Chapter 5 Flashcards
Carbohydrate family includes
starch, fiber, and sugar
Most of the carbohydrates are composed of
carbon, oxygen, and hydrogen
The main source of carbohydrates
Plants
General formula of carbohydrate
Cn(H2O)n or (CH2O)n
Simpler form
Monosaccharide单糖, disaccharide二糖
Complex form of carbohydrate
Polysaccharide
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转朱阁，低绮户，照无眠。不应有很，何事长向别时圆。人有悲欢离合，月有阴晴圆缺，此事古难全。但愿人长久，千里共婵娟。
Monosaccharide are
Glucose, Fructose, galactose
Glucose葡萄糖
The most abundant monosaccharide. Can form disaccharide or poly when they glucose link together.
Glucose in blood
Blood sugar
Fructose果糖
Found in fruits, vegetables, honey, and higher fructose corn syrup. Used to sweeten the products, we eat it almost everyday.
Galactose半乳糖
Usually link with glucose and form lactose which is found in diary products.
Disaccharide
Carbohydrates which have two monosaccharide. The reaction is condensation reaction. During the reaction, a H2O is formed and released.
Disaccharide includes
Lactose, sucrose, and maltose
Lactose, sucrose, and maltose contains
Lactose contains beta, maltose and sucrose contains alpha
Beta bonds differ from alpha
Beta bonds are not easily be broken by the digestive enzyme for absorption in small intestine.
Maltose 麦芽糖
Formed by two glucose molecules joined by alpha. Those sugar provide energy for seeds to grow.
table sugar
蔗糖，食用糖
Sucrose 蔗糖
Common table sugar, glucose and fructose linked together by alpha bond. Large amount of sucrose is found naturally in plants. Can be purified into various degrees like brown, white, and powdered sugar.
Lactose
Primary sugar in milk or milk products, glucose and galactose joined together by beta bonds. This will cause intestinal gas, bloating.
Polysaccharide 多糖
Contain thousands of glucose molecules. It includes some digestible sugar like starch, and some indigestible sugar like fiber. It depends on whether it is linked by beta or alpha.
Oligosaccharide 低聚糖
Contains 3-10 sugar units.
Which oligosaccharide is in the nutrition importance?
Stachyose and raffinose.
Where can we find oligosaccharide?
Onion, broccoli, cabbage, whole wheat, legumes.
What happened when we eat oligosaccharide?
It is linked by beta bonds, so it cannot be broken. Therefore, the undigested sugar pass into the large intestine and produce gas and other by-products.
Digestible polysaccharide
Starch and glycogen
Starch in plants
Is the storage form of the glucose in plants.
Two types of starch in plants
amylose and amylopectin. Source of energy for plants and the animals which eat plants. Found in starchy products like potatoes, rice, and pasta.
Typically ratio of amylose and amylopectin
1:4
Similarity between amylose and amylopectin
Are linked with alpha bonds.
Differences between amylose and amylopectin
Amylose is a linear and unbranded chain of glucose molecules that contains only one type of alpha bond(1-4). Amylopectin is highly branched structure of glucose molecules, and it contains two types of alpha bonds (1-4 and 1-6)
Alpha 1-4 is broken by ______.
Amylase enzymes produced in mouth and pancreas.
Alpha 1-6 is broken by ______.
Intestinal enzyme called alpha-dextrinase.
Glycogen
The storage form of carbohydrates in human and other animals body. Glucose linked by alpha bonds.
The structure of glycogen
It is similar to amylopectin, but even more brunched. It can be quickly broken up by enzymes in body cells where it is stored.
Major storage sites of glycogen
Muscle and liver cells.
Indigestible polysaccharide
Dietary and functional fibers
Fibers are composed primarily by non starch polysaccharide:
Cellulose, hemicellulose, pectins, gums, mucilages.
Insoluble fiber
Cellulose, hemicellulose, and lignins
Soluble fiber
Mucilages, pectins, gums, some hemicellulose
Nutritive sweeteners
Can be metabolized to yield energy. Monosaccharide and disaccharide are classified as nutritive sweeteners.
Non nutritive sweeteners
Provide no energy.
Sugar alcohol
Nutritive sweeteners used in sugarless gums and candies.
Large amount of sugar alcohol can cause
Diarrhea.
The metabolize and absorption of sugar alcohol
are more slowly than sucrose to form glucose.
Non-nutritive sweeteners provides
low calories or non-calory. Fit for diabetes and people who trying to lose weight.
ADI
Acceptable Daily Intake.
Saccharin 糖精
The oldest alternative sweetener. 300 times sweeter than sucrose
Aspartame
Lose the sweet taste in high temperature.
Neotame
Are allowed to use in variety of food by FDA, especially in baked food and nonalcoholic beverage. It is heat stable , can be used in cooking as tabletop sweetener。
Which sugars are classified as nonnutritive sweetener?
Saccharine, Aspartame, Neotame, Acesulfame-K, Sucralose, Tagatose, Stevia, Luo Han Guo.
Recommended Carbohydrate Intake
Adults 130g/Day
45% - 65% of total energy intake
Age up to 50, Female 25g, Male 38g.
over 50 21g, 30g
Adequate of fiber aimed to reduce
diverticular disease, cardiovascular disease, and other chronic disease.
Nutritious diet with ample carbohydrate should includes
6 oz grains, 2.5 cups vegetables, 2 cups fruits, 3 cups of milk.
The functions of digestive carbohydrates
They are broke down to glucose and provide the primary source of energy, spare protein from use as an energy source, and prevent ketosis.
How much energy does glucose provide?
4 kcal/gram
Provide Energy
Red blood cells and cells of central nervous system derive most of the energy from glucose
Spare protein from use as an energy source
Amino acids are used to build body tissues and perform other vital functions, but it must get enough energy from glucose. If one does not gain adequate carbohydrate, the body will be forced to break down amino acids in muscle tissues and other organs to make glucose.
Gluconeogenesis
The process that animo acids in muscle tissue and other organs break down to make glucose.
Minimal intake of carbohydrate
50 - 100g/day
dehydration
脱水
Function of fiber
It helps to integrity GI tract and overall health. It prevent the constipation and diverticular disease, and enhances the body weight, blood glucose level and blood cholesterol level.
Promoting bowel health
When adequate fiber and fluid is consumed, the stool will become large and soft, because fiber absorbs water. In opposite, the stool will become small and hard. The constipation will caused. Overtime, constipation will become hemorrhoid.
Cholesterol
胆固醇
Digestion of carbohydrates
Begins in the mouth, an enzyme called saliva amylase in the saliva breaks the starch into polysaccharide and disaccharide when chewing. And the saliva amylase is inactivated by the acid in stomach, the digestion of carb is stopped until it reach the small intestine. The polysaccharide is digested by pancreatic amylase and dextrinase. And disaccharide is broken into monosaccharide by another specialized enzyme in small intestine.
Enzymes for lactose, maltose, and sucrose
Lactase, maltase, and sucrase.
Carbohydrates in large intestine
Monosaccharide that occur in food does not need further digestion in small intestine. Indigestible carbohydrate cannot be broken down by the enzyme in small intestine. It will pass into large intestine and be fermented with the bacteria into acid, gas or excrete fecal waste.
People who have diarrhea should
Avoid lactose for a week, because of temporary lactose maldigestion and malabsorption
Absorption of fructose
Is taken by the absorptive cells via facilitated diffusion. A carrier is used, but no energy input. The process is much slower than the glucose and galactose
Absorption of glucose
Glucose is transported in bloodstream for the use by the cells of the body. If blood glucose is adequate for use, the extra glucose will be stored in the liver(or muscle) as glycogen.
High fiber consumption can cause
High fiber consumption with low amount of fluid will cause dry and hard stools which are painful to eliminate. Overtime, this will cause hemorrhoids.
Very-high-fiber intake may cause
reduce the absorption of certain minerals and cause deficiency. Because some minerals will bind to fibers and prevent the absorption of minerals.
High sugar diet can cause
Increase risk of weight gain, obesity (high sugar does not directly cause diabetes), and cardiovascular(心血管疾病). Also cause hyperactivity in children. Also cause dental caries(龋齿)
Primary lactose intolerance
The insufficiency of lactase. Can cause abdominal pain, bloating gas, and diarrhea after consuming lactose.
Secondary lactose intolerance
Occurs when conditions of the small intestine. It also cause gastrointestinal symptoms, but it is temporary.
Diabetes
If a fasting blood glucose level is higher than 126 mg/lb, it is classified as diabetes.
Hypoglycemia
If glucose level is lower than 50 mg/lb, it is a condition of hypoglycemia
What is the most important organ to control the amount of blood glucose level?
Liver is the most important in controlling the amount of the glucose in bloodstream. It is the first screen with sugar and determine how much sugar enter the bloodstream after a meal. Pancreas is also important, it begins to release small amounts of insulin as soon as a person starts to eat.
Metabolic Syndrome
It is grouped of factors that increase the risk of type 2 diabetes and cardiovascular disease
Two types of hypoglycemia
Fasting hypoglycemia and reactive hypoglycemia.
Reactive hypoglycemia
Is caused by exaggerated insulin response after eating.
Symptom of hypoglycemia
Irratability, sweating, anxiety, weakness, headache, and confusion in 2 to 5 hours after meal.
Fastering hypoglycemia
A condition of low blood glucose after fasting for 8 hours or more.
Glycemic Index
It is a ratio of the blood glucose response of a given food compared with a standard. It is influenced by the food’s starch structure, fiber content, food processing, physical structure, temperature, and amount of protein and fat in the meal.
Foods with high GI
Potatoes, bread, Gatorade, short-grain white rice, honey, and jelly beans.
