The diet of pheynylketonurics should have

Options

A. No phenylalanine and no tyrosine
B. Low phenylalanine and normal tyrosine
C. Normal recommended amount of phenylalanine
D. Normal recommended amount of phenylalanine and tyrosine

Answer

### Step-by-Step Solution:

1. **Understanding Phenylketonuria (PKU)**:
- Phenylketonuria is a genetic disorder caused by the deficiency of the enzyme phenylalanine hydroxylase (PAH). This enzyme is responsible for converting the amino acid phenylalanine into another amino acid, tyrosine.

2. **Consequences of PAH Deficiency**:
- Due to the lack of PAH, phenylalanine accumulates in the body, leading to toxic levels that can cause neurological damage and other health issues.

3. **Dietary Requirements for PKU Patients**:
- To manage PKU, the diet must be low in phenylalanine to prevent its accumulation.
- Since phenylalanine cannot be converted to tyrosine in PKU patients, it is crucial to ensure that tyrosine is included in the diet in adequate amounts.

4. **Evaluating the Options**:
- **Option 1**: No phenylalanine and no tyrosine - Incorrect, as tyrosine is necessary.
- **Option 2**: Low phenylalanine and normal tyrosine - Correct, as it meets the dietary needs of PKU patients.
- **Option 3**: Normal recommended amount of phenylalanine - Incorrect, as this would lead to high levels of phenylalanine.
- **Option 4**: Normal recommended amount of phenylalanine and tyrosine - Incorrect, for the same reason as option 3.

5. **Conclusion**:
- The best dietary option for individuals with phenylketonuria is **Option 2: Low phenylalanine and normal tyrosine**.