Protein 101 for Seniors
Protein is a highly complex substance present in all living organisms, although interestingly proteins are species-specific in that the proteins of one species differ from those of another species. They are also organ-specific in that muscle proteins differ from those of say the brain and liver.
Protein is composed of long chains of amino acids (I'm not going to go into the chemical make-up of proteins, get your school books out) with 21 amino acids common to all life forms. In humans, 13 of the amino acids can be manufactured by your body but 9 cannot be manufactured and are called the essential amino acids. They must be supplied through your diet.
Protein fulfils many roles in your body - as a structural component of cells and tissues, as a constituent of enzymes that aid the thousands of biochemical reactions in your body, as a constituent of hormones which are the chemical messengers that aid communication in your body, as a regulator of the concentrations of acids and bases in your blood and other bodily fluids, as a constituent of antibodies to fight infection, as a transporter of substances and nutrients around your body and as a supplier of energy. This list is not exhaustive, but you get the picture that they are pretty vital to maintaining your body and your life.
The optimal daily protein intake depends on many factors including your weight, your body composition, your age and your level of physical activity and it's intensity and can range from a recommendation of 1.2 g to 3.3 g of protein per kg of your weight. So, for me, at the bottom range that would be 83 (my weight in kg) * 1.2 g resulting in a need of 99.6g of protein per day.
Roughly, 1 egg has about 7g of protein, a chicken breast and a steak (of about 6oz) have about 54g of protein and a can of tuna has about 40g of protein. So, you can imagine that a balanced and nutritious diet should give you all the protein you need at that level.
However, certain demographics may benefit from higher protein intakes either through their diet or through a protein supplement. This would include highly active individuals, athletes and say bodybuilders and weightlifters. In addition, and my reason for writing this blog, there is accepted evidence that higher intake of protein is beneficial to older adults, of which I am one now (over 50!).
As you get older the prevalence of sarcopenia increases significantly. Sarcopenia is a muscle disorder that results in impaired physical function as well as muscle mass loss. It is the primary age-related cause of frailty. In the US over 40% of men and 60% of women over 50 have sarcopenia (see below).
On the bright-side, sarcopenia is neither inevitable nor is it irreversible. It is a challenge though, as the older you get the greater your muscles resist growth and then the greater the volume of protein and exercise volume required to stimulate muscle protein synthesis.
Several authorities now recommend that older adults consume 1.2-1.5 g/kg on a daily basis. It has been demonstrated that even a small increase in protein intake has benefits towards lean mass and overall body composition, thereby reducing the potential impact of sarcopenia. Indeed, for active seniors it is recommended to have a daily protein intake of up to 2.0g/kg.
I am pretty active, run a couple of times a week and do CrossFit 3 or 4 times per week. At that upper level, that would be a daily intake of 166g protein for me. I don't watch my macronutrient consumption that closely, maybe I should, but I don't believe I consume that amount of protein through my diet naturally and so I add additional protein to my diet through a plant-based protein supplement via a smoothie or shake during the day - usually after exercise. A couple of scoops adds about 50g of protein. If you do choose to supplement your protein choose a reputable source and ensure that it is providing a complete amino acid profile - that is, it includes those 9 essential amino acids I mentioned at the start.
