1. Key Concepts in Nutrition
Chapter 2
Key Concepts in Nutrition

2. Learning Objectives
After completing this chapter, you should be able to:
• Define calorie, nutrient density, and empty-calorie food and explain why people should decrease consumption of empty-calorie food.
• Identify the six basic types of nutrients found in food and
describe their characteristics.
• Describe the major functions of carbohydrates, proteins, lipids, vitamins, minerals, and water in the body.
• Explain the effect of alcohol consumption on the body.

3. Learning Objectives continued:
After completing this chapter, you should be able to:
• Explain how the senses affect a person’s intake of food.
• Identify the structures of the digestive system and describe digestion, absorption, transport, and utilization of nutrients from food.
• Describe the body mass index and explain why it is important to achieve and maintain a healthy weight.

4. Food’s Nutritional Value: The Six Basic Nutrients
Carbohydrates
Proteins
Lipids
Vitamins and Minerals
Water: The Most Important Nutrient

5. What Is Nutrient Density?

6. Alcohol: A Non-nutrient Source of Calories

7. The Senses and Our Enjoyment of Food
Sweet
Salty
Sour
Bitter
Umami

8. Spice: Not Quite a Taste
Building a Palate

9. Digestion, Absorption, and Transport
of Nutrients

11. Body Mass Index and the Importance
of a Healthy Weight

12. Weight Adjustments
Children and Weight

13. 1. Define calorie, nutrient density, and empty-calorie food and explain why people should decrease consumption of empty calorie food.
The amount of energy that a person derives from food is measured in units called calories.
A calorie is the amount of energy needed to heat one kilogram of water (about 2.2 pounds) by approximately two degrees Fahrenheit (one degree Celsius).
Nutrient density refers to the number of nutrients per calorie of a food.
For the most part, if you eat nutrient-dense food, you receive more nutrition in a smaller number of total calories.
An empty-calorie food is one that contains higher proportions of calories but few if any nutrients.
Empty-calorie food usually contains high amounts of sugar and fat.

14. 1. Define calorie, nutrient density, and empty-calorie food and explain why people should decrease consumption of empty calorie food continued…
Often one or two servings of empty-calorie food per day can add the extra three hundred to four hundred calories that cause weight gain in the general population.
Therefore, it would be wise for most people to decrease consumption of these foods.

15. 2. Identify the six basic types of nutrients found in food and describe their characteristics.
The six essential nutrients are carbohydrates, proteins, lipids, vitamins, minerals, and water.
Carbohydrates include starch, sugar, and dietary fiber.
Carbohydrates provide the body with four calories of energy per gram.
Proteins are large, complex molecules that contain long chains of amino acids.
Lipids can be triglycerides, cholesterol, or phospholipids.
Lipids provide abundant energy, as each gram contains nine calories.
Vitamins are organic compounds, while minerals are inorganic elements.
Both are needed in relatively small amounts by the body for regulation of metabolic processes.

16. Water is the most important nutrient.
2. Identify the six basic types of nutrients found in food and describe their characteristics continued…
Water is the most important nutrient.
It is a universal solvent and a critical component of metabolic processes.

17. 3. Describe the major functions of carbohydrates, proteins, lipids, vitamins, minerals, and water in the body.
The primary role of carbohydrates in the diet is to supply energy.
The primary function of protein is to provide amino acids, which the body uses to build and repair muscles and other tissues.
In addition, the body uses protein to form enzymes, hormones, and antibodies.
Lipids provide energy at a rate of nine calories per gram of food eaten.
Vitamins and minerals are needed in relatively small amounts by the body for regulation of metabolic processes.
Water is essential to all forms of life.
It is a perfect medium for the metabolic processes of the body.
In addition, water aids in temperature regulation, waste removal, and hydration.

18. 4. Explain the effect of alcohol consumption on the body.
Alcohol has mixed effects on the body.
Some studies have indicated that alcohol, when consumed in moderation, can reduce the risk of cardiovascular events and decrease the occurrence of diabetes and dementia.
However, an excessive amount of alcohol in the diet is associated with cancers of the digestive system as well as cirrhosis, a fatal liver disease.

19. 5. Explain how the senses affect a person’s intake of food.
There are five recognized primary tastes: sweet, salty, bitter, sour, and umami.
In addition, when we see a very attractively presented dish, we anticipate its taste.
Smell and taste sensations work together to provide most of the flavor.
People also describe the consistency or feel of food in the mouth as important.
The sizzling of steaks or the accompanying sound of a flaming dish as it is served can also add to the excitement and pleasure of eating.

20. 6. Identify the structures of the digestive system and describe digestion, absorption, transport, and utilization of nutrients from food.
The structures of the digestive system include the oral cavity, the pharynx, the esophagus, the stomach, the small intestine, the large intestine, the rectum, the anus, the liver, the gallbladder, and the pancreas.
The digestive process includes both the physical movement of food down the digestive tract and the secretion of enzymes and fluids.
The teeth chew the food, the salivary glands secrete saliva, and the stomach holds and mixes the food.
The small intestine is responsible for most digestive and absorptive roles.
The major role of the large intestine is to reabsorb water, minerals, and bile salts.
The rectum stores the waste, and the anus allows for elimination.

21. The long-chain fats enter the lymphatic system.
6. Identify the structures of the digestive system and describe digestion, absorption, transport, and utilization of nutrients from food continued…
The liver produces bile, the gallbladder stores it, and the pancreas adds bicarbonate and enzymes to the chyme in the small intestine for the final phase of digestion.
When digestion is completed, starches and sugars have been broken down into monosaccharides, and lipids have been disassembled into glycerol, fatty acids, and monoglycerides.
The long-chain fats enter the lymphatic system.
The monosaccharide and short-chain fatty acids are sent to the liver for use in metabolism.
Proteins are broken down into amino acids and then absorbed, and the amino acids travel through the blood to the liver to be used by the body.

22. 7. Describe the body mass index and explain why it is important to achieve and maintain a healthy weight.
The body mass index (BMI) is a numerical calculation that reflects the relationship between a person’s height and weight.
This calculation can indicate if the person’s weight is in a healthy range.
Statistically, individuals who have high BMI values are at increased risk of what are generally referred to as the chronic diseases.
These diseases include obesity, type 2 diabetes, arthritis, cardiovascular disease (including high blood pressure, or hypertension), stroke, and coronary heart disease.

23. Key Terms:
Amino acid A chemical compound that has special functions in the body, including building and repairing muscles; supplying nitrogen for tissue growth and maintenance; maintaining fluids; keeping the body from getting too acidic or basic; and acting as a transporter of lipids, vitamins, minerals, and oxygen as part of the blood.
Basal metabolism Bodily functions such as respiration, muscle contraction, nervous system and hormonal functions, production of body heat, and circulation.
Body mass index (BMI) A numerical calculation that reflects the relationship between a person’s height and weight that is used to determine if the person’s weight is in a healthy range.
Calorie An energy unit that is one-thousandth of a kilocalorie. In the United States, another term for kilocalorie.
Carbohydrate A basic class of nutrients containing the elements carbon, hydrogen, and oxygen; it includes starch, sugar, and dietary fiber.

24. Key Terms continued:
Digestion The process of breaking food down to its simplest or most elemental parts, which the body can then absorb and use.
Digestive tract The part of the body composed of the oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, rectum, and anus.
Empty-calorie food Food that contains higher proportions of calories and relatively few, if any, nutrients.
Energy balance Eating the same number of calories as the number of calories utilized or expended daily, assuming that the level of physical activity remains consistent.
Enzyme A protein substance that speeds up metabolic reactions.
Essential nutrient A nutrient that is required by the body and has to be obtained through the diet on a daily or near-daily basis.
Fatty acid An organic molecule found in animal and vegetable fats; it consists of a carbon and hydrogen chain with an acid at one end.

25. Key Terms continued:
Fiber A complex carbohydrate that cannot be digested by the human body but which goes through the digestive tract and provides bulk for regularity.
Glucose Blood sugar.
High-density lipoprotein (HDL) A complex of lipids and proteins in approximately equal amounts that functions as a transporter of cholesterol in the blood; also referred to as good cholesterol because it lowers blood-cholesterol levels.
Kilocalorie The amount of energy needed to heat one kilogram of water (about 2.2 pounds) by approximately two degrees Fahrenheit (one degree Celsius).
Lipid A fatty substance that is present in blood and body tissues; lipids include cholesterol, triglycerides, and phospholipids.

26. Key Terms continued:
Low-density lipoprotein (LDL) A complex of lipids and proteins with greater amounts of lipids than protein, which functions as a transporter of cholesterol in the blood; also referred to as bad cholesterol because it can increase the risk of cardiovascular disease.
Metabolism The process by which living organisms and cells break down complex chemicals into their components and reassemble the components into larger molecules needed by the body.
Mineral An inorganic essential nutrient that provides no calories but is needed for regulatory activities of the body.
Nutrient density The number of nutrients per calorie of a particular food.
Obesity A condition of people with a body mass index (BMI) of 30 or greater.
Overweight A condition of people with a body mass index (BMI) of 25 to 29.9.

27. Key Terms continued:
Phytochemical A plant chemical that may assist the body in preventing or fighting diseases; also known as a phytonutrient.
Protein A large, complex molecule that provides amino acids as its primary role.
Vitamin An organic essential nutrient that provides no calories but is needed for regulatory activities of the body.

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