Nutrition Basics

Foundations of a Healthy Diet

Nutrition is the science of how food and drink affect our bodies with special regard to the essential nutrients necessary to support human health. A healthy diet provides the body with the nutrients it needs to function optimally and prevent disease.

• Diet: The total intake of food and beverages consumed by an individual.

• Factors Affecting Food Choices:

  • Habit

  • Emotional factors

  • Convenience

  • Nutrition knowledge

  • Time limitations

  • Religious beliefs

  • Socioeconomic factors

  • Advertising

  • Ethnicity

  • Learned behaviors

  • Genetics

  • Health factors

  • Ability to shop and cook

  • Taste

Primary Goals of Good Nutrition

• Consume a variety of nutrient-dense foods and beverages.

• Supply all nutrients in adequate amounts by developing a balanced eating pattern.

• Maintain recommended caloric intake to support ideal body weight.

• Nutrient needs are higher during adolescence.

• Caloric requirements depend on age and, more importantly, activity level.

Key Nutrition Concepts

• Kilocalorie (kcal): A measure of heat energy; used to quantify the energy provided by foods.

• Different foods have different energy values per equal weight.

• Nutrient Density: The amount of a given nutrient per calorie; nutrient-dense foods provide many vitamins and minerals with relatively few calories.

Macronutrients and Micronutrients

Macronutrients

Macronutrients are nutrients required in large amounts that provide energy for the body. They include carbohydrates, proteins, and fats.

• Carbohydrates

  • Major source of energy for the body.

  • Simple carbohydrates: Sugars that provide quick, short bursts of energy (e.g., cakes, candies, soda, table sugar).

  • Complex carbohydrates: Provide longer, sustained energy (e.g., pasta, cereals, breads, grains). Whole grains are preferred for health.

  • Fiber: A type of complex carbohydrate that reduces the risk of colon disease and aids regularity.

  • Energy value:

  • Recommended intake: 45-60% of total diet.

• Proteins

  • Essential for growth, cell production, and repair.

  • Broken down into amino acids by the body.

  • Animal sources: Meats, cheeses, eggs, milk.

  • Plant sources: Beans, nuts, soy products.

  • Complete proteins: Contain all essential amino acids (mostly animal sources).

  • Incomplete proteins: Lack one or more essential amino acids (mostly plant sources).

  • Energy value:

  • Recommended intake: About 15% of total diet.

• Fats

  • Provide energy, support cell growth, absorb nutrients, and produce hormones.

  • Energy value:

  • Saturated fats: Solid at room temperature, mainly from animal sources.

  • Unsaturated fats: Liquid at room temperature, mainly from plant sources.

  • Polyunsaturated fats: Found in corn, sunflower, and vegetable oils.

  • Monounsaturated fats: Found in peanut and olive oils.

  • Trans fatty acids: Unsaturated fats altered by hydrogenation to become solid; increase risk of heart disease.

  • Recommended intake: Less than 25-35% of total calories from fat; saturated fat less than 7%; trans fat less than 1%.

  • Cholesterol: Intake should be less than 300 mg per day.

Micronutrients

Micronutrients are nutrients required in small amounts, including vitamins and minerals, which are essential for various physiological functions.

• Vitamins

  • Promote growth and maintain health.

  • Fat-soluble vitamins: Absorbed with fats (A, D, E, K).

  • Water-soluble vitamins: Dissolve in water (B, C).

  • Excessive intake can cause vitaminosis (toxic condition).

• Minerals

  • Inorganic elements aiding physiological processes.

  • Macrominerals: Needed in large amounts (e.g., sodium, calcium, potassium).

  • Trace minerals: Needed in small amounts (e.g., iron, zinc, iodine, copper).

  • Sodium: Regulates blood and body fluids. Recommended: 1,500-2,400 mg/day (average intake is about 6,000 mg/day).

  • Calcium: Essential for bones, teeth, muscle contraction, blood clotting, nerve transmission, heartbeat regulation, and fluid balance. Recommended: 1,000-2,000 mg/day (higher for children, teens, and postmenopausal women).

  • Iron: Found in all living cells; essential for oxygen transport. Recommended: Women 18 mg/day, men 10 mg/day. Deficiency leads to anemia.

Phytonutrients

Phytonutrients are natural compounds found in plants that are believed to promote health and prevent disease.

• Examples include flavonoids, carotenoids, and polyphenols.

• Found in fruits, vegetables, whole grains, and legumes.

Water

Importance of Water

Water is essential for life, making up a significant portion of the human body and playing a role in nearly every bodily function.

• Recommended intake: 6-8 glasses (8 oz each) per day.

• Individual needs vary based on age, activity, and environmental temperature.

• Inadequate intake leads to dehydration, which can impair physical and mental performance.

Cholesterol and Lipoproteins

Types and Functions

Cholesterol is a waxy, fat-like substance found in all cells of the body, necessary for hormone production, vitamin D synthesis, and digestion.

• The body produces all the cholesterol it needs.

• LDL (Low-Density Lipoprotein): "Bad" cholesterol; leads to buildup in arteries.

• HDL (High-Density Lipoprotein): "Good" cholesterol; carries cholesterol to the liver for removal.

• High-cholesterol foods include eggs, red meat, dairy products, fried foods, and certain seafood.

Summary Table: Macronutrients and Their Properties

Example: Applying Nutrition Principles

For a college student with moderate activity, a balanced daily diet might include whole grain bread (complex carbohydrates), grilled chicken (complete protein), a salad with olive oil (monounsaturated fat), and a serving of fruit (vitamins, fiber, and phytonutrients). Limiting processed snacks and sugary drinks helps maintain nutrient density and manage caloric intake.