Nutrition: Class Content, Student Questions

Fall 2011

Nutrients

• Nutrients are substances the body needs to live

• Humans need six nutrients– Three contain energy (calories)– Three do not contain energy

Energy-Containing Nutrients

• Carbohydrates– 4 calories per gram

• Protein– 4 calories per gram

• Fat– 9 calories per gram

Image source: public domain

Nutrients Without Energy

• Vitamins– Organic substances found

in plant and animal sources– A, C, D, E, K, & B

vitamins (8 of them)

• Minerals– Inorganic substances found

in many of the body’s structures (teeth, bones, muscles, blood cells, etc)

– Examples: calcium, sodium, iron, chromium, potassium

Student Question: Do we need all vitamins? A combination?

• A: We need all vitamins. What one person needs, however, will differ from another person based on their dietary behaviors. – Example: person who consumes many fruits &

vegetables vs “fast food” eater– Example: a person with nutrient absorption

issues may need larger doses than average individual

Student Question: Do we need all vitamins? A combination?

• Common dietary needs are those vitamins found in fruits & vegetables since many of us do not consume enough

• Recommendations:– RDA = Recommended Dietary Allowances– AI = Adequate Intake, if no RDA value set– UL = Upper Limit (highest intake without

negative side effects)

Student Question: What kinds of fruits & vegetables are most beneficial?

• Generally, brightly-colored produce– Vitamins– Minerals– Antioxidants

• Variety• Green, leafy vegetables• Bright berries• Tomatoes• Sweet potatoes

Photo: Scott Bauer, public domain

Student Question: What are the nutritional differences in fruits and vegetables?

• Both have nutrients• Generally, vegetables

are favored over fruits– Sugar content in fruits

• Fructose

• Too much = fat storage

– Slower absorption rate

Student Question: What are the nutritional differences in fruits and vegetables?

• Both have nutrients• Generally, vegetables

are favored over fruits– Sugar content in fruits

• Fructose

• Too much = fat storage

– Slower absorption rate

Student Question: Is a vegetarian diet healthy?

• Vegetarian diets can be “healthy” or “unhealthy”– Whole foods: grains,

vegetables, fruits, herbs

– Fried tofu, mashed potatoes with butter, mac and cheese, candy

Student Question: What foods are low-calorie but also filling?

• Carbohydrate-based foods are usually digested more quickly, resulting in hunger– Since the body needs carb as its primary energy

source, cutting isn’t terribly helpful– Complex carbohydrates take longer to digest

than simple carbohydrates• Brown (instead of white) rice

Student Question: What foods are low-calorie but also filling?

• Foods higher in fiber tend to take longer to digest– Whole grains (barley, bran flakes, oatmeal)– Nuts & seeds (almonds, flax seeds, pistachios)– Fruit (raspberries, pear, strawberries, prunes)– Legumes (lentils, black beans, split peas)– Vegetables (peas, greens, corn, artichoke)

Student Question: What foods are low-calorie but also filling?

• Water-based foods: soups/broths• Leafy green vegetables• Including protein and healthy fats with

carbohydrate at meals can slow digestion– Eggs– Fish– Chicken– Tofu– Almond butter/peanut butter– Avocado

Student Question: What Harms Might Vitamins Cause the Body?• WebMD shows RDA

or AI, and UL values for vitamins and minerals

• Dangers are usually associated with megadoses– Besthealth

Student Question: What food chemicals should we look out for?

• Challenge: People have varying sensitivities• Challenge: Often, the issue is accumulation

rather than one dose at a given time• Challenge: Combinations of chemicals• Challenge: chemicals used for a variety of

attractive purposes • Challenge: some chemicals are naturally

occurring (estrogenic foods)

Student Question: What food chemicals should we look out for?

• Challenge: Chemicals used for a variety of purposes attractive to consumer– Preservatives– Sweeteners, flavorings– Fat replacers– Emulsifiers, thickeners– Color additives– List at FDA

Student Question: What food chemicals should we look out for?

• Guideline: the more processed the food, the more chemicals present

• Guideline: shopping around the perimeter of a grocery store usually the healthiest approach

Student Question: What food chemicals should we look out for?

• Per Center for Science in the Public Interest• Sodium nitrite

– Found in meat salty, processed meat products

– World Cancer Research Fund, May 2011: processed meats too dangerous for human consumption (totalhealthbreakthroughs.com)

• Saccharin, aspartame, Acesulfame-K• Beverages, snack foods, dairy products, gums, soups, snacks

• Increased cancer risk

Student Question: What food chemicals should we look out for?

• Caffeine– Addictive– Stimulant properties

• Olestra– Fat substitute in snack chips– Digestive problems– Reduce absorption of some fat-soluble vitamins

• Food dyes• Blue 2, Green 3, Orange B, Red 3, Yellow 5, et. Al.• Candy, baked goods, beverages

Student Question: What food chemicals should we look out for?

• High fructose corn syrup– Beverages, cereals, candy, cookies, condiments– Increases sweetness of food products– Consumers not consuming less sugar– Connection to corn allergies?– Metabolic problems? (insulin resistance)

• Bisphenol A in cans, plastics (cancer, reproductive health, CV disease)