Nail the Certified Nutrition Specialist (CNS) Exam 2026 – Fuel Up for a Health-Packed Future!

The omega-3 fatty acid that consists of 18 carbons and 3 double bonds is known as alpha-linolenic acid (ALA). ALA is one of the essential fatty acids, meaning that it cannot be synthesized by the human body and must be obtained through diet. It is primarily found in plant-based sources such as flaxseed, chia seeds, walnuts, and certain oils, including flaxseed oil.

In terms of structure, each carbon atom in the fatty acid chain can bond with hydrogen atoms, and the presence of double bonds indicates unsaturation. ALA is notable for having three double bonds which contributes to its chemical properties and health benefits, including anti-inflammatory effects and potential cardiovascular benefits.

DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid) are also omega-3 fatty acids, but they have longer carbon chains and a different number of double bonds than ALA. ARA (arachidonic acid), on the other hand, is an omega-6 fatty acid, which does not fit the criteria of being an omega-3 fatty acid and has a different structure altogether. Thus, the question correctly identifies ALA as the omega-3 fatty acid with 18 carb