Module 4 The Lipids

Lipids

the second most abundant macronutrient in the typical human diet

The AMDR for fat

20-35% of total calories consumed

Types of Lipids

• triglycerides

• phospholipids

• sterols

Triglycerides

• make up nearly 95% of dietary fat

• how our bodies concentrate and store fat

• broken down and burned for fuel when needed

Where does our body stores triglycerides

adipocytes (fat cells)

Phospholipids

• 2% of dietary lipids

• have a unique structure compared to other lipids

• are phosphate-containing lipids that form the primary structure of human cell membranes

• non-essential

Sterols

• structurally different from other lipids

• perform various structural and regulatory functions

• include cholesterol, bile acids and salts, and phytosterols

Functions of Lipids

• absorption of vitamins and bioavailability

• energy reserves

• produce and regulate hormones

• protection of vital organs

• insulation and temperature regulation

• smell, taste, and satiety

• dietary fat provides essential fatty acids

The structure of a triglyceride

glycerol backbone and three fatty acids

The structure of a phospholipid

a phosphorus group and two fatty acids attached to glycerol

What are the characteristics of a phospholipid?

• water soluble

• fat-soluble

• allows fats and oils to be blended together

amphiphilic

both fat- and water-soluble

Emulsifiers

mixtures of two liquids that do not normally mix

Lecithin

a phospholipid found in egg yolk, soybean, and wheat germ, is often used as a food emulsifier

Sterols

• most do not contain any fatty acids but rather are multi-ring structures

• complex molecules that contain interlinking rings of carbon atoms, with side chains of carbon, hydrogen, and oxygen attached

Cholesterol

• the best-known sterol

• present in all body cells because it is a vital substance in cell membrane structure

• used in the body as a precursor in the synthesis of a number of essential substances

what sources contain cholesterol

only animal sources

Cholesterol can be found in

• meat

• poultry

• fish

• egg yolks

• butter

• dairy products made from whole milk

Typical chain length of fatty acid

4 to 24 carbons

what does the term "saturation" refers to?

whether the carbon atom in a fatty acid chain is filled (or "saturated") to capacity with hydrogen atoms

What is the difference between saturated fat and unsaturated fat?

unsaturated fats have some double bonds between carbons, but saturated fats have single bonds

Monounsaturated fatty acid

a fatty acid with one double bond

Polyunsaturated fatty acid

a fatty acid with two or more double bonds

Lipids differ in their degree of saturation or unsaturation due to their number of

double bonds

Food sources of saturated fatty acids

• animal fats

• dairy products

• tropical oils (like coconut and palm oil)

• cocoa butter

• partially or fully hydrogenated oils

Fat sources with a high percentage of saturated fatty acids tend to be

solid at room temperature

Fat sources rich in unsaturated fatty acids tend to be

liquid at room temperature

Food sources of predominately monounsaturated fats

• Nuts and seeds like almonds, pecans, cashews, and peanuts.

• Plant oils like canola, olive, and peanut oils.

• Avocados

• Poultry and eggs also contain monounsaturated fatty acids

Food sources of predominately polyunsaturated fats

• plant oils (vegetable, soybean, corn)

• fish

• flaxseed

• some nuts like walnuts and pecans

Fatty acids that the body cannot synthesize

• linoleic acid (an omega-6)

• alpha-linolenic acid (ALA, an omega-3)

Food sources of linoleic fatty acid (omega-6)

• plant oils

• corn oil

• soybean oil

• salad dressings

• margarine

Food sources of alpha-linolenic acid (omega-3)

• fish and seafood

• walnuts

• flaxseed

• canola oil

• seeds

• dark green leafy vegetables

Eicosanoids

a large family of important signaling molecules

Function of Eicosanoids

• regulating inflammation

• regulate circulation,

• regulate respiration, and

• regulate muscle movement

Effects of Omega-6 fatty acids

• increase blood pressure

• increase blood clotting

• increase immune response

• increase inflammation

Effects of omega-3 fatty acids

• lower blood pressure

• lower inflammation

• lower blood clotting

Eicosapentaenoic acid (EPA)

Docosahexaenoic acid (DHA)

• long-chain polyunsaturated fatty acids

• helps lower blood triglycerides and blood pressure, reduce inflammation, and prevent blood clot formation

• promote normal growth and development in infants

Good sources of EPA and DHA

• fish

• shellfish

• fish oils

• seaweed

• algae

Trans Fatty Acids

unsaturated fatty acids but have the linear shape of saturated fatty acids

Trans Fats are generated from

partially hydrogenated oils

Hydrogenation

the process of adding hydrogen to the carbon-carbon double bonds, thus making the fatty acid saturated

Why do trans fats have a linear structure?

the hydrogen atoms are bonded on opposite sides of the carbon chain

Uses for Hydrogenation

• make oils semi-solid at room temperature

• makes oils more stable and less likely to go rancid (smelling or tasting unpleasant)

Evidence that trans fats is worse than saturated fats

• increases LDL ("bad") cholesterol

• decreases HDL ("good") cholesterol

• increases inflammation in the body

• increased risk of coronary heart disease

What must happen before lipids can be used or stored?

they must be absorbed in the gastrointestinal tract

lipases

enzymes that enzymatically digest lipid molecules

Lipoproteins

transport vehicles for moving water-insoluble lipids around the body

Lipoproteins are made of

• cholesterol

• triglycerides

• phospholipids

• proteins

Main Types of lipoproteins

• Very-low-density lipoprotein (VLDL)

• Low-density lipoproteins (LDL)

• High-density lipoproteins (HDL)

Very-low-density lipoprotein (VLDL)

similar to chylomicrons, the main job is delivering triglycerides to the body's cells

Low-density lipoproteins (LDL)

• main job is to deliver cholesterol to the body's cells

• too much of it can lead to cardiovascular disease

Too much LDL can lead to

increase in risk of cardiovascular disease

High-density lipoproteins (HDL)

• made in the liver and gastrointestinal tract

• they are mostly made up of protein, so they are very dense

• their job is to pick up cholesterol from the body's cells and return it to the liver for disposal

• "clean out" the arteries and reduce the risk of cardiovascular disease

LDL is often called

bad cholesterol

HDL is often called

good cholesterol

A lipid panel test

• measures lipoprotein levels in the blood and estimate cardiovascular disease risk

• measure amounts of serum triglycerides

Ways to improve LDL/HDL Ratios

• Replace saturated fat intake with unsaturated fat

• Consume foods rich in omega-3 fatty acids

• Eliminate trans fats

• Limit refined grains and added sugars

• Increase soluble fiber intake

• Exercise regularly

• Lose weight, if needed

• Quit Smoking

• Consume alcohol only in moderation

• Statin cholesterol-lowering medications (when indicated by the physician)

Cardiovascular disease (CVD)

any disease affecting the heart or blood vessels

Cardiovascular disease (CVD) can include

• atherosclerosis

• coronary heart disease (CHD)

• myocardial infarction (MI, or heart attack)

• stroke

Coronary Heart Disease (CHD)

a disease that is defined by the inability of the arteries to carry enough blood to the heart

Stroke

occurs anytime blood flow to the brain is blocked and, like a heart attack, may result in death

Risk factors of a Stroke

• hypertension

• smoking

• diabetes

• elevated LDL blood cholesterol

• age

• family history

• ethnicity

• drug use

• certain medications

Hypertension

• chronic, elevated blood pressure

• a leading risk factor for cardiovascular disease

• often does not produce symptoms

Constant high blood pressure can lead to

• enlarge and weaken the heart,

• damage arterial walls, and

• cause arteries to burst

Aneurysm

a bulge in the wall of an artery

Main organ that regulates blood pressure

kidney

Normal blood pressure

120/80 or less

Congestive Heart Failure (CHF)

the heart can no longer adequately pump blood through the circulatory system

Risk factors of Congestive heart failure

• coronary heart disease (CHD)

• obesity

• hypertension

Foods high in cholesterol

• eggs

• organ meats

• red meat

• full-fat dairy products

• shellfish

Dietary Cholesterol Intake recommendations

• reducing saturated fat

• eliminating trans fat

• avoiding excess carbohydrate intake

Carbohydrates intake includes

• foods rich in whole grains and fiber

• low in refined carbohydrates and sugar

Effects of Processed carbohydrates

• elevated blood sugar

• elevated triglycerides levels

• increased inflammation

Consuming a diet with adequate calcium, magnesium, and potassium can

lower blood pressure

Sodium intake should be less than 2,300 mg per day and less than 1,500mg

• less than 2,300 mg per day

• less than 1,500mg for those w/ h