Carbohydrate Unit 2nd of Nutrition for BSc Nursing and GNM Ist year

2. Objective
 Definition of carbohydrate
 Classification of carbohydrate
 Daily requirement
 Dietary source
 Function of carbohydrate
 Digestion , absorption and storage of carbohydrate
 Metabolism of carbohydrate
 Deficiencies due to carbohydrate
 Over consumption of carbohydrate

3. Introduction
 Carbohydrate is the main source of energy and forms
the bulk of our diet. They are available in the market in
the natural form, processed form or modified form as
an additive in many different products. Carbohydrate
holds a great part of our Indian diet.

4. Definition :-
 Carbohydrate are polyhydroxy aldehydes or
polyhydroxy ketones or substances that yield such
compounds on hydrolysis.
 Carbohydrates are organic compounds made up of
carbons, hydrogen and oxygen.
 They are called carbohydrates because they contain
hydrogen and oxygen in same proportion as found in
water i.e; 2:1
 Caloric value of carbohydrates is 4 kcal

5. Classification of carbohydrates
 Carbohydrates are classified on the basis of the
number of sugar units or saccharide units which are
present in their structures.

7. Monosaccharide
 Monosaccharide also called simple sugar, are the
simplest form of sugar and the most basic units
of carbohydrate. They cannot be further hydrolyzed to
simpler chemical compounds. The general formula
is C6H12O6(Glucose).
 They are usually colourless, water-soluble,
and crystalline solids. Some monosaccharide's have
a sweet taste.

8. Cont…
 Glucose:- It is the most important of all the
monosaccharide's as it is the primary carbohydrate
used by the body. Glucose is the sugar which is
absorbed into the bloodstream after carbohydrates are
digested in the body. It is also known as dextrose and
available in powder and liquid form.

9. Cont…
 Fructose :-It is the sweetest of all sugars and is also
known as fruit sugar because it is found in fruits and
honey. In human body, it is converted to glucose and
oxidized as a source of energy. It is also called
levulose.
 Galactose- It is found in combination with glucose in
milk. This sugar is converted to glucose in human body.

10. 2. Disaccharides
 Disaccharides - These are double sugars composed of
two monosaccharide linked together with the removal
of water molecule. The disaccharides which are of
importance in the diet are sucrose, maltose and
lactose. Their general formula is C12H22011

11. Cont…
 Sucrose:- Sucrose is the name given to sugar which we use
daily. It is prepared from-sugar cane and sugar beet. It is
made up of one unit of glucose and one unit of fructose.
 Lactose- It is the sugar present in milk. It is made up of one
unit of glucose and one unit of galactose. It is the least
sweet of all the sugars and is easily fermented to lactic acid
and cheese.
 Maltose:- It is formed when whole grains are sprouted and
in the commercial preparation of malt from starch. In the
body, maltose is formed during digestion of starch. It is
composed of two units of glucose.

12. 3. Oligosaccharides
 Oligosaccharides -They are composed of three to ten
monosaccharide units linked to each other by the
removal of water molecules.
 They are not as common in food as the mono, di and
polysaccharides.

13. 4. Polysaccharides
 Polysaccharides - These are complex carbohydrate
made up of 100 to 2000 glucose units linked to each
other in a chain or branched form.
 Starches- They form approximately half the dietary
carbohydrates which are consumed. They are present
in abundance in cereals, pulses, tapioca, sago, roots
and tubers.

14. Cont…
 Glycogen -This is also called animal starch as it is the
form in which the animal body stores
CARBOHYDRATES as a reserve source of energy. One
third of the glycogen is stored in the liver and two-
third is stored in muscles.
 Dextrin :This is formed in the first stage of starch
breakdown either by enzyme during digestion or by
the action of dry heat on starch during toasting a bread
or browning flour.

15. Function of carbohydrates
1. The chief function of carbohydrate is to provide energy to
the body so that it can carry out day to day work and
maintain body temperature.
2. They are required for complete oxidaton of fat.
3. Carbohydrates spare proteins from being broken down
for energy and are used for body building and repair.
4. Glucose in the only form of energy used by the CNS.
5. The sugar lactose help in the absorption of the minerals
calcium and phosphorus.
6. Lactose also helps certain bacteria to grow in the
intestine.
7. Dietary fibers help in preventing constipation.

16. Sources

17. Daily requirements of carbohydrate
 Minimum of it should be 100 g daily and maximum
70% of total calories / day Majority of people in
developing countries take it as high as 60-70 % while
40-50% in Europe and 30-40 % in U.S.A. The
carbohydrate calories should be at least 40% in well-
balanced diet. Again it depends upon the availability of
fats and economic conditions of people, as fat is costly.

18. Digestion and absorption of carbohydrates
 Complex carbohydrates and sugars are too large to be
absorbed through intestinal wall. Only monosaccharide can
be absorbed into blood stream. The first stage in the
digestion of carbohydrates takes place in the mouth when
food is chewed.
 Ptyalin enzyme in the saliva acts on starch, splitting it
into dextrin and maltose. As soon as the food reaches the
stomach it mixes with the gastric juice. Lastly, its digestion
is accomplished in the small intestines by pancreatic
amylase and intestinal amylase, sucrose, lactase, maltase
and iso-maltase present in the intestinal juice.

20. Metabolism of carbohydrates
 Glucose, galactose and fructose are absorbed in the
intestines and pass to the liver through portal
circulation. In the liver, a part of glucose and the entire
galactose and fructose are converted into glycogen. A
part of glucose passes into the general circulation, to
the various tissues for being oxidized and used as
energy.
 A small part of glucose is stored in the liver and
muscles as glycogen and some portion of glucose is
converted into fat and stored in adipose tissue.

21. Regulation of blood sugar
1. The fasting level of blood sugar in normal person is
80-100 mg per 100 ml. After consuming a meal, this
glucose level steadily rises and may reach to 130-150
mg%. If the level exceeds 180 mg%, it is excreted in
the urine and this condition is called diabetes
mellitus.
2. A fasting blood sugar level above 140 mg% is called
hyperglycaemia and below 70 mg% is
hypoglycaemia. The hormone insulin secreted by the
cells of the Islets of Langerhans in the pancreas
helps in regulating the blood glucose level.

22. Deficiency of CHO
 A deficiency of carbohydrates in diet results in
utilization of fat for energy and in severe deficiency,
incomplete oxidation of fats causes ketone bodies to
accumulate in the blood. It also results in PEM when it
accompanies with protein deficiency.

23. Excessive carbohydrates
 Excessive consumption of refined sugars
could be one of the causes of dental
caries and tooth decay.
1. Excessive sugar depresses the appetite, provides hollow
calories and could result in malnutrition.
2. High intake of sugar and refined carbohydrates increases
the blood triglyceride level leading to heart diseases.
3. Excessive carbohydrates are converted into fat and
deposited in the adipose tissue, which could lead to
obesity.
4. Excessive fibres could irritate the intestinal lining causing
cramps or bloating due to gas formation.

24. Question to be Ask ?
 Define cho ?
 Define cho , source of cho and function of cho ?
 Write a short note on digestion and absorption of cho ?
 Deficiencies and over consumption of cho ?