino acids.
Dietary protein has many vital roles and functions in the body including the growth, repair and maintenance of our cells, bone, skin and tissue, which is particularly important as we age.
Protein is delivered to us from an array of animal and plant-based forms from all food groups. Examples include egg, chicken, beef, nuts, fish, tofu, legumes (such as chickpeas or kidney beans) and some cereal-based products. Despite this, it is important to recognise that not all dietary proteins (or supplements) are created equal.
Protein quality often trumps protein quantity regarding its overall impact on our health, as the prevalence of protein deficiency among the general population in Australia is quite rare. However, if present, the main symptoms of protein deficiency are sarcopenia (muscle atrophy or wastage), oedema (excess fluid build-up such as swelling of the feet or ankles) and anaemia [1].
As we get older our protein requirement increases, yet consumption often declines. This can be due to a lack of appetite, loss of taste or smell, a decline in interest in food or cooking, poor dentition or reduced mobility [2]. In such circumstances the quality of the protein and the food matrix in which it is consumed are very important considerations in the maintenance of an individual’s good health.
Protein quality can be simply defined by how well or how poorly a given protein can perform its metabolic function in the body. This is underpinned by the digestibility and quantitative supply of essential amino acids for providing proteins in the correct ratios for human consumption [3,4].
There are 20 ‘metabolically essential’ amino acids required for protein synthesis and for sustaining our body’s nitrogen equilibrium. However, only nine of these; histidine, leucine, isoleucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine, need to be obtained from the diet, otherwise known as ‘indispensable’ or essential amino acids (EAAs). The other amino acids are conditionally essential (especially in times of illness or stress) or non-essential because they can be self-synthesised in the body.
However, in order to sustain protein quality integrity, all essential amino acids must be present in the diet. Complete protein sources contain all EAAs and are therefore considered ‘high quality’, whereas ‘low quality’ protein sources are incomplete proteins as they do not contain all EAAs.
Examples of high quality protein sources include:
Examples of low quality protein sources include:
Therefore, for individuals to appropriately meet both their minimum and/or additional dietary protein requirements, it is recommended to consume high quality proteins or a combination of at least two or more low/insufficient protein sources to adequately attain all EAAs through the formation of complementary proteins. The American Dietetic Association in 2003 concluded that complementary proteins do not all need to be consumed during the same meal and can be spread throughout the day to meet protein needs while also ensuring adequate nitrogen retention [5].
It is also worth considering the many benefits of consuming enough high-quality protein sources to meet our needs. Eating meals containing high quality protein can help increase satiety levels more than carbohydrate or fat sources; this can assist in reducing overall energy consumption and the desire to consume extra snacks. Adopting a moderately higher protein diet can also help to maintain and grow lean muscle mass and reduce body fat [6].
There are a range of different methods currently used to determine protein quality.
The most common is referred to as the ‘Biological Value’ (BV) protein scoring system. BV expresses the body’s nitrogen utilisation as a percentage (nitrogen retention for tissue formation is divided by the nitrogen absorption from food).
The Protein Digestibility Corrected Amino Acid Score (PDCAAS) is an internationally standardised system which assesses protein quality via combining estimates of protein digestibility with an age-related amino acid profile pattern, also factoring in bodily protein excretion [6,7].
DIAAS, or the Digestible Indispensable Amino Acid Score, DIAAS uses a mathematic equation to calculate the “individual indispensable amino acids in the dietary protein relative to human reference amino acid requirement pattern” [8]. Dietary proteins are ranked according their score, to indicate dietary protein quality. This is beneficial when looking for foods with higher scores to complement less nutritious proteins.
Acquiring a deeper understanding of the importance of both protein and protein quality can lead to better food choices to support our physiological health and general wellbeing.
Posted by ProPortion Foods Blog on Sep 13, 2017 in Muscle, Protein, Sarcopenia
Age-related muscle loss is one of greatest health issues for older adults. Up to a third of people over 50 experience sarcopenia – the age-related loss of muscle mass and strength. This can lead to many other health complications. However, it can also be prevented and managed with just a few simple interventions.
Sufficient muscle mass is essential for health and wellbeing at any age. One of the key roles of muscle is utilisation of carbohydrates for energy production. More muscle mass means more is used for energy, instead of being stored as fat.
Muscle mass can protect against conditions such as diabetes, cardiovascular disease, premature ageing and poor cognitive function. Unfortunately, many older adults experience sarcopenia, which increases the risk of illness and injury.
When people are inactive for any reason, muscle can waste away. This is known as muscle atrophy or muscle loss.
One of the most common causes of muscle loss is ageing. There are multiple factors that cause age-related muscle loss. It’s believed that a reduction of testosterone and growth hormone combined with an increase in pro-inflammatory cytokines play a big role (1).
There are other causes of muscle loss aside from ageing. Significant injuries, malnutrition, stroke, long-term steroid use and general inactivity can all lead to atrophied muscles. Conditions that restrict movement can also contribute.
Unfortunately, muscle loss can have a significant impact on health and wellbeing.
Muscle loss can negatively impact on health in a number of ways. By losing muscle mass, people are likely to gain body fat instead. This is due to the reduced carbohydrate usage by the muscles, leading to more energy being stored as fat.
People may also experience stiffer joints with muscle loss. This will make it harder for them to move around, which contributes further to muscle loss and fat gain.
This may lead to other health conditions and complications, including cardiovascular disease, diabetes and arthritis. Many of these can become serious or even fatal if left untreated. It is essential to intervene in the early stages of muscle loss, to slow or even reverse the process.
It’s possible to halt and even reverse muscle loss through simple interventions. By using the right nutrition and exercise, muscles can grow and regain strength.
One of the most important interventions is to consume sufficient protein to meet dietary needs. Research suggests that eating similar quantities at each meal is more effective than a large intake in one meal (2).
Keeping physically active is essential for maintaining muscle mass. Even small, regular movement can help in those with limited movement. Research has demonstrated that even 15 minutes of cardiovascular exercise can stimulate muscle growth (3).
Ideally, resistance exercise is included so that muscle strength can be restored. One study demonstrated that just 3 resistance-training sessions per week for 12 weeks could increase muscle strength (4).
These interventions are inexpensive but highly effective in preventing and reversing age-related muscle loss.
Sarcopenia and muscle loss can cause many health issues. However, simple interventions such as nutrition and exercise provide a safe, easy and effective way to prevent and reverse muscle loss.
Posted by ProPortion Foods Blog on Sep 7, 2017 in Muscle, Protein
Did you know that the human body is comprised of about 16 per cent protein[1]? Proteins are complex molecules which are required for the structure, function, and regulation of the body’s tissues and organs[2].
The functions of protein in the human body are grouped into five categories[3]:
Long chains of amino acids are the building blocks of protein, which can be broken down into 2 categories.
Complete and incomplete proteins can be further examined and ranked by their quality. Protein quality is determined by either PDCAAS (protein digestibility-corrected amino acid score) or DIAAS (digestible indispensable amino acid score). Both of these scores were created by the Food and Agriculture Organization of United Nations (FAO), and it is their recommendation that DIAAS be used as the preferred method[4].
The DIAAS uses a mathematic equation to calculate the “individual indispensable amino acids in the dietary protein relative to human reference amino acid requirement pattern” [5]. Foods are then assigned a score, and ranked. Unlike DIAAS, PDCAAS truncates values to 1, so it isn’t able to account for minor variations like DIAAS[6].
How much is enough protein to consume?
EAR & RDI
The Australian and New Zealand governments created the Nutrient Reference Values based on currently available scientific knowledge[7]. The research body lists the EAR (estimated average requirement) and RDI (recommended dietary intake) for adults.
Even distribution & higher protein consumption
Recent research into the timing and consumption of protein suggests that even distribution throughout the day, with 25g-30g at each meal, can maximize muscle protein synthesis[8]. This amount of protein is significantly greater than the current RDI for women.
This study is of particular interest to older adults who are encouraged to consume considerably higher than the minimum protein requirements for optimal health[9]. The EAR and RDI do not “account for the compensatory loss of muscle mass”9 or lower rates of protein synthesis in older adults.
An increase in dietary protein for older adults has shown to increase lean mass gain, when combined with resistance exercise. 40 per cent of Australians in their 70s experienced a fall in the past 12 months[10]. An increase in lean muscle mass from dietary protein and resistance exercise has been found to reduce the incidence of falls among this cohort[11].
[1] https://www.britannica.com/science/human-nutrition
[2] https://ghr.nlm.nih.gov/primer/howgeneswork/protein
[3] http://www.livestrong.com/article/407936-what-are-the-functions-of-protein-in-the-human-body/
[4] http://www.ift.org/Food-Technology/Daily-News/2013/March/07/FAO-proposes-new-protein-quality-measurement.aspx
[5] http://www.fil-idf.org/wp-content/uploads/2016/03/IDF-Factsheet-Interpretation-of-Protein-Quality.pdf
[6] https://www.arlafoodsingredients.com/the-whey-and-protein-blog/research/determining-protein-quality-the-current-state-of-play/
[7] https://www.nrv.gov.au/
[8] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2760315/
[9] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4555150/
[10] http://www.racgp.org.au/afp/2012/december/falls-prevention/
[11] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3136106/