1. CARBOHYDRATES (Ch 3)

2. Carbohydrates (CHO) Body’s preferred energy source Needed for brain functioning Milk is the only animal- derived food that contains significant CHO All unrefined plant foods provide abundant carbohydrate, fiber, & little fat –Grains –Vegetables –Legumes –Fruits

3. A Chemist’s View of Carbohydrates Simple Sugars –Monosaccharides (single sugars) –Disaccharides (double sugars) Complex CHOs –Starch & fiber: Polysaccharides

4. Monosaccharides Glucose –Needed by every cell & especially the brain & nervous system –Blood glucose Fructose –Sweetest of all sugars –Fruits, honey, saps, soft drinks, ready- to-eat cereals Galactose –Part of double sugar lactose; lactose is milk sugar

5. Dissacharides Sucrose –Table or white sugar –Composed of glucose & fructose –Fruit, Vegetables, sugar cane & sugar beets Lactose –Principle CHO of milk –Composed of glucose & galactose Maltose –A plant sugar –Composed of 2 glucose molecules

7. Polysaccharides Starch –Storage form of glucose in plants –Grains, legumes, root vegetables –Most valuable energy nutrient –Contain abundant fiber, protein, & other nutrients Glycogen –Storage form of glucose in humans –Stored in muscles & liver CHO surplus Muscles = activity usage (2/3) liver = blood sugar regulation (1/3)

8. Polysaccharides Fiber –Most are polysaccharides –Bonds cannot be broken by human digestion Yield little if any energy –Vegetables, fruits, whole grains, legumes –Soluble and insoluble

9. Types of Fiber Soluble –Dissolves in water –Is viscous –Easily fermented in colon –Barley, legumes, fruits, oats, vegetables –Associated with low risk of chronic disease Insoluble –Does not dissolve in water –Not viscous –Not easily fermented in colon –Outer layers of whole grains, strings of celery, hulls of seeds, skins of corn –Health of GI tract

12. Diverticulosis: The outpocketings of intestinal linings that balloon through the weakened intestinal wall muscles are known as diverticula.

13. Harmful Effects of Excessive Fiber Minerals may bind to it & be excreted People with marginal intakes (malnourished, elderly, young children) may not meet their energy needs Fibers remove water & people can become dehydrated Too much fiber & too little water can cause an obstruction

14. Complex Carbohydrates Whole food: a food that is altered as little as possible from the plant or animal tissue from which it was taken—such as milk, oats, potatoes, or apples. –The more a food resembles the original, farm-grown product, the more nutritious it is likely to be.

15. The Bread Box Refined: process by which the coarse parts of food products are removed. Enrichment: process by which B vitamins (thiamin, riboflavin, niacin, folic acid) and iron are added to refined grains and grain products. Fortification: Foods to which nutrients have been added; help prevent a deficiency of a nutrient (iodized salt, milk with vitamin D) or to reduce the risk of chronic disease (juices with added calcium).

16. Complex CHO: The Wheat Kernel - A Whole Grain Germ: the nutrient-rich and fat-dense inner part of a whole grain. Endosperm: provides energy; contains starch grains embedded in a protein matrix. Bran: the fibrous protective covering of a whole grain and source of fiber, B vitamins, and trace minerals. Husk: (chaff) the outer, inedible covering of a grain.

18. Complex Carbohydrates Whole grain: refers to a grain that is milled in its entirety (all but the husk), not refined. –Look for whole wheat, brown rice, oatmeal, whole oats, bulgur, popcorn, whole rye, graham flour, pearl barley, whole-grain corn, etc. as the first ingredient on the label.

19. We are advised to increase our intakes of complex carbohydrates. Choose plenty of whole foods like this… …and fewer foods like these—foods that no longer resemble their original farm-grown products.

20. Digestion and Absorption of Carbohydrates Glucose is the form of CHO our body uses for energy. Digestive system disassembles double sugars and starch into single sugars so they can be absorbed into the blood. –Single sugars are absorbed into blood & travel to liver. The liver: sends glucose to blood --- all cells (as needed) converts fructose/galactose into Glucose --- sends to cells (as needed) Once cells have enough glucose for fuel, any excess glucose will be used to build glycogen.

21. Digestion and Absorption of Carbohydrates Mouth –salivary enzymes take begin to take starch apart. Small intestine –Enzymes release single glucose units –Most CHO digestion Liver –Regulates amount of glucose going into blood

22. CHO Surplus: Once cells have enough fuel (Glucose) (1) Glycogen: a polysaccharide stored in the liver & muscles –Muscle glycogen (2/3 of glycogen storage capacity) Exercise usage –Liver glycogen= (1/3 of glycogen storage capacity) Maintain BG; can be broken down by the liver to maintain a constant BG level when CHO intake is inadequate –Glycogen storage capacity is limited (2) Fat – excess glucose converted to fat –Stored in adipose tissue –unlimited storage capacity

23. When a person eats, blood glucose rises. High blood glucose stimulates the pancreas to release insulin. Insulin serves as a key for entrance of blood glucose into cells.

24. Later, when blood glucose is low, the pancreas releases glucagon, which serves as the key for the liver to break down stored glycogen into glucose and release it into the blood to raise blood glucose levels

25. Regulation of Blood Glucose Insulin: a hormone secreted by the pancreas in response to high blood glucose levels; it assists cells in drawing glucose from the blood. Glucagon (glue-cuh-gon): a hormone released by the pancreas as a result of low blood glucose levels; sends signal to the liver to release glucose into the blood.

26. Sugar (sucrose) Accused of causing:

27. Added Sugars: Use Discretion Choose and prepare foods with little added sugar (Dietary Guidelines). Choose most often the naturally-occurring sugars.

29. Naturally-Occuring vs Added Sugars Naturally-occurring: –Sugar found naturally in fruit, veggies, milk Added: –Sugar cane and sugar beets are purified to make sucrose. –Examples include white (table) sugar, brown sugar, powdered sugar.

30. Recommendations Carbohydrates –DRI 45-65% of energy 2000 kcalorie diet –225-325 g/day –Daily Value 300 g/day Added Sugars –WHO: > 10% of total calories Fiber –DRI 14 g per 1000 kcalories –Daily Value 11.5 g per 1000 kcalories –American Academy of Nutrition and Dietetics 20-35 g/day –WHO set UL at 40 g/day

31. CHO Food Sources Breads, Cereal, Rice, & Pasta –15 grams of CHO per ounce Vegetables –5-15 grams of CHO per ½ cup Fruit –15 grams of CHO per ½ cup Milk –12 grams of CHO per cup Meat, Poultry, & Fish –No CHO Legumes –15 grams of CHO per ½ cup

32. Food Labels Lists –Amount in grams of total carbohydrate per serving –Sugar grams are listed separately Added sugars Naturally occurring sugars –Fiber grams are listed separately Total CHO and fiber also expressed as % Daily Values for 2000 kcalories