Transcript Chapter ---- Carbohydrates: Sugar, Starches and Fiber

Chapter 4
Carbohydrates:
Sugar, Starches and
Fiber
Carbohydrates in Our Diet
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Carbohydrates make up most of the energy
in a healthy diet.
Grains are sources of carbohydrates.
Refined carbohydrates lack fiber and many
rich nutrients.
Unrefined carbohydrates are healthier to eat.
Unrefined and Refined Foods
Whole Grains
Whole grains are made up of
 bran: containing fiber and vitamins
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germ: mainly protein and vitamins
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endosperm: starch, protein, vitamins, and
minerals
Empty Calories
Many processed/ready to
eat foods contain added
sugar that reduces nutrient
density (empty calories)
Empty Calories:
Energy with few nutrients. Compare to
kiwi soda has much less vitamins and
minerals
Types of Carbohydrates
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Glucose, fructose and galactose are simple
carbohydrates.
Glucose is the blood sugar and found in cells.
Sucrose is made up of a molecules of
glucose and a molecule of fructose is a
disaccharide.
Maltose is made up of two glucose
molecules.
Lactose contains one glucose and one
galactose.
Monosaccharides
Dissaccharides
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Simple carbohydrates have one or two
molecules of single sugars.
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maltose, sucrose and lactose are simple
carbohydrates.
Glucose, galactose and fructose are single
carbohydrates.
Glucose is the blood sugar and source of energy
from carbohydrates.
Galactose is milk sugar important in producing
milk in lactating women and animals.
Dissaccharides
Complex Carbohydrates
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Complex carbohydrates contain many
molecules of glucose.
Starch, glycogen and cellulose are complex
carbohydrates.
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Starch and glycogen are synthesized by a chain
of glucose molecules joined by alpha 1–4 and 1–6
bonds they also have branched chain attached.
Fiber (cellulose) is a chain of glucose molecules
joined by beta 1–4 bond that human intestine
does not produce the enzyme to digest it.
Complex Carbohydrates
Glucose is Produced by Plants through
Photosynthesis
Chemistry of Carbohydrates
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Starch is stored in the grains, stems and root
of the plant.
Fiber is found in the bran of the grains, stem,
leaf, and other structures of the plants.
There are two types of fiber in the plant
varieties:
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Soluble fiber in fruits, oats and legumes
Insoluble fiber mostly in grains and vegetables
Soluble and Insoluble Fiber
Beans:
Pectin:
Soluble fiber found in
fruits and vegetables
Soluble fiber and small
Polysaccharides that can NOT
be broken down by human
digestive enzyme
Fiber
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Humans do not produce enzyme to digest
fiber—therefore, no calories from fiber.
Fiber provides many health benefits to
humans:
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Insoluble fiber:
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provides bulk in the intestine to ease elimination.
prevents constipation, diverticulitis, appendicitis, and
may prevent colon cancer.
Soluble fiber:
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combines with bile, eliminate it,
preventing elevated blood cholesterol
Carbohydrate Digestion & Absorption
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Mouth
Small intestine
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Absorption through the small intestinal villi
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Digestive enzymes from pancreas
Active absorption
Passive diffusion
Large intestine
Elimination of undigested starch and fiber
Modification of intestinal microflora
Role of the pancreas
Carbohydrate Digestion
Glycemic Index
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Different carbohydrate containing foods are
absorbed at different rate.
Simple carbohydrates and potato starch are
absorbed fast and make a large spike in the
blood sugar (a high glycemic index) causing
a high insulin response.
Beans, legumes and some mixed foods are
absorbed slower and have lower glycemic
index.
Glycemic Index
Carbohydrate Functions
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Getting glucose to the cells, role of insulin.
Problems of glucose metabolism
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Type 1 diabetes, pancreases loss of insulin
producing ability. Autoimmune problem
Type 2 diabetes
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increased body fat cells causing resistance to insulin
delivery of glucose to the cells
Role of insulin in regulating blood glucose levels
Functions of Monosaccharide
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Absorbed monosaccharids enter liver where
galactose and fructose are converted to glucose.
Glucose enters the blood and circulates.
Insulin helps glucose enter the cells for energy.
Glucagon helps excess blood glucose return to
liver and muscles to form storage and form
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glycogen
Glucose also is a part of genetic DNA, RNA,
ATP and other functional molecules in the body.
Blood Glucose Regulation
Cellular Carbohydrate Metabolism
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In cells, glucose is metabolized to produce
energy.
There are two pathways for producing energy:
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Anaerobic pathway (incomplete metabolism) with
production of lactate.
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Happens in absence of oxygen. Resulting in lower energy
production
Aerobic pathway (complete metabolism) with end
products of CO2 and H2O.
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Happens when oxygen is present. Produces lot more energy.
Cellular Respiration
Breakdown of Fat and Protein
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In the absence of carbohydrates body breaks down
protein to form glucose to feed the brain.
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About ½ of amino acids skeletons can produce glucose
Other amino acids produce ketone
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acidic molecules that changes the pH of body environment to
acid.
Body also breaks down the stored fat to provide
energy for body needs
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Fat breakdown in the absence of carbohydrates results in
ketone production.
Ketone bodies are harmful to the body and are excreted
through the urine.
Severe ketosis can occur with untreated diabetes and can
cause coma and even death.
Ketone Formation
Carbohydrates and Health
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Are carbohydrates good or bad for you?
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What kind of carbohydrates are beneficial to
health?
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Whole grains, complex carbohydrates foods are healthy
carbohydrates.
What kind are not healthy carbohydrates to
consume?
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Refined carbohydrates and food with added sugar are
not healthy and may cause risk of chronic diseases.
Diabetes
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Carbohydrates are generally blamed for
diabetes. The interesting fact is again which
kind of carbohydrates are to be blamed.
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Whole grain and complex carbohydrates prevent
type 2 diabetes by preventing fat cells
accumulation in the body.
Refined carbohydrates increase empty calories in
the diet may cause weight gain, increase
resistance to insulin causing type 2 diabetes.
Diabetes
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Type 1 diabetes is due to lack of production
of insulin from pancreas causing blood
glucose to elevate.
It can be controlled by a diet very low on fast
absorbing starches (potato) and refined
sugars.
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A diet high in fiber and whole grains help slow
absorption and prevent fast rise in blood sugar.
In sever cases insulin must be injected to regulate
blood sugar levels.
Blood Glucose Levels in Diabetes
Diabetes
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Incidences of diabetes in the US is on the rise.
Certain racial groups are more susptible to
diabetes than others.
Lifestyle, dietary habits physical activity and
environment also play a role.
Managing diabetes with diet, exercise and
medication.
Symptoms and complications of diabetes.
Incidence of Diabetes
Other Health Problems
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Hypoglycemia:
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Reactive hypoglycemia
Fasting hypoglycemia
Due to lack of food intake
Dental caries:
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After rise in blood glucose due
to consumption of high
carbohydrate foods, then rapid
fall to abnormally low level due
to too much insulin secretion
Dental hygiene
Refined sugars
Carbohydrates and weight management:
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Which kind to consume?
Carbohydrates and Weight Management
Fat added to high carbohydrate
food increases calorie intake
A diet high in sugar-sweetened beverages
increase calorie intake because beverages
do NOT produce satiety
Carbohydrates & Body Weight
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Carbohydrates and weight management.
Role of refined carbohydrates in storage of fat.
Role of insulin in body fat accumulation.
The consequence of low or no carbohydrate
diets?
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Ketosis and ketogenic diets
Role of ketones in weight loss
Benefits and harms of nonnutritive sweeteners.
Nonnutritive Sweeteners
ADI: Acceptable
Daily Intake
Carbohydrates and Heart Disease
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Diets with high sugar, added sugar
glucose or any simple sugar raise
blood sugar, cholesterol and the risk
of heart disease.
High fiber containing diets with both
soluble and insoluble fiber reduce the
risk of heart disease.
Carbohydrates and Heart Disease
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Consuming foods high in soluble fiber reduce
cholesterol synthesis by liver.
Soluble fiber in legumes, fruits, oats, brown
rice, etc. bind with bile in the intestine,
removing it from the body preventing bile
reabsorption, and cholesterol re-synthesis.
Soluble fiber may also reduce blood
cholesterol by other means.
Cholesterol and Soluble Fiber
Carbohydrates and Heart Disease
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Diets with high insoluble help reduce risk of
heart disease by:
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Reducing absorption of starch and sugars.
Keeping blood glucose normal
Reducing food intake by filling the stomach and
reducing the appetite.
Preventing obesity
Reducing blood pressure.
Preventing formation of diverticula
Diverticula
Out-pouches form in the wall of colon where fecal matter can accumulate,
causing irritation, pain and inflammation
Intestinal Health and Fiber
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Insoluble fiber is not digested, absorbs water
in the intestine and increase in volume
conferring benefits:
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Softens the stool, making elimination easy.
Preventing constipation, diverticulitis, appendicitis,
hemorrhoids, and possibly colon cancer.
Speed up the movement of waste materials from
the bowl.
Modify the bowl micro flora environment
positively.
Meeting Carbohydrate Needs
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Carbohydrates intake is to meet the needs of:
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Recommendations are:
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Adequate blood glucose levels to meet the brain, red
blood cells and nerves energy requirements (about
300 grams/day).
Minimum carbohydrate intake to prevent ketosis
is 100 grams/day
45% – 65% of total daily calorie intake should come
from complex carbohydrates.
In the US diet, the right percentage of calories
consumed from carbohydrates, but it is mostly
refined or added sugars.
Healthy Carbohydrate Choices
Choosing Carbohydrates Wisely
End of Chapter 4
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