• The Process of Digestion
• Food Safety
• Preventing Food Poisoning
• Nutrition and Health·Essential Nutrients
• Functions of Some Vitamins and Minerals
• Dietary Guidelines for Healthful Eating
• The Food Guide
• Facts About Fat
• The Importance of Calcium
• The Importance of Fruits and Vegetables
• Healthful Weight Control vs Fad Diets
• Healthful Snacking

The Process of Digestion

Digestion is the process that breaks down food we eat into forms that can be taken up the gastrointestinal tract and absorbed into the bloodstream to be used by the body. Digestion begins in the mouth. Saliva in the mouth contains enzymes, which help to break down the food, and chewing breaks food down into small pieces, exposing more food surface to digestive action. The tongue helps to move the food from the mouth to the esophagus (the tube that connects the mouth to the stomach). The food then enters the stomach, where it is broken down further by digestive acids and enzymes. A meal usually leaves the stomach within two to three hours after it has been eaten. Once it leaves the stomach, the food moves into the small intestine, where muscular contractions mix the food further. Food remains in the small intestine from three to ten hours. Most of the absorption of nutrients into the bloodstream occurs during this time. The undigested material from the small intestines moves into the large intestine, where it waits to be eliminated some 24 to 72 hours later through the rectum.

Food Safety

The United States has two main government agencies that oversee the safety of the food supply-the Food and Drug Administration (FDA) and the U.S. Department of Agriculture (USDA). The FDA conducts tests, sets safety standards and enforces laws regulating food quality and processing. When a manufacturer makes a request to put food additives or color additives into a food, the FDA reviews the safety of the chemicals to ensure that they are safe. The FDA also reviews, approves and regulates drugs. The USDA has the responsibility of regulating and inspecting all meats and poultry during slaughter and processing to ensure their quality and safety. The USDA and the FDA have enormous jobs ensuring the safety of the food supply for the 250 million people in the United States. The amount of food that is produced, shipped, processed, packaged, stored and prepared is absolutely astounding. In fact, every year each person in the United States consumes approximately:

• 233 pounds of milk and cream
• 126 pounds of potatoes
• 112 pounds of red meat
• 95 pounds of vegetables (not including potatoes)
• 92 pounds of fresh fruit

Although the United States has the safest food supply in the world, there are still many opportunities for the food to become contaminated from the time food leaves the farm to the time it is in the hands of the consumer. Knowledge about food safety hazards is the best line of defense.

Unfortunately, many people do get sick every year from foodborne illness. Foodborne illness is a disease that is transmitted to humans by food and is caused by bacteria present in the food. Symptoms include diarrhea, vomiting, fever, cramps or upset stomach; they appear hours or even days after the contaminated food has been eaten. The most common causes for foodborne illness are improper holding temperatures, poor personal hygiene, inadequate cooking, contaminated equipment and food from an unsafe source.

Preventing Food Poisoning

• Wash.
  • Always wash hands in hot, soapy water before handling, preparing or serving food and after using the bathroom.
  • Always wash cutting boards, utensils and countertops with hot, soapy water after preparing each food item.
  • Use paper towels instead of cloth towels to dry hands and clean up surfaces. Cloth towels may harbor bacteria, thereby spreading it to hands and surfaces.
• Don't cross-contaminate.
  • Separate raw meat, poultry and seafood from other food in the grocery cart.
  • Store raw meats, poultry and seafood in the bottom of the refrigerator so that juices from the meats don't leak onto other foods.
  • Never place cooked food on a plate that previously held raw meat.
  • Cross-contamination spreads bacteria from one food to another.
• Cook thoroughly.
  • Cook roasts and steaks to at least 145 degrees F.
  • Cook ground beef to at least 160 degrees F. Don't eat ground beef that is still pink inside.
  • Cook eggs until the yolk and white are firm.
  • Make sure that there are no cold spots in food when cooking in a microwave oven. Bacteria can survive in those spots.
  • Refrigerate as soon as possible.
  • Keep your refrigerator at no more than 40 degrees F and your freezer at 0 degrees F or below.
  • Refrigerate perishables, prepared food and leftovers within two hours.
  • Never defrost food on the kitchen counter. Use the refrigerator, cold running water or the microwave.
  • Leaving foods out at room temperature for extended periods of time is dangerous, because microbes can grow on foods and cause illness. Many bacteria thrive at room temperature.
• Use good sense when shopping.
  • Don't buy foods in dented, rusty, bulging or leaky containers. Damaged containers may have small holes that allow bacteria to enter. Some food bacteria can cause cans to bulge.
  • Don't buy cracked eggs. Cracked eggs are more susceptible to bacterial growth, and they may leak on to other foods, contaminating them with Salmonella or other bacteria.
  • Always pick the frozen and perishable foods last and get them into the freezer or refrigerator as soon as possible. Allowing foods to sit for long periods of time at room temperature may allow bacteria to grow and multiply.
• If there is ever a doubt, throw it out. Don't take any chances with food-it's not worth the risk.
  • If you don't know how long a food has been sitting out, throw it out.
  • If you don't know how old a food is and can't find a date on the packaging, throw it out.
  • If a food smells funny or looks funny, throw it out.

Nutrition and Health
The poor eating habits of many youth in the United States put them at risk for health problems later in life. More than 84 percent of young people eat too much fat, and 91 percent eat too much saturated fat. Only one out of five youths eat the recommended five servings of fruits and vegetables per day. Additionally, one out of five students ages 15 to 18 regularly skips breakfast, which is considered the most important meal of the day. Moreover, 9 percent of high school girls take diet pills regularly, and 8 percent of high school girls take laxatives or vomit to lose weight or to keep from gaining weight.

The benefits of healthful eating include better growth and development; better performance in the school setting; prevention of childhood and adolescent problems such as obesity, eating disorders and cavities; and prevention of major chronic diseases in adulthood such as heart disease, cancer, stroke and diabetes.

Terms to Know

• Carbohydrates provide the main source of energy for the body. There are two types of carbohydrates:
  • Simple carbohydrates, which supply quick energy, are found in sugar, honey, fruits and many desserts.
  • Complex carbohydrates, which provide long-lasting energy, are found in pasta and breads.
• Cholesterol is a fatty substance found in animal and dairy products.
  
• Dietary Guidelines provide dietary recommendations based on the latest scientific and medical research about eating healthfully and decreasing risk for major diseases.
• Fat provides a source of energy. There are three types of fat:
  • Saturated fat, which is found in animal products such as meat and dairy foods, can cause heart disease.
  • Monounsaturated fat is found in olive, peanut and canola oils.
  • Polyunsaturated fat is found in sunflower, corn, soybean and cottonseed oils.
    
• Minerals are natural substances from the Earth's crust, which have many different functions in the body. For example, calcium helps to build strong teeth and bones, and iron assists the formation of red blood cells.
• Nutrients are the building blocks of the body, substances needed for proper growth and functioning.
• Vitamins are nutrients that help keep the body alive and functioning properly. Without vitamins, the cells would not be able to carry out the basic chemical reactions necessary for proper functioning.

Essential Nutrients
Nutrients, which are vital for survival, are the essential substances obtained from food. They provide energy and materials for body growth and repair of cells; they also help to regulate all the chemical processes that occur in the body. The six major classes of nutrients are carbohydrate, fat, protein, vitamins, minerals and water. For the most part, the body cannot manufacture these substances by itself; therefore, they must be obtained from food.

The six classes of nutrients can be sorted into three groups: those that provide energy; those that are needed for growth, maintenance and repair; and those that help the body function smoothly.

Nutrients That Provide Energy:

• Carbohydrates provide the major source of energy for the body. Nutritionists recommend that people's food intake consist of 50 to 65 percent carbohydrates. Major sources of carbohydrates are cereals, fruits, breads and some vegetables. Each gram of carbohydrate contains four Calories. There are two types of carbohydrates:
  • Simple carbohydrates are used for quick, immediate energy. They are found in fruits, milk and table sugar.
  • Complex carbohydrates are used to supply long-lasting energy. They include starches, glycogen and fiber. Starch is found in pasta, bread, wheat, corn and potatoes. Glycogen is starch that is stored in the liver and muscles and is used during exercise or physical activity. Dietary fiber is found in vegetables, fruits, beans, peas and grains. It passes through the intestinal tract undigested to provide bulk for the stool formed in the large intestine.
• Fats (lipids) are another major energy supply for the body. By definition, fats are solid at room temperature, and oils are liquid. The fatty acid is the basic structural unit of fat. There are two types of fatty acids found in lipids:
  • Saturated fatty acids are found predominately in animal fat such as meats and cheese. Generally, they form fats that are solid or semi-solid at room temperature.
  • Unsaturated fatty acids are found predominately in plant oils. They form fats that are liquid at room temperature.
    Certain unsaturated fats are essential nutrients in the diet. They help to promote healthy skin and nails, synthesize and repair vital cell parts and produce certain hormones in the body. However, fats are a high source of calories; each gram of fat contains nine Calories. The average American diet contains about three times the amount of fat necessary for essential functioning. Nutritionists recommend that people consume no more than 30 percent of their daily intake of Calories from fat. Major sources of fat are oils, meats, fish, dairy products and some seeds and nuts.

Nutrients That Are Important for Growth and Maintenance:

• Protein is made up of chains of amino acids that link together to form a protein. Proteins serve to build and repair body tissue and make hormones and components of the immune system that help to fight off infections. They also form parts of muscle, hair, skin, nails, connective tissue and glands. Proteins can also serve as a source of energy. Each gram of protein has four Calories. Ten to fifteen percent of food intake should come from protein. Meats, fish, legumes, nuts, eggs and dairy products are major sources of protein.

Nutrients That Act to Keep the Body Functioning Smoothly:

• Vitamins are compounds that allow many of the chemical processes in the body to occur. Vitamins themselves provide no energy to the body; however, without vitamins, the cells would not be able to carry out chemical reactions that permit the body to function properly. Vitamins are found in a variety of foods. Thirteen different vitamins are essential for health. They are placed in one of two groups:
  • Fat-soluble vitamins dissolve in fat. The four fat-soluble vitamins are D, K, A and E. These vitamins are not disposed of rapidly in the body and can quickly build up in the body. Too much of these vitamins may cause toxic reactions. For this reason, it is necessary to track the amount of fat-soluble vitamins that we ingest.
  • Water soluble vitamins dissolve in water. Vitamins B and C are water soluble. Because these vitamins are excreted very rapidly from the body through the kidneys, they must be taken daily.
• Minerals are natural substances found in the earth's crust. They play many different roles in the body, including: regulating blood pressure, facilitating muscle contraction, providing major components of bones, healing wounds and helping conducting nerve impulses. Minerals are found in a variety of foods. There are two classifications of minerals in the human body, both of which are of equal importance to proper physiologic function. An insufficiency of any of the minerals in either classification is equally significant.
  • Trace elements are needed only in small amounts. This group includes iron, copper, fluorine, iodine, selenium, zinc, chromium, cobalt, manganese and molybdenum.
  • Major elements are minerals that are needed in large quantities. This group includes calcium, potassium, sodium, magnesium, phosphorus, chloride and sulfur.
• Water makes up about 50 to 60 percent of the body's weight. Muscle contains around 73 percent water and fat tissue is about 20 percent water. Water is crucial to survival. Every cell in the body must have water in order to survive. An adult can survive about eight weeks without food but only a few days without water. Water is responsible for many processes that occur in the body. It is the perfect medium for all of the chemical reactions. Water aids in temperature regulation-heating and cooling of the body. Water helps remove waste products from the body. Water is also responsible for controlling the concentration of nutrients in the body. In addition, water aids in the digestive and respiratory processes. Most water comes from the liquid people consume; however, some comes from the foods people eat, and the rest is created through the chemical reactions that occur in the body. Water is excreted through respiration (lungs), urination (kidneys), perspiration (skin) and (defecation) the bowels. Experts recommend that people drink eight to ten glasses of water a day.

Functions of Some Vitamins and Minerals

Vitamins

• Vitamin A aids in vision and maintains health of cells, especially for the skin and eyes: it is necessary for cell growth and development. Dietary sources of vitamin A include dark green and orange vegetables such as spinach, sweet potatoes, pumpkin, carrots, turnip greens, tomatoes and broccoli. It is also found in some fruits, including cantaloupe, mango, papaya, peaches and nectarines.
• Vitamin D helps to build healthy bones. Dietary sources include fortified milk, fish oils, salmon and tuna fish. Vitamin D is mostly obtained through exposure to sunlight; people need about 15 minutes of direct sunlight on the face and hands every day.
• Vitamin C helps to synthesize the protein collagen, which is found in skin, teeth, bones, tendons and blood vessels. Vitamin C promotes wound healing and has immune system benefits, as well. It has been hypothesized that Vitamin C may help prevent some types of cancer. It also aids in iron absorption. Dietary sources include citrus fruits (oranges, grapefruits), green peppers, broccoli and strawberries.
• B vitamins include thiamin, riboflavin, pantothentic acid, biotin, B-6, B-12, folate. The B vitamins play a major role in metabolism (chemical reactions throughout the body). Different foods contain different B vitamins. For example, thiamin is found in pork products and sunflower seeds; niacin is found in mushrooms, wheat bran, tuna, chicken, asparagus and peanuts. Folate can be found in green, leafy vegetables. B-6 is found in bananas, cantaloupe, broccoli and spinach. B-12 is found in clams, oysters and hot dogs.

Minerals

• Calcium serves to strengthen teeth and bones and aids nerve transmission and muscle contraction. Dietary sources include dairy products, canned fish, leafy vegetables, tofu and fortified orange juice.
• Potassium aids nerve transmission. Dietary sources include spinach, squash, bananas, orange juice and milk.
• Sodium also aids nerve transmission. It is found in table salt and processed foods.
• Phosphorus promotes strengthening of teeth and bones and is part of various chemical reactions throughout the body. Dietary sources include dairy products, processed foods, soft drinks and fish.
• Iron is needed for the formation of healthy blood cells, and it helps carry oxygen to the cells. Dietary sources include red meat, shellfish, leafy green vegetables and legumes.
• Iodine is important for temperature regulation, synthesis of the thyroid hormone, metabolism, and nerve and muscle function. Dietary sources include seafood and iodized salt.
• Fluoride increases resistance to cavities and is needed for healthy bones and teeth. Dietary sources include seafood, tea and fluoridated water.

Dietary Guidelines for Healthful Eating
Healthful eating is crucial to overall health. Without proper nutrition, the body and mind cannot function to their fullest potential. Diet and patterns of physical activity account for 300,000 adult deaths per year in the United States. Furthermore, at least four of the ten leading causes of death in the United States are linked to the way people eat. Diseases linked to dietary patterns include heart disease, stroke, cancer and diabetes. Unfortunately, the initial stages of some of these diseases can begin in early childhood or adolescence.
Following the Dietary Guidelines for Americans helps people eat healthfully and obtain all of the nutrients needed for good health. First published in 1980 and updated every five years, the Dietary Guidelines provide recommendations based on the latest scientific and medical research. The first two guidelines, eating a variety of foods and being physically active, help people obtain all of the nutrients the body needs while maintaining a healthy weight. The next two guidelines, choosing a diet low in fat and cholesterol and eating plenty of fruits and vegetables, help prevent diseases related to nutrition. The remaining guidelines underscore the need to avoid the foods that are not nutrient-dense, such as sugar and alcohol.

The Guidelines

• Eat a variety of foods. No single food provides all the nutrients people need. Eating a variety of foods increases the chances of getting all the vitamins, minerals and other nutrients needed for good health.
• Balance food intake with some physical activity in order to maintain a healthy weight. Combining exercise with healthy eating helps people lose or maintain weight and stay healthy. High body fat can increase the risk of some types of diseases.
• Choose a diet with plenty of grains, vegetables and fruits. Grains [such as rice, cereal and whole wheat bread], vegetables [such as green beans, broccoli and salads] and fruits [such as bananas, apples and oranges] provide excellent sources of vitamins, minerals and complex carbohydrates. These foods are the foundation of a healthful eating plan.
• Choose a diet low in fat and cholesterol. Diets high in fat, specifically saturated fat [from animal products] and cholesterol also increase risk of diseases such as heart disease and some types of cancer. In addition, whether from a plant or an animal source, fat is a very high source of calories and needs to be eaten sparingly. A healthful eating plan should consist of no more than 30 percent of calories from fat per day.
• Choose a diet moderate in sugars. Some foods with sugar, such as candy and soda, contain a lot of Calories without many nutrients. These foods should be used in moderation because they are comprised of empty Calories-Calories that don't add any significant amount of needed nutrients.
• Choose a diet moderate in salt and sodium. Sodium regulates and balances fluids in the body, but too much salt in the diet can affect blood pressure. Eating a diet low in salt may help lower blood pressure levels.
• Alcohol only in moderation (for adults who choose to use it). Alcohol should not be consumed by children, adolescents, pregnant women, people on prescription or over-the-counter medications and people who plan to drive. Alcohol is legal only for adult use. Many adults cannot moderate their alcohol intake and need to avoid all use of alcohol. Alcohol is also very high in calories and may add unwanted weight. Most importantly, drinking too much alcohol impairs judgement and can lead to alcoholism and other life threatening diseases.

The Food Guide Pyramid
Created in 1992, the Food Guide Pyramid is simply a framework of what to eat each day in order to meet Dietary Guidelines. It is a tool that allows one to more easily understand and identify what foods should be eaten in order to obtain all of the nutrients our bodies need. The recommended serving sizes are based on scientific research and expert recommendations.

Food Groups and Serving Sizes

The Grains Group
One serving in the grains group consists of the following:

• 1 slice of bread
• 1 ounce of cereal (½ to 1 cup, depending on the cereal)
• ½ cup of rice
• ½ cup of spaghetti
• ½ hamburger bun
• ½ bagel
• 1 tortilla
• 1 ounce of pretzels

The Vegetable Group
One serving of vegetables consists of the following:

• 1 cup of raw leafy vegetables such as lettuce
• ½ cup of other vegetables such as broccoli, green beans, corn, tomatoes or mashed potatoes
• ¾ cup of vegetable juice

The Fruit Group
One serving of fruit consists of the following:

• 1 medium apple, banana or orange
• ½ cup of grapes
• ½ cup of cooked, chopped or canned fruit such as watermelon or fruit cocktail
• ¾ cup of fruit juice, such as orange juice and apple juice

The Dairy Group
One serving of dairy consists of the following:

• 1 cup of milk or yogurt
• ½ cup of ice cream
• ½ cup of pudding
• 2 ounces of American cheese (1 to 2 slices)

The Meat, Poultry, Fish and Dry Beans Group
One serving of meat, poultry, fish or dry beans consists of the following:

• 2 to 3 ounces of cooked meat, chicken or fish
• 1 egg
• 1 hot dog
• 2 tablespoons of peanut butter
• ½ cup of cooked beans

Fats, Oils and Sweets
The following foods are to be used sparingly:
Jelly, candy, soda, mayonnaise, butter, margarine, salad dressing

Facts about Fat
Fat is a nutrient that is necessary for survival. It provides a major source of energy; it is vital for cell growth and repair; it is needed for temperature regulation; and it serves as a layer of protection. Fat is crucial for human functioning. However, the average American diet supplies more than three times the needed amount of fat.

The Importance of Calcium
The mineral calcium is crucial for the body in many respects. First of all, it is very important for strong teeth and bones. In fact, more than 99 percent of the calcium found in the body is used to strengthen the teeth and bones. In addition, calcium is essential for muscle contraction and nerve transmission. If calcium levels fall too low, muscles will stiffen and nerve transmission will fail. Calcium is also a vital component in the formation of blood clots. Finally, calcium is needed to help regulate cell metabolism by influencing the activities of certain enzymes and hormones.

Osteoporosis is a disease in which the bones become weak and brittle. Lack of calcium over a number of years, especially in the childhood years, can contribute to this condition. As people age, osteoporosis may cause loss in height, greater chance of hip fractures and the loss of teeth.

Sources of Calcium
Foods rich in calcium include:

• dairy products-milk, yogurt and cheese (provide most of the calcium in many people's diets)
• green leafy vegetables-broccoli, spinach and kale
• white bread, rolls, crackers and other foods made with milk products
• calcium-fortified foods-orange juice, other fruit drinks and soy
• canned sardines and salmon with bones

Serving Sizes
It is recommended that most Americans obtain at least 800 mg of calcium every day; however, children ages 9-18 and pregnant women need 1300 mg of calcium each day. Adults ages 19-30 need about 1000 mg of calcium per day. Adults over the age of 50 should try to obtain 1200 mg every day.

The following quantities equal one serving of calcium:

• 1 cup skim or low-fat milk
• 1½ ounces of cheese
• 1 cup fortified juice
• 3 ounces sardines with bones

The following quantities equal one-half a serving of calcium:

• 1 cup cooked broccoli or kale
• 1 ounce calcium-fortified cereal
• 3 ounces canned salmon with bones
• 4 ounces tofu (made with calcium)

Importance of Fruits and Vegetables
Fruits and vegetables provide many essential vitamins and minerals, as well as fiber. These vitamins and minerals are essential for the body to function at the highest possible level. Eating at least five fruits and vegetables every day lowers risk for cancer and heart disease, increases the capacity of the immune system and helps control our weight, thereby reducing the risk for developing diabetes and high blood pressure.

Unfortunately, research suggests that America's children are not consuming the recommended daily amount of fruits and vegetables. Only 26 percent of children are eating five servings of fruits and vegetables per day. On average, children eat about 3.6 servings of fruits and vegetables per day-french fries and potato chips account for a large percentage of the vegetables eaten. Although adults are consuming more fruits and vegetables than children (40 percent of adults eat five servings a day), there is still room for improvement.

Benefits of Eating Fruits and Vegetables
In addition to providing vitamins, minerals and fiber, fruits and vegetables have other benefits.

• They add interesting shapes, colors and tastes to meals.
• Most fruits and vegetables are low in fat and calories.
• Eating fruits and vegetables helps decrease risks of disease.

Healthful Weight Control versus Fad Diets
More than half of the adult population of the United States does not engage in even moderate exercise, and one-fourth of adults fail to participate in any leisure-time physical activity. In addition, Americans consume more fat and more Calories than recommended for healthful eating.

These unhealthful patterns are believed to account for 300,000 deaths among adults in the United States each year. Unhealthful eating behaviors combined with lack of physical activity contribute to a variety of chronic diseases, including heart disease, stroke, cancer, diabetes, high blood pressure and osteoporosis.

The body needs energy (food) in order to function. A Calorie is a measure of potential food energy. Everybody has his or her own individual Caloric needs based on body type and physical activity level. Recommendations for weight control include increased physical activity rather than greatly restricted food intake.

While our society is preoccupied with "model" thinness, more children are overweight or obese in this country than ever. Unfortunately, overweight and obese children are likely to become overweight and obese adults, with increased risk for chronic disease in adulthood.

Healthful Weight Control
The only way to ensure healthful weight loss is by following the U.S. Dietary Guidelines and living an active lifestyle. In some cases, underlying physical and emotional problems may contribute to a weight problem, and they will need to be addressed in order for weight loss to occur.

Students with concerns about their weight should be encouraged to eat a variety of healthful foods and to increase their physical activity level. Students should also be encouraged to recognize the natural diversity of body sizes.

Consumer Awareness-Recognizing Fad Diets
Almost all fad diets fail. Fad diets offer only a quick fix and not a solution to the problem. They do not attempt to change the behaviors of the person who is dieting. All too often, dieters are left with feelings of guilt and inadequacy because of their perceived failure to lose weight and maintain weight loss.

• Characteristics of fad diets include:
• promises of quick weight loss
• limits on food choices
• recommendations for expensive supplements or special products
• claims to be better than recommendations from doctors and scientists
• no requirements for physical activity

Healthful Snacking
The key to healthful snacking is choosing foods that are full of nutrients and not those that contain only empty Calories. The U.S. Dietary Guidelines and the Food Guide Pyramid provide guidance. Healthful snacks include:

• fruit (canned, fresh, dried)
• raw vegetables with dip
• fruit juice
• fig bars
• bagels with cream cheese or peanut butter
• graham crackers with peanut butter
• unbuttered popcorn
• rice cakes
• cereal with skim milk

Nutrition Resources