Lipids Human nutrition

Short-chain fatty acid

A fatty acid with fewer than six carbon atoms that is rapidly absorbed into the portal vein.

Chylomicron

A large lipoprotein particle with a triglyceride‑rich core that transports dietary lipids from enterocytes into the lymphatic system.

Sterol

A lipid built from four fused carbon rings

Trans double bond

A configuration where the hydrogen atoms attached to the double‑bonded carbons are on opposite sides

Essential fatty acid

A polyunsaturated fatty acid that cannot be synthesized by humans and must be obtained from the diet.

Cholesterol

A sterol that modulates membrane fluidity and is the substrate for steroid hormones

Olestra

A synthetic fat replacer that binds dietary lipids in the gut

LDL receptor

A cell‑surface protein that binds LDL particles

Cis double bond

A configuration in which the two hydrogen atoms attached to the double‑bonded carbons lie on the same side

Phospholipid

A lipid consisting of a glycerol backbone

Eicosanoid

A signaling molecule derived from 20‑carbon polyunsaturated fatty acids such as prostaglandins and leukotrienes.

Micelle

A spherical aggregate of bile salts and phospholipids that solubilizes fatty‑acid products for absorption across the intestinal brush border.

Pancreatic lipase

An enzyme secreted by the pancreas that hydrolyzes triglycerides within micelles to free fatty acids and 2‑monoacyl‑glycerol.

Monounsaturated fatty acid

A fatty acid that possesses exactly one carbon–carbon double bond

Very-low-density lipoprotein (VLDL)

A hepatic‑derived lipoprotein that carries endogenous triglycerides to peripheral tissues.

High-density lipoprotein (HDL)

A lipoprotein that collects excess cholesterol from peripheral tissues and returns it to the liver for elimination.

Triglyceride

An ester formed from glycerol bound to three fatty‑acid molecules

Atherosclerotic plaque

A layered structure composed of a lipid core

Saturated fatty acid

A fatty acid that lacks carbon–carbon double bonds

Reverse cholesterol transport

The process by which HDL removes cholesterol from peripheral cells

Long-chain fatty acid

A fatty acid with twelve or more carbon atoms that requires incorporation into chylomicrons for lymphatic transport.

Polyunsaturated fatty acid

A fatty acid with two or more carbon–carbon double bonds

Acceptable macronutrient distribution range (AMDR)

The recommended proportion of total energy that should come from fat

Plant sterol

A non‑cholesterol sterol found in vegetables and fortified foods that competes with dietary cholesterol for intestinal absorption.

Omega-6 fatty acid

An essential polyunsaturated acid whose first double bond occurs at the sixth carbon from the methyl end

Foam cell

A macrophage that has ingested oxidized LDL and become laden with lipid droplets

Omega-3 fatty acid

An essential polyunsaturated acid with the first double bond at the third carbon from the methyl end

Omega notation

A shorthand where the first number indicates total carbons

Medium-chain fatty acid

A fatty acid containing six to ten carbon atoms that is also transported directly to the portal circulation.

Low-density lipoprotein (LDL)

A lipoprotein whose core consists mainly of cholesterol esters and whose primary role is to deliver cholesterol to cells.

Hydrogenation

A chemical process that adds molecular hydrogen to unsaturated lipids

Bile salt

A surfactant produced from cholesterol in the liver that emulsifies dietary lipids into smaller droplets.