The carbohydrates: sugars, starches, and fibers

Simple carbohydrates: Monosaccharides – single sugars Disaccharides – sugars composed of pairs of

monosaccharides

Complex carbohydrates: Polysaccharides – large molecules composed of

chains of monosaccharides

The molecules

Galactose

Monosaccharides

Disaccharides Maltose

Sucrose

Lactose

The complex carbohydrates: polysaccharides

Glycogen – storage form of energy in the animal body Many glucose molecules linked together in highly

branched chains.

Starches – storage form of energy in plants Long, branched or unbranchedchains of hundreds or

thousands of glucose molecules linked together Are packed side by side in grainssuch a wheat or rice, in

root crops and tubers such as yams or potatoes, and in legumes such as peas and beans.

Fibers Are the structural parts of plants Found it in all plant-derived food – vegetables, fruits,

whole grains and legumes

Glycogen and starch molecules compared

Starch and fiber molecules compared

Fibers

Soluble fibers

•Disolve in water and form a gel.•Easily digested by bacteria in the colon.•Oats, barley, legumes, and citrus fruits.•Associated with protecting against heart disease.

Insoluble fibers

•Do not dissolve in water and are less readily fermented.•Whole grain (bran) and vegetables.•Promote bowel movements and alleviate constipation.

Glucose in the body

Storing glucose as glycogen1. The liver stores about one-third of the body’s

total glycogen.1. Glucose becomes available to supply energy to the

brain and other tissues .

2. Muscle cells can also store glucose as glycogen (the other two-thirds), using it just for themeselves during exercises.

3. The brain mantains a small amount of glycogen, to provide an emergencyenergy reserve during times of severe glucose deprivation.

The body can store only enough glycogen to provide energy for relatively short periods of time

Supplying the body’s cell for energy

The hormone insulin is the key that unlocks the body cell's glucose channel, allowing glucose ("blood sugar") to enter the cell and refuel it. Without the insulin key, glucose is locked out of the cell and must remain in the bloodstream.

Making glucose from protein Gluconeogenesis.

The making of new glucose.

But protein has jobs of its own that no other nutrient can do.

Making ketone bodies from fat fragments Fat takes an alternative metabolic pathway

Fat fragments combine with each other, forming ketone bodies, which provide an alternate fuel source during starvation

When their production exceeds their use, they accumulate in the blood, causing ketosis.

This condition disturbs the body’s normal acid-base balance

Using glucose to make fat The body must find a

way to handle any extra glucose.

At first, energy metabolism shifts to use more glucose instead a fat.

If that isn’t enough, the liver breaks glucose into smaller molecules and puts them together into the more permanent energy-storage compound – fat.

Fat is either conserved or created!

What happens when glucose falling outside the normal range?

Diabetes and Hyglycemia

The glycemic response How quickly glucose is absorbed after a

person eats, how high blood glucose rises, and how quickly it returns to normal

The glycemic response

- Slow absorption- Modest rise in blood glucose- Smooth return to normal

- Fast absorption- Surge in blood glucose- Overreaction that plunges below normal

Desirable

Less Desirable

Low glicemic response

High glicemic response

Glycemic index A method of classifying foods according to

their potential to raise blood glucose

Some studies have shown that selecting foods with a low glycemic index is a practical way to improve glucose control

Low glycemic diet: May improve blood lipids, and; May also help with weight management

Glycemic index

LOW HIGH

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Health effects and recommended intakes of sugars

Nutrient deficiencies. Cakes, candies, and sodas You recieve about the same amount and kinds of

sugars from and orange as from a tablespoon of honey, but the packaging makes a big nutrition difference

Dental caries Bacteria in the mouth ferment the sugars and, in

the process, produce an acid that erodes tooth enamel

Each of these concentrated sugars provides about 500 kcal

40 oz cola

½ c honey

125 jelly beans

23 marshmallows

30 tsp sugar

WHO/FAO suggest restricting

consumption of added sugars to less than 10 percent of

total energy

Health effects and recommended intakes of starch and fibers

Fosters weight management Lowers blood cholesterol May help prevent colon cancer Helps prevent and control diabetes Helps prevent and alleviates hemorrhoids

Excessive intake of fiber: Causes intestinal discomfort and distention May interfere with mineral absorption

Heart disease, Diabetes, GI health, Cancer, Weight management

Recommended intakes of starch and fibers RDA (Recommended Dietary Allowance)* for carbohydrate:

130 g/day 45-65% of energy intake

Daily value: 300 g carbohydrate (based on 60% of 2000 kcal diet)

To increase the fiber intake: Eat whole grain cereals (+5g per saving) Eat raw vegetables Eat fruits and vegetables with their skins Adds legumes to soups, salads and casseroles Eat fresh and dried fruits for snacks

Daily fiber: 25 g fiber

* The average daily amount of a nutrient considered adequate to meet the known nutrient needs of practically all healthy people.

Oral presentations Lipids (1) and Proteins (2)

Roles in the body Lipid or proteins metabolism Health effects Recommended intakes (RDA)

Mexican Food Guide (3) and USA Food Guide (4) Legal aspects Image Cultural assignments

Energy balance and Body composition (5) Components of energy expenditure Body weight, body composition and health Common methods used to assess body fat