Overview
This lecture covers how to calculate calories in food, the factors influencing food choices, trends in American diets, nutritional genomics, and the importance of seeking credible nutrition information.
Calorie Calculations
- A calorie (kilocalorie) is a measurement of heat and energy in food; for this course, calorie and kilocalorie are used interchangeably.
- Macronutrients provide calories: carbohydrates and protein offer 4 calories per gram, lipids 9, and alcohol 7; vitamins, minerals, and water do not provide energy.
- To calculate total calories: multiply grams of each macronutrient by its respective calories per gram, then sum the values.
- To find the percentage of calories from a nutrient: divide the calories from the nutrient by total meal calories and multiply by 100.
Factors Influencing Food Choices
- The main reason for food choice in the U.S. is taste, followed by nutrient preferences, cost, culture, social reasons, environment, advertising, convenience, time, emotions, habits, knowledge, socioeconomic status, and current trends.
- Environmental factors like living in a food desert impact food availability and choices.
- Advertising, especially to children, heavily promotes high-sugar, high-fat foods.
- Convenience and lack of time drive many food choices, often at the expense of healthiness.
- Eating with others increases food intake by around 40%.
Trends in American Diets
- Americans consume excessive calories and large portions, often high in sodium and added sugars.
- Recommended sodium intake is ≤2300 mg/day, but average intake is 5500 mg/day.
- Added sugars should make up ≤10% of the diet, but often exceed this; average fiber intake (10-12g/day) is much lower than recommended (25-38g/day).
- Many chronic conditions and disabilities in the U.S. have nutritional links, such as osteoporosis and arthritis.
Nutritional Genomics
- Both genetics (nature) and environment/lifestyle (nurture) influence disease risk.
- Nutritional genomics studies the relationship between genes, gene expression, and nutrients.
- Advances in technology may soon allow for personalized diets based on DNA, but current consumer tests are often unreliable.
- Example: variation in the “mother gene” (MTHFR) affects folate processing and may require specific dietary interventions.
Credible Nutrition Information
- There is widespread nutrition misinformation; seek guidance from registered dietitians and credible sources.
Key Terms & Definitions
- Calorie/Kilocalorie — Unit of energy; for this course, both terms mean the same thing.
- Macronutrients — Nutrients required in large amounts: carbohydrates, proteins, and fats.
- Food Desert — An area with limited access to affordable and nutritious food.
- Nutritional Genomics — The study of how genes and nutrients interact to affect health.
- Registered Dietitian (RD) — A qualified health professional who provides reliable nutrition advice.
Action Items / Next Steps
- Practice calorie and percentage calculations using examples from the textbook.
- Watch the embedded video in the first section of the textbook.
- Read about top causes of death and their nutritional links in your textbook.