Nutrition Chapter 4
role of fiber
1. aids elimination and some soluble forms may help to reduce serum cholesterol 2. prevents constipation
Fiber recommendations
25-30 g/day
How many people in the world digest and absorb lactose efficiently throughout their adult life?
35% of people
One teaspoon sugar= ____ grams CHO= ____ kcals
4 grams CHO 20 kcals
Amount of CHO needed to prevent ketosis and/or promote protein-sparing
50-100 grams per day
Hydrolysis
A chemical reaction in which one water molecule is split into two molecules, with hydrogen (H) added to one and a hydroxyl group (OH) to the other (from H2O). (occurs during digestion, requires energy)
Condensation
A chemical reaction in which water is released as two molecules combine to form one larger product. (separate monosaccharides link together with a single oxygen to form water, releases energy)
recommendations for CHO and fiber (AMDR, RDA, DRI)
DRI: 45-60% (900-1300 kcals) RDA: 130 grams per day AMDR: 55-70%
Disaccharides
Di meaning two sucrose (glucose and fructose), lactose (glucose and galactose), maltose (glucose and glucose)
Signs and symptoms of lactose intolerance
cramping, bloating, gas, diarrhea, vomiting after ingestion of lactose
define satiety
feeling of fullness
functional fiber
fiber added to foods that has been shown to provide health benefits
soluble fiber
fiber that dissolves in water or is broken down by bacteria in the large intestine
insoluble fiber
fiber that does not dissolve in water and is not broken down by bacteria in the large intestine
blood-glucose homeostasis hormones
glucagon and insulin
lactose intolerance
impaired ability to digest lactose due to reduced amounts of the enzyme lactase
(CHO alternative pathway) When the body is lacking glucose, fat fragments can combine to form
ketone bodies
Acidic compounds produced by the liver during the breakdown of fat when carbohydrate is not available
ketone bodies
treatment for lactose intolerance
lactose free or lactose restricted diet; can use Lactaid milk or tablets or soy milk; watch calcium intake IMPORTANT: people should LIMIT their dairy intake, not eliminate it.
What enzymes digest disaccharides?
maltase, sucrase, and lactase
organ that secretes blood glucose hormones
pancreas
Fiber Transport
passes through GI system
dietary fiber
plant material that cannot be digested
Pectin is an example of what
protein enzyme
ways to prevent dental cavities
reduce amount of sugar foods eaten
Where in the GI tract is not active in CHO digestion?
stomach
CHO storage (muscle)
stored in skeletal muscle
total fiber
the sum of dietary fiber and functional fiber
Where does CHO digestion begin and which enzyme initiates?
In the mouth with salivary amylase
How is excess CHO stored?
It is converted into and stored as fat.
Monosaccharides
Mono meaning one glucose (blood sugar), fructose (occurs naturally in fruits), galactose (table sugar)
Fiber: large intestine-
Most fiber passes intact through the digestive tract to the large intestine. Here, bacterial enzymes digest fiber. Some fiber is broken down by bacterial enzymes into short-chain fatty acids and gas. Fiber holds water; regulates bowel activity; and binds substances such as bile, cholesterol, and some minerals carrying them out of the body.
Polysaccharides
Poly meaning many Glycogen (found in limited meats and not all plants, body stores glucose as glycogen), starches (all starchy foods come from plants, plant cells store glucose as starch)
What is the order in which the saccharides break down?
Polysaccharides-> disaccharides-> monosaccharides
Fiber role in digestion?
Since we do not digest it, the fiber in food passes into the intestine and absorbs water. The undigested fiber creates "bulk" so the muscles in the intestine can push waste out of the body. Eating enough fiber helps prevent constipation.
Starch: stomach-
Stomach acid inactivates salivary enzymes, halting starch digestion.
CHO storage (liver)
The blood circulates through the liver, where cells there take up fructose and galactose and most often convert them to compounds within the same metabolic pathways as glucose.
Starch: small intestine
The disaccharidase enzymes on the surface of the small intestinal cells hydrolyze the disaccharides into monosaccharides. Maltose is broken down with maltase into two glucose molecules. Sucrose is broken down with sucrase into a glucose molecule and a fructose molecule. Lactose is broken down with lactase into a glucose molecule and a galactose molecule. Intestinal cells absorb these monosaccharides.
Indirect sources of glucose (metabolized by the liver)
The liver supplies sugar or glucose by turning glycogen into glucose in a process called glycogenolysis. The liver also can manufacture necessary sugar or glucose by harvesting amino acids, waste products and fat byproducts. This process is called gluconeogenesis.
Fiber: mouth-
The mechanical action of the mouth crushes and tears fiber in food and mixes it with saliva to moisten it for swallowing.
Starch: pancreas-
The pancreas produces an amylase that is released through the pancreatic duct into the small intestine. Starch is broken down with pancreatic amylase and is broken into small polysaccharides and maltose.
Populations most affected by lactose intolerance
The prevalence of lactose intolerance is lowest among northern Europeans and highest among east Asians.
Starch: mouth and salivary glands-
The salivary glands secrete saliva into the mouth to moisten the food. The amylase salivary enzyme begins digestion. Starch is broken down by amylase and is broken down into small polysaccharides and maltose.
What is the main site for CHO digestion?
The small intestine
What is meant by fermentable
able to undergo the process in which a substance breaks down into a simpler substance.
define ketone bodies
acidic compounds produced by the liver during the breakdown of fat when carbohydrate is not available
CHO transport and absorption
active transport (requires energy) facilitated transport (requires a different transporter for) small intestine absorbs CHO through these transport techniques and the blood circulates from the small intestine to the liver and the cells take it in
sources of fiber
all plant substances (ex: vegetables, fruits, grains legumes)
ketosis
an undesirably high concentration of ketone bodies in the blood and urine
Foods rich in CHO
bread, beans, milk, popcorn, potatoes, cookies, spaghetti, soft drinks, corn (sugars, fibers, and starches)
most effective way to prevent dental cavities
brush and floss regularly
Characteristics of monosaccharides
Each have 6 carbon atoms, 12 hydrogens, and 6 oxygens.
Characteristics of disaccharides
Each is made up with a pair of monosaccharides but must contain at least one monosaccharide of glucose.
Amylase
Enzyme in saliva that breaks the chemical bonds in starches
Low CHO diet similar to low ____ diets with weight loss
FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols)
Replacing simple CHO with complex CHO can be achieved in a diet that is higher in?
Fiber
epinephrine
a hormone of the adrenal gland that modulates the stress response; formally called adrenaline. When administered by injection, epinephrine counteracts anaphylactic shock by opening the airways and maintaining heartbeat and blood pressure. FIGHT OR FLIGHT
role of insulin
a hormone secreted by special cells in the pancreas in response to elevated blood glucose concentration. Insulin controls the transport of glucose from the bloodstream into the muscles and fat cells.
role of glucagon
a hormone secreted by special cells in the pancreas in response to low blood glucose concentration. Glucagon elicits release of glucose from the liver glycogen stores.
Fiber: small intestine-
Fiber is not digested, and it delays absorption of other nutrients.
Fiber: stomach-
Fiber is not digested, and it delays gastric emptying.
Fiber absorption
Fiber isn't broken down, instead it passes through your body; therefore, it is not absorbed.
Digestion (delays of gastric emptying)
Gastroparesis, also known as delayed gastric emptying, is a motility disorder in which the stomach doesn't empty food as quickly as it should.
beverages account for what % of added sugars in the US diet
This is the leading source that accounts for almost half of the added sugars consumed.
Lactase deficiency
a lack of the enzyme required to digest the disaccharide lactose into its component monosaccharides (glucose and galactose)
hyperglycemia
an abnormally high concentration of glucose in the blood
hypoglycemia
an abnormally low concentration of glucose in the blood
Direct sources of glucose
carbohydrates, fats, proteins
benefit of fiber
reduced risk of heart disease, diabetes, and cancer; better GI health; a healthy weight management.
Where are disaccharides digested?
small intestine
define glycemic response
the extent to which a food raises the blood glucose concentration and elicits an insulin response
Gluconeogenesis
the metabolic process by which organisms produce sugars (namely glucose) for catabolic reactions from non-carbohydrate precursors.
