Nutrition - Chapter 3

Sugar on nutrient deficiencies

§ Added sugars contribute to nutrient deficiencies by displacing nutrients. · Empty-kcalorie foods that contain lots of added sugars such as cakes, candies, and sodas provide the body with glucose and energy, but few, if any, other nutrients. · A person spending 200 kcalories of a day's energy allowance on a 16-ounce soda gets little of value for those kcalories. In contrast, a person using 200 kcalories on three slices of whole-wheat bread gets 9 grams of protein, 6 grams of fiber, plus several of the B vitamins with those kcalories.

Sugar on heart disease

§ Fructose stimulates the body's fat-making pathways and impairs its fat-clearing pathways in ways that could lead to an unhealthy buildup of blood lipids § people with higher fructose intakes had blood lipid values indicating an increased risk of heart disease § As little as the equivalent of one or two fructose- or sucrose-sweetened soft drinks a day consumed for only a few weeks significantly changes blood lipids in ways that may pose risks to the heart and arteries

o Disaccharides

§ In disaccharides, pairs of single sugars are linked together. Three disaccharides are important in nutrition: maltose, sucrose, and lactose. All three contain glucose as one of their single sugars.

Sugar on obesity

§ Over the past several decades, as obesity rates increased sharply, consumption of added sugars reached an all-time high— largely because high-fructose corn syrup use, especially in beverages, surged § High- fructose corn syrup is composed of fructose and glucose in a ratio of about 50:50 § When they are eaten in excess of need, energy from added sugars contributes to body fat stores, raising the risk of weight gain

o Nutritive sweeteners side effects

· Unlike sucrose, sugar alcohols are fermented in the large intestine by intestinal bacteria. Consequently, side effects such as gas, abdominal discomfort, and diarrhea make the sugar alcohols less attractive than the nonnutrtive sweeteners

§ Starch

· a plant polysaccharide composed of glucose and digestible by human beings. · is a long, straight or branched chain of hundreds or thousands of glucose units linked together · These giant mol- ecules are packed side by side in grains such as rice or wheat, in root crops and tubers such as yams and potatoes, and in legumes such as peas and beans. o When a person eats the plant, the body splits the starch into glucose units and uses the glucose for energy. · All starchy foods come from plants. Grains are the richest food source of starch

Dietary fibers

o Dietary fibers are the structural parts of plants and thus are found in all plant- derived foods—vegetables, fruits, whole grains, and legumes. § Most dietary fibers are polysaccharides—chains of sugars—just as starch is, but in fibers the sugar units are held together by bonds that human digestive enzymes cannot break § Consequently, most dietary fibers pass through the body, providing little or no energy for its use

· Sucrose

o Glucose + Fructose o (table, or white, sugar) is the most familiar of the three disaccharides and is what people mean when they speak of "sugar."

· Lactose

o Glucose + Galactose o the principal carbohydrate of milk. Most human infants are born with the digestive enzymes necessary to split lactose into its two monosaccharide parts, glucose and galactose, so as to absorb it

Maltose

o Glucose + Glucose o is a plant sugar that consists of two glucose units. Maltose is produced whenever starch breaks down—as happens in plants when they break down their stored starch for energy and start to sprout and in human beings during carbohydrate digestion

· Discuss glycogen's role in the body.

o Glycogen is a polysaccharide that is a storage form of energy for human beings and animals o The human body stores much of its glucose as glycogen in the liver and muscles

· Identify major sources of added sugars in the U.S. population.

o Soft drinks and other sugar-sweetened beverages are a major source of added sugars in the diets of U.S. consumers. § largely because high-fructose corn syrup use, especially in beverages, o An estimated 75 percent of the packaged foods in the United States contain sweeteners, mostly added sugars

· Galactose

o The third single sugar, galactose, occurs mostly as part of lactose, a disaccharide also known as milk sugar. During digestion, galactose is freed as a single sugar.

· List foods that are good sources of starch.

o These giant molecules are packed side by side in grains such as rice or wheat, in root crops and tubers such as yams and potatoes, and in legumes such as peas and beans § Legumes include peanuts and "dry" beans such as butter beans, kidney beans, "baked" beans, black-eyed peas (cowpeas), chickpeas (garbanzo beans), and soybeans o All starchy foods come from plants. Grains are the richest food source of starch o rice in Asia; wheat in Canada, the United States, and Europe; corn in much of Central and South America; and millet, rye, barley, and oats elsewhere o Root vegetables (tubers) such as potatoes and yams are a third major source of starch

· Fructose

o a monosaccharide; sometimes known as fruit sugar. (fruct = fruit) o Fructose is the sweetest of the sugars. o Fructose occurs naturally in fruits, in honey, and as part of table sugar. However, most fructose is consumed in sweet beverages such as soft drinks, in ready-to-eat cereals, and in other products sweetened with high-fructose corn syrup or other added sugars

· Glucose

o a monosaccharide; the sugar common to all disaccharides and polysaccharides; also called blood sugar or dextrose o Most cells depend on glucose for their fuel to some extent, and the cells of the brain and the rest of the nervous system depend almost exclusively on glucose for their energy

Sugar on type 2 diabetes

§ Since diabetes involves blood sugar, it was once believed that eating sugar caused diabetes by overworking the pancreas. We now know that this is not the case · Excess body fatness is more closely related to type 2 diabetes than is diet composition § Nevertheless, the incidence of type 2 diabetes often rises in populations as they take in more added sugars. § Also, when kcalorie intakes do not exceed daily needs, links between sugar intakes and obesity, and sugar and type 2 diabetes, diminish § the person who is physically active, limits alcohol, and doesn't smoke reduces those risks dramatically

o Monosaccharides

§ Single sugar unit (mono = one) (saccharide = sugar) § Three monosaccharides are important in nutrition: glucose, fructose, and galactose. All three monosaccharides have the same number and kinds of atoms but in different arrangements.

recommendations for the intake of total carbohydrate

§ The DRI committee advises that carbohydrates should contribute about half (45 to 65 percent) of the energy requirement. § A person consuming 2000 kcalories a day should therefore obtain 900 to 1300 kcalories' worth of carbohydrate, or between 225 and 325 grams. § This amount is more than adequate to meet the RDA for carbohydrate, which is set at 130 grams per day based on the average minimum amount of glucose used by the brain

recommendations for the intake of fiber

§ The FDA set the Daily Value for fiber at 28 grams for a 2000-kcalorie intake. This is based on the DRI recommendation of 14 grams per 1000-kcalorie intake—roughly 25 to 35 grams of dietary fiber daily

o Non-cariogenic foods

§ Yes, foods that stimulate saliva flow, neutralize mouth acid- ity, or induce the clearance of food particles from the teeth can help to prevent caries formation · Examples include cheese, which increases salivary secretions and contains nutrients that neutralize acid; milk, which reduces mouth acidity due to its nearly neutral pH; and raw vegetables, which require vigorous chewing and therefore stimulate saliva flow. § The sequence in which foods are eaten influences caries development; for example, eating cheese after consuming an acidic fruit dessert can raise plaque pH and reduce caries risk, whereas drinking sugared coffee at the end of the meal can prolong plaque acidity

o Cariogenic foods

§ conducive to the development of dental caries § The most cariogenic foods are carbohydrate-containing foods that remain in contact with the teeth for prolonged periods, are difficult to clear from the mouth, or are consumed fre- quently or over an extended time period · hard candies or lozenges that dissolve slowly in the mouth; sticky or chewy foods such as dried fruit or chewy bread; starchy snack foods such as pretzels or chips; and sweetened beverages that are repeatedly sipped. These foods can be eaten without provoking tooth decay if they are consumed quickly and removed from tooth surfaces promptly · Acidic foods and beverages

o Soluble fibers

§ indigestible food components that readily dissolve in water and often impart gummy or gel-like characteristics to foods. · An example is pectin from fruit, which is used to thicken jellies § Sources and health effects § Commonly found in barley, legumes, fruits, oats, and vegetables, these fibers are often associated with lower risks of chronic diseases · In addition to food sources, extracted single soluble fiber preparations are used as medications or as food additives

o Polysaccharides

§ polysaccharides are composed almost entirely of glucose (and, in some cases, other monosaccharides). Three types of polysaccharides are important in nutrition: glycogen, starch, and fibers.

o Non-nutritive sweeteners

§ sweeten with minimal or no carbohydrate or energy. The human taste buds perceive many of them as extremely sweet, so just tiny amounts are added to foods to achieve the desired sweet taste § synthetic or natural food additives that offer sweet flavor but with negligible or no kcalories per serving; also called artificial sweeteners, intense sweeteners, noncaloric sweeteners, and very-low-calorie sweeteners. § A rigorous, large analysis of research, however, does suggest that substituting nonnutritive sweeteners for sugar results in modest weight loss and may be helpful in improving compliance with weight-loss or weight-maintenance plans

o Nutritive sweeteners wj ej ec

§ sweeteners that yield energy, including both the sugars and the sugar alcohols. § Sugar alcohols · are carbohydrates, but they trigger a lower glycemic response and yield slightly less energy (2 to 3 kcalories per gram) than sucrose (4 kcalories per gram) because they are not absorbed completely · sugarlike compounds in the chemical family alcohol derived from fruits or manufactured from carbohydrates; sugar alcohols are absorbed more slowly than other sugars, are metabolized differently, and do not elevate the risk of dental caries. o Examples are maltitol, mannitol, sorbitol, isomalt, lactitol, and xylitol

Sugar on dental caries

§ the gradual decay and disintegration of a tooth. § Any carbohydrate-containing food, including bread, bananas, or milk, as well as sugar, can support bacterial growth in the mouth § These bacteria produce the acid that eats away tooth enamel. · Of major importance is the length of time the food stays in the mouth. This, in turn, depends on the composition of the food, how sticky the food is, how often a person eats the food, and especially whether the teeth are brushed afterward. § populations whose diets provide no more than 10 percent of kcalories from sugar have a low prevalence of dental caries

o Insoluble fibers

§ the tough, fibrous structures of fruits, vegetables, and grains; indigestible food components that do not dissolve in water. § do not form gels (are not viscous), and are less readily fermented § Insoluble fibers, such as cellulose and many hemicelluloses, are found in the outer layers of whole grains (bran), the strings of celery, the hulls of seeds, and the skins of corn kernels. These fibers retain their structure and rough texture even after hours of cooking. § In the body, they aid the digestive system by easing elimination

§ Fibers

· Dietary fibers are the structural parts of plants and thus are found in all plant- derived foods—vegetables, fruits, whole grains, and legumes. o Most dietary fibers are polysaccharides—chains of sugars—just as starch is, but in fibers the sugar units are held together by bonds that human digestive enzymes cannot break o Consequently, most dietary fibers pass through the body, providing little or no energy for its use · a general term denoting in plant foods the polysaccharides cellulose, hemicellulose, pectins, gums, and mucilages, as well as the nonpolysaccharide lignins, which are not digested by human digestive enzymes, although some are digested by GI tract bacteria

§ Glycogen

· a polysaccharide composed of glucose, made and stored by liver and muscle tissues of human beings and animals as a storage form of glucose. Glycogen is not a significant food source of carbohydrate and is not counted as one of the polysaccharides in foods. · Glycogen molecules are made of chains of glucose that are more highly branched than those of starch molecules · Glycogen is found in meats only to a limited extent and not at all in plants.