In discussing amino acid combinations, the term “high biological value” is frequently used. What exactly does this term mean?
Biological Value (BV) is the most common method of determining and labeling the quality of proteins.
Unlike many other measurements, biological value is measured directly in human beings. A protein is ingested on an empty stomach. Then, measurements are taken to determine nitrogen balance (how much nitrogen stays in body versus the amount excreted).
Biological Value is an index, and the results are indicated in comparison to the BV of egg protein, which is 100. For instance, if it takes twice the amount of a given protein to attain an even nitrogen balance vs. the amount of egg protein required, that particular protein has a BV of only 50.
One common misconception of the biological value is: the figure ‘100’ for egg protein does not mean that 100% of the amino acids found in egg protein are utilized. It is simply an arbitrary value to compare egg protein to other proteins. There are various other proteins, and especially combinations of proteins, that have a higher Biological Value.
Biological Values show how efficiently a food protein can be metabolized into a protein the body can use, and that in relation to egg protein.
Another important aspect: if a given food protein lacks one of the nine essential amino acids, it always has a Biological Value of zero. For example, gelatin does not contain tryptophan. The body therefore cannot convert gelatin into a protein without having other sources of tryptophan available.
Maximal Biological Value with Protein Combinations
One of the essential amino acids in any given protein is always the limiting factor. Careful combination of both animal and plant sources of protein can achieve a Biological Value of up to 136:
Please consider the following when interpreting combinations: the percentages reflect the isolated proteins that are required. Accordingly, 36 grams of eggs and 64 grams of potatoes are not what achieve such a good BV. Rather, it is the combination of 36 grams of protein derived from egg and 64 grams of protein derived from potatoes. However, to get 10 grams of protein from potatoes, you need about half a kilogram of potatoes.