Fatty Acid Metabolism & Balance Flashcards

Which pair of fatty acids are considered essential because humans cannot synthesize them?

Answer: Linoleic acid and alpha-linolenic acid

Linoleic acid (omega-6) and alpha-linolenic acid (omega-3) must come from the diet.

Approximately how efficiently do humans convert ALA to DHA?

Answer: Less than 5%

Conversion of ALA to EPA and especially DHA is very low in humans, often under 5%.

Which enzyme is shared by both the omega-6 and omega-3 pathways, creating competition between them?

Answer: Delta-6 desaturase

Delta-6 desaturase is the rate-limiting step for both families, so excess omega-6 can crowd out omega-3 conversion.

Which nutrients serve as key cofactors for the desaturase and elongase enzymes in EFA conversion?

Answer: Zinc, magnesium, and vitamin B6

Zinc, magnesium, and B6 (along with biotin and niacin) support fatty acid desaturation.

What omega-6 to omega-3 ratio is typical of the standard Western diet?

Answer: 15:1 to 20:1

The modern Western diet is heavy in vegetable oils, producing ratios of roughly 15:1 to 20:1 versus an ancestral estimate near 1:1 to 4:1.

Arachidonic acid is a precursor to which group of compounds?

Answer: Pro-inflammatory eicosanoids such as 2-series prostaglandins and 4-series leukotrienes

Arachidonic acid is converted by COX and LOX enzymes into inflammatory mediators when released from membranes.

Which oil is a rich source of gamma-linolenic acid (GLA)?

Answer: Evening primrose oil

Evening primrose, borage, and black currant seed oils supply GLA, which can be converted to anti-inflammatory DGLA.