Protein has both structural and functional roles in the body. It’s important for building muscles, tendons and membranes, as well as forming the base of enzymes which regulate many functions in our body (1). Most hormones are made from protein , and our immune system requires protein to function. Protein can also be used to fuel exercise, but it’s not preferable – we’d rather use carbohydrates or fat to fuel energy, and leave protein for building muscles, ligaments, tendons, enzymes, hormones and optimising our immune health (1).
The different types of protein
Proteins are made up of amino acids. Whey proteins are the richest in leucine, the prime amino acid responsible for muscle rebuilding, compared to soy or casein proteins (1). Whey protein is also more easily and rapidly digested than soy or casein proteins. Exercise always improves the amount of protein rebuilding, even with proteins low in leucine (1). Adding leucine to Casein also improves the protein rebuilding qualities of casein (1).
How Much Protein do we Need?
Sadly we tend to eat most of our protein at night with dinner. However our body can only absorb 20-30g of protein per meal. That leaves us quite short as breakfast and lunch tend to be carb loaded. As a result we really need to eat around 20g of good quality protein per meal, or 3 times per day. 1 glass of milk has 8g of protein. 1 large egg has 6g.
Below are Australian Health guidelines (athletes need a lot more)
Women: 0.75g/kg (ie 60kg = 45g/day)
Men: 0.84 g/kg
Pregnant and breastfeeling women, or women over 70yrs: 1 g/kg
Children 1-3yrs: 14g/day
Children 4-8yrs: 20g/day
Children 9-13yrs : 35-40g / day
Adolescents 14-18yrs: 45-65g/day (girls/ boys)
A tip would be to make sure your kids are getting enough dairy per day (milk, cheese) to ensure they are healthy, happy and meeting their growth needs.
Why Protein is important for Athletes
The main advantages of protein for athletes are around rebuilding muscle, maintaining lean body mass, optimising immune function, not for improving performance. During heavy exercise an athletes body will be breaking down protein, whereas during recovery the focus will be on rebuilding protein in their bodies, especially their muscles and tissues (1). Athletes need to consume protein after exercise and throughout the day, to enhance the uptake and retention of amino acids in their muscles, and facilitate this protein rebuilding (1).
Athletes involved in strength training to increase muscle function and bulk may require extra protein in the initial stages of intense resistance exercise (1). Once an athlete is well trained, muscle adaptions to exercise take place, so that their protein requirements are only marginally higher than an untrained athlete (1). A lean body mass and a high power to weight ratio is also important for endurance athletes. It’s important that athletes trying to lose weight to achieve an ideal body composition for performance are focused on fat loss, not muscle loss, through keeping eating sufficient protein. Protein can also reduce appetite when it’s eaten in large volumes.
Protein for Vegans and Vegetarians
Some of the essential amino acids your body needs to source from food require very specific and large intakes of non animal protein – eg pulses. An example is lysine which affects immune function, the skin, anxiety, gut health and function (which then affects hormones). Its found mostly in animal products. This is really important for teenagers and pregnant/ breastfeeding women. Are your teenager vegans eating enough pulses? A 60kg vegan needs around 1.5 cups of cooked beans, peas or tofu per day to meet their lysine requirements, or a cup of almonds. They can achive this, if they have sufficient planning, knowledge, or expert guidance, because not every protein source is created equal. Vegetarians could eat 4 eggs or drink 3 cups of milk.
The following meals contain approximately 20g of protein:
- 500ml of low fat milk, or 600ml of Soy Milk
- 70g of lean beef, lamb or pork*
- 80g of lean chicken*
- 100g of grilled fish*
- 100g canned tuna or salmon*
- 400g reduced fat yoghurt
- 400g Baked Beans
- 3 Large eggs (in an omelette)*
- Sports Bar or liquid protein supplement (ie sustagen)*
* highest in Leucine
Too much of a good thing?
Protein consumption should be spread out over a 24 hour period to increase absorption, as the body can only absorb approximately 20g of protein in one dose, the rest will be excreted. Aiming for 20g of protein per meal is ideal. Daily consumptions under 2g per kg of body weight per day are unlikely to cause complications. High protein intakes are known to exacerbate pre-existing kidney complications and can also increase the level of calcium excreted in the urine which may cause problems with people already at risk of weakened bones. Worse still, too much protein in the diet can displace the consumption of other nutrient rich foods which are essential in anyone’s diet.
- Tarnopolsky, Mark. “Protein requirements for endurance athletes.” Nutrition7 (2004): 662-668.