Move Jutsu

If you’ve ever spent any time trying to gain mass or improve overall strength and performance then you will have come across protein supplements.

There’s at least 6 different methods used to determine how effective a certain protein source is for the body and each has its drawbacks.  So I decided to bring together all of them to get educated and understand the whole mess better.  First some interesting points that affect all of these.  Accurately measuring protein utlisation by the body is almost impossible due to the huge array of ‘other’ factors such as:

• Additional foods which may interact positively or negatively (anti-nutritional effects)
• Metabolic rate.
• Levels of protein intake (see: Bilogical Values drawbacks)
• Organism recycling of amino acids.
• Not basing the science on humans (PER was done on rats)

Biological Value

This value is based on the fact that protein is the body’s main source of nitrogen.  For the sake of science it assumes it’s the only source and so it measures the ratio of absorbed nitrogen to excreted which gives you the protein usability.  This is the most common source of values quoted by the protein supplement industry due to its favourable figures on whey protein and ease of understanding.  Egg is often used as a standard and placed at 100.

Drawbacks: Althoguh one of the most oft quoted this measure of protein usefullness is full of holes – worthy of a post in its own right.  But I’ll summarise…

• The measurement is taken when sub-maintenance levels of protein are taken.  The BV drops as protein intake increases.  For example milk has a BV of 100 but drops to 70 when you double the intake.
• When protein is digested very quickly – as is the case with whey protein isolate – it is sent to the liver for gluconeogenesis.  In other words it gets burned as fuel instead of protein synthesis.

Net Protein Utilisation (NPU)

This uses a similar method to the Biological Value by measuring amino acid intake against nitrogen excretion.  I won’t bore you with the formula but a value of “1.0″ indicates 100% usage of the supplied protein.  It has all the usual drawbacks though and its now been superseded by the PDCAAS (below).
I also couldn’t find a table of comparison values for this so its useless.  If you know of one then let me know.

Protein Efficiency Ratio

Uses an unusual and less than scientific method.  Invented in 1919 by measuring the body weight increase of a test subject divided by the intake of a particular food protein over a period of time.  The drawbacks to this method are obvious but its legacy still lasts as the RDA of protein is determined using this method in the US.

Nitrogen Balance

This uses similar ideas to the NPU and BV values.  Its the value of nitrogen in – nitrogen out.  Its tested by measuring the nitrogen balance of urine and has three main levels:

• Positive – You’ve got more going in than coming out.
• Negative – You’ve got more going out than in.  Sign of illness or malnutrition.
• Equilibrium – The bare minimum your body should be.

There are no values about the NB level of foods as its more of a body-state indicator that is used by other measuring methods to find the protein usefulness of foods.
Interesting article about it here: Nitrogen Balance

Protein Digestibility Corrected Amino Acid Score (PDCAAS)

This is the biggy that everyone uses – World Health Organisation, US FDA, FAO, etc.  But just because everyone and his uncle uses it doesn’t make it the best.  It measures the quality of proteins based on human amino acid requirements and adjusted for the relative digestibility of these proteins.  Its upper limit is 1.0 and lower limit 0.0 with a value of 1.0 meaning 100% of the essential amino acids are provided for.
Drawbacks:

• It doesn’t take into account where the protein was digested.  Some can be digested by bacteria for example.
• Also it suffers from the same effects as the others as it doesn’t take into account anti-nutritional factors of mixing foods.
• Having a varied diet means the PDCAAS value of the individual components becomes meaningless as a food lacking in essential amino acids can be covered by one of abundance.  You’d need to ascertain the PDCAAS value of an entire meal in that instance and a good meal will most likely have a value of 1.0.
• All proteins have a max-cieling of 1.0 which poorly reflects true values.  For example egg has an actual score of 1.19.

Conclusion

So just which is the best?  Well according to the numbers above you’re better off with Whey (PDC, BV, PDCAAS) or eggs (PDCAAS, PER).  I think it all ultimately boils down to what your mother tells you: “A good varied diet will make you healthy and strong”.
I’ll be covering protein requirements in another post.  If you’re interested then subscribe to the RSS feed or bookmark below.