The Carbohydrates

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The Carbohydrates

• Sugar, Starch,
• Glycogen, and Fiber

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Introduction

• Carbohydrates meet your bodys energy needs
• Feed your brain and nervous system
• Keep your digestive system fit
• Within calorie limits, help keep your body lean
• Together with fats and protein, digestible
  carbohydrates add bulk to foods
• Indigestible carbohydrates yield little or no
  energy but provide other benefits

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A Close Look at Carbohydrates

• Carbohydrates contain energy that plants captured
  through photosynthesis
• Photosynthesis makes use of chlorophyll to
  capture energy and sunlight
• In this process, water donates hydrogen and
  oxygen, and carbon dioxide donates carbon and
  oxygen
• Water and carbon dioxide combine to form the
  sugar glucose

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A Close Look at Carbohydrates

• Glucose produced by photosynthesis provides
  energy for the work of all parts of the plant
• Plants do not use all the energy stored in their
  sugars
• Some remains available for use by the animal or
  human that consumes the plant
• Carbohydrates are the first link in the food
  chain that supports all life on Earth

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A Close Look at Carbohydrates

• Carbohydrate-rich foods come almost exclusively
  from plants
• Milk is the only animal-derived food that
  contains significant amounts of carbohydrate

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Introduction

• Complex carbohydrates
• Starch and fiber
• Simple carbohydrates
• Sugars

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A Close Look at Carbohydrates

• Sugars
• The three single sugars (monosaccharides) are
  glucose, fructose, and galactose
• Fructose is the sweet sugar of fruit
• Galactose is a component of milk sugar
• Glucose, fructose, and galactose all have the
  same number and kind of atoms arranged in
  different ways

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A Close Look at Carbohydrates

• The three double sugars (disaccharides) are
  lactose, maltose, and sucrose
• Lactose is milk sugar
• It is made of glucose linked to galactose
• Maltose has two glucose units
• It appears wherever starch is being broken down
• Sucrose is table sugar, which is obtained from
  sugar beets or sugar cane
• It is made of glucose linked to fructose

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A Close Look at Carbohydrates

• Single sugars are absorbed directly into the
  blood
• Disaccharides must be split into monosaccharides
  before they can be absorbed

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A Close Look at Carbohydrates

• All products of digestion are delivered to the
  liver
• The liver contains enzymes that modify nutrients,
  making them useful to the body
• The liver quickly converts fructose or galactose
  to glucose or to smaller pieces that can be used
  to make glucose, fat, or other needed molecules
• Glucose is the most used monosaccharide in the
  body

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A Close Look at Carbohydrates

• Most of the energy of fruits and vegetables comes
  from sugars
• However, eating them is not the same as eating
  concentrated sweets such as candy or colas

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A Close Look at Carbohydrates

• Starch
• Polysaccharides
• Starch
• Glycogen
• Fiber

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A Close Look at Carbohydrates

• Starch
• Starch is a plants storage form of glucose
• For example, corn stores clusters of starch
  molecules in granules and packs the granules into
  its seeds
• This insoluble starch will nourish the seed until
  the new plant is capable of photosynthesis
• Soluble glucose would be washed away by rain
• Starch is nutritive for people because they can
  digest starch to glucose and obtain the suns
  energy stored in its chemical bonds

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A Close Look at Carbohydrates

• Glycogen
• Glycogen is the storage form of glucose in
  animals
• The glucose chains that make up glycogen are
  longer and more highly branched than those that
  make up starch
• There is little glycogen in meats because it
  breaks down rapidly when the animal is
  slaughtered

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A Close Look at Carbohydrates

• Fiber
• Some plant fibers provide support to plant
  structures
• Fibers also retain water to protect seeds from
  drying out
• Most fibers are polysaccharides

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A Close Look at Carbohydrates

• Human digestive enzymes cannot break the bonds
  that hold together the sugar units of starch
• Thus, most fibers pass through the human body
  without providing energy
• Bacteria within the human large intestine can
  digest fibers to varying degrees by fermenting
  them
• The fibers are broken down to waste products
• Mainly small fatlike fragments that the colon
  absorbs

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A Close Look at Carbohydrates

• Soluble fibers dissolve in water
• Form gels (are viscous)
• Easily digested by bacteria in the human colon
• Found in barley, legumes, fruits, oats,
  vegetables
• Are associated with a lower risk of chronic
  disease
• Add a pleasing consistency to foods
• Thickening them

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A Close Look at Carbohydrates
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• Insoluble fibers do not dissolve in water
• Are less easily fermented
• The outer layers of whole grains, the strings of
  celery, etc. contain insoluble fibers such as
  cellulose and hemicellulose
• These fibers retain their structure and texture
  even after hours of cooking
• They aid the digestive system and ease
  elimination

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The Need for Carbohydrates

• The DRI committee recommends that 45 - 65 of
  daily calories come from carbohydrates
• Fats are not normally used as fuel by the brain
  and central nervous system
• Glucose is the primary energy source for nerve
  cells

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The Need for Carbohydrates

• Sugar
• Complex sugar molecules coat almost every cell of
  the body
• Sugar molecules dangle from many of the bodys
  fat and protein molecules
• Sugars can alter protein shape and function
  affect cell communication and may play roles in
  disease processes

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The Need for Carbohydrates

• Recommendations are for complex carbohydrates not
  refined sugars
• Complex carbohydrates contribute needed nutrients
  
• Pure sugars displace nutrient-dense foods from
  the diet
• Contain no other nutrients and thus are
  empty-calorie foods

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The Need for Carbohydrates

• Overuse of sugars may, in many obese people,
  alter blood lipids in ways that increase
  cardiovascular risks
• Such people should lose weight on a
  calorie-controlled diet
• High in whole grains, fruits, and vegetables

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The Need for Carbohydrates

• Most people should increase their intake of
  fiber-rich, whole foods
• Such as whole grains, fruits, and vegetables
• Refined white flour, sugars, and fats associated
  with heart disease should be used in moderation

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The Need for Carbohydrates

• Why Do Nutrition Experts Recommend Fiber-Rich
  Foods?
• Fiber-rich foods supply vitamins, minerals, and
  phytochemicals
• These foods also contain little or no fat
• Viscous fibers such as those found in apples have
  a significant cholesterol-lowering effect
• Insoluble (nonviscous) fiber such as that found
  in wheat bran is a stool-softener

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The Need for Carbohydrates

• Benefits of fiber include
• Promotion of normal blood cholesterol
  concentrations
• Modulation of blood glucose concentrations
• Maintenance of healthy bowel functions
• Help in the maintenance of a healthy body weight

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The Need for Carbohydrates

• Foods rich in viscous fibers lower blood
  cholesterol by binding with cholesterol-containing
  bile and carrying it out with the feces
• Bile is needed for digestion, so the liver
  responds to its loss by drawing on the bodys
  cholesterol to make more

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The Need for Carbohydrates

• Foods rich in viscous fibers lower blood
  cholesterol by binding with cholesterol-containing
  bile and carrying it out with the feces
• During bacterial fermentation of fiber, a small
  fatty acid is produced, absorbed, and travels to
  the liver where it may help reduce cholesterol
  synthesis

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The Need for Carbohydrates

• Blood Glucose Control
• Viscous fibers trap nutrients and delay their
  transit through the digestive tract
• As a result glucose absorption slows and this
  helps maintain steady levels of blood glucose and
  insulin
• Large fluctuations in blood glucose and insulin
  are thought to be associated with the onset of
  the most common form of diabetes

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The Need for Carbohydrates

• In people with diabetes, high-fiber foods play a
  role in modulating blood glucose and insulin
  levels
• Lowering the likelihood of medical complications

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The Need for Carbohydrates

• Maintenance of Digestive Tract Health
• Fiber, along with fluid intake, play a role in
  maintaining proper colon function
• Fibers such as cellulose enlarge and soften
  stools
• Speeding their passage through the intestine and
  making for easier elimination
• These fibers help alleviate or prevent
  constipation

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The Need for Carbohydrates

• Fiber prevents compaction of intestinal contents
• Such compaction could obstruct the appendix and
  permit bacteria to invade and infect it
  (appendicitis)
• Fiber stimulates the GI tract muscles so they
  retain their strength and resist bulging out into
  pouches (diverticula)
• Diverticulitis is the inflammation of diverticula
  

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The Need for Carbohydrates

• Recommendations and Intakes
• DRI recommendations for fiber
• Men, age 19-50 38 g/day
• Men, age 51 30 g/day
• Women age 19-50 25 g/day
• Women age 51 21 g/day
• The ADA recommends 20 to 35 grams of total fiber
  per day
• This is about 2x higher than the average intake

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The Need for Carbohydrates

• Recommendations and Intakes
• A good way to add fiber while lowering fat is to
  substitute plant sources of proteins for animal
  sources of protein
• Also, focus on eating 5-9 servings of fruits and
  vegetables each day
• Eat a variety of high-fiber foods and drink ample
  fluids

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Consumer Corner Refined, Enriched, and
Whole-Grain Breads

• When wheat was ground between two stones, the
  shaft (husk) was removed and the nutrient-rich
  brand, germ, endosperm were retained

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Consumer Corner Refined, Enriched, and
Whole-Grain Breads

• Modern milling machinery removes the germ and
  bran
• Leaving a whiter, smoother-textured flour
• That has an increased starch content and lower
  fiber content

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Consumer Corner Refined, Enriched, and
Whole-Grain Breads

• Turning to white bread has meant a loss of
  nutrients
• Nutrients formerly received from whole-grain
  bread
• When this problem was recognized, Congress passed
  the Enrichment Act requiring the addition of
  iron, niacin, thiamin, riboflavin, and folate to
  refined grains

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Consumer Corner Refined, Enriched, and
Whole-Grain Breads

• The enrichment of grain products eliminated known
  deficiency problems
• However, other deficiencies went undetected for
  many years
• Enriched products still contain less magnesium,
  zinc, vitamin B6, vitamin E, chromium and fiber
  than whole-grain products

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From Carbohydrates to Glucose

• Starch found in refined grains is rapidly broken
  down to glucose which is then absorbed
• Starch, such as that of cooked beans, digests
  more slowly and releases glucose later in the
  digestive process

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From Carbohydrates to Glucose

• Why Do Some People Have Trouble Digesting Milk?
• As they age, 75 - 95 of people lose much of
  their ability to produce lactase
• This results in lactose intolerance, symptoms of
  which include
• Nausea, pain, diarrhea, excessive gas
• Intestinal bacteria ferment the undigested
  lactose resulting in the production of gas and
  intestinal irritants

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From Carbohydrates to Glucose

• The inability to digest lactose affects people to
  differing degrees
• Many can tolerate 1 - 2 cups of milk a day
• Some can tolerate lactose-reduced milk
• Rarely lactose cannot be tolerated at all
• People often overestimate the severity of their
  lactose intolerance
• A mistake that could adversely affect the health
  of their bones

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From Carbohydrates to Glucose

• Infants produce abundant lactase helping them
  absorb the sugar of breast milk and milk-based
  formulas
• A few suffer inborn lactose intolerance and must
  be fed lactose-free formulas
• Due to their need for calcium, a milk substitute
  must be found for any child who becomes lactose
  intolerant

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From Carbohydrates to Glucose

• Disadvantaged children of the developing world
  sustain the most severe consequence of lactose
  intolerance when it combines with
• Disease
• Malnutrition
• Parasites

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Splitting Glucose for Energy

• Below a Healthy Minimum
• Body fat cannot be converted into glucose to
  adequately feed the brain
• With a severe carbohydrate deficit the body must
  use protein to make glucose
• Diverting protein from critical functions of its
  own
• Therefore, carbohydrates prevent the use of
  protein for energy
• This is the protein-sparing action of
  carbohydrate

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Splitting Glucose for Energy

• Fat fragments usually combine with a compound
  derived from glucose (or protein) before being
  used for energy
• Without this compound, fat fragments combine with
  each other producing acidic ketone bodies
• The accumulation of ketone bodies in the blood
  (ketosis) can disturb normal acid-base balance

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Splitting Glucose for Energy

• Ketosis during pregnancy can cause brain damage
  to the fetus
• Resulting in irreversible mental retardation
  after birth
• Adults with chronic ketosis may face
• Vitamin and mineral deficiencies, loss of bone
  minerals, altered blood lipids, increased kidney
  stone risk, impaired mood and sense of
  well-being, and glycogen stores that are too low
  to meet a metabolic emergency or support maximal
  high-intensity muscular work

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Splitting Glucose for Energy

• The minimum DRI to feed the brain and reduce
  ketosis is 130 grams a day for an average person
• 3x or 4x this minimum is recommended (45 - 65
  of total energy) to maintain health and glycogen
  stores

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Storing Glucose as Glycogen

• As blood glucose rises, the pancreas releases
  insulin
• Insulin signals the bodys tissues to take up
  glucose
• Two thirds of the bodys total glycogen is stored
  in and used by muscle
• A small emergency store is found in the brain
• The remainder is stored in the liver, which makes
  it available to the body as blood glucose

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Storing Glucose as Glycogen

• When blood glucose concentration drops and cells
  need energy, the pancreas produces glucagon
• Enzymes in the liver break down glycogen
  releasing it into the blood as glucose

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Returning Glucoseto the Blood

• Regulation of Blood Glucose
• Two safeguards are involved in this
• Replenishment from liver glycogen stores
• Removal of glucose from the blood with the liver
  converting the excess into glycogen or fat and
  muscle converting it into glycogen

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Returning Glucoseto the Blood

• When blood glucose starts to fall too low
• Glucagon triggers the breakdown of liver glycogen
  to glucose
• Hormones that promote the conversion of protein
  into glucose are released
• Only a little protein can be spared

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Returning Glucoseto the Blood

• Epinephrine also breaks down liver glycogen as
  part of the bodys defense mechanism in times of
  danger
• To a person living long ago, this internal source
  of quick energy was indispensable to a life
  filled with physical peril
• This quick-energy response to stress also works
  to our advantage today
• To meet emergencies, we are advised to eat and
  store carbohydrates at regularly timed meals

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Returning Glucoseto the Blood

• Sugary foods and drinks are not the best choices
• Balanced meals, eaten on a regular schedule, help
  the body maintain its blood glucose
• Meals containing starch, fiber, some protein, and
  a little fat slow digestion
• So that blood glucose enters the blood gradually
  in an ongoing steady supply

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Returning Glucoseto the Blood

• The Glycemic Response
• The glycemic index (GI) is a measure of the
  ability of a food to elevate blood glucose and
  insulin levels
• Scores are compared with a standard, usually
  white bread or glucose
• A foods score depends on several factors
• For example, ice cream, a high-sugar food, ranks
  lower than baked potatoes, a high-starch food

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Returning Glucoseto the Blood

• Glycemic load
• Glycemic index multiplied by grams carbohydrate

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Returning Glucoseto the Blood

• The glycemic index, along with glycemic load, may
  be important to people with diabetes who must
  regulate their blood glucose
• The idea being that the lower the glycemic load,
  the less glucose builds up in the blood, and the
  less insulin is needed to maintain normal blood
  glucose concentration

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Returning Glucoseto the Blood

• Evidence suggests that a low glycemic load may
  help control body weight
• The carbohydrates of such foods release a steady
  flow of glucose into the blood and extend
  feelings of fullness
• High glycemic load foods seem to promote
  overeating in some overweight people
• And may lead to an increase in the presence of a
  marker of cardiovascular disease risk

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Returning Glucoseto the Blood

• The glycemic load may be a better tool for diet
  planning than the glycemic index
• The glycemic load of carrots is much lower than
  its glycemic index

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Returning Glucoseto the Blood

• Many factors can affect glycemic index test
  results
• Time of day, body size and weight, blood volume,
  metabolic rate
• A foods glycemic effect may vary from person to
  person
• And depend on how the food is prepared, its
  ripeness, and which other foods accompany it in a
  meal

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Diabetes and Hypoglycemia

• Diabetes mellitus
• A disease characterized by high blood glucose
  levels and inadequate or ineffective insulin

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What Is Diabetes?

• Worldwide, the prevalence of diabetes in on the
  rise
• In the United States diabetes is the leading
  cause of blindness

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What Is Diabetes?

• Additional complications include
• Amputations
• Complications in pregnancy
• Heart disease
• Kidney disease
• Premature death
• Increased risk of death from flu or pneumonia

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What Is Diabetes?

• Half of those with diabetes are unaware of their
  condition
• And therefore fail to take action to prevent its
  damage
• Early stages often present few or no warning
  signs
• Recommendations call for everyone over 45 years
  old (40 in Canada) and younger people with risk
  factors, such as obesity, to be tested regularly

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What Is Diabetes?

• Type 1 and Type 2 are the most common forms of
  diabetes
• Both are disorders of blood glucose regulation

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What Is Diabetes?

• Type 1 Diabetes
• Little or no pancreatic secretion of insulin
• Often diagnosed in childhood
• Less common (up to 20 of cases)
• But is on the rise
• Most common chronic disease among children and
  young adults

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What Is Diabetes?

• Type 1 diabetes is the result of a persons
  immune system attacking the insulin-making cells
  of the pancreas
• An immune system attack on the pancreas may be
  provoked by
• Genetics, viral infection and other diseases,
  toxins, allergens, disordered immune system

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What Is Diabetes?

• Treatment
• Receipt of an external source of insulin
• Meal planning to balance blood insulin and
  glucose concentrations
• Future treatment
• Insulin nasal spray and inhaler
• Transplant insulin-producing cells
• Vaccine to prevent occurrence of the disease

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What Is Diabetes?

• Insulin is a protein
• If taken orally it will be digested
• Must be given as injection
• Daily shots or an insulin pump

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What Is Diabetes?

• Type 2 Diabetes
• Pancreas makes sufficient insulin
• Bodys cells resist insulins action
• Often diagnosed in adulthood
• Incidence has increased by over 60 since 1991

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What Is Diabetes?

• Characterized by insulin resistance
• A condition in which insulin is less then
  effective in moving glucose from the bloodstream
  into the cells
• As blood glucose rises, so does blood insulin
• Eventually, the pancreas may become less able to
  make insulin
• With age, people may require insulin to
  supplement their own supply

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What Is Diabetes?

• If drugs are necessary
• A drug that stimulates the pancreas to secrete
  sufficient insulin to overwhelm the cells
  resistance
• Or a drug that improves tissue uptake of glucose

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What Is Diabetes?

• Type 2 Diabetes and the Genes
• There is a genetic component to Type 2 diabetes
  susceptibility
• Not everyone with these genetic variations gets
  the disease
• Genetic factors may increase a persons risk by
  30
• Diet and exercise play a major role

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What Is Diabetes?

• In the majority of cases, prevention is likely to
  occur when individuals control their lifestyle
• Middle-aged men and women can reduce their risk
  if they
• Maintain a healthy body weight
• Consume a diet high in vegetables, fruit, fish,
  poultry, and whole grains
• Exercise regularly
• Restrict alcohol
• Dont smoke

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What Is Diabetes?

• Type 2 Diabetes and Obesity
• Type 2 diabetes tends to occur late in life
• Now, overweight children and adolescents are
  being diagnosed with the condition

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What Is Diabetes?

• Compared with normal-weight people with diabetes,
  obese people require much more insulin to
  maintain normal blood glucose
• The more body fat, the more insulin resistant,
  the higher the blood glucose
• Even moderately overweight people exhibit
  slightly elevated blood glucose (impaired glucose
  tolerance)

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What Is Diabetes?

• Impaired glucose tolerance
• Blood glucose levels higher than normal
• Not high enough to be diagnosed as diabetes

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