Which statement best describes the relationship between sunlight exposure and vitamin D status?

Which statement best describes the relationship between sunlight exposure and vitamin D status?

• A. Sunlight exposure has no effect on vitamin D status
• B. Limited sunlight exposure is a risk factor for vitamin D deficiency
• C. Vitamin D status is determined only by diet
• D. Vitamin D deficiency cannot be prevented

Answer: (B)

Sunlight drives the skin’s production of vitamin D, so when exposure is limited, cutaneous synthesis drops and the risk of vitamin D deficiency rises. While dietary sources and fortified foods contribute, they often aren’t enough on their own to maintain adequate levels, and factors like season, latitude, skin pigmentation, age, and use of sunscreen can further reduce production. Therefore, the statement that limited sunlight exposure is a risk factor for vitamin D deficiency best captures the relationship. The other ideas—no effect from sunlight, vitamin D status being determined only by diet, or that deficiency cannot be prevented—don’t fit because sun exposure clearly influences status, diet alone isn’t the sole determinant, and adequate sun exposure (along with diet or supplements) can help prevent deficiency.

Sunlight drives the skin’s production of vitamin D, so when exposure is limited, cutaneous synthesis drops and the risk of vitamin D deficiency rises. While dietary sources and fortified foods contribute, they often aren’t enough on their own to maintain adequate levels, and factors like season, latitude, skin pigmentation, age, and use of sunscreen can further reduce production. Therefore, the statement that limited sunlight exposure is a risk factor for vitamin D deficiency best captures the relationship. The other ideas—no effect from sunlight, vitamin D status being determined only by diet, or that deficiency cannot be prevented—don’t fit because sun exposure clearly influences status, diet alone isn’t the sole determinant, and adequate sun exposure (along with diet or supplements) can help prevent deficiency.