A patient who follows a strict vegan diet relies heavily on carrots for vitamin A. Analyze the biochemical implication of this dietary pattern compared with consuming animal liver for vitamin A status.

• A. Beta-carotene from carrots is a preformed vitamin that bypasses intestinal digestion and is incorporated directly as retinol in chylomicrons, whereas liver provides molecularly bound retinol that must first be broken down to beta-carotene before conversion, reversing the true biochemical pathway.
• B. Because provitamins like beta-carotene are converted into retinol with 100% efficiency in all individuals, carrots provide equal amounts of active vitamin A compared to liver, so vegan diets require no special consideration regarding vitamin A status.
• C. Animal liver contains provitamin forms of vitamin A that must be converted to retinol similarly to plant sources, meaning liver and carrots are functionally identical in both absorption and conversion efficiency, so dietary recommendations should not differentiate them.
• D. Carrots supply beta-carotene, a provitamin that must be enzymatically converted to active retinol and is less bioavailable and convertible, so relying solely on carrots risks lower retinol status compared with liver, which supplies preformed retinol that is absorbed and used directly.

Answer: (D)