Phenylketonuria (PKU) is a recessive human disorder in which an individual cannot appropriately metabolize the amino acid phenylalanine. This amino acid is not naturally produced by humans. Therefore, the most efficient and effective treatment is which of the following?
a. Transfuse the patients with blood from unaffected donors.
b. Regulate the diet of the affected persons to severely limit the uptake of the amino acid.
c. Feed them the substrate that can be metabolized into this amino acid.
d. Feed the patients an excess of the missing product.
e. Feed the patients the missing enzymes in a regular cycle, such as twice per week.

This is the effective way of managing PKU, if diet is not regulated, the blood plasma Phenylketonuria levels continue to build up from usual protein consumption. This leads to toxicity of the brain and brain dysfunctions. Nausea constipation, fatigues, health headaches are some of the results of the build up.

Therefore to reduce the blood build up of phenylalanine and thus PKU; Special diet formulas rich in essential amino acids, and other needed nutrients which may be absent in phenylalanine low diet should be adopted. Amino acids substitutes notably Tyrosine which is lacking from failure of phenyalanine breakdown in phenylketouria is heavily supplemented. Tyrosine is important in brain function for alertness, focus,nervous communication.

The adoption of protein substitutes diet or regulated amino acid diet is very important because , all the needed amino acid are available , thus protein catabolisms which may trigger phenylalanine build up from muscles and liver storage withdrawal is prevented thus stabilizing its blood concentration.