Which of these substances cannot be synthesized by the human body & mist be obtained from the diet.

• A. Vitamin D.
• B. Carnitine, lipoic acid, and inositol.
• C. Vitamin E.
• D. All of the above can be synthesized by the human body.

Answer: (C)

Verified step by step guidance

1. Understand the question: The problem is asking which substance cannot be synthesized by the human body and must be obtained from the diet. This requires knowledge of essential nutrients and their synthesis in the body.
2. Review the options provided: Vitamin D, carnitine, lipoic acid, inositol, and Vitamin E. Determine which of these substances are essential nutrients that the body cannot produce.
3. Recall that essential nutrients are those that the body cannot synthesize in sufficient quantities and must be obtained from the diet. For example, Vitamin E is an essential nutrient, while Vitamin D can be synthesized in the skin with sunlight exposure.
4. Analyze the other substances: Carnitine, lipoic acid, and inositol are considered non-essential nutrients because the body can synthesize them in adequate amounts under normal conditions.
5. Conclude that the correct answer is Vitamin E, as it is an essential nutrient that must be obtained from the diet, while the other substances listed can be synthesized by the human body.