fats, oils, and other lipids Flashcards
three classifications of lipids
triglycerides, phospholipids, and sterol
triglycerides description
most common lipid found in foods and body, “fats and oil”
triglycerides structure
three fatty acids connected to glycerol “backbone”
phospholipids description
made up of 2 fatty acids and phosphate, emulsifiers, make up cell membranes
phospholipids structure
hydrophilic polar head with glycerol and phosphate group and hydrophobic nonpolar tail with two fatty acids
sterol description
important role (converted into vitamin d and other substances), not required in diet since body makes all cholesterol needed
sterol structure
hydrocarbon ring structure, composed mainly of four connecting rings of carbon and hydrogen
what are associated with digesting, absorbing, and transporting fat in the body ?
mouth, stomach, small intestine, and lipoproteins
mouth’s contribution to fat in body
chewing and lingual lipase start digestion
stomach’s contribution to fat in body
gastric lipase breaks down fat into diglyceride and one fatty acid
small intestine’s contribution to fat in body
most digestion and absorption occurs here (bile acids emulsify fat and break fat globules into smaller pieces, pancreatic lipase breaks down to two fatty acids and monoglyceride, lecithin in bile is packaged with monoglycerides and fatty acids to create micelles (small carriers) for absorption)
lipoprotein’s contribution to fat in body
transport fat through lymph and blood
types of lipoproteins
chylomicrons, very low-density lipoproteins (vldl), low-density lipoproteins (ldl, “bad” cholesterol), and high-density lipoproteins (hdl, “good” cholesterol)
chylomicron’s function
carry digested fat through lymph into bloodstream
very low-density lipoprotein’s (vldl) function
deliver fat made in liver to cells
low-density lipoprotein’s (ldl, “bad” cholesterol) function
deposit cholesterol on walls of arteries
high-density lipoprotein’s (hdl, “good” cholesterol) function
remove cholesterol from body and deliver to liver for excretion
functions of fat in the body
energy-dense source of fuel, glucagon stimulates the release of fat from fat cells to provide energy for heart, liver, and muscle when blood glucose level declines, is needed for absorption of fat-soluble vitamins a, d, e, k, and carotenoids, insulates body to maintain body temperature, and cushions bones, organs, nerves
dietary recommendations for total fat
20-35% of total calories
dietary recommendations for essential fatty acids
1:1 to 1:4 ratio of omega-6 and omega-3, 1-2% or 2-4 grams of linoleic acid (omega-6) and 1.5 g in females and 2.06 g in males for alpha-linolenic (omega-3)
dietary recommendations for saturated fat
less than 20 grams per day
dietary recommendations for cholesterol
limit dietary cholesterol to less than 300 mg daily
dietary recommendations for trans fat
less than 2.2 grams per day
major food sources for essential fatty acids
vegetable oils, nuts, flaxseeds, fish, salmon, soybean, meat, poultry, and eggs