Linoleic acid and alpha-linolenic acid are essential fatty acids for humans because

• A. They cannot be synthesized by humans and must be obtained through diet
• B. They are the only fatty acids used for ATP production
• C. They are the only fatty acids absolutely required to sustain life
• D. They require L-carnitine to enter the mitochondria

Answer: (A)

Essential fatty acids must come from the diet because the body cannot synthesize them. Linoleic acid and alpha-linolenic acid are essential for that reason: humans lack the enzymatic steps to create these polyunsaturated fats from simpler fats, so they must be obtained through food. They also serve as precursors to longer-chain fatty acids that are integral to cell membranes and signaling molecules, underscoring why their dietary presence is necessary. The idea that they are the only fats used for energy, or the only fats absolutely required to sustain life, isn’t accurate, and the notion that they need L-carnitine to enter mitochondria isn’t relevant to why they’re essential.