1. Man shall not live by bread alone.
Chapter 2
Carbohydrates
Man shall not live by bread alone.

2. Key Concepts
Carbohydrate foods provide practical energy (calorie) sources because of their availability, relatively low cost, and storage capability.
Carbohydrate structures vary from simple to complex to provide both quick and extended energy for the body.
Dietary fiber, an indigestible carbohydrate, serves separately as a regulatory agent within the gastrointestinal tract.
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3. Nature of Carbohydrates
Relation to energy
Basic fuel source
Plants, through photosynthesis, transform solar energy into carbohydrate, which is the stored fuel form in plants.
Energy production system
Digests carbohydrate to produce glucose
Absorbs glucose and transports it to cells
Metabolizes glucose to ultimately release energy
Dietary importance
Widely available and easily grown
Low cost
Easily stored

4. Classes of Carbohydrates
Saccharide = Carbohydrate class
Simple carbohydrates have 1 or 2 sugar units
Monosaccharides (1)
Disaccharides (2)
Complex carbohydrates have many sugar units
Polysaccharides

5. Classes of Carbohydrates
Monosaccharides
Simple sugar
Simple carbohydrate
Glucose: basic single sugar in human metabolism
Fructose: primarily found in fruits and honey
Galactose: product of lactose (milk sugar) digestion
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6. Classes of Carbohydrates, cont’d
Disaccharides
Double sugar
Simple carbohydrate
Sucrose- common table sugar (glucose and fructose)
Lactose- sugar found in milk (glucose and galactose)
Maltose- product of intermediate digestive breakdown of starch within the body (glucose and glucose)
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7. Classes of Carbohydrates, cont’d
Polysaccharides (complex carbohydrates)
composed of many single-sugar units.
Starch- the most significant polysaccharides
Glycogen- formed within body tissues; crucial
Dietary fiber- important dietary asset
Glycogen

8. Starch Most significant polysaccharide in the diet
Whole grains retain the bran layer, inner germ, and endosperm, including the nutrients naturally found in the plant
Enriched grains are refined grains that have nutrients added back to them
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9. Dietary Fiber
Dietary fiber cannot be broken down for energy in humans.
Sources:
Whole grains
rice, wheat, corn, potatoes
Legumes
Vegetables
Fruits with as much skin remaining as possible
Health organizations emphasize role of dietary fiber
Increases should be gradual
Diets high in fiber can help prevent and treat disease

10. Dietary Fiber (cont’d)
Benefits
Lowers blood cholesterol levels
Promotes normal bowel function and prevents constipation
Increases satiety, which helps with the prevention of obesity
Protects against disorders of the small and large intestines
Slows glucose absorption, thereby reducing blood glucose spikes and insulin secretion.
Health professionals can assist members of the public with evaluating their fiber intake by educating and encouraging the use of food labels.

11. Focus on Dietary Fiber, cont’d
Divided into two groups based on solubility
Insoluble-hold less water - relief of constipation (cellulose, most hemicelliloses, and lignin)
Soluble- hold more water-binds bile acids-reducing blood cholesterol levels (gums, mucilages, Algals and most pectins)
Many health organizations recommend increasing intake of dietary fiber
38 g/day for men
25 g/day for women
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12. Focus on Dietary Fiber Cellulose
Remains undigested in the gastrointestinal tract and provides bulk to a diet
Bulk helps move the food mass through the intestine (prevents constipaton)
Examples:
Stems, leaves of vegetables, corn hull, beans, coverings of seeds and grains
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13. Focus on Dietary Fiber, cont’d
Noncellulose polysaccharides
Absorb water and swell to a larger bulk, aids in satiety by slowing food passage through digestive tract and absorbing bile acids and cholesterol
Examples: pectins from fruit; gums & mucilages – secretions from plants like okra; algal substances - seaweed
Lignin
Only noncarbohydrate type of dietary fiber
Binds bile salts, cholesterol and metals
Woody parts of plants (broccoli stems & seeds)
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14. Summary of Dietary Fiber Classes

15. Focus on Dietary Fiber, cont’d
Sudden increases in fiber can result in gas, bloating, and constipation
Excessive amounts of dietary fiber can trap small amounts of minerals and prevent their absorption into the gastrointestinal tract
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16. Other Sweeteners Nutritive sweeteners Non-nutritive sweeteners
Sugar alcohols (sorbitol, mannitol, xylitol)
Nutritive sweeteners that provide 2 to 3 kcal/g
Non-nutritive sweeteners
Artificial sweeteners in food
Most common: acesulfame-K, aspartame, luohan guo, neotame, saccharin, stevia, sucralose

17. Energy Function of Carbohydrates
Primary basic fuel supply
Energy for physical activities and all work of body cells
Reserve fuel supply
Provided by stored glycogen
Liver stores about 100 g of glycogen
Primarily maintains blood glucose and ensures brain function
Skeletal muscles can stores 300 to 400 g
Available to maintain a normal blood glucose level

18. Special Tissue Functions of Carbohydrates
Liver
Stored glycogen protect cells from depressed metabolic function
Protein and fat
Carbohydrates regulate proteins and fat used for energy
Heart
Glycogen is vital emergency back up fuel for heart muscle
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19. Digestible Food Sources of Carbohydrates
Central nervous system
Brain dependent on minute-to-minute supply of glucose
Starches
Provide fundamental complex carbohydrates
Sugars
Readily absorbed
Simple sugars are used to treat hypoglycemia
High-sugar diets carry health risks
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20. Food Sources of Carbohydrates
Starches
Most important carbohydrate in the diet
Whole-grain starches such as rice, wheat, corn, and potatoes
Sugars
Not necessarily bad
Added sugars provide empty calories
Moderation is key

21. Digestion of Carbohydrates
Mouth
Mechanical or muscle functions break food mass into smaller particles
Chemical digestion begins with salivary amylase
Stomach
Peristalsis continues mechanical digestive process
Gastric secretions mix with food particles to facilitate chemical digestion
Secretions do not break down carbohydrates but stop action of salivary amylase
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22. Digestion of Carbohydrates, cont’d
Small intestine
Peristalsis continues mechanical digestion
Pancreatic secretions - Enter duodenum through common bile duct
Pancreatic amylase breaks starches down into disaccharides and monosaccharides
Intestinal secretions - Sucrase, lactase, and maltase help break down their respective disaccharides to render the monosaccharides—glucose, galactose, and fructose—ready for absorption directly into the portal blood circulation.

23. Recommendations for Dietary Carbohydrates
Dietary Reference Intakes
45% to 65% of adult’s total caloric intake should come from carbohydrate foods
Limit sugar to no more than 25% of calories consumed
Dietary Guidelines for Americans,
Consume at least half of all grains as whole grains.
Increase vegetable and whole fruit intake.
Choose more nutrient-dense foods and less foods and beverages with added sugar.
Reduce the intake of calories from added sugars to less than 10% of total calories.
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24. Summary
Carbohydrates are the primary source of energy for most of the world’s population.
Carbohydrates are distributed as the plant sources: grains, legumes, vegetables, and fruits.
The two basic types of carbohydrates are simple and complex.
Simple carbohydrates are composed of single- and double-sugar units (monosaccharides and disaccharides)
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25. Summary, cont’d
Complex carbohydrates are composed of many sugar units.
Dietary fiber is a complex carbohydrate that is not digestible and is found mainly in the structural parts of plants.
Carbohydrate digestion begins in the mouth, continues in the stomach, moves to the small intestine, and finally arrives in the large intestine and exits through the anus.
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26. Lesson 3.1: Fats
Dietary fat supplies essential body tissue needs, both as an energy fuel and structural material.
Foods from animal and plant sources supply distinct forms of fat that affect health in different ways.
Excess dietary fat, especially from animal food sources, is a negative risk factor in overall health.
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27. The Nature of Fats Dietary importance Concentrated fuel for energy
Classes of fats
Lipids
Glycerides
Triglycerides
Fatty acids
Lipoproteins
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28. Fatty Acids
ESSENTIAL fatty acids means that it is ESSENTIAL that we eat them
Saturated fatty acids
Filled or “saturated”
with hydrogen
Two essential fatty acids
Linoleic
Alpha-linolenic 28

29. Fatty Acids Unsaturated fatty acids Omega 3 and omega 6
Not completely filled with hydrogen
Less heavy, less dense
Monounsaturated: one unfilled spot
Polyunsaturated: two or more unfilled spots
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30. Fatty Acids (cont’d) Roles of essential fatty acids
Related to tissue strength, cholesterol metabolism, muscle tone, blood clotting, and heart action
Trans-fatty acid
Hydrogen atoms around carbon double bond are on opposite sides (trans form)
Negative health consequences related to cardiovascular disease
Essential means these fats MUST come from the foods we eat. We cannot produce these as we can the other types of fatty acids.

31. Phospholipids
Triglyceride derivative: third fatty acid replaced by phosphate group
Partially hydrophobic, partially hydrophilic – remember cell wall?
Allow transport of fats through bloodstream 31

32. Lipoproteins Lipoproteins: chemical complexes of fat+protein
Major carriers of lipids in the plasma (since water and “oil” don’t mix)
They vary in density according to the size of the fat load being carried (i.e., the lower the density, the higher the fat load).
The combination package with water-soluble protein makes possible the transport of non–water-soluble fatty substances in the water-based blood circulation.

33. A QUESTION FOR YOU! Why are trans fats “worse” than saturated fats?
Studies show they lower HDL cholesterol and raise LDL cholesterol, whereas saturated fats only raise LDL cholesterol, leaving HDL the same or better
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34. Lipoproteins (cont.)

35. Cholesterol Not a fat A fat-related compound (sterol)
synthesized only in animal tissues (cell membranes)
a normal constituent of bile
a principal constituent of gallstones
A fat-related compound (sterol)
Only from animal foods
Egg yolks
Liver, kidney
Meats
Synthesized in the liver
Diet should be low in cholesterol
Linked with heart disease 35

36. Functions of Fat in Foods
Fat in foods provide:
Energy
Essential nutrients
Flavor and satisfaction
Fat substitutes are not absorbed and therefore do not provide energy or essential nutrients but may provide flavor and satisfaction
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37. Functions of Fat in the Body
Adipose tissue
Supports and protects organs
Helps regulate temperature
Cell membrane structure
Forms part of cell membrane
Helps transport nutrients across cell membranes
Composes protective myelin sheath that surrounds neurons
Second energy source
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38. Food Sources of Fat Animal fats Plant fats
The chief dietary supply of saturated fat and cholesterol comes from animal sources.
Plant fats
Plant foods supply mostly monounsaturated and polyunsaturated fats, including the essential fatty acids.
Hydrogenated fats (trans fats)
Commercial fat products raise health concerns
Food industry now offers trans-free products
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39. FDA Health Claims
Claims that link one or more dietary components to the reduced risk of a specific disease need to be approved by the FDA
Fat and cancer
Saturated fat and cholesterol and heart disease
Food label information
Mandatory information
Total fat
Saturated fat
Trans fat
Cholesterol 39

40. Key Concepts
Dietary fat supplies essential body tissue needs, both as an energy fuel and a structural material.
Excess dietary fat, especially from animal food sources, is a negative risk factor in overall health.
Food fat has 2 sources
Visible fats
butter, margarine, separate cream, salad oils and dressings, lard, shortening, poultry with skin
Invisible fats
Nuts, seeds, olives, skinless chicken, cream portion of milk
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41. Dietary Fat and Health The American diet is high in fat.
Excess calories are stored as fat.
Animal food sources contribute to excess cholesterol and saturated fat in the diet.
A decrease in saturated fat reduces serum total cholesterol.
Monounsaturated fats reduce LDL cholesterol when substituted for saturated fat.
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42. Digestion of Fats Mouth - mechanical Stomach - mechanical
Small intestine – chemical & mechanical
Bile (emulsifier) from the liver & gallbladder
Enzymes from the pancreas (Pancreatic lipase)
Enzymes from the small intestine
The type of fat and cooking temperature affect the digestibility of fats. Fried food cooked at high temperatures are harder to digest and form carcinogins. 42

43. Absorption
Since fats are not soluble in water they are not absorbed into the blood directly they are mixed with bile and form micelles to enter the epithelial cells.
Bile is recycled by the hepatic portal system.
Triglycerides are remade from digested fats and collet to form chylomicron to carry them with the cholesterol, phospholipids and protein to the lacteals of the lymph system and them to blood circulation.
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44. Dietary Fat and Health The American diet is high in fat. Amount of Fat
Excess calories from any source are stored as body fat.
Excess body fat is associated with higher rates of mortality and risk for chronic diseases.
Type of Fat
Omega-3 fats, when replacing saturated and trans fats, and monounsaturated fats are cardio-protective.
Mediterranean diet
Diets high in trans-fatty acids can raise LDL levels and lower HDL levels.
FDA
removed trans-fatty acids from GRAS food additives list
requiring food manufacturers to discontinue use of partially hydrogenated oils (main source of trans-fatty acids) in any food product by 2018
Why are excess calories stored as fat and not carbohydrate or protein? (Explain that storing excess energy as fat is the way the body is supposed to work. It is a machine meant to store the most energy in the least amount of space.)
Heart disease continues to be one of the leading causes of death in developed countries. Much attention is focused on reducing risk factors leading to this disease.
GRAS list means generally recognized as safe.

45. Dietary Fat Requirements
Healthy diet guidelines:
Stress the health benefits of a diet low in fat overall, but more so with saturated fat, and cholesterol
Recommend that the fat content should not exceed 20% to 35% of total kilocalories
Less than 10% of kilocalories should be from saturated fat
Dietary cholesterol should be limited to 300 mg/day
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46. Dietary Fat and Health Essential fatty acid deficiency
May result from following a fat-free diet
Linked to health problems including:
Hair loss
Infertility
Low blood platelet levels
Impaired vision
Compromised brain function
Growth retardation in children

47. Health Promotion
Reduce risk factors for chronic diseases, especially heart disease, the leading cause of death
Obesity
Diabetes
Elevated triglycerides
Elevated blood pressure
Lifestyle risk factors = smoking, increased stress, physical inactivity
Balance caloric intake with energy output
[Ask students if they have noticed changes at restaurants with regard to fat content of foods.]

48. Dietary Guidelines for Americans
Control saturated fat and cholesterol
Keep trans-fatty acid consumption as low as possible
Use only lean cuts of all meats; use more poultry and seafood (shellfish are low in fat but high in cholesterol)
Limit eggs to two or three per week
Can discard the yolk to decrease fat
Use low-fat or fat-free milk and milk products
Choose fat-free or low-fat milk and milk products.
replace solid fats where possible.
Avoid adding too much fat in food preparation – food should not slide across the plate!
Slide 48 48

49. Summary
Classes of fat include lipids, triglycerides, fatty acids, and lipoproteins
Fatty acids can be saturated or unsaturated
Essential fatty acids are necessary to aid in tissue strength, muscle tone, cholesterol metabolism, blood clotting, and heart action
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50. Summary, cont’d
Cholesterol is a sterol only found in animal foods that is vital in human metabolism
Digestion of fat includes digestive agents such as bile and pancreatic lipase
Fatty acids and glycerides are incorporated into chylomicrons and absorbed via the lymphatic system into the bloodstream
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