Final answer:
A dietitian should monitor a patient's daily food intake and body weight, alongside blood pressure levels, when dietary intervention is used to lower blood pressure.
Step-by-step explanation:
When a patient is attempting to lower blood pressure levels with dietary intervention, a dietitian should monitor not only the blood pressure itself but also the patient's daily food intake and body weight. This is because dietary habits can significantly impact blood pressure, and changes in body weight can reflect the success of dietary interventions. Additionally, monitoring body weight can help in assessing the effectiveness of the dietary plan and making necessary adjustments. Monitoring the patient's medication is also essential, as dietary changes could potentially affect how certain medications work or the need for them.