Questions and Answers
Which macronutrient yields the most energy per gram?
Micronutrients are required in larger amounts compared to macronutrients.
False
What does the acronym DRI stand for?
Dietary Reference Intakes
The maximum amount of nutrient consumption before it becomes toxic is called the ______.
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Match the dietary terms with their descriptions:
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Which of the following factors could influence food choices?
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Alcohol is considered a nutrient necessary for health.
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What does the Recommended Dietary Allowance (RDA) aim to meet?
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What is the primary function of basal metabolic rate (BMR)?
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In general, males have a higher basal metabolic rate than females.
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Which environmental condition can increase basal metabolic rate?
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The energy required to process food in the typical American diet is approximately ___ of the kilocalories ingested.
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What percentage of daily energy expenditure is attributable to resting metabolic rate in sedentary individuals?
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Match the following factors with their effect on BMR:
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Diet-induced thermogenesis refers to the energy used during exercise.
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What is the estimated BMR for a 70 kg man?
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What is the approximate range of energy expenditure from physical activity for a very sedentary person?
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The thermic effect of food is always included in calculations of daily energy expenditure.
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What does AMDR stand for?
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For lipids, the acceptable caloric intake range is ______%.
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What percentage of daily caloric intake from carbohydrates is recommended?
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Match the macronutrient with its acceptable percentage of caloric intake:
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What are two potential outcomes of malnutrition?
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Engaging in several hours of heavy exercise per day requires about 100% or more of RMR.
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What is one role of vitamin A in the body?
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Vitamin A has no impact on gene expression in target tissues.
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What is released from the liver to transport retinol to peripheral tissues?
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Retinol is oxidized to _________, which binds to specific receptor proteins in the nucleus.
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What is a common symptom of vitamin A deficiency?
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Match the following components of vitamin A absorption and transport:
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Carotenes are not involved in the production of retinol.
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What is the physiological role of retinoids in epithelial tissues?
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What condition is severe vitamin A deficiency most commonly associated with?
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Vitamin A deficiency can lead to keratomalacia, characterized by a normal epithelium.
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What is a potential effect of untreated xerophthalmia?
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Excessive intake of vitamin A can cause a condition known as ______.
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Match the following vitamin A deficiency symptoms with their descriptions:
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All of the following may indicate a deficiency of vitamin A EXCEPT:
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Vitamin A deficiency can potentially cause iron deficiency-like anemia.
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What is one dermatologic problem that can be treated with retinoic acid?
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Study Notes
Classifications of Nutrients
- Macronutrients: Essential substances needed in larger quantities; includes carbohydrates, proteins, lipids, and water.
- Micronutrients: Vital vitamins and minerals required in smaller amounts.
Energy Yielding Nutrients
- Carbohydrates and proteins provide 4 kcal/g.
- Lipids provide 9 kcal/g.
- Alcohol provides 7 kcal/g but is a toxic substance, not classified as a nutrient.
Energy Calculation Example
- Total energy from 10g carbs (40 kcal), 5g protein (20 kcal), and 2g fats (18 kcal) equals 78 kcal.
Factors Influencing Food Choices
- Social Factors: Food availability during events (e.g., weddings), economic constraints, and convenience of fast foods.
- Behavioral Factors: Emotional influences (stress, boredom), religious beliefs, and perceptions of body image.
- Genetics: Influence on dietary preferences and behaviors.
- Personal Preference: Taste preferences (sweet vs salty), upbringing influences, habitual consumption, and overall views on food.
Dietary Reference Intakes (DRI)
- Estimated Average Requirement (EAR): Sufficient intake for half the population.
- Recommended Dietary Allowance (RDA): Covers dietary needs for 98% of the population.
- Adequate Intake (AI): Set when evidence is limited; may eventually become RDAs.
- Tolerable Upper Intake Levels (UL): Maximum daily intake before toxicity occurs, assisting in preventing over-consumption.
Basal Metabolic Rate (BMR)
- Energy required for basic bodily functions (e.g., breathing, circulation).
- Affected by gender, body temperature, environmental temperature, thyroid status, pregnancy/lactation, and age.
- Average BMR estimates: 1,800 kcal for men (70 kg) and 1,300 kcal for women (50 kg).
Diet-Induced Thermogenesis
- Increased metabolic rate post-consumption due to energy demands for digestion, absorption, and storage.
- Energy expended can rise by up to 30% during food processing.
- Typical American diet requires about 10% of caloric intake for thermogenesis.
Physical Activity and Energy Expenditure
- Energy expenditure varies significantly by type and intensity of physical activity.
- Sedentary individuals may expend 30-50% of their BMR, while active individuals may expend 60-100% or more based on activity levels.
Acceptable Macronutrient Distribution Ranges (AMDR)
- Recommended caloric intake: 45-65% from carbohydrates, 20-35% from fats, and 10-35% from proteins.
- Proper macronutrient balance helps prevent chronic diseases and malnutrition (deficiency and excess).
Vitamin A Overview
- Role: Antioxidant with potential cancer prevention and immune support.
- Absorption and Transport: Vitamin A is absorbed in the intestines as retinyl esters, hydrolyzed to retinol, then transported by retinol-binding protein.
Mechanism of Action of Vitamin A
- Retinol converts to retinoic acid, influencing gene expression by interacting with nuclear receptors, affecting protein synthesis in epithelial tissues.
Vitamin A Deficiency Effects
- Night Blindness: Difficulty adapting to darkness and seeing in poor light.
- Xerophthalmia: Severe deficiency leading to corneal damage, dryness, and potential blindness.
- Skin Changes: Dry, rough skin due to excess keratin synthesis.
Severe Vitamin A Deficiencies
- Keratomalacia: Disorder with keratinization of cornea leading to blindness.
- Increased susceptibility to infections and potential iron deficiency anemia.
Vitamin A Toxicity (Hypervitaminosis A)
- Occurs with excessive intake (over 7.5 mg/day).
- Symptoms include dry skin, bone pain, nausea, and enlarged liver and spleen.
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Description
Explore the classifications of nutrients, including macronutrients and micronutrients, and their energy contributions. This quiz also examines factors influencing food choices such as social, behavioral, genetic, and personal preferences. Test your knowledge on the essentials of nutrition!