Nutrition Exam 2: Ch. 5,6,7

Carbohydrates

are a class of nutrients that is a major source of energy for the body

Monosaccharide

a simple sugar that is the basic molecule of carbohydrates; the major dietary ones are:

glucose

fructose

galactose

Glucose

monosaccharide that is a primary fuel for muscles and other cells; “blood sugar”

Fructose

monosaccharide in fruits, honey, and certain vegetables; “fruit sugar”

Galactose

monosaccharide that is a component of lactose

Disaccharide

a simpler sugar comprised of two monosaccharides; the major dietary ones are:

maltose

sucrose

lactose

Maltose

disaccharide composed of two glucose molecules; “malt sugar”

Sucrose

disaccharide composed of a glucose and fructose molecule; “table sugar”

Lactose

disaccharide composed of a glucose and a galactose molecule; “milk sugar”

Condensation reaction

disaccharides form as a result of this; two molecules bond to form a larger molecule, releasing water in the process

High-fructose corn syrup

a syrup obtained from processing of corn

Nutritive sweeteners

substances that sweeten and contribute energy to foods

Added sugars

sugars added to foods during processing or preparation

Alternative sweeteners

(also referred to as “artificial” sweeteners or sugar substitutes) substances that sweeten foods while providing few or no kilocalories

Sugar alcohols

alternative sweeteners used to replace sucrose in some sugar-free foods

Nonnutritive sweeteners

(also called “high-intensity sweeteners”) a group of compounds that are intensely sweet-tasting compared to sugar

Complex carbohydrates

have three or more monosaccharides bonded together

polysaccharides

oligosaccharides

Polysaccharides

carbohydrates comprised of 10 or more monosaccharides bonded together

Oligosaccharides

carbohydrates comprised of 3 to 10 monosaccharides bonded together

raffinose

stachyose

Raffinose

nondigestible oligosaccharide made of 3 monosaccharides

Stachyose

nondigestible oligosaccharide made of 4 monosaccharides

Starch

a storage polysaccharide in plants

Glycogen

a highly branched storage polysaccharide in animals

Dietary fiber

non-digestible plant material; most types are polysaccharides

soluble fiber

insoluble fiber

Soluble fiber

forms of dietary fiber that dissolve or swell in water; include pectins, gums, mucilages, and some hemicelluloses

Insoluble fiber

forms of dietary fiber that generally do not dissolve in water; include cellulose, hemicelluloses, and lignin

Digestion in the small intestine

the small intestine is the main site for carbohydrate digestion and absorption

pancreatic amylase

maltase

sucrase

lactase

Pancreatic amylase

enzyme secreted by the pancreas that breaks down starch into maltose molecules

Maltase

enzyme that splits maltose into two glucose molecules

Sucrase

enzyme that splits sucrose into glucose and fructose

Lactase

enzyme that splits lactose into glucose and galactose

Resistant starches

starches found in seeds, legumes, whole grains, and some fruits and vegetables that resist digestion and are not broken down in the human GI tract

Insulin

a hormone secreted from the beta cells of the pancreas that contributes to a decrease in blood glucose levels

Glucagon

a hormone secreted from the alpha cells of the pancreas that contributes to an increase in blood glucose levels

Lipolysis

process by which triglycerides (fats) are broken down into glycerol and fatty acids, which are released into the bloodstream

Ketosis

when blood glucose levels are low, cells metabolize fat for energy; adaptive metabolic state in which the body primarily uses fat for energy

Ketone bodies (“ketones”)

molecules formed from the metabolism of fat that can be used as an alternative fuel for certain cells in the body when glucose levels are low

Ketoacidosis

condition in which ketone bodies accumulate in the blood; can result in loss of consciousness and death in severe cases

DIabetes mellitus

a group of serious, chronic conditions characterized by abnormal glucose, fat, and protein metabolism

Hyperglycemia

abnormally elevated blood glucose levels; over time, untreated or poorly controlled hyperglycemia damages nerves, organs, and blood vessels

Type 1 diabetes

an autoimmune disease that results in destruction of the beta cells of the pancreas; as a result, insulin must be supplied to the affected person regularly through exogenous sources

Type 2 diabetes

the most common type of diabetes; beta cells of the pancreas produce insulin, but the hormone’s target cells are insulin-resistant, leading to elevated blood glucose levels

Gestational diabetes

a type of diabetes that can develop during pregnancy

Hemoglobin A1c (HbA1c)

or glycated hemoglobin; blood test used to measure a person’s average blood glucose over several months

Classifying Diabetes According to Hemoglobin A1c Values

Diagnosis A1c Level

Normal 4.5 to 5.6%

Pre-diabetes 5.7 to 6.4%

Diabetes 6.5 or above

Carbohydrate counting

a diabetes management tool in which an individual tracks his or her daily carbohydrate intake

Glycemic index (GI)

a tool to measure the body’s insulin response to a carbohydrate-containing food

EX: popcorn has a high GI but a low GL

Glycemic load (GL)

a tool to measure the body’s insulin response to a carbohydrate-containing food; similar to the glycemic index, but also factors in the total carbohydrate content of a typical serving size of the food

EX: popcorn has a high GI but low GL

Hyperinsulinemia

a condition in which the pancreas releases an excessive amount of insulin; overtime, condition may contribute to the development of type 2 diabetes

Therapeutic lifestyle changes (TLC)

there is no way to prevent type 1 diabetes, the risk of developing type 2 diabetes can be decreased by this.

actions, such as avoiding excess body fat, exercising daily, and improving the diet, that promote health and reduce risk for chronic disease

dietary factors seem to have the greatest impact on type 2 diabetes risk in persons with a family history of the disease

Hypoglycemia

a condition that occurs when blood glucose level is too low

Epinephrine (adrenaline)

a hormone produced by the adrenal glands; secreted in response to declining blood glucose levels

Reactive (postpandrial) hypoglycemia

low blood glucose that occurs within 4 hours of eating

Metabolic syndrome

a condition that increases risk of type 2 diabetes and CVD

signs: large waist circumference, chronically elevated blood pressure (hypertension), chronically elevated fasting blood fats (triglycerides), low fasting high-density lipoprotein cholesterol (HDL cholesterol), high fasting blood glucose

Syndrome

is a group of signs and symptoms that occur together and indicate a specific health problem

Lactose intolerance (lactose maldigestion)

the inability to digest lactose properly because of a deficiency in lactase (the enzyme that breaks lactose into glucose and galactose)

Summary of Carbohydrate Digestion and Absorption

1. Mouth: some starch is broken down to maltose by salivary amylase

2. Stomach: the activity of salivary amylase soon stops in the acidic environment of the stomach

3. Small intestine: an amylase secreted by the pancreas (pancreatic amylase) breaks down starch into maltose. maltase digests maltose into glucose. sucrase digests sucrose into glucose and fructose. lactase breaks down lactose into glucose and galactose.

4. Liver: glucose, fructose, and galactose are absorbed by intestinal cells and transported to the liver via the hepatic portal vein

5. Large intestine: some soluble fiber is fermented by bacteria in the large intestine

6. Rectum: very little dietary carbohydrate is excreted in feces

Lipids

a class of nutrients that do not dissolve in water; an important property for understanding their functions and the way they are transported in the body.

lipids include: triglycerides, phospholipids, and sterols

Fatty acid

a hydrocarbon chain found in lipids; one end of the chain forms a carboxylic acid, and one end forms a methyl group

Hydrocarbon chain

a chain of carbon atoms bonded to each other and to hydrogen atoms

Omega (methyl) end

the end of a fatty acid containing a methyl (-CH3) group

Carboxylic acid

an organic molecule with a carboxyl (-COOH) group

Saturated fatty acid (SFA)

a fatty acid that has each carbon atom within the chain filled with hydrogen atoms

Unsaturated fatty acid

a fatty acid that is missing hydrogen atoms and has one or more double bonds within the carbon chain

monounsaturated fatty acid (MUFA)

polyunsaturated fatty acid (PUFA)

Monounsaturated fatty acid (MUFA)

fatty acid that has one double bond within the carbon chain

Polyunsaturated fatty acid (PUFA)

fatty acid that has two or more double bonds within the carbon chain

Linoleic acid

an 18-carbon polyunsaturated fatty acid with two double bonds; an essential fatty acid

Alpha-linolenic acid

an 18-carbon polyunsaturated fatty acid with three double bonds; an essential fatty acid

Omega-3 fatty acid

a type of polyunsaturated fatty acid with the first double bond at the third carbon from the omega end of the molecule

Omega-6 fatty acid

a type of polyunsaturated fatty acid with the first double bond at the sixth carbon from the omega end of the molecule

Essential fatty acids

fatty acids that must be supplied by the diet; linoleic and alpha-linolenic acid are essential fatty acids

arachidonic acid (AA)

eicosapentaenoic acid (EPA)

docosahexaenoic acid (DHA)

all are essential fatty acids that are precursors to eicosanoids

Eicosanoids

a group of long-chain fatty acids with hormonelike functions; there are three classes:

thromboxanes

leukotrienes

prostaglandins

essential fatty acids are necessary in small amounts for good health

Prostaglandins

a class of eicosanoids that produce a variety of important effects on the body

Trans fats

are unsaturated fatty acids that have at least one trans double bond

Partial hydrogenation

the food manufacturing process that adds hydrogen atoms to liquid vegetable oil, forming trans fats

triglyceride

a lipid that has three fatty acids attached to a three-carbon compound called glycerol

Glycerol

a three-carbon alcohol that forms the “backbone” of fatty acids

Monoglyceride

a lipid that has one fatty acid attached to a three-carbon compound called glycerol

Diglyceride

lipid that has two fatty acids attached to a three-carbon compound called glycerol

Phospholipid

a type of lipid needed to make cell membranes and for proper functioning of nerve cells; chemically similar to triglyceride, except that one of the fatty acids is replaced by a chemical group that contains phosphorus

Hydrophilic

part of a molecule that attracts water

Hydrophobic

part of a molecule that avoids water and attracts lipids

Choline

a water-soluble, vitamin-like compound; component of lecithin

Sterols

type of lipid that has a more chemically complex structure than triglycerides and phospholipids

Cholesterol

a lipid found in animal foods; precursor for steroid hormones, bile, and vitamin D

Plant sterols and stannous

chemicals found in plants that are structurally similar to cholesterol

Lipases

enzymes that break down lipids

Pancreatic lipase

the digestive enzyme that removes two fatty acids from each triglyceride molecule

Bile salts

a component of bile; aid in lipid digestion

Micelle

water-soluble, spherical lipid cluster; bile salts create a shell around each cluster, allowing for the structure to be suspended in watery digestive juices

Fat malabsorption

impaired fat absorption; symptoms include diarrhea, fatty stools, and rapid weight loss

Chylomicron

a type of lipoprotein formed in enterocytes to transport lipids away from the GI tract

Lipoproteins

water-soluble structures that transport lipids through the bloodstream

Lipoprotein lipase (LPL)

an enzyme in capillary walls, breaks down triglycerides

Very-low-density lipoprotein (VLDL)

a lipoprotein made in the liver; carries much of the triglycerides in the bloodstream

Low-density lipoprotein (LDL)

a lipoprotein that carries cholesterol into tissues

elevated LDL is linked to increased risk of CVD

High-density lipoprotein (HDL)

a lipoprotein that transports cholesterol away from tissues and to the liver, where it can be eliminated

low HDL is linked to increased risk for CVD

Enterohepatic circulation

process that recycles bile salts in the body

Gallstones

hard particles that can accumulate in the gallbladder or become lodged in one of the ducts carrying bile from the gallbladder to the small intestine

Cholecystectomy

surgery to remove a diseased gallbladder