Carbohydrates Will Brown Lecture 4 1/12/2012

Outline and Content Objective – To identify basic structure, sources, and digestion of carbohydrates. Also to identify how carbohydrates affect blood glucose and some of the issues associated with to little or to much Content Eat This, Not That Carbohydrate Simple Complex

Which should you eat? Nutrition Facts Serving Size:32 pieces 150 cal 9g fat (1.5g saturated) 290 mg Sodium Nutrition Facts Serving Size: 15 chips 120 cal 3.5 g fat (0.5g saturated) 220 mg sodium In addition, the Dorito's come with 2 g of fiber.

Introduction What are carbohydrates? Sugar molecules arranged in various ways Why do we love carbohydrates do much? One of the primary flavors was developed for carbohydrates – sweet! Provide the main energy source for the body 4 kcal/gram Stored in either liver or muscles as glycogen Also available in the blood as glucose

Where are carbohydrates produced? Primarily made by green plants Plants are able to transform solar energy into chemical energy What is the name of this process?

6 CO2 + 6 H2O → C2H12O6 + 6 O2 So 6 carbon dioxides along with 6 water molecules and some energy from the sun results in 1 glucose molecule and oxygen

Simple carbohydrates

Simple Carbohydrates Two main forms of simple carbohydrates Monosaccharides – One sugar Disaccharides – Two sugars Can anybody give an example of a simple carbohydrate? Food labels list both mono and di under “Sugars”

glucose, fructose, galactose Monosaccharides glucose, fructose, galactose Disaccharides Sucrose glucose+fructose Maltose glucose+glucose Lactose glucose+galactose

Monosaccharides Single unit of sugar Three most basic forms Glucose Fructose Galactose

Glucose Most common form of sugar found in the body AKA: Dextrose Not common in food as single sugar Most comes from breakdown of sucrose Most forms of sugar are converted to glucose once in the body

Fructose AKA: Fruit sugar After absorption transported to liver Either converted to glucose or converted to other compounds, i.e.: fat Most fructose comes from the refined product high-fructose corn syrup Forms the other half of the sucrose molecule

Galactose Very similar in structure to Glucose Not found in large amounts in nature Forms half of the disaccharide Lactose Glucose forms the other half Converted to Glucose or Glycogen in the liver

Disaccharides Two molecules of sugar Sucrose Lactose Maltose Glucose and Fructose bonded together Sources: honey, sugarcane, sugar beets, and maple sugar Not produced by animals Lactose Glucose bonded to Galactose Produced in milk synthesis Maltose Glucose bonded to Glucose Comes from breakdown of starch Important sugar in fermentation process

Complex Carbohydrate

Stored in muscle + liver Polysaccharides Starches Made in plants Digestible Glycogen Made by animals Stored in muscle + liver Fiber Made in plants Indigestible Amylose Straight chain Pectins Soluble Amylopectin Branched Cellulose Insoluble

Stored in muscle + liver Polysaccharides Starches Made in plants Digestible Glycogen Made by animals Stored in muscle + liver Fiber Made in plants Indigestible Amylose Straight chain Pectins Soluble Amylopectin Branched Cellulose Insoluble

Digestible Complex Carbohydrates AKA: Polysaccharides and starch Long chains of sugar molecules bonded together – can be >1000 molecules of sugar Plants store CC in 2 main forms Amylose Amylopectin

Digestible Complex Carbohydrate Enzymes breakdown starch at the end of the chain Amylose is slower to digest than amylopectin As a result amylopectin raises blood sugar faster All carbs are listed on nutrition labels as “Other Carbohydrates” Glycogen is primary sugar found in the body Stored in muscles and liver Glucose molecules bonded together Highly branched; even more so than amylopectin Can quickly raise blood glucose levels

Stored in muscle + liver Polysaccharides Starches Made in plants Digestible Glycogen Made by animals Stored in muscle + liver Fiber Made in plants Indigestible Amylose Straight chain Pectins Soluble Amylopectin Branched Cellulose Insoluble

Complex Carbohydrates: Fiber Made up primarily of polysaccharides Can not be digested by humans 6 types of Fiber Cellulose Hemicellulose Pectins Gums Mucilages Lignin -- Carbohydrate fibers -- Non-carbohydrate fiber

Stored in muscle + liver Polysaccharides Starches Made in plants Digestible Glycogen Made by animals Stored in muscle + liver Fiber Made in plants Indigestible Amylose Straight chain Pectins Soluble Amylopectin Branched Cellulose Insoluble

Soluble fibers Pectins, gums and mucilages AKA: viscous fiber Dissolve or swell when placed in water Source: found around and inside plants Readily digested by bacteria – fermentable Found in foods under various names Guar gum Gum arabic Locust bean gum Pectin for jam and jellies

Soluble fiber Pectin Mucilages Galacturonic acid Also others Galactose Manose And others

Stored in muscle + liver Polysaccharides Starches Made in plants Digestible Glycogen Made by animals Stored in muscle + liver Fiber Made in plants Indigestible Amylose Straight chain Pectins Soluble Amylopectin Branched Cellulose Insoluble

Insoluble Fiber Comprised of cellulose, hemicellulose, and lignin AKA: nonfermentable fiber Do not readily dissolve in water Sorce: form the structural parts of plants Cell wall, bark, etc. Not readily metabolized by commensal bacteria Bran is rich in hemicellulose and lignin Outer covering of all whole grains

Insoluble Fiber Cellulose Hemicellulose Lignin Glucose Xylose Galactose Small amounts of other monosaccharides Lignin Multi-ringed alcohols That is why it is called a “noncarbohydrate”

Carbohydrates on Food Labels Sugars = all mono and disaccharides Dietary fiber = fiber present in the food Does not include added or “functional” fiber Now you can find “total fiber” Number of complex carbs is total carbs – DF – sugars

Carbs in the Diet Recommended Daily allowance of Carbohydrate = 130g Should comprise 45-65% of daily calories Example: for 2000 calorie diet that is between 900 to 1300 calories Look for nutrient dense carbohydrates Fruit, vegetables, beans, etc. Avoid processed carbohydrates Refined sugars and refined grains

Carbs in the Diet Why is it necessary to eat whole grains? What is a whole grain? During the refinement process the bran is removed Leaves very little if any fiber – mostly starch Why is this a problem? Easily digestible carbohydrates quickly raise blood sugar

Which should you eat? Nutrition Facts Serving Size: 1/2 cups dry 150 cal 3 g fat (0.5 g saturated) 1 g Sugar 4 g fiber Nutrition Facts Serving Size: 2 packets 200 cal 0 g fat 2g Fiber Process of making grits has high concentration of starch and reduced fiber

Carbs in the Diet: Sweeteners Two categories Nutritive Alternative Nutritive sweeteners provide calories Sugars – Used in many types of food Sugar alcohols – limited uses Alternative sweeteners provide no calories Saccharin Aspartame Alternative sweeteners are “sweeter” on a per gram basis compared to nutritive sweetners

Carbs in the Diet: Nutritive Sweeteners All monosaccharides and disaccharides Sucrose is the benchmark to measure relative sweetness Sucrose = 1.0 If >1 then sweeter than sucrose If < 1 then not as sweet as sucrose High Fructose Corn Syrup (HFCS) is used extensively as a sweetener is food ~55% Fructose Made by refining corn As sweet as sucrose but cheaper to make

Carbs in the Diet: Nutritive Sweeteners Other types of sugars found in food Brown Sugar – sucrose with molasses Turbinado sugar – partially refined sugar; AKA: raw sugar Honey – plant nectar enzymatically broken down by bees Can cause botulism in infants – recommended to not give to children under the age of 2 Inverted sugar – sucrose that is heated until “inverted”

Which should you eat? Nutrition Facts Serving Size: ¼ cup 240 cal 0 fat 40 g Sugar Nutrition Facts Serving Size: ¼ cup 210 cal 0 g fat 50g Sugar Natural maple syrup not only has fewer calories but also is high in manganese.

Carbs in the Diet: Nutritive Sweeteners Sugar Alcohols Sorbitol and Xylitol are examples Much lower calorie content than sugars Sugar = 9 kcal/g Sugar alcohol = ~2.6 kcal/g Converted to glucose much slower; resides longer in SI If consumed in large amounts can cause diarrhea Found in sugarless gum, breath mints, and candy Must be listed on food labels If one is used, must be listed by name If 2 or more than “sugar alcohol” is listed

Carbs in the Diet: Alternative Sweeteners AKA: artificial sweeteners Found in many forms and many brand names Yield little to no calories when eaten No RDA, instead have ADI – Acceptable Daily Intake The amount 100 times less than the no harmful effect level in animal studies 6 are approved in the US Saccharin Aspartame Sucralose Neotame Cyclamate Acesulfame-K

Saccharine The oldest alternative sweetener First produced in 1879 Approved for use in over 90 countires Sold in pink packets – Brand name Sweet ‘N Low® 50% of market share in USA Originally thought to increase cancer risk No longer listed as carcinogen Studies had the rats consuming a crazy amount of it and saw marginal increases in bladder cancer

Aspartame Sold in blue packets – brand name Equal® Approved in over 90 countries Endorsed by numerous diet and medical groups 200 times sweeter than sucrose Yields 4 kcal/g Made of phenylalanine, aspartic acid and methanol Because more protein than sugar, looses sweetness with prolonged heating, not good for cooking ADI – 50mg/kg of body weight ~80 packets of Equal® Some adverse effects have been reported Considered safe for pregnant women – consult your physician

Sucralose Sold as the brand name Splenda® 600 times sweeter than sucrose Made by adding 3 Cl to sucrose Does not breakdown when heated Not readily absorbed so most excreted in feces Small amounts taken up secreted by kidneys

Neotame Recently approved by FDA Approved for use in many applications Not meat or poultry 7000-13,000 times sweeter than sucrose Does not breakdown when heated Similar in structure to aspartame Safe in general population and does not carry the PKU warning of aspartame

Acesulfame-K Sold under the brand name Sunette® 200 times sweeter than sucrose Heat stable Approved by FDA in 1988 – in Europe since ’83 Not digested by the body K stands for potassium

Tagatose Brand name = Naturlose® Altered form of fructose Poorly absorbed Yields 1.5 kcal/g Eventually fermented in LI so thought to act as prebiotic

Stevia Brand name = Sweet Leaf® Derived from South American shrub 100-300 times sweeter than sucrose Provides no energy Available in Japan since ‘70s but not approved in US till 2008