Nutrition Basics Chapter 10 Review

• Nutrition: The science of food and dietary supplements, encompassing how the body utilizes these substances to maintain health, support growth, and repair tissues. It involves understanding the biochemical and physiological processes by which nutrients are absorbed and metabolized.

• Essential Nutrients: Approximately 45 nutrients must be obtained from food to sustain health and well-being.

  • Macronutrients: These include proteins, fats, carbohydrates, and water, which are required in large amounts for energy production, structural components, and overall metabolic functions.

  • Micronutrients: Comprising vitamins and minerals, these are needed in smaller quantities but are essential for various metabolic processes, including immune function, bone health, and wound healing.

• Digestion: The complex process of breaking down food into smaller molecules so the body can absorb essential nutrients effectively. It involves mechanical and chemical processes, starting in the mouth, continuing in the stomach, and culminating in nutrient absorption in the intestine.

Energy and Nutrient Density

• Energy Measurement: Measured in kilocalories (kcal), commonly referred to as calories.

  • Definition: One kilocalorie is defined as the energy needed to raise the temperature of one liter of water by 1°C, serving as a standard measure of energy content in food.

• Sources of Energy:

  • Fat: Provides 9 kcal/gram, functioning as the most concentrated source of energy, critical for energy reserves and metabolic processes.

  • Protein: Provides 4 kcal/gram, serving as a building block for muscles and tissues and playing a role in numerous enzymatic reactions.

  • Carbohydrates: Also provides 4 kcal/gram; they are the body's primary source of energy, particularly for the brain and during high-intensity physical activities.

• Nutrient Density: Describes the ratio of a food’s essential nutrients to its calorie content; a higher nutrient density indicates a more healthful choice, promoting overall health and reducing the risk of chronic diseases.

Digestive System Overview

• Digestion Process:

  • Food is physically broken down by chewing and is mixed with saliva, which contains enzymes that initiate carbohydrate digestion.

  • The bolus then travels through the esophagus to the stomach, where it is subjected to gastric acids and enzymes, further breaking it down into a semi-liquid form called chyme.

  • Nutrient absorption predominantly occurs in the small intestine, where villi increase the surface area, allowing for efficient absorption of nutrients into the bloodstream.

  • The large intestine is responsible for the reabsorption of water and electrolytes, converting liquid chyme into solid waste for excretion, while also hosting beneficial bacteria that play a role in fermentation and vitamin synthesis.

Protein: The Basis of Body Structure

• Role: Proteins are a major component of muscle, bone, blood, hormones, and enzymes, essential for the structure, function, and regulation of the body's cells, tissues, and organs. They are crucial in repair processes and immune responses.

• Amino Acids:

  • The human body utilizes 20 common amino acids, categorized into 9 essential amino acids (which must be obtained from dietary sources) and 11 nonessential amino acids (which can be synthesized by the body).

• Complete Proteins: These proteins, mainly derived from animal sources, contain all nine essential amino acids necessary for human health. Examples include meat, fish, dairy products, and eggs.

• Recommended Intake: It is generally advised to consume 0.8g of protein per kilogram of body weight, with the Acceptable Macronutrient Distribution Range (AMDR) suggesting that protein should constitute 10–35% of total daily calorie intake to support bodily functions effectively.

Fat: An Essential Nutrient

• Fats (Lipids): These are the most concentrated energy source available, providing 9 kcal/gram and are vital for various bodily functions, including insulation, energy storage, protecting vital organs, and fueling low-intensity activities.

• Functions: In addition to energy provision, fats aid in the absorption of fat-soluble vitamins (A, D, E, K) and play a crucial role in hormone production and cellular membrane structure.

• Types of Fats:

  • Saturated Fats: Typically found in high amounts in animal fats (e.g., red meat, butter) and certain plant oils (e.g., coconut oil), these fats are solid at room temperature and can influence cardiovascular health if consumed in excess.

  • Unsaturated Fats: Including monounsaturated (found in olive oil and avocados) and polyunsaturated fats (found in fish and walnuts), these are considered healthier fats that can improve cholesterol levels.

• Trans Fats:

  • Created by hydrogenation, trans fats are artificially produced and are linked to increased levels of low-density lipoprotein (LDL) cholesterol, raising cardiovascular disease risk.

  • In 2015, the FDA banned artificial trans fats from processed foods due to their detrimental health effects.

• Recommended Fat Intake: Dietary guidelines recommend that fats should comprise 20–35% of total daily calories, with saturated fat intake limited to less than 10% to minimize health risks.

Carbohydrates: Significant Energy Source

• Types:

  • Simple Carbohydrates: Comprising monosaccharides (such as glucose and fructose) and disaccharides (like sucrose and lactose), these sugars provide quick energy but can lead to rapid spikes in blood sugar levels.

  • Complex Carbohydrates: These include starches and fiber, providing sustained energy and more nutritional value, as they contain vitamins and minerals along with fiber.

• Digestion: Carbohydrates are eventually broken down into glucose, which is then utilized by the body for energy or stored as glycogen in the liver and muscles for later use.

• Recommended Intake: It is recommended to consume a minimum of 130g of carbohydrates daily, with the AMDR suggesting they should account for 45–65% of total daily calories.

Fiber: Health Benefits

• Types:

  • Dietary Fiber: Naturally found in plant foods, it aids digestive health by promoting regular bowel movements and preventing constipation.

  • Functional Fiber: This includes isolated or synthesized fibers added to foods for beneficial health effects, such as inulin and psyllium.

• Health Benefits: Dietary fiber has been shown to reduce the risk for type 2 diabetes, heart disease, and obesity, while also promoting digestive health and enhancing satiety.

• Recommended Intake: The suggested daily fiber intake is 38g for men and 25g for women, with an emphasis on obtaining fiber from whole and minimally processed foods for optimal health benefits.

Vitamins: Organic Micronutrients

• Types:

  • Fat-Soluble Vitamins: Included are vitamins A, D, E, and K, which can be stored in the body’s fatty tissues and liver, making regular intake important for long-term health.

  • Water-Soluble Vitamins: Comprising vitamin C and B-complex (including B1, B2, B3, B6, B12, and folate), these vitamins need to be consumed regularly as they are not stored in large quantities in the body.

• Functions: Vitamins are critical for energy release, red blood cell production, nerve function, and maintaining healthy skin and mental health. They play roles in various metabolic pathways and support immune function.

• Sources: These micronutrients are primarily derived from fruits, vegetables, whole grains, and lean proteins, highlighting the importance of a varied and balanced diet.

Minerals: Inorganic Micronutrients

• Categories:

  • Major Minerals: Essential minerals needed in larger amounts include calcium, potassium, and magnesium, playing vital roles in bone health, fluid balance, and muscle function.

  • Trace Minerals: Required in minute amounts are iron, zinc, and selenium, crucial for enzyme functions and other biochemical processes in the body.

• Functions: Minerals support growth, maintenance of body tissues, and the release of energy from food. They are involved in numerous physiological functions, including nerve transmission, muscle contraction, and hormone regulation.

Water: Essential for Life

• Function: Water constitutes 50-60% of body weight and is essential for various physiological functions including digestion, nutrient transportation, regulating body temperature, and serving as a solvent in biochemical reactions.

• Recommended Intake: Daily water recommendations are approximately 3.7 liters for men and 2.7 liters for women, varying based on activity level, climate, and health conditions.

Dietary Guidelines and Nutrition Planning

• Tools:

  • Dietary Reference Intakes (DRIs): They provide guidance on the appropriate levels of intake for essential nutrients to prevent deficiencies and promote optimal health.

  • Dietary Guidelines for Americans: These offer science-based recommendations for nutritional needs and healthy living practices to encourage overall wellness and disease prevention.

  • MyPlate: A visual guide designed to help individuals create balanced meals based on different food groups, promoting the inclusion of a variety of foods.

MyPlate Guidance

• Emphasizes Portioning Food Groups:

  • Fruits: 2 cups/day

  • Vegetables: 2.5 cups/day

  • Grains: 6 ounces/day (with half as whole grains to increase fiber intake)

  • Proteins: 5.5 ounces/day (including a variety of protein sources)

  • Dairy: 3 cups/day (preferably low-fat or fat-free options)

Food Safety and Nutrition Labels

• Foodborne Illness Prevention: Focus on cleanliness in food preparation, understanding cross-contamination, separating raw and cooked foods, cooking to safe internal temperatures, and promptly chilling perishable items to reduce the risk of foodborne illnesses.

• Understanding Food Labels: Familiarity with serving sizes, daily values, and ingredient lists empowers consumers to make healthier food choices and supports overall nutritional goals.