A patient presenting with an inflamed tongue that appears smooth and red may be deficient in which one of the following?

A smooth and red tongue is often indicative of a condition known as glossitis, which can be a sign of nutritional deficiencies. One common deficiency associated with a smooth, red tongue is iron deficiency. In cases where a patient is deficient in iron, the body struggles to produce hemoglobin, which is vital for carrying oxygen in the blood. This can lead to changes in the tongue's appearance as well as other symptoms like fatigue, weakness, and pallor.

While deficiencies in other nutrients can cause various oral manifestations, they do not specifically present in the same way as iron deficiency. For example, fluoride impacts dental health and cavity prevention but does not typically result in changes to the tongue itself. Gluten, when associated with celiac disease, can cause a range of gastrointestinal symptoms and possibly affect oral health, but a smooth and inflamed tongue is not a hallmark of gluten sensitivity. Similarly, vitamin C deficiency can lead to scurvy, which presents with symptoms like swollen gums and skin issues but does not typically result in a smooth, red tongue either.

Thus, the presence of a smooth and red tongue is more commonly linked to iron deficiency, making it the most accurate choice among the options provided.