Alimentation and nutrition

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Alimentation and nutrition

Fact & Background Information about Nutrition

Unit Vocabulary

Nutrition – the science that deals with food and how it is used in the body. (Burton 24)
Balanced Diet – an everyday diet that is healthy (high in good nutrients like vitamins and minerals, and low in harmful nutrients like saturated and trans fats), and contains the recommended servings from each of the five food groups. Eating more of the recommended servings in one food group and less in another would not be considered a balanced diet.
Nutrients – compounds in foods that sustain your body processes. There are six classes of nutrients: carbohydrates, fats (lipids), proteins, and water are considered macronutrients; vitamins and minerals are considered micronutrients. (Blake – Glossary)
Healthy Food (nutritious food) – foods that are considered good for your health. Should be a good source of vitamins and should be low in fats, sugars, and sodium.
Unhealthy Food (junk food) – foods that are perceived to have little to no nutritional value. These foods are generally pre-packaged and high in calories, fats, sugars, sodium, and contain little to no fruit, vegetable, dietary fiber, vitamins, and minerals. Common junk food includes: candy, packaged salty food, fried fast food, and carbonated beverages. (Wikipedia)
Canada’s Food Guide – a diet planning document produced by Health Canada. (Wikipedia)
Canada’s First Nations, Inuit, and Métis Food Guide – a food guide tailored to reflect traditions and food choices of First Nations, Inuit and Métis, and is a complement to the 2007 Canada's Food Guide. This tailored food guide has recommendations for healthy eating based on science. It recognizes the importance of traditional and store-bought foods for First Nations, Inuit and Métis today. This food guide can be an important tool for individuals, families and communities to learn about and share ways of eating well, including traditional and store-bought foods. (Health Canada)
Fast Food – the term given to food that can be prepared and served very quickly. While any meal with low preparation time can be considered to be fast food, typically the term refers to food sold in a restaurant or store with preheated or precooked ingredients, and served to the customer in a packaged form for take-out/take-away. Common fast food restaurants include: McDonalds, Burger King, KFC, A&W, Wendy’s, Taco Bell etc. (Wikipedia)
Fat – triglycerides are the most common fat lipid found in foods and our bodies.

Saturated Fat – fats in which the fatty acid chain is saturated with hydrogen. Foods high in saturated fats with long fatty acid chains are soli at room temperature, and are unhealthy. (Blake – Glossary)
Trans Fat – fats primarily resulting from the hydrogenation of unsaturated fatty acids, a process used widely in commercially-made foods to add texture, longer shelf life and better resistance to rancidity. Trans fats are bad for heart health in numerous ways. (Blake – Glossary)

Calories – Measurement of food energy. Depending on one’s age, height, and weight (BMI), people are required to eat different amounts of calories, the average being a 2000 calorie-per-day diet.

Empty Calories – Calories with little or no nutrition value. (Blake – Glossary)

Carbohydrates – Carbohydrates include sugars, starches and fiber. They constitute a large part of foods such as rice, noodles, bread, and other grain-based products. Carbohydrates are not essential nutrients but are typically an important part of the human diet. While it would not be accurate to categorize all carbohydrates as "bad" nutritionally, some carbohydrate sources may well have negative effects on health, especially when consumed in large quantities. (Wikipedia)
Vitamins – are essential nutrients. Vitamins are essential for the normal growth and development of a multicellular organism, as they maintain the health of cells, tissues, and organs. (Wikipedia)
Dietary Minerals – are the chemical elements required by living organisms. Examples include calcium, magnesium, potassium, sodium, zinc, and iodine. (Wikipedia)
Sodium – a very common electrolyte; not generally found in dietary supplements, despite being needed in large quantities, because the ion is very common in food: typically as sodium chloride, or common salt. Excessive sodium consumption can deplete calcium and magnesium which has been shown can lead to high blood pressure, weight gain, and osteoporosis. (Wikipedia)
Fiber – a portion of plant food that is not digested in the small intestine. Fiber is essential to have as part of a balanced diet because it serves to aid many important functions in the body having to do with digestion. (Blake – Glossary)
Health Claim – a claim on a food label that describes a relationship between a food or dietary compound and a disease or health-related condition. (Blake – Glossary)
Daily Values (DVs) – percentage levels of nutrients that are used on food labels (right side), based on a 2000 calorie-per-day diet. 5% or less of a nutrient is low, 15% or more of a nutrient is high. (Blake – Glossary)
Metabolism – the process in which food calories are converted into energy. (Blake – Glossary)

Additional Nutrition Facts (from Burton pg. 24)

Nutritionists advise a certain number of daily servings from each of the five food groups: vegetable; fruit; bread, cereal, rice, and pasta; milk, yogurt, and cheese; and meat, poultry, fish, dry beans, eggs, and nuts.
Nutrients from food perform these functions: maintain body tissues, regulate body processes, provide energy.
Water is the most important nutrient and is used to carry out all of the body’s life processes. It is needed in large amounts because the body consists of 50-75% water.
Carbohydrates, fats, and proteins are needed to provide energy.
Minerals and Vitamins are needed in small amounts to promote growth.
A balanced diet is the key to good nutrition.
Nutrition labels reveal calories, fat, carbohydrates, cholesterol, and nutrients and are required on all packaged and processed food sold in the United States and Canada.

Essential Question &Unit Questions

Essential Question:

Why is it important to eat healthy, nutritious food as part of a balanced diet?

Additional Unit Questions:

What is a balanced diet?
How do I know if I’m getting enough vitamins and minerals?
How can I eat healthy without having to sacrifice foods I like and that taste good?
How many meals should I eat a day?
How big is a serving?
Is serving size different for children and adults?
How many calories should I consume a day?
Why is junk food bad for you?
What can happen if you eat more unhealthy foods than healthy foods?
Is it possible to get healthy food choices at my favorite fast food restaurants?
Is it okay to eat junk food sometimes?
If a food is low in calories, is it considered healthy?
Is fruit juice better to drink than pop (carbonated beverages)?
How do I know if the food I’m eating is healthy?
Just because a food label claims to be healthy does it actually mean it is healthy?
How do food advertisements persuade us to buy certain foods?
What can happen to our bodies if we don’t eat the right kinds of foods?
How are food and nutrition different in other countries/cultures?

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Water—The Most Essential Nutrient

Water in the body participates in many chemical reactions and serves as a solvent, transportation medium, lubricant, and regulator of body temperature. Water is by far the nutrient most needed by the body. Water makes up part of every cell, tissue, and organ in the body and accounts for about 60% of body weight. Inside the body, water performs many tasks vital to life.

The Major Minerals

Like the vitamins, minerals do not themselves contribute energy to the diet. Most minerals have diverse functions within the body and work with enzymes to facilitate chemical reactions. Minerals are inorganic compounds that occur naturally in the Earth’s crust, and most minerals are required in the diet in very small amounts. Each of the major food groups supplies a number of minerals. The minerals are traditionally divided into two large classes: the major minerals and the trace minerals.

About 99% of the body’s calcium is a structural component of the bones and teeth. The 1% of calcium found in body fluids is essential for transmission of nerve impulses, muscle contraction, cell membrane integrity, and blood clotting. A deficit of calcium during the growing years and in adulthood contributes to adult bone loss and osteoporosis.

Phosphorus is so abundant in foods that deficiencies are unlikely. It participates with calcium in forming the crystals of bone and therefore is found in large quantities in the body. Sulfur is present in all proteins and is a constituent of body tissues. Skin, hair, and nails contain some of the body’s more rigid proteins, and these have a high sulfur content. Magnesium plays a role in the synthesis of body proteins and thus is important to all body functions; it also helps to relax muscles after contraction. A dietary deficiency of magnesium is not likely, but may occur as a result of vomiting, diarrhea, alcohol abuse, or protein malnutrition.

Special conditions are needed to regulate the amounts of water inside and outside the cells so that the cells do not collapse from water leaving them or swell up under the stress of too much water entering them. Sodium, potassium, and chloride are examples of electrolytes—dissolved substances in blood and body fluids that influence the distribution of fluids among the various body compartments.

Sodium is abundant in the diet, as part of salt. Deficiencies are rare except in dehydration. Chloride, which occurs in salt, contributes to the formation of the stomach’s hydrochloric acid. Potassium is primarily involved in the working of nerve and muscle cells and is critical to maintaining the heartbeat.

The Trace Minerals

The trace minerals occur in the body in minute quantities and are needed in smaller amounts in the daily diet.

Iron is the body’s oxygen carrier. Bound into the protein hemoglobin in the red blood cells, it helps transport oxygen from lungs to tissues and so permits the release of energy from fuels to do the cells’ work. When the iron supply is too low, iron-deficiency anemia occurs. Meats, fish, and poultry are good sources of iron. Whole-grain or enriched breads and cereals and legumes also provide dietary iron. Iron absorption from plant sources can be enhanced by vitamin C and other factors.

Zinc is found in every cell of the body and plays a major role with more than 50 enzymes that regulate cell multiplication, normal growth and sexual development, and metabolism. The richest food sources of zinc include shellfish, meat, and liver. Milk, eggs, and whole-grain products are also good sources.

Iodine forms part of the thyroid hormones; deficiency may cause goiter, slowed metabolism, and cretinism. The use of iodized salt protects against deficiency. The fluoride ion combines with calcium and phosphorus to stabilize the crystalline structure of bones and teeth. Copper is important for red blood cell formation, manufacturing collagen, and central nervous system function. Chromium works with the hormone insulin in promoting glucose uptake into the cells and normal carbohydrate metabolism. Selenium acts as cofactor for an antioxidant enzyme. Manganese and molybdenum function as part of several enzyme systems.

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Weight Management

The escalating epidemic of obesity results in thousands of preventable deaths each year. Many factors, including genetics, influence body weight, but excess energy intake and physical inactivity are the leading causes of overweight and obesity. Both underweight and overweight increase the risk of incurring various illnesses as well as various social and psychological stigmas.

A Closer Look at Obesity

The WHO considers obesity an epidemic with many contributing factors: genetics, large portion sizes, availability of energy-dense foods, sedentary lifestyles, and a built environment that fails to facilitate fitness.

Problems Associated with Weight

Underweight renders a person more vulnerable to physical stressors. Overweight increases risks of hypertension, heart disease and diabetes in those who are genetically predisposed, and has also been associated with gallbladder disease and breast cancer.

What Is a Healthful Weight?

To determine health risks associated with overweight and obesity, health professionals use three factors: body mass index, waist circumference and current health status. The latter may include heart disease, type 2 diabetes, high blood cholesterol, high blood pressure, cigarette smoking, osteoarthritis, gallstones, or sleep apnea. An initial goal for treatment of overweight and obese people with risk factors is to reduce body weight by about 10% at a rate of about 1 to 2 pounds per week. An overweight person who wants to lose weight needs to understand the concept of total energy needs as well as successful weight-loss strategies.

Energy Balance

Unhealthy weight results from an unbalanced energy budget (food energy in vs. energy expended on basal metabolism and activity). While the majority of energy used by the body fuels basal metabolism—accounting for 60%—the person’s physical activity level is important as well, and can help determine whether that person will have a healthy or unhealthy weight.

Causes of Obesity

In general, two schools of thought address the problem of obesity’s causes. One attributes it to inside-the-body causes (genetics, set-point theory, fat-cell theory); the other, to environmental factors (external cue theory). Eating behavior may be a response not only to hunger or appetite but also to complex human sensations such as yearning, craving, or compulsion. No doubt, the causes of obesity are complex and many causes may contribute to the problem in a single person. Given this complexity, it is obvious that there is no panacea for successful weight maintenance. The top priority should be prevention, but where prevention has failed, the treatment of obesity must involve a three-pronged approach, including adopting healthful eating habits, moderate levels of exercise, and behavior change.

Weight Gain and Loss

Weight change may be related to any of the body’s components, including fat and lean tissues, water and bone minerals. Excess energy is stored within the body as limited quantities of glycogen and virtually unlimited quantities of fat. During a fast, glycogen is soon exhausted, and then the body metabolizes fat plus muscle tissue, because the nervous system cannot use fat for fuel. If the fast continues, the body adapts by manufacturing ketone bodies, which the brain can use when glucose is unavailable.

Successful Weight-Loss Strategies

The problem with going on a rigid diet with a goal of, say, a 15-pound weight loss in 3 weeks is that it’s a quick fix—the dieter attempts to gain a temporary solution to what is typically a chronic problem. People are attracted to fad diets because of the dramatic weight loss that occurs within the first few days. Such people would be disillusioned if they realized that the major part of this weight loss is a loss of body protein, along with quantities of water and important minerals. A more healthful alternative is to develop habits gradually that you can live with permanently and that will help you shed pounds and keep them off over the long run. Instead of measuring your success by the needle on the scale, gauge your progress by the strides you make in adopting good eating and exercise habits as well as healthful attitudes about yourself and your body. Criteria for success are permanent changes in eating and exercise habits and maintenance of the goal weight over time.

Medications to assist obese persons with weight loss include, among others, Meridia, an appetite-suppressing drug, and Xenical, which reduces the body’s absorption of fat. Treatment of severe obesity includes medically supervised, very-low-calorie diets providing fewer than 800 calories or surgery on the stomach to reduce its volume.

Weight Gain Strategies

Healthful weight gain consist of building up muscle mass through weight training and increased calorie intake.

The Eating Disorders

The term eating disorder involves a wide spectrum of conditions, including anorexia nervosa, bulimia nervosa, and binge-eating disorder. Although the various conditions differ in their origin and consequences, they appear to have similarities among them—all of the conditions exhibit an excessive preoccupation with body weight, a fear of body fatness, and a distorted body image. Some researchers suspect that a complex interplay among environmental, social, and perhaps genetic factors triggers the development of eating disorders, mostly in women.

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