NR228 Nutrition
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Chapter_004.pptxChapter 4
Carbohydrates
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Identify the simple carbohydrates and their components.
Explain the types of complex carbohydrates.
List the dietary recommendations for carbohydrates.
Discuss the functions of carbohydrates as a carbohydrate source of energy and dietary fiber.
Describe differences and health benefits of soluble and insoluble fiber.
Compare the nutrient content of refined versus unrefined grains.
Learning Objectives
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Carbohydrates (CHO): organic compounds composed of carbon, hydrogen, and oxygen in the form of simple carbohydrates or sugars
Source of energy, sweetness, and dietary fiber
Role in Wellness (1 of 3)
Dietary Reference Intake (DRI) for carbohydrates is 130 g/day for adults between 19 and 30 years of age.
Acceptable Macronutrient Distribution Range (AMDR) for carbohydrates is 45% to 65% of kcal intake per day as primarily complex carbohydrates.
Role in Wellness (2 of 3)
Consideration of carbohydrates through health dimensions provides perspective on their role in wellness
Physical health
Intellectual health
Emotional health
Social health
Environmental health
Role in Wellness (3 of 3)
Structure of a Molecule of Carbohydrate
Fig. 4.1 Structure of a molecule of carbohydrate.
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Primarily plant-based
Three sizes:
Monosaccharides
Disaccharides
Polysaccharides
Divided into two categories
Simple carbohydrates
Complex carbohydrates
Food Sources of Carbohydrate
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Complex Carbohydrates
Fig. 4.2 Structure of monosaccharides, disaccharides, and polysaccharides.
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Function
Provides energy
Dietary fiber
Naturally occurring sweeteners (sucrose and fructose)
Brain and nerve tissues require CHO (glucose) as fuel.
Protein-sparing effect
Carbohydrate as a Nutrient in the Body
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Digestion
Digestive process begins in mouth
Breakdown to monosaccharides
Mechanical digestion
Chemical digestion function of enzymes
Lactose intolerance
Digestion and Absorption (1 of 2)
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Absorption
Active transport process of glucose
Liver conversion of fructose and galactose to glucose
Digestion and Absorption (2 of 2)
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Summary of Carbohydrate Digestion and Absorption
Fig. 4.3 Summary of carbohydrate digestion and absorption. (From Rolin Graphics.)
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Glycogen: storage form of CHO in liver and muscles
Glycogenesis: process of converting glucose to glycogen
Effects of training on glycogen storage
Limited energy source
Glycogen: Storing Carbohydrates
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Blood glucose: source of energy to all cells
Metabolism: primarily maintenance of blood glucose homeostasis at 70 to 100 mg/dL
Conversion to and from glucose
Glycogenolysis
Gluconeogenesis
Ketones
Metabolism
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Hormonal system controls glucose metabolism and blood glucose level regulation
Insulin: pancreatic hormone that regulates blood glucose uptake
Glucagon: pancreatic hormone that releases glycogen from liver
Somatostatin: pancreatic and hypothalamus hormone that inhibits insulin and glucagons
Hormones from adrenal, pituitary, and thyroid glands
Blood Glucose Regulation
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Glycemic index: level to which food raises blood glucose levels in comparison with reference food; highest ranking is 100
Factors affecting glycemic index
Glycemic load: total glycemic index; effect of mixed meal or dietary plan
Health effects: chronic disease
Glycemic Index and Glycemic Load
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Monosaccharides
Glucose
Fructose
Galactose
Disaccharides
Sucrose: glucose + fructose
Maltose: glucose + glucose
Lactose: glucose + galactose
Simple Carbohydrates
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Sources in the food supply
Sugar cane and sugar beets
Honey, brown sugar, dextrose, and molasses
Other sources, such as corn syrup and high-fructose corn syrup (HFCS)
Consumption levels
Health effects
Acceptable levels of intake
Sugar: a Special Carbohydrate
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Examples of Sources of Carbohydrates
Fig. 4.4 Consuming products with added sugars (left) can displace more nutrient-dense foods (right). (From Joanne Scott/Tracy McCalla.)
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Sugar alcohols
Sorbitol, mannitol, and xylitol
Alternative sweeteners (artificial sweeteners)
Aspartame
Saccharin
Acesulfame potassium
Sucralose
Stevia
Other Sweeteners
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Benefits and risks
Sucrose consumption
Alternative sweeteners consumption
Decisions about Consumption of Sweets
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Complex carbohydrates: polysaccharides composed of many units of monosaccharides held together by different kinds of chemical bonds
Starch
Fiber
Complex Carbohydrates: Polysaccharides
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Starch
Storage form of plant carbohydrate
Food sources: grains, legumes, root vegetables (potatoes)
Starch
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Fiber: carbohydrate (polysaccharide) and lignin in plant foods; cannot be digested by humans
Soluble fiber
Insoluble fiber
Fiber (1 of 5)
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Fiber (2 of 5)
Fig. 4.5 In an apple, insoluble fiber (cellulose) inside and in the skin provides structure, and soluble fiber (pectin) inside adds substance.
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Health effects
Obesity
Constipation
Diverticular disease
Colon cancer
Heart disease
Diabetes control
Fiber (3 of 5)
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Food sources and issues
Recommended adequate intake (AI): 25 to 38 g/day
Unrefined versus refined grains
Whole (unrefined) grains
Refined grains
Enrichment
Fiber (4 of 5)
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Fiber (5 of 5)
Fig. 4.7 Inside a wheat kernel.
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Tailoring
“Cutting,” “shaping,” and “sewing” help fit a health recommendation to limitations or requirements (or “size”) of a person’s individual lifestyle.
Toward a Positive Nutrition Lifestyle: Tailoring
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