Carbohydrates

Monosaccarides

Monosaccharides Simplest of all sugars Most common Glucose Fructose Galactose

Carbohydrates

More than just "sugar" and "starch" Provide the majority of calories in almost all human diets Carbohydrate classifications Carbohydrates Class of energy-yielding nutrients that contain only carbon, hydrogen, and oxygen, hence the common abbreviation of CHO Simple carbohydrates contain only one or two sugar molecules. Complex carbohydrates contain many sugar molecules.

Concentrate on Fiber and Whole Grains

Most consistent benefit of consuming adequate fiber is to relieve or prevent constipation. Linked to a decreased risk of heart disease, cancer, diabetes, and obesity Dietary guidelines recommend that adults and children consume at least one-half of their grain servings from whole grains. Results in 20% to 30% lower risk of atherosclerotic cardiovascular disease Dietary guidelines—(cont.) Less likely to develop insulin resistance and metabolic syndrome, common precursors of type 2 diabetes Associated with improved body weight management Tips for choosing whole grains On average, Americans eat one serving per day of whole grains. Factors contributing to the low intake of whole grains include consumers' inability to identify whole grains, a lack of awareness of their health benefits, cost, taste, and unfamiliarity with how to prepare whole grains.

Protein Sparing

Need to consume adequate carbos.

Empty Calories

"Extras" Carbohydrate content varies

"Refined" Grains

"Refined" grains Rich in starch but lack the fiber, vitamins, trace minerals, fat, and phytochemicals found in whole grains Enrichment Required to be fortified Examples include white flour, white bread, white rice, and refined cornmeal.

Fruits

Almost all of the calories in fruit come from sugar (mostly fructose), with small amounts of starch and minute quantities of protein providing negligible calories. Exceptions to this are avocado, olives, and coconut, which get the majority of their calories from fat. Fiber is located in the skin of fruits.

Avoiding Dental Carries

Choose between-meal snacks that are healthy and teeth-friendly. Limit between-meal carbohydrate. Avoid high-sugar items. Brush promptly after eating. Chew gum sweetened with sugar alcohols. Use fluoridated toothpaste.

Polysaccharides

Complex carbohydrates Do not taste sweet Starch, glycogen, and fiber are types of polysaccharides.

Digestion

Cooked starch begins to undergo digestion in the mouth by the action of salivary amylase. Most carbohydrate digestion occurs in the small intestine. Disaccharidase enzymes split disaccharides into monosaccharides. Monosaccharides are the only form of carbohydrates the body is able to absorb intact. Normally, 95% of starch is digested usually within 1 to 4 hours after eating.

Metabolism

Fructose and galactose are converted to glucose in the liver. Liver releases glucose to maintain blood sugar level. Rise in blood sugar causes pancreas to release insulin. Postprandial state Blood glucose concentration begins to drop. Pancreas releases glucagon. Stimulates liver to release glucose

Fiber

Generally considered a group name for polysaccharides that cannot be digested by human enzymes Commonly referred to as "roughage" Categorized as insoluble or soluble "Dietary" fiber "Functional" fiber Commonly assumed that fiber does not provide any calories Source of energy for colon lining

Using Glycogen to make other compounds

Glycogen Body's backup supply of glucose One-third of the body's glycogen reserve is in the liver. Nonessential amino acids Carbohydrate-containing compounds Fat

Sources of Carbos

Grains, Vegetables, Fruits, and Dairy are the MyPlate groups that provide the majority of carbohydrates. Nuts and dried peas and beans Grains Synonymous with "carbs" Classified as "whole" or "refined"

Grains

Grains—(cont.) Whole grains Consist of the entire kernel of a grain Can be cracked, ground, or milled into flour Composed of three parts The bran The endosperm The germ (embryo)

Disaccharides

Made of two linked monosaccharides Sucrose, maltose, and lactose are disaccharides

Glucose

A monosaccharide Also known as dextrose Component of all disaccharides Sugar into which the body converts all other digestible carbohydrates

Galactose

A monosaccharide Does not occur in appreciable amounts in foods Combines with glucose to form lactose

Fructose

A monosaccharide Sweetest of all natural sugars High-fructose corn syrup (HFCS)

Glycogen

Animal (including human) version of starch Liver glycogen releases glucose into the bloodstream to maintain blood sugar between meals. No dietary source of glycogen

Sucrose

Disacch. Sucrose or "sugar" Composed of glucose and fructose Difference among sugars is degree of refining. Occurs naturally in some fruits and vegetables

Lactose

Disacch. Composed of glucose and galactose Found naturally in milk What does it do? Least sweet of all sugars

Maltose

Disacch. Composed of two joined glucose molecules Not found naturally in foods

Glycemic Response

Increase in blood glucose levels Glycemic index Determined by comparing the impact on blood glucose after 50 g of a food sample is eaten compared to the impact of 50 g of pure glucose or white bread May help diabetics and athletes Glycemic load More accurately define a food's impact on blood glucose levels Not reliable for choosing healthy diet Functions of carbohydrates Glucose metabolism = balance between catabolism and anabolism

Dairy

One cup of milk provides 12 g of carbohydrate in the form of lactose. Cottage cheese, which has about 6 g of carbohydrate per cup

Starch

Poly. Starch Glucose not used by plants stored as starch Grains World's major food crops Foundation of all diets Potatoes, dried peas and beans, and other starches

Glucose for Energy

Primary function of carbohydrates is to provide energy for cells. Brain is totally dependent on glucose for energy. Spares protein and prevent ketosis

How to Increase Dietary Fiber

Replace refined grains with whole grains. Choose a ready-to-eat cereal with 5 g of fiber or more per serving. Eat dried peas and beans two to three times per week. Eat at least five servings of fruits and vegetables daily. Eat a variety of plant foods daily. Increase fiber intake gradually to avoid GI intolerance. Consume adequate fluid.

Vegetables

Starch and some sugars provide the majority of calories in vegetables. "Starchy" vegetables provides three times more carbohydrate than the same amount of "watery" vegetables.

Limit Added Sugars

Sugar adds flavor and interest. Inaccurately blamed for a variety of health problems Limiting intake is prudent. Sugar alternatives Sugar alcohols Nonnutritive sweeteners Sugar alcohols Sorbitol, mannitol, and xylitol Natural sweeteners derived from monosaccharides Most are commercially synthesized. Incompletely absorbed Side effects Offer sweetness without promoting cavities

Absorption

Sugars are absorbed through intestinal mucosa cells. Undigested starch passes with stools. Fibers may impair the absorption of some minerals—namely, calcium, zinc, and iron—by binding with them in the small intestine.

Dietary Reference Intakes

Total carbohydrate The RDA for carbohydrates is set at 130 g for both adults and children. Acceptable macronutrient distribution range Fiber Adequate intake for total fiber is set at 14 g/ 1000 calories. Sugar Maximal level of 25% of total calories or less from added sugars is recommended.

Preventing Ketosis

Without adequate glucose, fat oxidation prematurely stops at the intermediate step of ketone body formation. Increased production of ketones causes nausea, fatigue, loss of appetite, and ketoacidosis. Dehydration and sodium depletion may follow