Lowest caloric value among listed lipids or fat substitutes For human nutrition, which listed substance effectively provides the lowest usable energy (kcal) per gram?

Introduction / Context:
Caloric yield depends on digestion, absorption, and metabolic oxidation. Most edible fats deliver about 9 kcal per gram. Olestra is a sucrose polyester engineered to be non hydrolyzable by human lipases, passing through the gut largely unabsorbed and thereby contributing essentially no metabolizable energy.

Given Data / Assumptions:

• Standard dietary fats (olive oil, margarine, MCT oil) are triacylglycerol based.
• Olestra’s ester linkages are sterically shielded from pancreatic lipase.
• Cardiolipin is a membrane lipid, not a typical human food source.

Concept / Approach:

Compare digestibility and absorption. Traditional fats are efficiently digested into fatty acids and monoacylglycerols and absorbed as chylomicrons, yielding high caloric value. By contrast, olestra is excreted intact, so its effective caloric contribution is approximately zero, making it the lowest energy value among the options for human nutrition.

Step-by-Step Solution:

Verification / Alternative check:

Human studies show intake of olestra does not raise postprandial triglycerides and contributes negligible energy; labels often list zero calories per serving.

Why Other Options Are Wrong:

Olive oil, margarine, and MCT oil are digestible energy dense fats. Cardiolipin is not consumed as a dietary fat and, if ingested as part of food, would still be metabolizable as phospholipids.

Common Pitfalls:

Confusing “low fat” with “zero calories,” or assuming all lipids yield the same energy regardless of digestibility.

Final Answer:

Olestra (a non-absorbable fat substitute)