Which of the following is an essential fatty acid:

BHU NO-2019

Biochemistry & Nutrition

Easy

Appeared in: BHU NO-2019

Explanation

Linoleic acid is a polyunsaturated fatty acid (PUFA) that the human body cannot produce on its own.
Because it cannot be synthesized endogenously, it must be obtained from dietary sources, making it an 'essential' nutrient.
It belongs to the omega-6 family of fatty acids and is a crucial component of cell membranes and a precursor for synthesizing other important molecules like arachidonic acid and eicosanoids.

Option B: Lanolin is a wax, which is a type of simple lipid. It is not a fatty acid and is not a dietary nutrient for humans.
Option C: A triglyceride is a storage molecule composed of a glycerol backbone and three fatty acids. It is the main form of fat in the body and diet, but it is not an essential fatty acid itself.
Option D: Cholesterol is a sterol, a type of derived lipid. The body can synthesize all the cholesterol it needs, so it is not considered an essential nutrient that must be obtained from the diet.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Biochemistry of Lipids: Essential Fatty Acids as background academic context rather than a clinical decision trigger.
Nurses often provide dietary counseling. Advising patients to include sources of essential fatty acids (like vegetable oils, nuts, and seeds) is important for cardiovascular health, reducing inflammation, and overall wellness.
A deficiency of essential fatty acids can manifest as skin conditions like phrynoderma ('toad skin'), characterized by dry, horny eruptions, as well as hair loss and impaired wound healing. Nurses should be able to recognize these signs.
What if? If a patient is on long-term Total Parenteral Nutrition (TPN) without a lipid source, they are at high risk for EFA deficiency. The nurse must ensure the TPN formulation includes an intravenous lipid emulsion to prevent this complication.

How to Approach the Question

First, identify the core concept of the question, which is 'essential fatty acid'.
Recall the definition of an 'essential' nutrient: a substance the body cannot synthesize and must obtain from the diet.
Apply this definition to fatty acids. The body can make most fatty acids, but it cannot create certain polyunsaturated ones like linoleic acid.
Evaluate each option against this definition.
Option A, Linoleic acid, is a known essential fatty acid.
Options B (Lanolin), C (Triglyceride), and D (Cholesterol) are all lipids but do not fit the specific definition of an essential fatty acid. Lanolin is a wax, a triglyceride is a storage fat, and cholesterol is a non-essential sterol.

Concept Tested & Keywords

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E6 textbook of Applied Biochemistry and Nutrition & DieteticsHarbans Lal (pp 26-464 of 479) p. 60-62

E6 Parks TextBook of Preventive & Social Medicine part 2 — Subpart A (pp 1-232 of 464) p. 145-147

E6 Biochemistry U Satyanarayana— Part 1 (pp 26-420 of 840) p. 20-22