Final answer:
The primary purpose of a sodium-restricted or low-sodium diet is to reduce blood pressure.
Step-by-step explanation:
The primary purpose of a sodium-restricted or low-sodium diet is to reduce blood pressure. Excessive sodium intake can lead to increased blood pressure, and by reducing the amount of sodium in the diet, blood pressure can be effectively managed. This is particularly important for individuals with hypertension or those at risk for developing high blood pressure.