A low sodium diet restricts intake of which substance?

A low sodium diet specifically limits the intake of salt. Sodium is a mineral found in many foods, but it is most commonly associated with table salt, which is made up of sodium chloride. Excessive sodium intake is linked to various health issues, particularly hypertension (high blood pressure) and cardiovascular diseases. Therefore, when following a low sodium diet, individuals are advised to reduce their consumption of salt to help manage their blood pressure and overall health.

Other options such as water, food, and sugar do not inherently relate to sodium intake in the same way. While it's true that individuals on a low sodium diet may modify their overall food choices to incorporate lower sodium options, they are not typically restricting water or food intake in general, nor are they focusing on limiting sugar as part of a sodium-specific dietary guideline. Thus, the emphasis on salt is what makes it the correct answer.