Nutrition - Chapter 5 - Carbohydrates: Sugars, Starches, and Fiber
five signs of metabolic syndrome
1. elevating fasting triglycerides 2. high fasting blood glucose 3. hypertension 4. low fasting HDL cholesterol 5. large waist circumference
according to 2020-2025 dietary guidelines for Americans, people should limit their added sugar intake to less then what percent of total calories
10%
RDA for carbohydrates
130 g/day
each gram of a sugar alcohol supplies how many kcal on average?
2 kcal
glycogen is found in (plant/animals)
animals
aspartame
artificial sweetener made from two amino acids (phenylalanine and aspartic acid) and methanol
what artificial sweetener must patients with PKU avoid?
aspartame
type 1 diabetes
autoimmune disease that results in destruction of the beta cells of the pancreas, so the individual must obtain an exogenous source of insulin regularly
how can people reduce their risk of type 2 diabetes?
avoiding excess body fat, exercising daily, improving their diets
why is bloating a common experience after eating foods containing oligosaccharides?
bacteria in the colon use them for fuel, in turn created waste products as gases
type 2 diabetes
beta cells of the pancreas produce insulin, but the hormone's target cells are insulin-resistant, leading to elevated blood glucose levels
benefits of soluble fiber
binds to bile in intestines, can aid in lowering blood cholesterol, may reduce risk of heart disease
hypoglycemia
blood glucose level is too low to provide enough energy for cells
hemoglobin A1c
blood test to measure the amount of glucose that remains attached to the hemoglobin for the life of the red blood cell or about 2-3 months
what does pancreatic amylase do?
break down starch into maltose in the small inestine
what does the body metabolize for energy when glucose levels are low?
fat
poorly controlled diabetes is a major cause of...
heart disease, kidney failure, blindness, and poor blood circulation
epinephrine
hormone produced by the adrenal glands, secreted in response to declining blood glucose levels
insulin
hormone secreted by pancreatic beta cells that contributes to a decrease in blood glucose levels
glucagon
hormone secreted from pancreatic alpha cells that contributes to an increase in blood glucose levels
how are oligosaccharides used in the body?
human enzymes cannot readily break down oligosaccharides, so they are used as fuel by bacteria in the colon
what is the primary sign of diabetes?
hyperglycemia - hyper = excess - glycemia = blood glucose
what happens to glucose when it is ingested?
if cells need energy, the glucose goes to those cells where it is metabolized if cells don't necessarily need energy, the body stores the extra glucose as glycogen (liver can also convert excess glucose into fat)
what makes a carbohydrate simple?
if it contains either only one or two units of sugar (monosaccharide or disaccharide)
what makes a carbohydrate complex?
if it has many units of sugar linked together (polysaccharide)
how do diets rich in soluble fiber reduce risk of cardiovascular disease?
improving blood lipid levels, lowering blood pressure, and reducing markers of inflammation
lactose intolerance
inability to digest lactose properly because of a deficiency in the enzyme lactase
what do beta cells produce?
insulin
how does insulin work?
insulin lowers blood glucose by facilitating uptake and the use of glucose by muscle and fat cells
what can lead to hypoglycemia?
intake of complex and whole grains, healthy fats, protein, and fiber (yogurt, brown rice, whole grain bread)
what can lead to hyperglycemia?
intake of mostly carbohydrates, simple sugars, no fiber (gatorade, candy, pretzels, soda)
where are fibers used in the body?
intestinal bacteria in the large intestine break down and metabolize (ferment) soluble fiber for energy
why does physical activity improve diabetes control?
it increases glucose uptake by muscles, reducing blood glucose levels and improving the body's insulin response
why is glucose so important?
it is a primary fuel for muscle and other cells (like red blood cells and brain cells)
starch and glycogen
large storage forms of glucose found in plants and animals
hepatic portal vein transports substances directly to the...
liver
starch is digested into
maltose
in industrial nations, people tend to eat (more/less) highly refined starches and added sugars?
more
why are most animal foods not sources of glycogen?
muscle glycogen breaks down quickly
what are the major sites for glycogen formation and storage?
muscles and liver
can the body use fatty acids to make glucose?
no
is fiber an essential nutrient?
no
is fiber digested in the small intestine?
no
eating high-fiber diets may reduce a person's risk of...
obesity, type 2 diabetes, certain intestinal tract disorder, and cardiovascular disease
how do plants make carbohydrates?
photosynthesis, using the sun's energy to combine carbon, oxygen, and hydrogen atoms from carbon dioxide and water
only ______ provides dietary fiber
plant foods
starch is found in (plant/animals)
plants
fad
practice that gains widespread popularity rapidly then loses its appeal when people tire of the behavior and follow a newer trend
most common oligosaccharides in food
raffinose and stachyose
eating insoluble fiber can make people have more (regular/abnormal) bowel movements?
regular
fructose
same chemical formula as glucose, but a slightly different structure, often found in fruits
galactose
same chemical formula as glucose, but a slightly different structure, often found in lactose (milk)
what increases someone's risk for developing type 2 diabetes?
sedentary lifestyle, overweight, genetics, certain ethnic groups
in which organ of the GI tract are all disaccharides and complex carbohydrates broken down into monosaccharides?
small intestine
what is the main site for carbohydrate digestion and absorption?
small intestine
where does absorption of monosaccharides occur?
small intestine
benefits of insoluble fiber
soften stool and accelerate passage of contents though the GI tract, decrease transit time
why have nonnutritive sweeteners been a subject of controversy?
some have been found to be harmful
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
nutritive sweeteners
substances that sweeten and contribute energy to foods
alternative sweeteners
substances that sweeten foods while providing few or no kilocalories
what artificial sweetener is considered useful in baking because it resists destruction by heat?
sucralose
examples of a nutritive sweetener
sucrose, fructose, honey, molasses, or high fructose corn syrup
examples of alternative sweeteners
sugar alcohols - sorbitol - xylitol - mannitol
why does sugar alcohol not supply more kcal/g?
sugar alcohols are not fully absorbed by the intestinal tract
nonnutritive sweeteners
sugar substitutes that provide negligible, if any, energy
what is much of the sucrose in the American diet refined from?
sugarcane and sugar beets
what contributes to a plant's fiber content?
supportive structures and protective seed coats
why do humans crave sweet foods?
sweet foods usually contain carbohydrates, which are a major source of energy for cells
lipolysis
the breakdown of fats and other lipids by hydrolysis to release fatty acids
ketone bodies
the by-products of the incomplete breakdown of fat
what is the difference between drinking orange juice and a soda if they both supply similar amounts of sugars?
the orange juice will contain micronutrients and antioxidant phytochemcials to the diet, which the soda will not
hemoglobin
the protein in red blood cells that carries oxygen
why is refined sugar not a good source of carbohydrates?
the refining process strips away the small amounts of vitamins and minerals in unrefined sugar (empty calories)
the FDA permits a grain to be labeled as "whole grain" if it contains...
the starchy endosperm, oily germ, and fiber-rich bran seed components in the same relative proportions as they exist in the intact grain
why is it important that intestinal bacteria can use fiber for energy?
their by-products can sometimes be used by the cells that line the large intestine for energy
does HFCS or sucrose have more fructose?
they have the same amount
how do cells get energy from glucose?
they metabolize glucose to release the energy stored in the chemical bonds
why are added sugars added to foods?
to contribute to flavor, browning and tenderness, and preservation of food
how can the liver use simple sugars?
to make glycogen or fat, can also release glucose into the bloodstream if the body needs energy
what do plants and animals use complex carbohydrates for?
to store energy or make certain structural components
glycemic index
tool to measure the body's insulin response to a carbohydrate-containing food
glycemic load
tool to measure the body's insulin response to a carbohydrate-containing food; similar to the glycemic index, but also factors in a typical serving size of the food
carbohydrates provide food for mouth bacteria that can cause...
tooth decay
T/F: fructose is sweeter than glucose
true
T/F: it is better to count carbohydrates thanes the glycemic index for choosing foods
true
T/F: refined starches often do not satisfy hunger
true
gestational diabetes
type of diabetes that can develop during pregnancy
under what conditions does the body form excessive keystone bodies?
when there is not enough glucose to metabolize for cellular energy
a meal plan for diabetes focuses on moderate intakes of...
whole grains, vegetables, fruits, legumes, poultry, fish, and low-fat dairy foods
do carbohydrates contribute to excess body fat?
- carbohydrate calories are easier to eat in excess than fat or protein - carbohydrate consumption reduces the body's ability to expend energy and burn calories
AI for fiber
38 g/day for men 25 g/day for women
each gram of mono- or disaccharide supplies how many kcal?
4 kcal
each gram of starch supplies how many kcal?
4 kcal
most healthcare professionals recommend an individual with diabetes having meals with how many grams of carbohydrates?
45-60g
what percent of calories in the diet should come from carbohydrates?
45-65%
AMDR for carbohydrates
45-65% of total calories
what percentage of kcal does a typical American get from carbohydrates?
47%
the standard to which the glycemic index compares all foods to is
50 g of digestible carbohydrates
according to the ADA, people with diabetes should try to maintain HbA1c levels below
7%
hypoglycemia may be diagnosed when the blood glucose level is
70 mg/dL
glucose
C6H12O6, most important monosaccharide in the body, often found in fruits and vegetables
T/F: since fiber is not digested, it also cannot be metabolized by gut microbiota
false
metabolic syndrome
a cluster of conditions that increase the risk of heart disease, stroke, and diabetes
high fructose corn syrup (HFCS)
a highly sweet syrup that is manufactured from corn
therapeutic lifestyle changes (TLC)
actions, such as avoiding excess body fat, exercising daily, and improving the diet, that promote health and reduce risk for chronic disease
ketosis
adaptive metabolic state in which the body primarily uses fat for energy
oligosaccharides
carbohydrate made up of 3 to 10 monosaccharide units
diets high in fiber, particularly soluble fiber, reduce the risk of _____ by improving blood lipid levels, lowering blood pressure, and reducing markers of inflammation
cardiovascular disease
how does glucagon work?
causes the liver to convert stored glycogen into glucose, which is released into the bloodstream
what additional role do carbohydrates play in the body (apart from being a source of energy)?
cellular membranes have carbohydrates, so they serve as the "glue" that holds cells together in tissues
examples of dietary fiber
cellulose, pectin, gums, lignins
pancreatic islet
cluster of endocrine cells in the pancreas that secretes hormones to regulate glucose metabolism
dietary fiber
complex carbohydrates that cannot be broken down by the digestive system
A1c
component of hemoglobin that attracts some glucose in the blood
what type of reactions form disaccharides?
condensation
hyperinsulinemia
condition in which the pancreas releases an excessive amount of insulin; over time, condition may contribute to the development of type 2 diabetes
ketoacidosis
condition that occurs in the absence of insulin when excess acetoacetate and betahydroxylbutane in the bloodstream lower the blood's pH
what does salivary amylase do?
converts starch into maltose in the mouth
T/F: sugary foods cause hyperactive behavior
false
potential outcome of consuming alternative sweeteners and why
diarrhea, because sugar alcohol are not fully absorbed by intestinal tract
lactase
enzyme that breaks down lactose molecule into glucose and galactose
maltase
enzyme that splits maltose molecule into two glucose molecules
sucrase
enzyme that splits sucrose molecule into glucose and fructose
primary risk factors of metabolic syndrome
excess abdominal fat and insulin resistance
major signs and symptoms of hyperglycemia
excessive thirst, frequent urination, blurred vision, poor wound healing
T/F: if a nutritive sweetener is the first or second ingredient on the product's ingredient label, the food probably does not contain a lot of added sugars
false
T/F: insulin is secreted more readily when fats and proteins are consumed, rather than carbohydrates
false
any fiber that is not used by microbiota comes out of the body as...
feces
how does gestational diabetes affect the baby?
fetus receives too much glucose from the hyperglycemic mother -- fetus gains weight rapidly and can be abnormally heavy at birth
a gram of fiber supplies how many kcal?
fewer than 3 kcal
soluble fiber
forms of dietary fiber that dissolve or swell in water
insoluble fiber
forms of dietary fiber that generally don't dissolve in water
what do alpha cells produce?
glucagon
galactose and fructose are converted to what in the liver?
glucose
sucrose
glucose + fructose
lactose
glucose + galactose
maltose
glucose + glucose
how are monosaccharides absorbed?
glucose and galactose are absorbed via active transport and fructose passes via facilitated diffusion
three most important dietary monosaccharides
glucose, fructose, galactose
diabetes mellitus
group of serious chronic diseases characterized by abnormal glucose, fat, and protein metabolism
women with poorly controlled diabetes or gestational diabetes are more likely to...
have miscarriages, stillbirths, and premature deliveries