Nutrition lecture 11

functions of lipids (fats)

provide energy, energy storage (triglyceride in adipose tissue), padding/insulation, components of cell membranes/compounds, absorb/transport fat-soluble vitamins, provide satiety, flavor, and taste to foods

what are the types of lipid molecules?

free fatty acids, triglycerides (TG, Fats), phospholipids, sterols

Fatty acids, short chain length

a chain fewer than 6 carbons, butyric acid (ex: butter)

Fatty acids, medium chain length

a chain made of 6-12 carbons, lauric acid (ex: coconut oil)

Fatty acids, long chain

a chain made of 14+ carbons, linoleic (ex: sunflower oil)

Saturated fatty acids

contains no carbon-carbon double bonds (ex: red meat, butter, cheese, whole milk)

unsaturated fatty acids

contains monounsaturated and polyunsaturated fatty acids

polyunsaturated fatty acids

contains more than one carbon-carbon double bond, contain omega 3 and 6 fatty acids

monounsaturated fatty acids

contains one carbon-carbon double bond (ex: canola, olive, and peanut oils, nuts, avocados)

omega 3 fatty acids

more than one carbon double bond; occurs if the first bond is between the 3rd and 4th carbon atoms (ex: flaxseed, canola oil, nuts)

omega 6 fatty acids

more than one carbon double bond; occurs if the first bond is between the 6th and 7th carbon atoms (ex: corn oil, sunflower oil, soybean oil, nuts)

The shape of fatty acids impacts…

…the stacking ability and fluidity of the acid

Long fatty acid chains will ___, while mono/poly unsaturated chains ___

stack well and make solid forms at room temp; don’t stack well and become liquid at room temp

trans fatty acids can be created during food processing by…

…hydrogenation, which can also cause some double bonds to become saturated

Hydrogenated fats can be found in…

…margarines, vegetable shortening and shelf-stable baked goods

Trans fatty acids have be shown to…

…raise blood cholesterol levels and increase the risk of heart disease

In cis fatty acids, the hydrogens are on the…

…same side of the double bond, causes a bend in the carbon chain (ex: veggie oil)

in trans fatty acids, the hydrogens are on the…

…opposite side of the double bond, making the chain straight and similar to saturated fatty acid (ex: margerine)

in saturated fatty acids, the hydrogens are…

…straight through bond angles similar to trans fatty acid (ex: red meat)

Saturated fatty acids affect cholesterol by…

…raising it, which is not good (ex: coconut/palm kernel oil, butter, cream, cheese, beef fat, whole milk)

monounsaturated fatty acids affect cholesterol by…

… doing nothing, its neutral (ex: olive/canola/peanut oil, cashews)

polyunsaturated fatty acids relationship with cholesterol is…

…good (ex: veggie oil, seeds, almonds, walnuts, soy, fish)

what are symptoms of essential fatty acid deficiency

dry scaly skin, liver abnormalities, poor wound healing, growth failure in infants, impaired hearing/vision

what is the use of essential fatty acids?

important for growth, skin integrity, fertility and structure/function of cell membranes

sources of essential fatty acids include…

…omega 6 fatty acids (usually linoleic) and omega 3 fatty acids (usually alpha linolenic)

Essential fatty acids

polyunsaturated fatty acids (PUFA) that must be provided by foods because they can’t be synthesized in the body but are necessary for health (omega 3 and 6)

omega 6 and omega 3 must be balanced in the body…

…10:1

triglycerides are made up of …

…3 fatty acid molecules (long chains of carbon bound to each other as hydrogen atoms) and 1 glycerol molecule (3-carbon alcohol that serves as a backbone)

Triglycerides are the major form of…

…lipid in food and in the body

Phospholipids are made of…

…2 fatty acids, glycerol, and a phosphorous containing molecule (have hydrophobic and hydrophilic ends)

What is the function of phospholipids?

helps w/fat absorption (an emulsifier like bile), transports dietary fats in circulation, part of cell membrane

The liver helps make phospholipids…

…not so essential to the body

what are some foods that contain phospholipids

animal cell membranes, egg yolks

Sterols

made of 4 carbon rings, found in food/made in body, appears as cholesterol in animals (high cholesterol increases CHD risk, while plant based can reduce CHD risk)

cholesterol

a type of sterol, bile salt precursor, helps maintain cell structure, hormones, and vitamin D, found in animal products, non essential to the diet, can raise health issues

process of lipids absorption and transport

biles work as an emulsifier to transport lipid digestion products into enterocytes, fatty acids wont mix well into water otherwise → they then reassemble in the mucosal cells and enter the lymph vessel

what are the body parts that play a role in lipase action

mouth (none, some in infants), stomach (gastric lipase), small intestine (gall bladder releases bile and pancreatic lipase, breaks down larger fatty acids)

Triglyceride digestion

3 fatty acids bound to a glycerol backbone; enzymes will break these down to release the fatty acids

Enterohepatic Circulation of Bile

the cycle in which bile is constantly reused to emulsify fats in the liver and sent back to gall bladder for storage

what are chylomicrons / reassembled lipoproteins made of?

cholesterol, phospholipids, and small protein; they are what enters the lymph then bloodstream during the process of lipids absorption and transport

Lipoprotein

Transports lipids & cholesterol in the blood