Optimising protein absorption

Gaining muscle advice is often simplistic; “eat more to gain more.”  I wouldn’t disagree with this statement, however it leaves a lot to be explained.  How do you absorb protein?  You might be consuming a lot of protein, but are you absorbing it effectively?  Does it matter when protein is consumed?  You could be wasting a lot of great effort if you’re body isn’t geared up to absorb and synthesise protein.

Here I outline the journey protein takes from your stomach to the muscle, whilst providing clinical advice on how to optimise each part of the journey so you’re getting the most of what you consume. 

Stomach acid

The stomach is the first place where we start to break down protein.  Hydrochloric acid and pepsin break down the long protein molecules into smaller polypetides.  Like breaking down a cube of lego blocks, the stomach acid breaks down the cube into smaller collections of lego blocks so the proteins will be easier to absorb in the small intestines.  Athletes are often hugging a water bottle to ensure they are hydrated throughout the day.  Glugging water before a meal can decrease the acidity of the stomach.  This can decrease pepsinogen levels in the stomach meaning proteins won’t be broken down as efficiently.  To overcome this, avoid drinking a lot of water 30 minutes before and after a meal. Sipping water is acceptable particularly if it has a teaspoon of apple cider vinegar in it.

Absorbing protein in the small intestines

The polypeptides (proteins) travel to the small intestine where brush border enzymes and enzymes from the pancreas breakdown the protein further.  This results in molecules small enough to enter the blood stream.  Before they enter the blood however, they have to pass through the small intestines border control check, the epithelial cell.  Sodium and potassium are needed to usher in the amino acids in from the small intestines into the endothelial cell and usher out to the blood stream.  This is why it’s important to maintain electrolyte balance.  Electrolytes are lost during sweat, so making sure they’re replenished before your protein feed post workout will help optimise the transport of amino acids into the blood.

The liver

The amino acids are then taken through the blood to the liver.  The liver decides if the amino acids will be used for energy production (this especially happens when glucose levels are low) or will send the amino acids to tissues like the muscles for its own protein synthesis (via the blood).  Interestingly liver cells don’t have the appropriate enzymes to break down Branch Chain Amino Acids so the BCAAs are released back to the blood where it then travels to the muscles.   

Muscle protein synthesis

“Inducing muscle protein synthesis is key to growing larger muscles”

Resistance training causes tears in the micro-fibres of the muscles that signal to the immune system to send growth hormones, stem cells and repair materials (AMINO ACIDS) to the muscles.

This in turn stimulates muscle protein synthesis (MPS), which is the process that repairs muscles.  Tears in the muscles also stimulate muscle protein breakdown (MPB), a necessary part of the process.  The analogy most used is the building of a brick wall.  MPS adds bricks to the wall making the wall (muscle) bigger and MPB removes the bricks.  What we want to create is a positive net balance between MPS and MPB, ie we want to be adding more bricks to the wall than is being taken away.  This is where nutritional intervention is pivotal.

  • Protein synthesis is very energy demanding.  Lowering ATP levels reduces MPS (ATP takes energy from food and uses it for cellular processes like this).  It takes 4 ATP molecules to add just 1 amino acid to the translation process.  What this means is for maximal muscle gains, a caloric balance is essential. 
  • A positive net balance between MPS and MPB is achieved only when amino acid availability is increased.  You’re only going to build a big wall quicker than the guy who’s breaking it down if you have more bricks to build with.  Hitting protein intake requirements is essential to build muscle.

Leucine (BCAA) triggers MPS.

  • Timing:  MPS is most active during and immediately after exercise.  Studies have shown that amino acid consumption before and during exercise optimises the positive net balance between MPS and MPB.  Providing amino acids at a time when blood flow is elevated maximises delivery to the muscle.  From the first point of muscle tear there’s a lag of approximately 30 minutes then there is a large increase in MPS with it peaking around an hour and a half after exercise before returning to baseline after approximately 2 hours.  It remains here despite increased availability of circulating amino acids and sustained “anabolic signalling”.  This means, consume protein as soon as possible after exercise, to supply the muscle with the necessary building blocks whilst productivity (MPS wise) is at its highest. 

Eating 20-40g of protein every 3 hours best supports increased MPS rates throughout the day and increases body composition and physical performance outcomes.

  • Insulin levels are raised due to carbohydrate consumption.  There is debate as to whether or not insulin stimulates MPS, however it is less contested that insulin has an inhibitory effect on MPB.  Even moderate levels of insulin (achieved by consuming a balanced meal with carbohydrates) are sufficient to reduce MPB by approximately 50%.  Going back to the wall building analogy, insulin slows down the guy who’s removing the bricks from the wall, creating a positive net balance for MPS.  It is worth noting that carbohydrates consumption after exercise replenishes muscle glycogen stores; glycogen (glucose) that would have been used during exercise. 
  • Muscle protein breakdown continues to occur during sleep.  Studies have demonstrated that 30-40g of casein (slow release protein) effectively stimulates MPS and improves whole body protein balance over a 7 hour sleep.  This is especially relevant to any athlete training in the evenings.
  • Stress and low energy intake from the diet prevent the stimulation of MPS.  So make sure to relax and hit your recommended calorie intake!


If muscle is going to gain mass, protein synthesis must exceed protein breakdown. 

  1. Sip water 30 minutes before and after the meal to prevent diluting stomach acid by glugging water.
  2. Replenish electrolytes after intense exercise.
  3. Consider consuming BCAAs before and during exercise.
  4. Consume protein as soon as possible after exercise.
  5. Consume carbohydrates with protein to ensure a net positive balance between muscle protein synthesis and muscle protein breakdown.
  6. Hit you calorie intake.  Anything below your recommended intake may impede your progress.
  7. Have stress management techniques in place.

If you would like to receive 1 – 1 support from a nutritionist and reap the benefits of a personalised plan based on your routines, sport, likes and dislikes, then get in touch today!

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