Nutrition exam 2: Carbohydrates

Glucose to Cellulose (fiber)

bonds that link glucose units together are different from the bonds in starch or glycogen - human enzymes cannot digest them.

Maintenance of digestive tract health

consumption of all kinds of fiber and ample fluid intake

Carbohydrate energy

contain the sun's radiant energy

Excess glucose

converted to fat by liver (stored in adipose tissue) - increased body fatness --> burning more glucose for energy in place of fat

Carbs as energy source

critical energy source - nerve cells, red blood cells, and brain - need glucose to fuel the body - alter the shape and function of certain proteins

Glycogen

highly branched polysaccharide that is made and stored by liver and muscle tissues of human beings and animals as a storage form of glucose - not a significant food source of carbohydrate and is not counted as one of the complex carbohydrates in foods - rapid breakdown at time of death

Glycemic index

ranking of foods according to their potential for raising blood glucose relative to a standard food such as glucose - elevation of blood glucose and insulin caused after consuming a given food - food score compared to standard (50g glucose) - can't base food choices on GI alone

Soluble fibers

readily dissolve in water, form gels - not digested --> fermented - add a pleasing consistency, such as the pectin that puts the gel in jelly and the gums that make bottled salad dressings more viscous - modulate blood glucose levels, lower blood cholesterol, and promote the health of the colon

Fiber-rich foods benefits

reduced risk of heart disease, diabetes, and bowel disease - promotion of healthy body weight, cholesterol synthesis, blood glucose control - complex carbohydrates --> more than just fiber

Digestible carbohydrates

with fats and protein, add bulk to foods and provide energy and other benefits for the body

Starch

plant's storage form of glucose - packed in granules - polysaccharide

Carbohydrate-rich foods

plants and milk

Bran

protective fibrous coating around a grain; the chief fiber donator of a grain

Whole grains advantages

provide greater amounts of vitamin B6 and the minerals magnesium and zinc that refined grains lack - provide substantial fiber, along with a wide array of potentially beneficial phytochemicals in the bran and the essential oils of the germ

U.S. Enrichment Act of 1942

requires that iron, niacin, thiamin, and riboflavin be added to all refined grain products before they were sold - 1996, the vitamin folate (often called folic acid on labels) was added - today, all refined grain products are enriched with at least the nutrients mandated by the Act

Glucose to glycogen

resembles starch in that the bonds between its glucose units can be broken by human enzymes, but the chains are more highly branched

Digestive tract cancers

risk of these cancers is lower among people with higher dietary fiber intakes - plant foods (vegetables, fruits, and whole-grain products) have attributes that may reduce the risks of colon and rectal cancers - fibers from food, not supplements - small fat molecules arising from bacterial fermentation of fiber may activate cancer-destroying mechanisms and inhibit inflammation in the colon

Monosaccharides

single sugars - glucose, fructose, galactose

Endosperm

soft, white inside portion of the kernel, containing starch and proteins that help nourish the seed as it sprouts - bulk of the edible part of a grain

Blood glucose control

soluble fibers delay the transit of nutrients through the digestive tract, slowing glucose absorption and preventing the glucose surge and rebound often associated with diabetes onset - w/ established diabetes, high-fiber foods can modulate blood glucose and insulin levels

Sugar digestion

split to yield free monosaccharides by enzymes on small intestine lining - travel from bloodstream to the liver --> converts fructose and galactose to glucose, circulatory system transports the glucose and other products to the cells

Simple carbohydrates

sugars, including both single sugar units and linked pairs of sugar units

Hemorrhoids

swollen, hardened (varicose) veins in the rectum, usually caused by the pressure resulting from constipation - eased by large, soft stools

Fiber & weight management

tend to be low in fats, added sugars, and calories - less energy per bite - absorb water from the digestive juices --> create feelings of fullness, delay hunger, and reduce food intake - make at least half the grain choices whole grains, and choose legumes several times per week

DRI Minimum Recommendation for Carbohydrate

to adequately feed the brain and reduce ketosis has been set at 130 grams a day for an average-sized person

Insoluble fibers

tough, fibrous structures of fruits, vegetables, and grains; indigestible food components that do not dissolve in water - not viscous, retain shape and texture, aid the digestive system by easing elimination - form structures such as the outer layers of whole grains (bran), the strings of celery, the hulls of seeds, and the skins of corn kernels

Diverticula

weakness in the wall of the large intestine that leads portions of the wall to bulge out into pouches - reduced by ample dietary fiber, but fiber cannot stop them from forming

Ketosis

an undesirable high concentration of ketone bodies, such as acetone, in the blood or urine - provide a fuel alternative to glucose for brain and nerve cells when glucose is lacking, such as in starvation or very low carbohydrate diets - shift in body's metabolism -->disruption of acid-base balance, vitamin/mineral insufficiencies, bone loss, depletion of glycogen stores

Starch digestion

begins in the mouth - splits starch into shorter units - digestion ceases in the stomach and resumes in small intestine --> enzyme from pancreas breaks starch down into disaccharides and small polysaccharides, other enzymes liberate monosaccharides for absorption

Carbohydrate and Weight Maintenance

bite for bite, carbohydrate-rich foods contribute less to body's available energy than do fat-rich foods, and they best support physical activity to promote a lean body - diet has 45 to 65% of its calories from mostly unrefined sources of complex carbohydrates

Blood glucose fasting

blood glucose starts to fall too low, glucagon enters bloodstream and triggers the breakdown of liver glycogen to single glucose molecules - enzymes in liver cells respond to glucagon by attacking many glycogen ends simultaneously to release a surge of glucose into the blood for use by all the body's cells

Splitting Glucose for Energy

broken in half --> glucose <--> pyruvate - glycolysis, CAC release ATP - can reassemble

Monosaccharide digestion

can absorb them directly into your blood

Glucose to fat

can be converted to fat, but fat cannot be converted to glucose - turns to body protein for energy source --> taken from blood, organ, or muscle proteins (protein-sparing action) - fat regenerates a small amount of glucose, not enough to feed the brain and nerve tissues

Photosynthesis process

carbon dioxide gas(CO2 ) absorbed into its leaves donates carbon and oxygen - water and carbon dioxide combine to yield the single sugar glucose

Carbohydrates

compounds composed of single or multiple sugars - name means "carbon and water," and a chemical shorthand for carbohydrate is CHO, signifying carbon (C), hydrogen (H), and oxygen (O) - form the first link in the food chain that supports all life on earth

Type 2 diabetes

diabetes of a form that develops especially in adults and most often obese individuals and that is characterized by high blood glucose resulting from impaired insulin utilization coupled with the body's inability to compensate with increased insulin production - much more common, diagnosed later in life typically, insulin produced but cells become desensitized to it, glucose levels remain high in blood

Type 1 diabetes

diabetes of a form that usually develops during childhood or adolescence and is characterized by a severe deficiency of insulin, leading to high blood glucose levels - less common, diagnosed earlier, body not producing insulin, take supplemental insulin

Constipation

difficult, incomplete, or infrequent bowel movements associated with discomfort in passing dry, hardened feces from the body - relieved by taking fiber supplements --> stimulate the colon lining to secrete mucus and water which enlarge and soften the stools, or swells with water, softening and giving weight to fecal matter, easing its passage from the system

Sucrose

disaccharide composed of glucose and fructose - sometimes known as table, beet, or cane sugar and, often, as simply sugar - occurs naturally in many vegetables and fruits - tastes sweet because it contains the sweetest of the monosaccharides, fructos

Maltose

disaccharide composed of two glucose units; sometimes known as malt sugar - appears wherever starch is being broken down; occurs in germinating seeds and arises during the digestion of starch in the human body

Carbs & losing weight

donate fewer calories than do dietary fats, and converting glucose into fat for storage is metabolically costly (gram for gram) - increase fiber-rich whole foods, reduce refined white flour and added sugars - avoid refined sugars --> contain no other nutrients, very low nutrient density

Disaccharide digestion

enzymes in your intestinal cells must split the disaccharides into separate monosaccharides so that they can enter the bloodstream - blood delivers all products of digestion first to the liver, which possesses enzymes to modify nutrients, making them useful to the body (makes abundant glucose for delivery) - galactose can be converted into glucose by the liver, adding to the body's supply - fructose used for fuel by the liver or broken down to building blocks for fat or other needed molecules

Fiber digestion

fermented by bacteria in the colon - process breaks down carbohydrate components of fiber into other products

Appendicitis

fiber prevents compaction of the intestinal contents, which could obstruct the appendix and permit bacteria to invade and infect it

Whole-wheat flour

flour made from whole-wheat kernels; a whole-grain flour - also called graham flour

Fiber

form the supporting structures of its leaves, stems, and seeds - indigestible parts of plant foods, largely nonstarch polysaccharides that are not digested by human digestive enzymes, although some are digested by resident bacteria of the colon - include cellulose, hemicelluloses, pectins, gums, mucilages, and a few non- polysaccharides such as lignin - digestion involves bacterial fermentation (produces tiny products, mainly fat fragments, which the human colon absorbs)

Grain kernel parts

germ, endosperm, bran, and husk

Glucose to starch

glucose units are linked in long, occasionally branched chains to make starch - human digestive enzymes can digest these bonds, retrieving glucose

Refined grains

grains and grain products from which the bran, germ, or other edible parts of whole grains have been removed; not a whole grain - low in fiber and are enriched with vitamins, as required by U.S. regulations

Whole grains

grains or foods made from them that contain all the essential parts and naturally occurring nutrients of the entire grain seed (except the inedible husk) - increased consumption for weight loss - uses all portions of grain (germ and bran), getting more fiber/vitamins/minerals than other grains

Lactose intolerance

impaired ability to digest lactose due to reduced amounts of the enzyme lactase - as they age, upward of 75 percent of the world's people lose much of their ability to produce the enzyme lactase to digest the milk sugar lactose - nausea, pain, diarrhea, and excessive gas on drinking milk or eating lactose- containing products - milk allergy --> immune system overreacts when it encounters milk protein

Indigestible carbohydrates

include most of the fibers in foods, yield little or no energy but provide other important benefits

Fiber and cholesterol steps

liver acts something like a vacuum cleaner, sucking up cholesterol from the blood, using it to make bile, and discharging the bile into the gallbladder - gallbladder empties its bile into the intestine, where bile performs necessary digestive tasks - in intestine, some of the cholesterol in bile associates with fiber - fiber carries cholesterol in bile out of the digestive tract with the feces - cholesterol that remains in the intestine is reabsorbed into the bloodstream

Carbohydrate Stored as Fat

liver breaks glucose to fatty acids - travel in the blood to the adipose tissues, where they are combined into larger fat molecules and stored, large capacity to store fat

Complex carbohydrates

long chains of sugar units arranged to form starch or fiber; also called polysaccharides

Role of fiber

maintains health of GI tract and feeds gut bacteria, slows digestion, controls blood glucose by slowing things down in digestion, helps maintain weight, useful for maintaining calories

Green plants

make carbohydrate through photosynthesis in the presence of chlorophyll and sunlight - do not use all of the energy stored in their sugars

Nutritional consequence lactose intolerance

milk substitute must be found for any child who becomes lactose intolerant - severe cases --> disease, malnutrition, or parasites to produce a loss of nutrients that greatly reduces the children's chances of survival - may later develop weak bones

Monosaccharide to disaccharide

monosaccharides connect to a glucose molecule (or 2) to form disaccharides

Low-fiber diet

more cholesterol (from bile) is reabsorbed and returned to the bloodstream

High-fiber diet

more cholesterol (in bile) is carried out of the body

Tissue glycogen stores

muscles hoard two-thirds of the body's total glycogen - brain stores a tiny fraction of the total as an emergency reserve to fuel the brain for an hour or two in severe glucose deprivation - liver stores the remainder and is generous with its glycogen, releasing glucose into the bloodstream for the brain or other tissues when the supply runs low - w/o carbohydrate from food to replenish it, the glycogen stores in the liver can be depleted in less than a day

Germ

nutrient-rich inner part of a grain - part that grows into a new plant

Soluble fibers abundant in

oats, barley, legumes, okra, and citrus fruits

Breakdown of complex carbohydrates

occurs in the digestive tract - starts in mouth, enzymes start to break down - nothing happens at the stomach - in small intestine, enzymes breaks these down to component parts, b/c it can only absorb monosaccharides - then travel into blood to the liver, where they are stored or sent to body tissues

Husk

outer, inedible part of a grain - AKA chaff, can be used in animal feed

Disaccharides

pairs of single sugars linked together - lactose, maltose, and sucrose ( all 3 contain glucose)

Enriched refined grains advantages

people who eat several servings a day obtain significantly more of these nutrients than they would from unenriched refined products - nutritionally comparable to whole-grain foods only with respect to their added nutrients

100% whole grain

a label term for food in which the grain is entirely whole grain, with no added refined grains

Sugar unit structure

a molecule containing six carbon atoms, together with oxygen and hydrogen atoms

Galactose

a monosaccharide; part of the disaccharide lactose (milk sugar) - one of two single sugars that are bound together to make up the sugar of milk - rarely occurs free in nature but is tied up in milk sugar until it is freed during digestion

Fructose

a monosaccharide; sometimes known as fruit sugar - occurs naturally in fruits, in honey, and as part of table sugar - consumed in sweet beverages, desserts, and other foods sweetened with high-fructose corn syrup (HFCS) or other added sugars

Multi-grain

a term used on food labels to indicate a food made with more than one kind of grain - not an indicator of a whole-grain food

Blood glucose feasting

after meal, pancreas releases insulin, insulin signals body tissues to take up glucose from the blood, muscle tissue takes up excess blood glucose and use it to build glycogen - done by liver cells and adipose tissue as well

Fiber Recommendations and Intakes

14 grams per 1,000 calories (total fiber) - 25 grams per day for most women and 38 grams for most men - substitute plant sources of protein (legumes) for some of the animal sources of protein (meats and cheeses) in the diet - consume the recommended amounts of fruits, vegetables, legumes, and whole grains each day

Whole grains examples

Amaranth, barley, corn, buckwheat, quinoa, oats, rice, rye, wheat, wild rice, etc

Lactose

a disaccharide composed of glucose and galactose; sometimes known as milk sugar