1. Carbohydrates
Chapter 4
BIOL1400
Dr. Mohamad H. Termos

2. Carbohydrates
- Main fuel source for brain, nervous system and red blood cells
- 4 kcal per gram
- Carbohydrates are readily available as fuel for all cells in the form of:
- Blood glucose
- Glycogen : Stored in muscles and liver . Helps maintain blood glucose

3. Simple carbohydrates or sugars
- Monosaccharides: most common forms: Glucose, Fructose (fruit sugar), and Galactose
- Disaccharides: two mono bonded together. Examples:
1- Sucrose: the table sugar
2- Lactose: milk sugar
3- Maltose
Two glucose molecules bonded together
Used in liquor industry
Cereal grains broken down to maltose
Note: Food labels lump all simple sugars (mono and disaccharides) into one group called "sugars"
Sucrose is made up of glucose and fructose and it is also found in sugarcane, sugar beets, honey and maple syrup. It is not produced by animals.
Lactose is made up of glucose and galactose.

4. Complex carbohydrates or starches
Polysaccharides are 1000 or more glucose units bonded together in chains
Found mostly in grains, vegetables and fruits
Food label calls them "other carbohydrates“
- Plants store carbohydrates in two forms that are digestible by humans: Amylose and Amylopectin.
- Enzymes break down Amylopectin faster and raise blood sugar quicker than Amylose

5. Forms of complex carbohydrates
Glycogen:
- Carbohydrates are stored as glycogen in animals
- About 1800 kcal
- Major storage sites are liver and muscles.
Fibers:
- Differ from starches in that the bonds that hold the sugar units together are indigestible by humans so they are not absorbed
- Forms of non-starch polysaccharides that food labels call "dietary fiber“: cellulose, pectins, and gums
Major storage sites of glysogen: - Liver (400 kcal), used to maintain blood glucose and - Muscle (1400 kcal), used to fuel muscle cells especially during high-intensity or endurance exercises

6. Forms of Fiber Insoluble fiber Do not dissolve in water
Not metabolized by intestinal bacteria
Include cellulose and lignin
Found in wheat, vegetables, wheat bran.

7. Forms of Fiber Soluble fiber Dissolve or swell in water
Fermented by intestinal bacteria
Pectins and gums
Found in fruits and vegetables

8. Carbohydrates in foods
- Table sugar, honey, jam, fruit and plain baked potatoes contain most of their kcal as carbs.
- Rice, bread, noodles, corn flakes are about 75% carbohydrate
- Foods with no carbohydrate include meat, fish, eggs and oils

9. Digestion and Absorption
Help make carbohydrates available for body use:
Digestion:
Starch digestion starts in the mouth. Salivary amylase produced by salivary glands breaks down starch into disaccharides (maltose)
Note: Salivary amylase will be inactivated by stomach acid

10. Digestion Small intestine
- Pancreas releases pancreatic amylase to breakdown to di and monosaccharides
- Enzymes attached to intestinal cells digest disaccharides to monosaccharides
Maltase acts on maltose
Lactase acts on lactose
Sucrase acts on sucrose

11. Absorption - Most monosaccharides are actively absorbed
- Requires a specific carrier and energy
- Glucose and galactose are absorbed with sodium
- Fructose undergoes facilitated absorption. Attracts water in the small intestines and can cause diarrhea
- Transported to the liver via the portal vein

12. Absorption - Liver transforms galactose and fructose into glucose
- Liver then has 3 options
Releases glucose into the bloodstream
Produces glycogen for storage
Produces fat
Note: Only about 10% of sugars escapes absorption, traveling to the large intestine where it's fermented by bacteria which promotes intestinal health

13. Simple carbohydrates functions in the body
A- Yielding energy
- Supply kcal to fuel the body
- Red blood cells can only use simple carbohydrates
- Brain and CNS use glucose but can use ketones
- Muscles fueled by glucose but can also use fat

14. Simple carbohydrates functions
B- Sparing protein from use as an energy source and preventing ketosis
- Under normal circumstances, CHO is used as energy and protein is reserved for building and maintaining vital organs
- When not enough CHO is consumed
Proteins are converted to glucose.
Fats are not metabolized completely and ketones are formed and can disturb acid-base balance

15. Regulating this energy source
Blood glucose is regulated in a very narrow range by the liver and pancreas
Pancreas releases insulin when blood glucose rises
Insulin directs liver to store glucose as glycogen
Insulin directs muscle, adipose and other cells to take up glucose

16. Regulating this energy source
Pancreas releases glucagon when blood sugar falls
Keeps blood sugar from falling too low
Prompts liver to breakdown glycogen to glucose
Adrenal gland also plays a role during stress
Located on kidneys
Releases epinephrine causing quick conversion of glycogen to glucose in the liver
This complex regulatory system safeguards against high blood glucose (hyperglycemia) and low blood glucose (hypoglycemia)

17. Failure of Blood Glucose Regulation
Diabetes mellitus
- Type 1 Diabetes
- Often occurs in childhood but can occur at any age
- Usually admitted with high blood glucose and ketosis
- Decreased release of insulin
- Glucose spills into urine

18. Type 1 Diabetes Pathology Treatment
Most cases begin with immune system disorder destroying the insulin producing cells of the pancreas
Pancreas loses ability to synthesize insulin
Treatment
Insulin therapy: injections or pump
Following suitable dietary recommendations: such as taking 3 meals and one or more snacks and consuming a regulated ratio of CHO: protein: fat

19. Type 1 Diabetes Risks associated with type 1 diabetes
- Cardiovascular disease
- Excessive ketone production
Ketones in urine
Pull sodium and potassium into urine with them
Can lead to dehydration, ion imbalance, coma and death
- Nerve deterioration
Mostly in extremities
Loss of sensation means not recognizing sores or problems
Increased risk of infection and amputation

20. Type 2 Diabetes Disease characteristics - Usually occurs after age 40
Most common type, 90% of cases
Pathology
Inactivity and obesity especially abdominal
Genetically linked
Insulin receptors on cell surfaces become insulin resistant and glucose is not taken up by the cells as well

21. Type 2 Diabetes Pathology (cont.) High blood glucose
Insulin production increases, insulin is high at the onset of disease
Pancreas can't keep up and insulin production is significantly reduced

22. Type 2 Diabetes
- To decrease risk, those with family history should avoid obesity, animal and trans fat intake, simple carbohydrates and inactivity
Treatment
- Achieve healthy weight
- Oral insulin therapy or injections
- Regular physical activity
- Dietary therapy (regular meals, calorie control, etc.)

23. Hypoglycemia Reactive hypoglycemia
Symptoms occur 2-4 hours after eating
Symptoms include: headache, dizziness, sweating, confusion
Unclear cause possibly overproduction of insulin

24. Hypoglycemia Fasting hypoglycemia Diagnosis Nutrition therapy
Rare and usually caused by pancreatic cancer
Blood glucose falls after fasting 8-24 hours
Diagnosis
Low blood glucose with symptoms
Low blood glucose is mg per 100 ml
Nutrition therapy
Eat regular meals
Include protein, fat and complex carbohydrates at meals
Moderate caffeine and alcohol intake

25. Dental caries
- Cavities are created when bacteria in mouth metabolize carbohydrates into acid that dissolves tooth enamel
- Worst offenders are sticky gummy carbohydrates like caramel
- Snacking regularly on sweets or chewing sugar gum between meals contributes greatly
- Fluoridated water and toothpaste decrease dental caries
- Cheese, peanuts and sugar free gum may decrease acid on teeth