carbs are essential source of energy

1. Carbohydrates
Prof.Dr.ir. Faisal
2rd Lecture in Nutrition

2. Outlines
Macro-nutrients: -
• Definition
• Main classes
Carbohydrates:-
• Definition
• Function and sources
• Nutritive value
• Classifications
• Digestion
• Healthy and bad carbohydrates
• Structure of the most common sugars
• Carbohydrates -related diseases (Lack/abundance)
• Regulation of blood glucose

3. What do macronutrients mean?
Carbohydrate
(Sugar)
Protein
(Amino acid)
Lipid
(Fatty acid)
Nucleic acids
(Nucleotide)
Macronutrients
Macronutrients are macromolecules that are involved in the
maintenance and metabolic process in the living cells.

4. What are Carbohydrates?
• Carbohydrates, also known as saccharides or
carbs, are biomolecules consisting of carbon,
hydrogen and oxygen atoms, usually with a
ratio of 1:2:1.
• Most of Carbs are dissolved in water
(hydrophilic).
• The molecular formula (CH2O)n.

5. Sources of carbs
• Natural foods
• Fruits: Whole fruit.
• Vegetables: broccoli, carrots , peppers
• Grains: wheat, oats, rice, barley, and
maize.
• Legumes: Beans, Peas, Soybeans, Chickpeas
• Starchy Vegetables. Potatoes and corn.

6. Cont., Processed foods
• Milk and milk products.
• Pasta
• Ice cream
• Bread: White bread, baked products.
• Sugary Sweets. Soda, candy, cookies, and
other desserts.

7. What are bad & healthy carbs?
Vegetables, whole fruit, legumes, and
whole grains. These foods are generally
healthy.
Refined carbs include sugar-sweetened
beverages, soda, fruit juices, pastries,
white bread, pasta, rice and others.

8. Where do Carbs originate?

9. What is the use of carbs in the
body?
• When you eat carbs, your body breaks them
down into simple sugars, which are absorbed
into the bloodstream.
• As the sugar level rises in your body, the
pancreas releases a hormone called insulin.
• Insulin is needed to move sugar from the
blood into the cells, where the sugar can be
used as an energy source.

10. What are the main functions of
carbs?
• Major sources of energy for cells function
and daily activity.
• Major sources of energy store mostly in liver
and muscle as glycogen.
• Building blocks for other biomolecules
(nucleic acids. proteins and lipids).
• Major structural component of plant cell.
• Flavor and sweeteners.
• One gram of CHO generates 4 Kcal.

11. Classification of carbs

12. Monosaccarides
• Micro-molecules Consist of one sugar unit.
• Simple sugars made of either aldehyde (CHO) or
ketone (C=O) functional group with two or multi-
hydroxyl groups.
• Sugars having aldehyde group called aldoses and
sugars with keto group are ketoses.
• Molecular Formula: C6H12O6.
• Contain a single carbon chain and classified based on
the number of carbon atoms (3C-6C).
• Ex: Glyceraldehyde, Glucose, Fructose, Galactose.

15. Sugar units
(C-H2O)n where n = 3 to 6
• Mono-saccharides=single sugar unit
(u).
• Di-saccharides= double sugar u
• Tri-saccharides= 3 sugars u
• Tetra-saccharides= 4 sugars u
• Penta-saccharides=5 sugars u
• Hexa-saccharides= 6 sugars u
• Depending on the number of
carbon atoms, the
monosaccharaides are named as
triose (C3), tetrose (C4), pentose
(C5), hexose (C6), and so on.
Greek=English
• -ose means sugar
• Saccharide=sugar=sweet
• monomer= one unit
• Dimer= two unit
• Polymer=many unit

16. Disaccharides

17. Polysaccharides (complex)
• Long-chains of sugar units bound together
by glycosidic bonds.
• Plant-derived food (grains, rice, potatoes).
• They range in structure from linear to
highly branched chains.

18. Polysaccharides (complex)
• Starch: storage form of branched and unbranched
glucose molecules in plants.
• Glycogen: storage form of highly branched glucose
molecules in animals.
• Cellulose (plant fiber): forms the structural
constituent of plant’s cell wall.

19. Dietary guidelines
• If you eat 2,000 calories diet a day, you should consume about
225-325 grams of complex carbohydrates per day.
• A good starting place for people with diabetes is to have
roughly 45 to 60 grams of carbs per meal and 15 to 30 grams
for snacks.
• The Daily Value for total carbohydrate is 300 g per day. This is
based on a 2,000 calorie diet, your Daily Value may be higher
or lower depending on your calorie needs.
• Focus on eating nutrient-dense foods that contain dietary
fiber combined with other beneficial nutrients and naturally
occurring sugars.

20. The Dietary Reference Intake (DRI)
• Total dietary carbohydrate: sugar, starch and fiber intakes.
• The more calories you eat each day, the more fiber you need; teens
and men may require upwards of 30 to 35 grams per day or more.
• According to the 2010 Dietary Guidelines for Americans, women
should aim for 25 grams of fiber a day and men should aim for 38
grams a day.
• According to the American Heart Association (AHA), the maximum
amount of added sugars you should eat in a day are : Men: 150
calories per day (37.5 grams or 9 teaspoons) Women: 100 calories
per day (25 grams or 6 teaspoons).

21. Digestion of Carbs
Polysacch Disacch Monosacch
(starch) (maltose) (glucose)
 Begins in the mouth:
-Salivary amylase hydrolysis carbs to maltose.
 Stop in stomach:
- HCL denatures amylase
 Resumes in small intestine:
- Pancreatic amylase hydrolysis carbs to maltose.
amylase

23. Monosaccharide enter capillaries
within the intestinal villi.

24. Transport & Use
• ALL monosaccharides are converted to
glucose by the liver.
• Glucose circulating in the blood is our
primary energy source.
• Excess glucose is converted to glycogen by
the liver and skeletal muscles.
• Eating too much glucose is converted into
fat.

25. Storage of Glycogen

26. Complex Fiber
 Dietary fiber is the non-digestible part of
plants.
Natural sources: Grains, seeds, legumes, fruits.
 Functional fiber is carbohydrate extracted
from plants and added to food.
Total fiber = dietary + functional fiber.

27. Digestion of fiber Carbohydrates
We do not have the enzymes necessary to
digest fiber.
Bacteria in large intestine can break down
some fiber Produce fatty acids and gas.
Most fiber remains undigested and is
eliminated with feces.

29. Question

30. Regulation of blood glucose
The normal level of blood glucose are
primarily regulated by the action of two
hormones.
Pancreatic cells store and secrete two
hormones: insulin & glucagon which control
level of glucose in the blood.
The two hormones work opposite for each
other.

31. Regulation of blood glucose:insulin
After eating pancreas release insulin
which:-
-Stimulate cells of the body to absorb
glucose from the bloodstream.
-Stimulate the liver to absorb glucose and
convert it to glycogen.

32. Regulation of Blood Glucose: Insulin

33. Regulation of blood glucose:glucagon
 During the hunger or starvation pancreas secrete
glucagon which:-
- Stimulates the breakdown (hydrolysis) of glycogen
to glucose to make quick energy available to cells of
the body.
- Stimulate gluconeogenesis:-production of glucose
from amino acids.

34. Regulation of Blood Glucose:
Glucagon

35. Carbs related diseases
• The most common disorders related to
carbohydrate metabolism :
1. Diabetes Mellitus (DM), it is commonly
referred to simply as diabetes.
2. hypoglycemia.
3.Lactose intolerance.

36. Diabetes

37. Diabetes
 Type 1 diabetes
- Most common in children and caused by
insulin deficiency or inadequate production
due to pancreatic cells damage (most
probably autoimmune disease).
- Causes hyperglycemia-high blood glucose.
- Patients treated with insulin injection
predominantly.

38. Diabetes
• Most diabetics have type 2 diabetes.
• Body cells insensitive or unresponsive to
insulin action (insulin resistance).
• Excess insulin is often produced but its not
active that causes hyperglycemia because
cells can't absorb or remove glucose from
blood.

39. Type 2 diabetes
- Most common in adults and its wide spread than Type 1
diabetes throughout the world.
 Causes:
- Genetic factors, obesity, physical inactivity.
 Signs & symptoms :
-Thirst, hunger, frequent urination, weight loss, fatigue.
 Treatment and prevention:
- Healthy diet (low carbs food), exercise, Healthy lifestyle
and possible oral medications.

40. Hypoglycemia
• Its low blood sugar (glucose).
• There are 2 types of hypoglycemia:
Reactive hypoglycemia:
Results when too much insulin is produced after a meal.
Fasting hypoglycemia: results from prolonged
fasting along with hyper-production of insulin.
-Symptoms: shakiness, dizziness, sweating, hunger.
anxiety or nervousness.
-Treatment: eating sugar or taking dextrose drip for
critical cases.

41. Lactose intolerance
 Causes:
Insufficient lactase production which leads to
inability to digest lactose (milk sugar).
 Symptoms:
Abdominal gases, bloating, nausea, cramping and
diarrhea.
 Prevention:
Eating alternative sources for calcium such as
fruits and vegetables.

42. Take home questions
• Glucose whose 2 other names, what
they are?
• What is the sweetener sugar and its
sources?
• How is diabetes diagnosed?

43. References & further readings
Essential of Biochemistry for Medical
students second edition.
Textbook of Biochemistry for Medical
Students sixth edition.

44. Thank you
‫؟‬