Chapter 3 Power Point

© 2016 Pearson Education, Inc.

Chapter 3 Lecture

Chapter 3: CarbohydratesPlant-DerivedEnergy Nutrients

Learning Outcomes

1. Distinguish between simple and complex carbohydrates.

2. List four functions of carbohydrates in our body.

3. Explain how carbohydrates are digested and absorbed by our body.

4. Define the glycemic index and glycemic load.


Learning Outcomes

5. Identify the RDA and the AMDR for carbohydrates, and the AI for fiber.

6. Identify the most common dietary sources of added sugars and the potential health risks of a diet high in added sugars.

7. List five foods that are good sources of fiber-rich carbohydrates.


Learning Outcomes

8. Compare and contrast a variety of alternative sweeteners.

9. Distinguish between type 1 diabetes, type 2 diabetes, and prediabetes.

10.Describe the lifestyle behaviors that can prevent or control diabetes.


What Are Carbohydrates?

• Carbohydrates• One of the three macronutrients• A primary energy source, especially for nerve

cells• Molecules composed of carbon, hydrogen,

and oxygen atoms• Most come from plant sources



• Glucose• The most abundant carbohydrate• Produced by plants through photosynthesis


Photosynthesis



• Simple carbohydrates are sugars• Contain one or two molecules• Monosaccharides contain only one molecule.

• Glucose, fructose, galactose

• Disaccharides contain two molecules.• Lactose, maltose, sucrose


Constituent Parts of Simple Carbohydrates



• Complex carbohydrates• Long chains of glucose molecules• Also called polysaccharides• Starch, glycogen, and fiber


Complex Carbohydrates



• Starch • Plants store carbohydrates as starch.• Humans digest (break down) starch into

glucose.• Grains, legumes, and tubers are good

sources of starch in our diet.



• Fiber• Fiber is the non-digestible part of plants.• Dietary Fiber occurs naturally in foods.

• Found in whole grains, vegetables, seeds, legumes, fruits

• Functional fiber is carbohydrate that is manufactured and added to food.• Cellulose, guar gum, pectin, psyllium

• Total fiber = dietary + functional fiber



• Soluble fiber• Soluble in water and viscous (forms a gel

when wet)• Found in citrus fruits, berries, oats and beans• May reduce risk of cardiovascular disease

and Type 2 diabetes• Insoluble fiber

• Insoluble in water• Found in whole grains and vegetables• Promote regular bowel movements



1. If you had to give nutrition advice to the general public, what foods would you recommend for increasing fiber intake?

2. Average fiber intake for Americans is much lower than recommended levels. What are the reasons Americans consume lower than recommended amounts of fiber in their daily diet?

3. How might one's living environment, cultural practices, socioeconomic status, and education level limit their consumption of fiber rich foods?



• Glycogen• Animals store carbohydrate as glycogen.• Stored in the liver and muscles• Broken down into glucose• Rarely found in food and therefore not a

dietary source of carbohydrate



• What makes a whole grain whole?


Whole Grains

1. How can we raise consumer awareness that there is a discrepancy between the marketing of grain products and the actual contents of grain products for consumption?

2. How can companies be held to a better standard to be more honest regarding the contents of products?

3. Provide an argument for the need for the FDA to define whole grains.


Grains and Cereals Defined


Why Do We Need to Eat Carbohydrates?

• Energy• Each gram of carbohydrate = 4 kcal• Important source of energy for all cells• Critical energy source for brain cells and red

blood cells• Glucose is especially important for energy

during exercise.



• Energy• Insufficient carbohydrate intake causes the

body to find an alternate source of glucose.• Often proteins are broken down and used for

gluconeogenesis – the production of new glucose.



• Fiber-rich carbohydrates• May reduce the risk of colon cancer• May reduce the risk of heart disease• May enhance weight loss• May reduce risk of type 2 diabetes• Help prevent hemorrhoids, constipation, and

diverticulosis


Fiber-Rich Carbohydrates Have Health Benefits


Fiber-Rich Carbohydrates Have Health Benefits


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Digestion of Carbohydrates


What Happens to the Carbohydrates We Eat?• Salivary amylase

• Enzyme from saliva that begins carbohydrate digestion in the mouth

• Breaks carbohydrates down into maltose• There is little digestion of carbohydrates in the

stomach; most of this happens in the small intestine.


What Happens to the Carbohydrates We Eat?• Most chemical digestion of carbohydrates

occurs in the small intestine• Pancreatic amylase

• Enzyme produced in the pancreas and released into the small intestine

• Converts carbohydrates into maltose


What Happens to the Carbohydrates We Eat?• Additional enzymes in the small intestine break

down any remaining disaccharides into monosaccharides.

• These enzymes include maltase, sucrase, and lactase.

• Monosaccharides are absorbed into the cells lining the small intestine (enterocytes) and enter the bloodstream.


Lactose Intolerance

• Lactose intolerance• Insufficient lactase production causes an

inability to completely digest the lactose found in dairy products.

• Symptoms include intestinal gas, bloating, nausea, cramping, diarrhea.

• Lactose-intolerant people may need to find alternate sources of calcium.


The Liver Converts All Sugars into Glucose

• Once absorbed into the bloodstream, 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.


Absorption of Carbohydrates


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the power point.


• We do not have the enzymes necessary to digest fiber.

• Bacteria in the large intestine can break down some fiber.

• Most fiber remains undigested and is eliminated with feces.


Storage of Glycogen




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Regulation of Blood Glucose

• The level of glucose in the blood must be closely regulated.

• Two hormones, insulin and glucagon, control the level of glucose in the blood.


Insulin

• Insulin• Produced by beta cells of the pancreas• Helps cells take in glucose from the blood• Stimulates the liver to take up glucose and

convert it to glycogen


High Blood Glucose


Glucagon

• Glucagon• Produced by alpha cells of the pancreas• Stimulates the breakdown of glycogen to

glucose to make glucose available to cells of the body

• Stimulates gluconeogenesis – the production of new glucose from amino acids


Low Blood Glucose




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point.


• Hypoglycemia• Low blood-sugar (glucose) levels• One cause is excessive insulin production• Causes shakiness, sweating, anxiety,

weakness, irregular heart beat


Effect of Food Upon Blood Glucose

• The glycemic index is a food's mathematical potential to raise blood glucose levels.

• Glycemic load = amount of carbs x glycemic index

• Foods with a low glycemic load:• Cause low or moderate changes in blood

glucose• Are better for people with diabetes• May reduce the risk of heart disease and

colon cancer


Glycemic Index Values for Selected Foods


How Much Carbohydrate Should We Eat?

• Recommended Dietary Allowance (RDA) is 130 grams/day just to supply adequate glucose to the brain

• A total of 45–65% of daily caloric intake should be in the form of carbohydrates.

• Focus on fiber-rich and unprocessed carbohydrates


Simple Sugars

• Diets high in simple sugars:• Can cause dental problems such as tooth

decay and gum disease• May contribute to unhealthy levels of blood

lipid levels (cholesterol, etc.)• Have not been proven to cause hyperactivity• May contribute to obesity and diabetes


Simple Sugars

1. What can you do to avoid overconsumption of sugar?

2. Why is added sugar unhealthy? What diseases can occur due to consuming high amounts of added sugar?

3. What are some of the replacement (counterconditioning) tactics that can help cut back on our "want" of added sugar?


Fiber-Rich Carbohydrates

• The Adequate Intake (AI) of fiber is: • 25 grams/day for women• 38 grams/day for men

• Most Americans eat only half the recommended amount of fiber.

• Whole-grain foods are a more healthful choice than foods with added sugar.



• Excessive fiber can cause:• Intestinal gas and bloating• Dehydration if water is not increased• Reduced absorption of certain nutrients• Malnutrition if feeling "full" precludes intake of

other nutrients




Click on the Diverticulosis link separate from the power

point.



Alternative Sweeteners

• Nutritive• Provide energy like simple carbohydrates• Sugar alcohols

• Mannitol, sorbitol, xylitol, isomalt• Decreased risk of dental caries• 2–3 kcals/gm• Can cause diarrhea

• Non-nutritive or alternative • Provide little or no energy


Alternative Sweeteners

• Acceptable Daily Intake (ADI)• Saccharin• Acesulfame-K• Aspartame• Sucralose• Neotame• Stevia


To Exceed the ADI for Aspartame


Carbohydrates in our Diet


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point.

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Carbohydrates in our Diet


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point.

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What is Diabetes?

• Diabetes• Inability to regulate blood glucose levels• Three types:

• Type 1 diabetes• Type 2 diabetes• Gestational diabetes

• Untreated diabetes can cause nerve damage, kidney damage, blindness, the need for amputations, and death.


What is Diabetes?

1. Examine reasons more young adults are developing type 2 diabetes now than in previous generations.

2. Should the government take more stringent guidelines to limit fast food restaurants from using ingredients (such as high fructose corn syrup) or offering large serving sizes that contribute to poor nutritional health among consumers?


Symptoms of Diabetes


Forms of Diabetes

• Type 1 diabetes• Accounts for 10% of all cases• Patients do not produce enough insulin.• Causes hyperglycemia – high blood sugar

(glucose)• Requires insulin injections• May be an autoimmune disease


Forms of Diabetes

• Type 2 diabetes• Most diabetics have type 2 diabetes.• Body cells are resistant or less responsive to

insulin.• Excess insulin is often produced.• Causes hyperglycemia because cells cannot

take in the glucose from the blood


Forms of Diabetes

• Pre-diabetes• Impaired fasting glucose levels are higher

than normal but not high enough for a diagnosis of type 2 diabetes

• Metabolic syndrome• Waist circumference• Blood pressure• Blood lipids• Blood glucose levels


Forms of Diabetes

• Type 2 diabetes• Cause is unclear, but genetics, obesity, and

physical inactivity play a role• Treated with weight loss, diet, exercise, and

possibly oral medications and/or insulin• Healthy lifestyle choices may prevent or delay

onset of type 2 diabetes.
