Which essential fatty acids must be obtained through diet because they cannot be synthesized by the body?

• A. Linoleic acid (omega-6) and alpha-linolenic acid (omega-3)
• B. EPA and DHA
• C. Oleic acid and palmitic acid
• D. Arachidonic acid and docosahexaenoic acid

Answer: (B)

Essential fatty acids are fats the body cannot make in sufficient amounts, so they must come from the diet. The two fatty acids that must be supplied are linoleic acid (an omega-6) and alpha-linolenic acid (an omega-3). The body can convert these into longer-chain fats like arachidonic acid, EPA, and DHA, but the conversion is limited, especially for DHA and EPA. That means EPA and DHA are not strictly required to be eaten because the body can synthesize some of them from the essential fatty acids, though dietary intake of EPA and DHA is still important for health in many guidelines. In contrast, oleic acid and palmitic acid can be synthesized by the body, so they are not essential. Arachidonic acid and docosahexaenoic acid are long-chain fats that can be derived from the essential fatty acids through metabolism, so they are not considered strictly essential to obtain from the diet.