Nutrition Advent Calendar – Day 16
Protein intake – the 3 Ts:
Part 2: Type
After outlining how much protein is required to maximise muscle protein synthesis (MPS) yesterday, the next most influential element of protein intake is the type of protein.
Protein is made up by 21 amino acids, of which 12 can be naturally produced by the body whereas the remaining 9 cannot and are considered essential, and therefore must be sourced through the diet. Including foods that contain all the essential amino acids (complete proteins) is important for maximising MPS.
Leucine is one of the 3 amino acids that make up branched-chain amino acids (BCAAs) and is the key to activating mammalian target of rapamycin (mTOR) which is the regulatory signalling pathway for MPS, It is activated in a dose-dependant manner, so foods with a higher leucine content will activate mTOR better than low-leucine containing foods.
BCAAs are a very common supplement taken by bodybuilders to support MPS, but is actually less effective than a whole protein source that contains all essential amino acids (EAAs).
So focusing on leucine rich food sources is the key to maximising MPS. Sources include:
Dairy (milk, yoghurt, cottage cheese)
Whey & casein protein
Plant based sources
Take home messages:
Animal sources are superior to plant based sources for promoting MPS, likely due to their higher leucine content, but also other EAA. Plant foods are typically lower in 1-2 EAAs, but this varies between each. Vegetarians should eat a variety of the protein containing foods listed above to enhance MPS.