Hello again! Over the past few months I have been talking through the Australian Guide to Healthy Eating and how it applies to older adults. This month I’d like to talk about the role that proteins play in supporting healthy bodies. One of the five food groups is listed as “Lean meats and poultry, fish, eggs, tofu, nuts and seeds and legumes/beans”. Whew, what a mouthful! The easiest way to categorise these are as protein rich foods. Whether you are an omnivore who eats meat, a pescatarian who eats seafood, an ovo-lacto vegetarian who eats eggs and dairy or a vegan that avoids all animal products, this category contains essential sources of proteins.
Proteins can be broken down into smaller pieces called amino-acids; these pieces can be put together in multiple different ways to create different things, kind of like Lego™ pieces. Every muscle in our body is a collection of connected building blocks working together to move our bodies. When we are exposed to a virus or bacteria our immune system launches antibodies to protect the body; antibodies are made up of these building blocks. If we cut our skin the wound first clots to stop the bleeding (the clotting factor is a special protein) and then the wound closes itself with more building blocks. We literally cannot function without amino acids.
There are twenty different amino acids that humans need to function. Many of these amino acids our body can create from scratch however, nine of these are called “essential” amino acids which simply means we must consume these from foods and drinks as we cannot create them.
One of the common myths about protein is that the more we eat, the more muscle we build however, unlike fat and carbohydrates, we do not really have a method for storing excess protein. Eating large quantities of protein is not converted into muscle, in fact our bodies can only process about 30g of protein at any one meal, more than that is broken down and excreted in our urine.
Even though excess protein is not converted into muscle our muscles are a storage site of protein (not for protein), this is a very important distinction. If, for any reason, we do not consume enough protein and amino acids then our bodies will try and get them acids in any way possible. This includes breaking down our muscles. Consider the fact that our heart is one of our strongest muscles, this is definitely not a muscle that we want to weaken! Likewise, if we do not consume enough energy (calories) our bodies will not only break down fat stores, but muscle too. In fact, in older adults, weight loss almost inevitably results in muscle loss which has multiple implications.
So, what are good sources of protein in our diet?
Animal proteins such as red meat, chicken, fish and eggs are considered to be “complete” proteins because they contain all nine essential amino acids. The Australian Dietary Guidelines suggest that men aged 50+ consume 2 ½ serves of protein rich foods and women aged 50+ consume 2 serves of protein rich foods per day. A serve varies depending on what type of protein you are eating. Some foods are more protein dense than others (often because some foods contain less water or fibre). For example, red meat is quite compact muscle and a serve is 65g cooked whereas for chicken it is 80g cooked and fish is 100g cooked as the muscle is less compact.
All plants contain some protein because all cells, including plant cells, require proteins to function however some are much better sources than others. Also, in the same way that some plants are richer in certain vitamins than others, plants can contain varying amounts of those amino acid building blocks. For example, grains and rice are rich in an amino acid called Lysine but low in another one called Methionine, whereas beans are rich in Methionine but don’t contain as much Lysine. It is not necessary to combine these complimentary foods (e.g. rice and beans) into the one meal to ensure you are getting enough amino acids; as long as you eat from a broad range of plant proteins across the day you will get everything you need.
Plant based protein foods include legumes and beans such as chick peas, lentils, split peas, kidney beans etc. As these have more fibre and water than muscle, you need to consume more volume to obtain the same amount of protein therefore one serve equals one cup cooked or canned. Another excellent source of protein is tofu, which is made from soybeans and is among the few plant proteins that are considered “complete”. Once again, due to the higher water content, to receive a similar amount of protein you need to eat 170g. Lastly, nuts and seeds are also packed with protein and these can be valuable for anyone who has a small appetite or struggles to get in enough protein.
To give you an idea of what that might look like a Sunday breakfast including two eggs (12g), a glass of milk (8g), two slices of bread (4g) and half a cup of baked beans (7.5g) would provide 31.5g protein. This means that ideally, we should aim for eating some protein at every meal rather than sitting down to a big chunk of it at dinner time. It is also important to remember that eating protein isn’t all that is required to maintain muscle mass, we all benefit from regular weight bearing exercise (e.g. walking) to keep our muscles strong.
If you are a regular reader you will know I stress the importance of individualised nutrition, especially for older adults. For anyone who is experiencing a loss of appetite or unintentional weight loss, it is essential that you adopt strategies that ensure adequate protein (and energy) intake. An Accredited Practicing Dietitian can calculate your daily protein requirements based on your age, gender and health status and work with you to devise a personalised strategy that supports your health.