Week 3 Notes
Week 3 Notes 2420-001
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This 8 page Class Notes was uploaded by Emma Trokel on Wednesday January 13, 2016. The Class Notes belongs to 2420-001 at University of Colorado at Boulder taught by S. Nelson in Spring 2016. Since its upload, it has received 10 views. For similar materials see Nutrition and Health Performance in Psychlogy at University of Colorado at Boulder.
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Date Created: 01/13/16
Week 3 Chapter 5 Carbohydrates How Carbohydrates are made plants use the sun’s energy to combine carbon, oxygen, and hydrogen to form carbohydrates plants autotrophic plants are the basis of the entire food chain Simple Carbohydrates: Sugars The simplest form of carbohydrate is sugar The simplest sugar is called monosaccharide it is the basic chemical unit of carbohydrates A disaccharide is a sugar comprised of two monosaccharides Monosaccharides The monomer of the “sugar world’ the smallest molecule ● Glucose primary energy source for cells ○ Also referred to as “dextrose” or ”blood sugar” ○ favored food source ○ Can make it through the microvilli ● Fructose ○ “Fruit sugar” or “levulose” ○ Can make it through the microvilli ● Galactose ○ Part of “milk sugar” (lactose) ○ Can make it through the microvilli Disaccharides ● Maltose ○ glucose + glucose ● Sucrose ○ glucose + fructose ● Lactose ○ glucose +galactose Sucrose table sugar Made from sugar cane or sugar beets Refinement ( from purple to white ) strips away small amounts of vitamins and minerals naturally present in cane and beets A tablespoon of table sugar is almost 100% sucrose Occurs naturally in honey, maple syrup, carrots, and sweet fruits such as pineapples Complex Carbohydrates healthy ● Polysaccharides ○ contain more than ten monosaccharides bonded together ○ storage form of carbohydrate in plants and animals ○ structural component of plants in stems and leaves Starch and Glycogen ● Starch ○ Storage form of carbohydrate in plants ○ Mainly in seeds, roots, and tubers ● Glycogen ○ Storage form of carbohydrate in humans and other animals ○ Stored primarily in live and muscles Fiber Most forms of fiber are complex carbohydrates that the human body cannot digest Two types soluble Delays stomach emptying; slows glucose absorption; can lower blood cholesterol insoluble increases fecal bulk and speeds fecal passage through GI tract What’s A Whole Grain? ● The intact, ground, cracked, or flakes seeds of cereal grains ● Must contain: ○ Fiberrich bran ■ you want 3 grams of fiber per peice of bread ○ Starchy endosperm ■ calories ○ Oily germ ■ where the seed is holding a packet of nutrients.. a bit more calories What Happens to Carbohydrates In the Body? ● Mouth Salivary amylase digests some starch ● Stomach a cid inactivates salivary amylase ● Small Intestine main site for carbohydrate digestion and absorption ● Liver absorbed monosaccharides travel to liver ○ store glucose in liver because of glycogen which is holding component for glucose ● Large Intestine some soluble fiber fermented ● Rectum very little dietary carbohydrate excreted in feces digestion breaking down absorption taking up of carbs are so important because they are the main energy source Maintaining Blood Glucose Levels ★ glucagon converts glucose back to glycogen What Happens After Eating Carbohydrates? Insulin released from pancreas: ● Enables glucose to enter cells ● Enhances production/storage of: ○ Fat ○ Glycogen ■ stores as fat when liver fills up with glycogen ○ Protein ● Decreases hunger What Happens When You Don’t Eat? When blood glucose decreases, pancreas releases glucagon, stimulating: ● Glycogenolysis ○ Glycogen breakdown releasing glucose into the blood ● Lypolysis ○ Breakdown of triglycerides (fat) for energy Ketone Bodies and Ketosis ● Ketone Bodies ○ ran out of glucose, then protein, ketone is the backup backup system ○ Form as a result of incomplete fat breakdown ■ poorly controlled diabetes ■ fasting or starving ■ lowcarbohydrate, highprotein diet ○ Used by certain cells for energy ● Ketosis ○ Condition that occurs with very high blood ketone bodies ○ Unconsciousness and death may occur Are Carbohydrates Fattening It may depend on the type of Carb… Probably “fattening”: ● Added sugars, including highfructose corn syrup ● Refines starches Healthier Choices: ● Fiberrich foods ( fruits, vegetables, and unrefined grains) What is Diabetes? Diabetes mellitus: ● Group of serious chronic diseases characterized by abnormal glucose, fat, and protein metabolism ○ Type 1 diabetes ■ Autoimmune disease ■ Beta cells stop making insulin ○ Type 2 ■ most common type ■ insulin resistant cells Hypoglycemia ● Abnormally low blood glucose levels ○ normal fasting blood glucose <70 mg/dl ● Blood glucose level is too low to provide cells adequate energy ● True hypoglycemia is rare in nondiabetics Reactive hypoglycemia ● In some people, blood glucose drops after eating highly refined carbohydrates ○ pancreas responds to the carb intake by secreting excess insulin Lactose Intolerance ● Inability to digest lactose caused by inadequate lactase ○ affects millions of Americans ○ very common in people of African , Asian, or Eastern European descent ● Bacteria in the large intestine break down undigested lactose, resulting in: ○ intestinal cramps, bloating, gas, and diarrhea Fiber and Health ● Fiber And the Digestive Tract ○ Low fiber intake is linked to constipation and straining to expel feces ○ Pressure on large intestine (colon) may result in diverticula formation ○ Diverticula ■ abnormal tiny sacs that form in the wall of the colon ● Fiber and Colorectal Cancer ○ Currently, it is unknown whether highfiber diets protect against colorectal cancer ● Fiber and Heart Health ○ Soluble fibers promote heart health ● Fiber and Weight Control ○ High fiber foods are “filling”, resulting in satiety Alternative Sweeteners ● What are alternative to sweeteners? ○ Substances added to a food to sweeten it but provide few or no calories ● What are sugar alcohols ○ Alternative sweeteners: ■ Sorbitol, xylitol, mannitol ○ Poorly absorbed and may cause diarrhea ○ Supply 2kcal/g ○ Do not contribute to dental cavities ● Diabetics can use alternative sweeteners as much as they want Nutrition Matters: Glycemic Index and Glycemic Load ● Glycemic index: ○ method of classifying carbohydraterich food by comparing the rise in blood glucose after eating a portion of food that contains carbohydrates that can be easily broken down ● Glycemic Load: ○ grams of carbohydrates in a serving of food multiplied by the food’s glycemic index ● fiber also dampens the spike, you want more fiber and protein and fat if concerned about glycemic index ● a quick spike in blood glucose is so bad because it's not a gradual increase your cells can get used to … high glycemic foods can cause this ● fiber absorbs the spike Criticism of GI and GL ● Some nutrition scientists do not think GIs and GLs are useful for meal planning GI and GL values for a particular food High Fructose Corn Syrup ● Background ○ 55% fructose / 45% glucose ○ Since human taste buds highly sensitive to fructose, mix tastes sweeter than 50% fructose/ 50% glucose mix from sucrose ○ is produced very cheaply from cornstarch, so most companies switched to HFCS in the 1980’s ○ corn in highly subsidized ● consumption of soda has gone up 200% in 30 years ● HFCS primary sweeteners in regular soft drinks ● Renamed corn sugar after a series of ads and parodies Why is it so heavily used? ● it mixes easily fruit juices ● extends shelf life by 20% by inhibiting microbial spoilage ● tastes extra sweet ● helps prevent freezer burn ● helps baked products brown better hot dog buns ● results in soft textures chewy cookies and protein bars Issues with HFCS ● causes flatulence and diarrhea ● corn sugar is the new name ● sugar uptake transporter in human gut best transports 1 glucose + 1 fructose; is slow in taking up extra fructose ● 30% of US population suffer from some “fructose malabsorption” from HFCS and resulting flatulence/diarrhea ● diarrhea can lead to mineral deficiencies (iron, magnesium, calcium, zinc) ● Metabolic syndrome ● mercury caustic soda used to separate corn starch from the kernel ● increased triglyceride levels ● increased dental cavities ● interferes with oral contraceptive efficacy interferes with birth control ● possible link to obesity: ○ 1 unlike glucose, fructose does not enhance production of hormones insulin ■ regulates blood glucose levels and signals satiety ○ 2 does not signal leptin How to avoid HFCS certified organic products cannot contain HFCS $0.10 difference eating more whole foods eat fewer processed foods / prepare foods yourself
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