Chapter 5: The Lipids: Triglycerides, Phospholipids, and Sterols

Flashcards covering key vocabulary related to lipids, including triglycerides, phospholipids, sterols, fatty acid classifications, digestion, absorption, transport, health effects, and dietary recommendations.

Lipids (General Overview)

Provide 9 kcal/g, act as major fuel at rest, offer stored energy, contain essential fatty acids and fat-soluble vitamins, maintain cell membranes, protect the body, provide food flavors and textures, and promote satiety.

Lipids

Molecules that are insoluble in water, including triglycerides, phospholipids, and sterols.

Fats

The lipid content of diets and foods.

Triglycerides

A type of lipid composed of three fatty acids attached to a glycerol molecule, representing most dietary lipids.

Phospholipids

A type of lipid found in foods, body cells, and tissues, characterized by solubility in both fat and water, and acting as an emulsifier.

Sterols

A type of lipid found in foods, body cells, and tissues, with a complex ring structure; examples include cholesterol and plant sterols.

Fatty Acids

Organic compounds composed of a carbon chain with hydrogen atoms attached, classified by their carbon chain length, saturation level, and shape.

Short-chain fatty acids

Fatty acids with a shorter carbon chain length, typically 2 to 6 carbons.

Medium-chain fatty acids

Fatty acids with a medium carbon chain length, typically 8 to 12 carbons.

Long-chain fatty acids

Fatty acids with a longer carbon chain length, typically 14 or more carbons.

Omega-carbon (Ω-carbon)

The methyl (CH3) end of a carbon chain in a fatty acid, used as a reference point for numbering carbons.

Saturated fatty acids

Fatty acids in which every carbon in the chain is surrounded by hydrogen atoms, containing no double bonds.

Monounsaturated fatty acids

Fatty acids that contain one double bond in their carbon chain, meaning they lack one pair of hydrogen atoms.

Polyunsaturated fatty acids

Fatty acids that contain more than one double bond in their carbon chain, meaning they lack more than one pair of hydrogen atoms.

Omega number

A naming convention for unsaturated fatty acids that indicates the location of the closest double bond to the methyl (omega) end of the carbon chain.

Cis fatty acids

Unsaturated fatty acids where hydrogen atoms around a double bond are on the same side of the carbon chain, causing the chain to bend into a U-like formation.

Trans fatty acids

Unsaturated fatty acids where hydrogen atoms around a double bond are on opposite sides of the carbon chain, resulting in a more linear shape; typically occurs in partially hydrogenated foods.

Hydrogenation

A process where hydrogen atoms are added to unsaturated fatty acids, making liquid oils more solid, more saturated, and more shelf-stable, often creating trans-fatty acids.

Firmness (of fats)

A characteristic of fats and oils influenced by carbon chain length and saturation, where unsaturated fats are typically liquid and saturated fats are solid at room temperature.

Stability (of fats)

A characteristic of fats referring to their resistance to spoilage when exposed to oxygen; unsaturated fats spoil most readily.

Emulsifier

A substance that can mix with both fat and water, allowing fats to be stably suspended in water, such as lecithin found in eggs and soy.

Lecithin

A well-known phospholipid that acts as an emulsifier, found in foods like eggs and soy, and helps transport fat in the bloodstream.

Cholesterol

A type of sterol that serves as a structural component of cell membranes and is used in the synthesis of Vitamin D, also found in food sources.

Plant sterols

Sterols found in plants that can help lower cholesterol absorption in the body.

Hydrophobic

'Water-fearing'; describes molecules that are insoluble in water, such as fats.

Hydrophilic

'Water-loving'; describes molecules that are soluble in water, such as digestive enzymes.

Monoglycerides

A product of triglyceride digestion, consisting of one fatty acid attached to a glycerol molecule.

Bile

A digestive fluid produced by the liver and stored in the gallbladder, which acts as an emulsifier in the small intestine to break down fats.

Lipases

Enzymes that break down lipids, found in pancreatic juice, breaking fats into fatty acids and monoglycerides.

Chylomicrons

The largest and least dense lipoproteins, formed in intestinal cells, that transport diet-derived lipids (primarily triglycerides) to the liver via the lymphatic system.

Lipoproteins

Transport vehicles for lipids in the bloodstream, composed of cholesterol, proteins, fatty acids, and phospholipids.

Very-low-density lipoproteins (VLDL)

Lipoproteins made in the liver that transport triglycerides from the liver to cells throughout the body.

Low-density lipoproteins (LDL)

Lipoproteins that transport cholesterol to cells in the body, often referred to as 'bad cholesterol' because elevated levels are a risk factor for heart disease.

High-density lipoproteins (HDL)

Lipoproteins that remove cholesterol from cells and carry it to the liver for recycling or excretion, often referred to as 'good cholesterol' due to their anti-inflammatory properties and role in reducing heart disease risk.

Essential fatty acids

Fatty acids that the body needs but cannot synthesize, and therefore must be supplied by the diet, including linoleic acid (omega-6) and linolenic acid (omega-3).

Linoleic acid

An essential omega-6 fatty acid found in vegetable oils and meats.

Linolenic acid

An essential omega-3 fatty acid found in fatty fish, flaxseed, and chia seed.

Adipose cells

Cells in the body that store excess dietary fat as body fat.

Saturated fats (health effects)

Dietary fats that increase LDL cholesterol and promote blood clotting, raising the risk for heart disease.

Trans fats (health effects)

Dietary fats, often created during partial hydrogenation, that increase LDL cholesterol and the risk of cardiovascular disease.

Dietary cholesterol

Cholesterol consumed through food, which typically has no significant effect on blood cholesterol levels in most individuals, unlike saturated and trans fats.

Obesity

A condition linked to excess dietary fat intake due to its high energy density, where cutting fat from the diet can help reduce total calorie intake and manage weight.

Acceptable Macronutrient Distribution Range (AMDR for fat)

The recommended daily energy intake from fat, which is 20 to 35 percent of total daily calories.

Monounsaturated fats (health benefits)

Dietary fats that help reduce LDL cholesterol, lowering the risk of heart disease and related deaths.

Polyunsaturated fats (health benefits)

Dietary fats, including omega-3s, that help reduce LDL cholesterol, lower the risk of heart disease, protect against some cancers, and suppress inflammation.

Mediterranean Diet

A dietary pattern characterized by low saturated and trans fat intake, emphasis on whole foods (vegetables, legumes, fruits), limited land meat, more seafood, and a focus on monounsaturated and polyunsaturated fats, complex carbohydrates, fiber, and phytochemicals, known for lowering heart disease risk.