Exam 2 Flashcards
what is a whole grain?
cereal grains, or foods made from cereal grains, that contain all the essential parts (starchy endosperm, germ, and bran) of the entire grain seed in its original proportions.
what is a refined grain?
cereal grains that have been milled, a process that removes the bran and germ; white flour is an example.
what is an enriched grain?
cereal grains that lost nutrients during processing but have vitamins and minerals added back in; refined grains are often enriched.
what are benefits of consuming whole grains?
reduced risk of heart disease, obesity, diabetes, and certain types of cancer.
what percentage of grains that Americans consume should be whole grains, according to the dietary guidelines for Americans?
at least 50%.
what molecules make up carbohydrates?
carbon, hydrogen, and oxygen.
what is a carbohydrate?
a single sugar unit.
how many calories are in 1 gram of carbohydrates?
4 kcal.
How are carbohydrates in regards to energy?
dominant source of energy for exercising muscles, exclusive source of energy for red blood cells, provide the vast majority of energy needed by the brain under normal circumstances.
How do carbohydrates affect amino acids?
reduces the use of amino acids to synthesize glucose, thereby sparing proteins from being broken down for this purpose.
what is the function of carbohydrates in food?
source of fiber, adds sweetness and flavor.
what are sources of carbohydrates?
fruits, vegetables, grains, milk, and mil products.
what percentage of calories should be from carbohydrates?
45-65%.
how are carbohydrates classified?
simple or complex.
what are simple carbohydrates made up of?
one or two sugar units.
what are monosaccharides?
sugar units that are made up of one sugar molecule.
what are disaccharides?
sugar units made up of two sugar molecules.
what are the three most abundant monosaccharides?
fructose, glucose, and galactose.
what is fructose?
the sweetest of the sugars, found in fruits, some vegetables, and honey.
what is glucose?
the most abundant sugar in our diet because it is part of all disaccharides, starches, and many fibers.
what is galactose?
one of the two monosaccharides that make up the disaccharide found in milk.
what are the three disaccharides?
maltose, lactose, and sucrose.
what is lactose?
made up of glucose and galactose, found only in dairy products, sometimes called “milk sugar.”
what is maltose?
made up of two glucose molecules, formed in large amounts as a product of starch digestion, very little is found in the foods we eat.
what is sucrose?
made up of fructose and glucose, “table sugar.”
how can disaccharides be digested?
they must be broken down to monosaccharides before they can be absorbed by cells of the intestines.
what are complex carbohydrates?
three or more monosaccharides linked together, often take the form of long or branched chains.
what are oligosaccharides?
3-10 linked monosaccharides.
what are polysaccharides?
chains (or polymers) of more than 10 monosaccharides.
what do most complex carbohydrates in our diet come from?
plants.
how can polysaccharides in plants function?
as a source of energy (starch) or as structure material (fiber).
what are starches?
a polysaccharide made up of many glucose units joined together by digestible bonds.
what are examples of starches?
amylose and amylopectin.
where are starches found?
grains, legumes, and starchy vegetables such as pease, potatoes, and corn.
what are fibers?
carbohydrates that include cellulose and hemicellulose, which make up plant cell walls and impart structure to the plant, humans lack the digestive enzymes to break down plant fiber, so it passes undigested through the digestive tract.
what are some fiber-rich foods?
whole grains, beans, vegetables such as winter squash, and fruit such as pears and raspberries.
what is glycogen?
a polysaccharide consisting of many glucose molecules, acts as storage form of glucose (carbohydrate) in animal tissue (liver and muscles).
what happens when glucose is needed?
the liver breaks down the glycogen into glucose and releases it into the blood.
what is the use of glycogen in skeletal muscles?
broken down to supply fuel for contracting muscles during intense exercise.
where is the energy found in carbohydrates from?
the sun.
what is photosynthesis?
the process by which plants convert the energy of the sun into chemical energy in the form of carbohydrates.
what is the endosperm?
the element of a grain that contains the highest amount of starch and protein, all hat remains when a grain is refined.
what is bran?
the element of a grain that contains the majority of dietary fiber and a significant amount of B vitamins and minerals.
what is the germ?
the embryo of the seed that germinates and grows and contains essential fatty acids and a number of B vitamins and minerals.
what are the 2 purposes of refining grains?
(1) helped keep flour from spoiling (because the germ becomes rancid quickly after being exposed to air) and (2) provides a desirable consistency (soft smooth texture).
what id the downside of refining grains?
the bran and germ contain the majority of healthful vitamins, minerals, phytochemical, and fiber
what is the whole grain stamp?
a front-of-package icon that tells consumers that a product contains at least 8 grams of whole grains per serving for 50% and at least 16 grams of whole grains per serving for 100%.
what total carbohydrate to fiber ration is advocated by the American Heart Association?
10:1.
what carbohydrates are the only ones that can be absorbed by the cells of the small intestine?
monosaccharides.
what enzyme breaks down starch molecules into shorter polysaccharides in the mouth?
salivary amylase.
what enzyme digests starch into oligosaccharides and maltose in the small intestine?
pancreatic amylase.
what is maltase?
the enzyme that breaks maltose down into two glucose units.
what is sucrase?
the enzyme that breaks sucrose down into fructose and glucose.
what is lactase?
the enzyme that breaks lactose down into glucose and galactose.
what happens to disaccharides after being broken down?
they are absorbed by the cells lining the small intestine and travel into the blood for distribution throughout the body.
what is lactose intolerance?
a condition characterized by diminished levels of the enzyme lactase and subsequent reduces ability to digest the disaccharide lactose.
what is the one monosaccharide that every cell in the body can use as fuel?
glucose.
what does the pancreas secrete after eating, and therefore having a rise in blood glucose levels?
insulin.
what is insulin?
a hormone produced by the pancreas that removes glucose from the bloodstream for use by cells.
what is glucagon?
a hormone produced in the pancreas that increases glucose availability in the blood in response to low blood glucose.
what are resistant starches?
a starch that remains intact after cooking, is not broken down by human digestive enzymes, and is not absorbed from the intestines.
what are the effects of a diets high in resistant starches?
improved responsiveness to insulin and a longer feeling of fullness.
what are some functional roles of added sugars?
preserving foods, browning baked items, and improving texture and appearance.
what is high fructose corn syrup made of?
55% fructose in relation to glucose (as opposed to 50%).
what accounts for the majority of added sugar in foods consumed in the United States?
beverages.
what are the two main issues are associated with excessive consumption of foods with added sugars?
adds substantial calories without adding significant bulk, provide no additional vitamins or minerals and therefore decreasing the nutrient density of foods.
what do the dietary guidelines for Americans recommend in regards to the percentage of calories from added sugars?
consume less than 10% of total calories from added sugar.
what are dental caries?
the progressive destruction of tooth enamel, and ultimately the tooth itself, through the action of bacteria on carbohydrates in the mouth, also called cavities or tooth decay.
what are the two types of sugar alternatives?
nutritive sweeteners and nonnutritive sweeteners.
what are nutritive sweeteners?
a source of calories, include polyols (alcohol forms of sugar), made from naturally occurring sugars in plants, provide 4 kcal per gram, poorly absorbed by the body, so excessive consumption of sugar alcohol often causes GI symptoms.
what are nonnutritive sweeteners?
not a source of calories, include aspartame products, which is made by linking two amino acids, 4 kcal per gram, but due to the intense sweetness, very little is used to achieve the same level of sweetness.
what is the recommended fiber intake per day for men under 50 years?
38 grams per day.
what is the recommended fiber intake per day for women under 50 years?
25 grams per day.
what is the average consumption of fiber per day for Americans?
17 grams per day.
where is fiber typically found in the plant?
in and around the cell walls.
what is soluble fiber?
a type of fiber that dissolves in water and often forms a viscous gel that acts to slow digestion and lower blood cholesterol and the risk of heart disease, readily fermented by bacteria in the colon.
what is insoluble fiber?
a type of fiber that does not dissolve in water, increases transit time through the GI tract, and contributes to “bulk” to still, fostering regular bowel movements.
what is dietary fiber?
naturally occurring carbohydrates and lignin from plants that cannot be digested in the intestinal tract or for which digestion is delayed.
what are the new fda regulations for dietary fiber on nutrition labels?
the fibers are naturally part of the intact food and certain added synthetic or isolated fibers that benefit human health, they must have been demonstrated to have at least one beneficial effect, such as lowering blood cholesterol or improving bowel function.
what are benefits of consuming insoluble fiber?
it softens stool and thereby helps maintain regular bowel movements, reduces the risk of hemorrhoids and diverticular disease, and has been shown to decrease the risk of diabetes.
what are benefits of consuming soluble fiber?
it has been shown to rescue the risk of coronary heart disease, slows the emptying of food from the stomach into the small intestine, which may extend the sensation of fullness following a meal and reduce the rise in blood glucose, which may improve blood glucose control in those with diabetes, and may rescue the risk of some types of cancer.
