Food Labels and Nutrition Facts

Understanding Food Labels

Food labels provide essential information to help consumers make informed dietary choices. They include details about serving size, calories, macronutrients, micronutrients, and ingredients.

• Calories from Macronutrients: Each macronutrient provides a specific amount of energy per gram:

  • Carbohydrates: 4 kcal/g

  • Proteins: 4 kcal/g

  • Fats: 9 kcal/g

• Low Sodium: For a food to be labeled "low sodium," it must contain 140 mg or less of sodium per serving, as regulated by the FDA. This is particularly important for individuals with high blood pressure.

• % Daily Values (%DV): These are based on a 2,000 kcal diet and help consumers understand the nutrient content in the context of total daily needs.

• High/Rich/Excellent Source: A product is considered "high," "rich in," or an "excellent source" of a nutrient if it contains 20% or more of the Daily Value for that nutrient per serving.

• Reading Food Labels: Pay attention to the number of servings per container and the serving size. Calories are typically listed per serving, not for the entire container.

• Ingredient List: Ingredients are listed in descending order by weight, with the most abundant ingredient first.

Definition of a Calorie

• Calorie: A calorie is a unit of energy that measures the amount of energy food provides to the body.

Vitamins and Minerals

Classification and Functions

• Total Number: There are 13 essential vitamins.

• Fat-Soluble Vitamins: Vitamins A, D, E, and K. These are stored in the body's fatty tissue and liver.

• Water-Soluble Vitamins: Vitamin C and the B vitamins (thiamine, riboflavin, niacin, pantothenic acid, pyridoxine, folate, biotin, cobalamin). These are not stored in large amounts and must be consumed regularly.

Factors Affecting Vitamin Content

• Heat, air, and water can diminish the vitamin content of foods during cooking and storage.

Vitamin Supplementation for Vegetarians

• Vegetarians, especially vegans, may need to supplement Vitamin B12, Vitamin D, and possibly iron and calcium due to limited dietary sources.

Sources and Deficiencies

• Vitamin D Sources: Sunlight, fortified milk, fatty fish, egg yolks.

• Vitamin A Sources: Liver, dairy products, carrots, sweet potatoes, leafy greens.

• Deficiency: A lack of a nutrient that leads to health problems.

• Anemia: Often caused by iron deficiency, but can also result from deficiencies in Vitamin B12 or folate.

• Dental Caries: Caused by a deficiency in fluoride.

• Most Common Nutritional Disorder: Iron deficiency anemia is the most prevalent worldwide.

• Vitamin Toxicity: Fat-soluble vitamins (A, D, E, K) are more likely to cause toxicity because they are stored in the body.

• Most Abundant Mineral: Calcium is the most abundant mineral in the human body.

Electrolytes

• Definition: Minerals that carry an electric charge and help regulate fluid balance.

• Examples: Sodium, potassium, chloride.

Omega-3 Fatty Acids

• Food Sources: Fatty fish (salmon, mackerel), flaxseeds, chia seeds, walnuts.

Bioavailability

• Definition: The proportion of a nutrient that is absorbed and utilized by the body.

• Layman’s terms: How much of a nutrient your body can actually use from what you eat.

MyPlate, Dietary Guidelines, and Nutrient Classification

MyPlate Food Groups

• Fruits

• Vegetables

• Grains

• Protein Foods

• Dairy

• Half of MyPlate should be fruits and vegetables.

• Examples of Protein Foods: Meat, poultry, seafood, eggs, nuts, seeds, soy products.

Classes of Nutrients

• Carbohydrates

• Proteins

• Fats

• Vitamins

• Minerals

• Water

• Energy-Yielding Nutrients: Carbohydrates, proteins, and fats provide calories.

Dietary Guidelines for Americans

• Provide science-based advice for healthy eating.

• Updated every 5 years.

Characteristics of a Healthy Diet

• Balanced, varied, moderate, adequate, and nutrient-dense.

Dietary Reference Intake (DRI)

• Definition: A set of reference values for nutrient intake to be used for planning and assessing diets.

• Minimum DRI for Carbohydrates: 130 grams per day, primarily to support brain function.

Registered Dietitian Nutritionist (RDN)

• A food and nutrition expert who has met academic and professional requirements, including a bachelor's degree and supervised practice.

Sustainability in Nutrition

• Definition: Eating in a way that supports long-term ecological balance.

• Examples: Choosing plant-based foods, local produce, and foods with minimal packaging are more sustainable than heavily processed or resource-intensive foods.

Food Production and Safety

• The majority of corn grown in the US is used for animal feed and industrial products, not direct human consumption.

• Foodborne Illnesses: Caused by bacteria, viruses, parasites, and toxins. The single largest cause in the US is norovirus.

Macronutrients: Carbohydrates, Fats, and Proteins

Carbohydrates

• Preferred Energy Source: Carbohydrates are the body's main source of energy.

• Glucose: The primary sugar used by the body for energy.

• Glycogen: The storage form of glucose in the liver and muscles.

• Added Sugar: Sugars added during processing or preparation. Examples include soda (with added sugar) vs. fruit (without added sugar).

Proteins

• Amino Acids: There are 20 amino acids; 9 are essential (must be obtained from the diet).

• Peptide Bond: The chemical bond that links amino acids together in proteins.

• Denaturation: The process by which proteins lose their structure due to heat, acid, or other factors.

• Risks of Excess Amino Acids: Consuming large amounts of single amino acids can disrupt absorption of others and cause imbalances.

• Protein in Meat: 3 ounces of cooked meat contains about 21 grams of protein.

• Role of Protein: Builds and repairs tissues, makes enzymes and hormones, supports immune function.

• Protein Needs: Recommended Dietary Allowance (RDA) is 0.8 grams per kilogram of body weight per day.

• Calculation:

Fats

• Saturated Fatty Acids: No double bonds; solid at room temperature (e.g., butter).

• Unsaturated Fatty Acids: One or more double bonds; liquid at room temperature (e.g., olive oil). Unsaturated fats are generally healthier.

• Cholesterol: Found only in animal-derived foods (meat, dairy, eggs).

Fiber

• Definition: Indigestible part of plant foods; not absorbed by the body.

• Recommended Intake: 25 grams per day for women, 38 grams per day for men.

Digestion and Anatomy

Overview of Digestion

• Digestion is the process of breaking down food into absorbable components.

• Absorption is the uptake of nutrients into the bloodstream.

• Elimination is the removal of indigestible substances from the body.

Sequence of the GI Tract

• Mouth → Esophagus → Stomach → Small Intestine → Large Intestine → Rectum → Anus

Digestion Details

• Digestion begins in the mouth.

• Most absorption occurs in the small intestine.

• Chemical Digestion: Enzymatic breakdown (e.g., amylase breaking down starch, proteases breaking down proteins).

• Mechanical Digestion: Physical breakdown (e.g., chewing, stomach churning).

• Amylase: An enzyme in saliva that begins starch digestion.

• Peristalsis: Wave-like muscle contractions that move food through the digestive tract.

• Heartburn: Caused by stomach acid entering the esophagus; dietary changes include avoiding spicy, fatty foods, and eating smaller meals.

• Bile: Produced by the liver, stored in the gallbladder; helps digest fats.

• Villi and Microvilli: Finger-like projections in the small intestine that increase surface area for absorption.

Satiety and Satiation

• Satiety: The feeling of fullness after eating; fat has the most dramatic effect on satiety.

• Satiation: The process that causes one to stop eating; carbohydrates pass through the stomach most quickly, leading to shorter satiation.

Diet, Exercise, and Personal Nutrition

Vegetarian Diets

• Vegan: Excludes all animal products.

• Lacto-Ovo Vegetarian: Includes dairy and eggs but excludes meat, poultry, and fish.

Food Safety

• Wash hands for at least 20 seconds to reduce the risk of foodborne illness.

Diabetes

• Type 1 Diabetes: Autoimmune; body does not produce insulin; requires insulin therapy.

• Type 2 Diabetes: Body becomes resistant to insulin; most common type.

Hydration and Exercise

• Water is recommended for most exercise; sports drinks are needed only for prolonged, intense activity.

• Substantial health benefits and reduced chronic disease risk are achieved with at least 150 minutes of moderate-intensity exercise per week.

Energy Balance and Body Composition

• Energy Balance: The relationship between calories consumed and calories expended.

• Gut Microbiome: The community of microorganisms living in the digestive tract, important for health.

• About 70% of Americans are overweight; about 40% are obese.

• Healthy BMI: 18.5–24.9

• Overweight BMI: 25–29.9

• Obese BMI: 30 or higher

• Visceral Fat: Fat stored around the organs in the abdomen; associated with higher health risks.

• Waist Circumference Recommendations: Men: less than 40 inches; Women: less than 35 inches.

• Basal Metabolic Rate (BMR): The energy required for basic body functions at rest; accounts for about 60–70% of daily energy needs.

Food Safety Temperatures

• Temperature Danger Zone: 40°F–140°F (4°C–60°C); bacteria grow rapidly in this range.

• Refrigerator Temperature: At or below 40°F (4°C).

• Freezer Temperature: 0°F (-18°C) or lower.

Tables

Macronutrient Caloric Values

Fat-Soluble vs. Water-Soluble Vitamins

BMI Classification

MyPlate Food Groups

Additional info: Some explanations and examples were expanded for clarity and completeness based on standard academic nutrition knowledge.