Chapter 5. Carbohydrates
In this chapter, you learned what carbohydrates are, the different types of carbohydrates in your diet, and that excess consumption of some types of carbohydrates cause disease while others decrease disease risk. Now that we know the benefits of eating the right carbohydrate, we will examine exactly how much should be eaten to promote health and prevent disease.
How Many Carbohydrates Does a Person Need?
The Recommended Dietary Allowance (RDA) of carbohydrates for children and adults at 130 grams per day. This is the average minimum amount the brain requires to function properly. The Acceptable Macronutrient Distribution Range (AMDR) for carbohydrates is between 45 and 65 percent of your total caloric daily intake. This means that on a 2,000 kilocalorie diet, a person should consume between 225 and 325 grams of carbohydrate each day. No more than 25 percent of total calories consumed should come from added sugars. The World Health Organization recommends much lower intakes of added sugars—10 percent or less of total calories consumed. The Adequate Intakes for dietary fiber, are 38 and 25 grams for men and women, respectively. The recommendations for dietary fiber are based upon the intake levels known to prevent against heart disease.
Table 5.2 Dietary Reference Intakes For Carbohydrates And Fiber
|Carbohydrate Type||RDA (g/day)||AMDR (% calories)|
|Added Sugars||< 25|
|Fiber||38 (men),* 25 (women)*|
|* denotes Adequate Intake|
Dietary Sources of Carbohydrates
Carbohydrates are contained in all five food groups: grains, fruits, vegetables, meats, beans (only in some processed meats and beans), and dairy products. Fast-releasing carbohydrates are more prevalent in fruits, fruit juices, and dairy products, while slow-releasing carbohydrates are more plentiful in starchy vegetables, beans, and whole grains. Fast-releasing carbohydrates are also found in large amounts in processed foods, soft drinks, and sweets. On average, a serving of fruits, whole grains, or starches contains 15 grams of carbohydrates. A serving of dairy contains about 12 grams of carbohydrates, and a serving of vegetables contains about 5 grams of carbohydrates. Table 5.3 “Carbohydrates in Foods (grams/serving)” gives the specific amounts of carbohydrates, fiber, and added sugar of various foods.
Table 5.3 Carbohydrates in Foods (grams/serving)
|Foods||Total Carbohydrates||Sugars||Fiber||Added Sugars|
|Banana||27 (1 medium)||14.40||3.1||0|
|Lentils||40 (1 c.)||3.50||16.0||0|
|Snap beans||8.7 (1 c.)||1.60||4.0||0|
|Green pepper||5.5 (1 medium)||2.90||2.0||0|
|Corn tortilla||10.7 (1)||0.20||1.5||0|
|Bread, wheat bran||17.2 (1 slice)||3.50||1.4||3.4|
|Bread, rye||15.5 (1 slice)||1.20||1.9||1.0|
|Bagel (plain)||53 (1 medium)||5.30||2.3||4.8|
|Brownie||36 (1 square)||20.50||1.2||20.0|
|Oatmeal cookie||22.3 (1 oz.)||12.00||2.0||7.7|
|Cornflakes||23 (1 c.)||1.50||0.3||1.5|
|Pretzels||47 (10 twists)||1.30||1.7||0|
|Popcorn (homemade)||58 (100 g)||0.50||10.0||0|
|Skim milk||12 (1 c.)||12.00||0||0|
|Cream (half and half)||0.65 (1 Tbs.)||0.02||0||0|
|Cream substitute||1.0 (1 tsp.)||1.00||0||1.0|
|Cheddar cheese||1.3 (1 slice)||0.50||0||0|
|Yogurt (with fruit)||32.3 (6 oz.)||32.30||0||19.4|
|Caesar dressing||2.8 (1 Tbs.)||2.80||0||2.4|
- National Nutrient Database for Standard Reference. US Department of Agriculture. http://www.nal.usda.gov/fnic/foodcomp/search/. Updated December 7, 2011. Accessed September 17, 2017.
- Database for the Added Sugars Content of Selected Foods. US Department of Agriculture. http://www.nal.usda.gov/fnic/foodcomp/search/. Published February 2006. Accessed September 27, 2017.
It’s the Whole Nutrient Package
In choosing dietary sources of carbohydrates the best ones are those that are nutrient dense, meaning they contain more essential nutrients per calorie of energy. In general, nutrient-dense carbohydrates are minimally processed and include whole-grain breads and cereals, low-fat dairy products, fruits, vegetables, and beans. In contrast, empty-calorie carbohydrate foods are highly processed and often contain added sugars and fats. Soft drinks, cakes, cookies, and candy are examples of empty-calorie carbohydrates. They are sometimes referred to as ‘bad carbohydrates,’ as they are known to cause health problems when consumed in excess.
Understanding Carbohydrates from Product Information
While nutrition facts labels aid in determining the amount of carbohydrates you eat, they do not help in determining whether a food is refined or not. The ingredients list provides some help in this regard. It identifies all of the food’s ingredients in order of concentration, with the most concentrated ingredient first. When choosing between two breads, pick the one that lists whole wheat (not wheat flour) as the first ingredient, and avoid those with other flour ingredients, such as white flour or corn flour. (Enriched wheat flour refers to white flour with added vitamins.) Eat less of products that list HFCS and other sugars such as sucrose, honey, dextrose, and cane sugar in the first five ingredients. If you want to eat less processed foods then, in general, stay away from products with long ingredient lists. On the front of food and beverages the manufacturers may include claims such as “sugar-free,” “reduced sugar,” “high fiber,” etc.
Table 5.4 Food Labels Pertaining to Carbohydrates
|Sugar-free||Contains less than 0.5 grams of sugar per serving|
|Reduced sugar||Contains 25 percent less sugar than similar product|
|Less sugar||Contains 25 percent less sugar than similar product, and was not altered by processing to become so|
|No sugars added||No sugars added during processing|
|High fiber||Contains at least 20 percent of daily value of fiber in each serving|
|A good source of fiber||Contains between 10 and 19 percent of the daily value of fiber per serving|
|More fiber||Contains 10 percent or more of the daily value of fiber per serving|
Source: Appendix A: Definitions of Nutrient Claims. Guidance for Industry: A Food Labeling Guide. US Food and Drug Administration. http://www.fda.gov/Food/GuidanceComplianceRegulatoryInformation/GuidanceDocuments/FoodLabelingNutrition/FoodLabelingGuide/ucm064911.htm. Updated October 2009. Accessed September 22, 2017.
Although the information above is based on American guidelines, The U.S. Food and Drug Administration (FDA) signed an arrangement with the Canadian Food Inspection Agency (CFIA) and the Department of Health Canada (Health Canada) recognizing each other’s food safety systems as comparable to each other. References to guidelines made by the FDA is this textbook applies to guidelines that are similar in Canada.
Carbohydrates are in most foods so you have a great variety of choices with which to meet the carbohydrates recommendations for a healthy diet. Health Canada recommends eating more unrefined carbohydrates and more fiber, and reducing consumption of foods that are high in added sugars. To accomplish these recommendations use some or all of the following suggestions:
- Get more daily carbohydrate servings from whole grains by eating a whole-grain cereal for breakfast, using whole-grain bread to make a sandwich for lunch, and eating a serving of beans and/or nuts with dinner.
- Make sure to get at least three servings (or more) of all the grains you eat as whole grains every day. A serving of whole grains is equal to one slice of whole-wheat bread, one ounce of whole-grain cereal, and one-half cup of cooked cereal, brown rice, or whole-wheat pasta.
Food products made with cornmeal use the whole grain so choose tortillas, corn cereals, and corn breads with cornmeal listed as the first ingredient.
- When baking, substitute whole-wheat flour or other whole-grain flour for some of the refined white flour.
- If you like bread at dinner, choose a whole-grain muffin over a Kaiser roll or baguette.
Add beans, nuts, or seeds to salad—they add texture and taste.
- Choose whole-grain pastas and brown rice, cook al dente, and add some beans and vegetables in equal portions.
- Change it up a bit and experience the taste and satisfaction of other whole grains such as barley, quinoa, and bulgur.
- Eat snacks high in fiber, such as almonds, pistachios, raisins, and air-popped popcorn.
Add an artichoke and green peas to your dinner plate more often.
- Calm your “sweet tooth” by eating fruits, such as berries or an apple.
- Replace sugary soft drinks with seltzer water, tea, or a small amount of 100 percent fruit juice added to water or soda water.
The Food Industry: Functional Attributes of Carbohydrates and the Use of Sugar Substitutes
In the food industry, both fast-releasing and slow-releasing carbohydrates are utilized to give foods a wide spectrum of functional attributes, including increased sweetness, viscosity, bulk, coating ability, solubility, consistency, texture, body, and browning capacity. The differences in chemical structure between the different carbohydrates confer their varied functional uses in foods. Starches, gums, and pectins are used as thickening agents in making jam, cakes, cookies, noodles, canned products, imitation cheeses, and a variety of other foods. Molecular gastronomists use slow-releasing carbohydrates, such as alginate, to give shape and texture to their fascinating food creations. Adding fiber to foods increases bulk. Simple sugars are used not only for adding sweetness, but also to add texture, consistency, and browning. In ice cream, the combination of sucrose and corn syrup imparts sweetness as well as a glossy appearance and smooth texture.
Due to the potential health consequences of consuming too many added sugars, sugar substitutes have replaced them in many foods and beverages. Sugar substitutes may be from natural sources or artificially made. Those that are artificially made are called artificial sweeteners and must be approved by the FDA for use in foods and beverages. The artificial sweeteners approved by the FDA are saccharin, aspartame, acesulfame potassium, neotame, advantame, and sucralose. Stevia is an example of a naturally derived sugar substitute. It comes from a plant commonly known as sugarleaf and does not require FDA approval. Sugar alcohols, such as xylitol, sorbitol, erythritol, and mannitol, are sugar alcohols that occur naturally in some fruits and vegetables. However, they are industrially synthesized with yeast and other microbes for use as food additives. The FDA requires that foods disclose the fact that they contain sugar alcohols, but does not require scientific testing of it. (Though many of them have undergone studies anyway.) In comparison to sucrose, artificial sweeteners are significantly sweeter (in fact, by several hundred times), but sugar alcohols are more often less sweet than sucrose (see Table 5.5 “Relative Sweetness of Sugar Substitutes”). Artificial sweeteners and Stevia are not digested or absorbed in significant amounts and therefore are not a significant source of calories in the diet. Sugar alcohols are somewhat digested and absorbed and, on average, contribute about half of the calories as sucrose (4 kilocalories/gram). These attributes make sugar substitutes attractive for many people—especially those who want to lose weight and/or better manage their blood-glucose levels.
Table 5.5 Relative Sweetness Of Sugar Substitutes
|Sweetener||Trade Names||Sweeter than Sucrose (times)|
Benefits of Sugar Substitutes
Consuming foods and beverages containing sugar substitutes may benefit health by reducing the consumption of simple sugars, which are higher in calories, cause tooth decay, and are potentially linked to chronic disease. Artificial sweeteners are basically non-nutrients though not all are completely calorie-free. However, because they are so intense in sweetness they are added in very small amounts to foods and beverages. Artificial sweeteners and sugar alcohols are not “fermentable sugars” and therefore they do not cause tooth decay. Chewing gum with artificial sweeteners is the only proven way that artificial sweeteners promote oral health. The Canadian Dental Association (CDA) allows manufacturers of chewing gum to label packages with a CDA seal if they have convincing scientific evidence demonstrating their product either reduces plaque acids, cavities, or gum disease, or promotes tooth remineralization.
There is limited scientific evidence that consuming products with artificial sweeteners decreases weight. In fact, some studies suggest the intense sweetness of these products increases appetite for sweet foods and may lead to increased weight gain. Also, there is very limited evidence that suggests artificial sweeteners lower blood-glucose levels. Additionally, many foods and beverages containing artificial sweeteners and sugar alcohols are still empty-calorie foods (i.e. chewing sugarless gum or drinking diet soda pop) are not going to better your blood-glucose levels or your health.
The most common side effect of consuming products containing sugar substitutes is gastrointestinal upset, a result of their incomplete digestion. Since the introduction of sugar substitutes to the food and beverage markets, the public has expressed concern about their safety. The health concerns of sugar substitutes originally stemmed from scientific studies, which were misinterpreted by both scientists and the public.
In the early 1970s scientific studies were published that demonstrated that high doses of saccharin caused bladder tumors in rats. This information fueled the still-ongoing debate of the health consequences of all artificial sweeteners. In actuality, the results from the early studies were completely irrelevant to humans. The large doses (2.5 percent of diet) of saccharine caused a pellet to form in the rat’s bladder. That pellet chronically irritated the bladder wall, eventually resulting in tumor development. Since this study, scientific investigation in rats, monkeys, and humans have not found any relationship between saccharine consumption and bladder cancer. In 2000, saccharin was removed from the US National Toxicology Program’s list of potential carcinogens.
There have been health concerns over other artificial sweeteners, most notably aspartame (sold under the trade names of NutraSweet and Equal). The first misconception regarding aspartame was that it was linked with an increase in the incidence of brain tumors in the United States. It was subsequently discovered that the increase in brain tumors started eight years prior to the introduction of aspartame to the market. Today, aspartame is accused of causing brain damage, autism, emotional disorders, and a myriad of other disorders and diseases. Some even believe aspartame is part of a governmental conspiracy to make people dumber. The reality is there is no good scientific evidence backing any of these accusations, and that aspartame has been the most scientifically tested food additive. It is approved for use as an artificial sweetener in over ninety countries.
Aspartame is made by joining aspartic acid and phenylalanine to a dipeptide (with a methyl ester). When digested, it is broken down to aspartic acid, phenylalanine, and methanol. People who have the rare genetic disorder phenylketonuria (PKU) have to avoid products containing aspartame. Individuals who have PKU do not have a functional enzyme that converts phenylalanine to the amino acid tyrosine. This causes a buildup of phenylalanine and its metabolic products in the body. If PKU is not treated, the buildup of phenylalanine causes progressive brain damage and seizures. The FDA requires products that contain aspartame to state on the product label, “Phenylketonurics: Contains Phenylalanine.” For more details on sugar substitutes please refer to Table 5.6 “Sweeteners”.
Table 5.6 Sweeteners
|Sweeteners with Trade Name||Calories||Source/Origin||Consumer Recommendations||Controversial Issues||Product Uses|
||4 kcal/g||Composed of two amino acids (phenylalanine + aspartic acid) + methanol.Two hundred times sweeter than sucrose.||FDA set maximum Acceptable Daily Intakes (ADI):50 mg/kg body weight = 16 12 oz. diet soft drinks for adults.
*Cannot be used in products requiring cooking.
People with PKU should not consume aspartame.
|Children have potential to reach ADI if consuming many beverages, desserts, frozen desserts, and gums containing aspartame routinely.||Beverages, gelatin desserts, gums, fruit spreads.|
||0 kcal/g||Discovered in 1878. The basic substance is benzoic sulfinide.Three hundred times sweeter than sucrose.||ADI: 5 mg/kg body weight.*Can be used in cooking.||1970s, high doses of saccharin associated with bladder cancer in laboratory animals. In 1977, FDA proposed banning saccharin from use in food
||General purpose sweetener in all foods and beverages.Sold as Sweet ‘n’ Low in United States; also found in cosmetics and pharmaceutical products.|
||0 kcal/g||Discovered in 1967. Composed of an organic salt, potassium (K). Structure is very similar to saccharin’s.It passes through the body unchanged which means it does not provide energy.
Two hundred times sweeter than sucrose.
|ADI: 15 mg/kg body weight.Body cannot digest it.
*Can be used in cooking.
|Chewing gum, powdered beverage mixes, nondairy creamers, gelatins, puddings, instant teas and coffees.|
||0 kcal/g||Thirty times sweeter than sucrose.Discovered in 1937.||No ADI available.||1949, cyclamate approved by FDA for use. Cyclamate was classified as GRAS (Generally Recognized As Safe) until 1970 when it was removed from GRAS status and banned from use in all food and beverage products within the United States on the basis of one study that indicated it caused bladder cancer in rats. Approval still pending for use in the United States since the ban.Canada and other countries use this type of sweetener.||Recommended as a substitute for table sugar for diabetics in 1950s, baked goods.|
||1 Splenda packet contains 3.31 calories = 1g||First discovered in 1976. Approved for use in 1998 in the United States and in 1991 in Canada.Derived from sucrose in which three of its hydroxyl (OH) groups are replaced by chlorine (Cl−).
Six hundred times sweeter than sugar.
|ADI: 5 mg/kg body weight.*Can be used in cooking.||General purpose sweetener, baked goods, beverages, gelatin desserts, frozen dairy desserts, canned fruits, salad dressings, dietary supplements; currently recommended as a replacement for table sugar and additive for diabetics.|
||N/A||Derived from stevia plant found in South America. Stevia rebaudiana leaves.||Classified as GRAS.Considered to be a dietary supplement and approved not as an additive, but as a dietary supplement.||Used sparingly, stevia may do little harm, but FDA could not approve extensive use of this sweetener due to concerns regarding its effect on reproduction, cancer development, and energy metabolism.||Sold in health food stores as a dietary supplement.|
||~4 kcal/g||Extracted from either sugar beets or sugar cane, which is then purified and crystallized.||It is illegal to sell true raw sugar in the United States because when raw it contains dirt and insect parts, as well as other byproducts. Raw sugar products sold in the United States have actually gone through more than half of the same steps in the refining process as table sugar.||Over-consumption has been linked to several health effects such as tooth decay or dental caries and contributes to increased risk for chronic diseases.||Biscuits, cookies, cakes, pies, candy canes, ice cream, sorbets, and as a food preservative.|
|Honey||3 kcal/g||Made from sucrose. Contains nectar of flowering plants. Made by bees.Sucrose is fructose + glucose; however, honey contains more calories than sucrose because honey is denser.||*Considered safe for baking and cooking.Infants under twelve months old should not be given honey because their digestive tracts cannot handle the bacteria found in honey. Older children and adults are immune to these effects. Honey contains some harmful bacteria that can cause fatal food poisoning in infants.||Sweeteners in various foods and beverages such as sodas, teas, alcoholic beverages, and baked goods.|
||Dry form: 4 kcal/g; Liquid form: 3 kcal/g||Corn is milled to produce corn starch, then the cornstarch is further processed to yield corn syrup.||Controversial because it is found ubiquitously in processed food products, which could lead to overconsumption. Study results are varied regarding its role in chronic disease.||Soft drinks, desserts, candies, jellies.|
||2–4 kcal/g.Not calorie free||Sugar alcohols.Sorbitol is derived from glucose.||Less likely to cause tooth decay than sucrose.Sugar alcohols have a laxative effect.||May cause diarrhea and gastrointestinal distress if consumed in large amounts.||Provide bulk and sweetness in the following sugar-free items: cookies, jams, jellies, chewing gum, candies, mints, pharmaceutical and oral health products.|
- Artificial Sweeteners and Cancer. National Cancer Institute. http://www.cancer.gov/cancertopics/factsheet/Risk/artificial-sweeteners. Updated August 5, 2009. Accessed September 22, 2017. ↵