What are the two essential fatty acids humans cannot synthesize?

The two essential fatty acids that humans cannot synthesize are alpha-linolenic acid and linoleic acid. These acids are termed "essential" because the body requires them for various physiological functions, but it cannot produce them internally, meaning they must be obtained through dietary sources.

Alpha-linolenic acid is an omega-3 fatty acid, while linoleic acid is an omega-6 fatty acid. Both play crucial roles in maintaining overall health, including the regulation of inflammation, the development of cell membranes, and the production of signaling molecules. A diet that incorporates these essential fatty acids is important for preventing deficiencies and promoting optimal health.

The other options mention fatty acids that are either non-essential or synthesized by the body. For example, arachidonic acid and EPA are derived from linoleic and alpha-linolenic acids, respectively, but are not considered essential as they can be produced from these precursors. Palmitic and stearic acids are saturated fatty acids that the body can synthesize, and oleic acid is a monounsaturated fatty acid that is also synthesized. Therefore, the correct choice identifies the two fatty acids that must be ingested through food, highlighting their importance in human nutrition.