Final answer:
A dietary restriction of tyrosine and phenylalanine is used to manage conditions like PKU and alkaptonuria, but is challenging due to difficulty in maintaining such a diet and the potential for nutritional deficiencies. This strategy also doesn't address symptoms like osteoarthritis in alkaptonuria. a. people have trouble staying on the diet
Step-by-step explanation:
The dietary restriction of tyrosine and phenylalanine can lower homogentisate levels in the body, which is beneficial for individuals with metabolic disorders such as phenylketonuria (PKU) and alkaptonuria. These individuals have trouble metabolizing these amino acids due to deficiencies in specific enzymes like phenylalanine hydroxylase.
One reason why this dietary strategy has met with limited success is that people have trouble staying on the diet. Maintaining such a restrictive regimen can be challenging over the long term. Another reason for the limited success is the potential for nutritional deficiencies to develop, as phenylalanine and tyrosine are found in many protein-containing foods. Additionally, though not mentioned in the options provided, such diets do not address symptoms unrelated to the metabolic processing of these amino acids, such as osteoarthritis in alkaptonuria patients.
People with PKU, in particular, require a diet low in phenylalanine to prevent brain damage and other severe complications. Dietary management is crucial from birth to avoid neurological issues and protect fetal development during pregnancy. While tyrosine becomes an essential amino acid requiring consumption through diet for individuals with PKU, care must still be taken to maintain safe levels of phenylalanine in the body to prevent its toxic buildup.