Carbohydrates in nutrition (lippincott and mushtaq ahmed) what are carbohydrates? Produced by plants during photosynthesis After eating plant foods, humans convert the carbohydrates into glucose Glucose Most abundant carbohydrate Preferred source of energy for the blood, brain, and nervous system Carbohydrate-rich plant foods make up the foundation of diets all over the world

1. CARBOHYDRATES IN
NUTRITION
Maryam Fida(o-
1827)

2. WHAT ARE CARBOHYDRATES?
Produced by plants during photosynthesis
After eating plant foods, humans convert the
carbohydrates into glucose
Glucose
Most abundant carbohydrate
Preferred source of energy for the blood, brain,
and nervous system
Carbohydrate-rich plant foods make up the
foundation of diets all over the world

3. CLASSIFICATION OF
CARBOHYDRATES
Simple carbohydrates
1. Monosaccharides
Glucose and fructose are the principal
monosaccharides
Glucose is abundant in fruits, sweet corn,
corn syrup, and honey.
Free fructose is found together with free
glucose and sucrose in honey and fruits
(for example, apples).

4. GLUCOSE
FRUCTOSE

5. DIETARY SOURCES OF GLUCOSE
AND FRUCTOSE

6. 2. Disaccharides
i. Sucrose
 made up of glucose + fructose
Sucrose is ordinary “table sugar” and is abundant
in molasses and maple syrup
ii. Lactose
Made up of glucose + galactose
Lactose is the principal sugar found in milk
iii. Maltose
Made up of glucose + glucose
Maltose is a product of enzymatic digestion of
polysaccharides.
It is also found in significant quantities in beer
and malt liquors

8. Perceived as sweeter than complex
carbohydrates
Mixes with saliva and reacts with taste buds
Action of α-Amylase
3. Oligosaccharides
More than two monosaccharides
Typically 3-10 sugar units
Maltodextrins, cellodextrins
result from the microbial breakdown of
larger polysaccharides such as starch or cellulose

9. COMPLEX CARBOHYDRATES
4. Polysaccharides
Most often polymers of glucose
More than ten glucose units
They do not have a sweet taste
i. Starch is an example of a complex
carbohydrate that is found in
abundance in plants
Common sources include wheat and other
grains, potatoes, dried peas and beans, and
vegetables
Amylose and Amylopectin

10. COMPLEX CARBOHYDRATES
ii. Glycogen
Glycogen is a multi-branched polysaccharide of glucose
that serves as a form of energy storage in humans,
animals, fungi, and bacteria.
The polysaccharide structure represents the main
storage form of glucose in the body.
 In humans, glycogen is made and stored primarily in
the cells of the liver and skeletal muscle.
Liver glycogen response to blood glucose (BG) levels
 BG  glycogen breakdown   BG
Muscle glycogen can be broken down for energy for the muscle

12. 5. FIBER
Dietary fiber is defined as the non-digestible,
non-starch carbohydrates and lignin (a non-
carbohydrate polymer of aromatic alcohols)
present intact in plants.
Soluble fiber is the edible parts of plants that
is resistant to digestion and absorption in the
human small intestine
completely or partially fermented by bacteria
to short-chain fatty acids in the large
intestine.
Insoluble fiber passes through the digestive
track largely intact.
 Dietary fiber provides little energy but has

13. First, it adds bulk to the diet.
 Fiber can absorb 10–15 times its own
weight in water, drawing fluid into the
lumen of the intestine and increasing
bowel motility and promoting normal
laxation.
Soluble fiber delays gastric emptying and
can result in a sensation of fullness. This
delayed emptying also results in reduced
peaks of blood glucose following a meal.
That’s why important in dieting and DM

14. Second, consumption of soluble fiber has now
been shown to lower LDL-C levels
For example, diets rich (25–50 g/day) in the
soluble fiber oat bran are associated with a
modest, but significant, reduction in risk for
CHD by lowering total cholesterol and LDL-C
levels.
Also, fiber-rich diets decrease the risk for
constipation

15. ACTIONS OF DIETARY FIBERS

16. DIETARY CARBOHYDRATE AND
BLOOD GLUCOSE
Glycemic Response:
Some carbohydrate-containing foods
produce a rapid rise followed by a steep
fall in blood glucose concentration,
Whereas others result in a gradual rise
followed by a slow decline

17. GLYCEMIC INDEX (GI)
GI is defined as the area under the blood
glucose curves seen after ingestion of a
meal with carbohydrate-rich food,
compared with the area under the blood
glucose curve observed after a meal
consisting of the same amount (50 g) of
carbohydrate either as glucose or white
bread
evidence suggests that a low-GI diet
improves glycemic control in diabetic

18. BLOOD GLUCOSE CONCENTRATIONS
FOLLOWING INGESTION OF FOOD WITH
LOW OR HIGH GLYCEMIC INDEX.

19. REQUIREMENTS FOR
CARBOHYDRATE
Carbohydrates are not essential
nutrients, because the carbon skeletons of
most amino acids can be converted into
glucose
However, the absence of dietary
carbohydrate
1. leads to ketone body production
2. degradation of body protein whose
constituent amino acids provide carbon
skeletons for gluconeogenesis

20. RDA OF CARBOHYDRATES
The RDA for carbohydrate is set at 130 g/day
for adults and children,
Adults should consume 45%–65% of their total
calories from carbohydrates.
It is recommended that added sugar represent
no more than 25% of total energy because of
concerns that sugar may displace nutrient-rich
foods from the diet, potentially leading to
deficiencies of certain micronutrients.

21. SIMPLE SUGARS AND DISEASE
There is no direct evidence that the consumption of
simple sugars is harmful.
Contrary to folklore, diets high in sucrose do not
lead to diabetes or hypoglycemia.
Also contrary to popular belief, carbohydrates are
not inherently fattening.
They yield 4 kcal/g (the same as protein and less
than one half that of fat)
Result in fat synthesis only when consumed in
excess of the body’s energy needs.
However, there is an association between sucrose
consumption and dental caries, particularly in the
absence of fluoride treatment.