Human Nutrition and Metabolism Quiz

Human Nutrition & Biochemical Parameters of Nutrition

• Nutrition science focuses on the qualitative and quantitative aspects of diet and the utilization of dietary components for health.
• Major components of human nutrition include carbohydrates, proteins, lipids, minerals, trace elements, vitamins, and fiber.
• Essential nutrients are biochemicals that the body cannot synthesize and must be obtained through diet. Examples include essential amino acids, fatty acids, vitamins A, E, K, and water-soluble vitamins. Vitamin D is essential for children but not adults.

Essential Amino Acids

• A list of essential and conditionally essential amino acids is provided.

Essential Fatty Acids

• Alpha-linolenic acid (ALA) and linoleic acid (LA) are essential fatty acids.

Energy Requirement

• Energy intake should balance energy expenditure, considering age, sex, reproductive status, altered nutritional demands, diseases, injuries, and therapeutic interventions.
• Body size and composition also influence energy requirements.
• In children, and pregnant or lactating women, energy requirements also account for tissue development and milk secretion.
• The body is in energy balance when the metabolizable energy intake equals the sum of energy expenditure and changes in stored energy.

Basal Metabolic Rate (BMR)

• BMR accounts for 60-70% of daily caloric expenditure.
• BMR includes energy used for maintaining basic bodily functions like heart beat, cell proliferation, respiration, temperature maintenance, circulation, and nutrient processing.
• Factors influencing BMR include age, weight, height, gender, environmental temperature, and exercise habits.

Determination of BMR

• BMR can be determined by direct calorimetry (measuring heat generation) or indirect calorimetry (measuring oxygen consumption and carbon dioxide production).

Nitrogen Balance

• Nitrogen balance estimates energy expenditure by measuring nitrogen balance. A positive nitrogen balance is crucial for growth (children and fetuses), pregnancy, lactation, and periods of physiological stress.
• Accurate assessment of nitrogen output requires detailed diet records and measurement of fecal and urinary nitrogen, adjusting for potential correction factors. Urinary urea nitrogen (UUN) is often used to assess total urinary nitrogen (TUN).

Excessive Nutrients

• Excessive nutrients are stored as fat, leading to obesity.
• Insufficient nutrients lead to mobilization of stored fats and muscle proteins for energy.

Starvation

• Starvation is defined as severe caloric energy deficiency needed to maintain human life.
• Prolonged starvation can result in permanent organ damage and death.
• The core cause is the imbalance between energy intake and expenditure.

Starvation vs. Hypermetabolic Status

• Starvation and hypermetabolic states are different but hormonal and cytokine responses can lead to similar physiological effects.
• During starvation, both fat and muscle stores are used for energy. In the hypermetabolic state, muscle proteins play the primary role in gluconeogenesis.

Observations Associated with Hypermetabolic State

• Patients with conditions like trauma, burns, and sepsis often enter a hypermetabolic state within a few weeks after the injury. Signs of the hypermetabolic state includes fever, increased basal metabolic rate, increased nutritional requirements, increased heart rate and cardiac output, negative nitrogen balance, increased hepatic gluconeogenesis, and synthesis of acute-phase proteins.

Carbohydrates

• Carbohydrates are the body's primary energy source, providing 50-60% of calories. - Excessive carbohydrate intake leads to weight gain. - Insufficient intake stimulates fat mobilization, potentially causing ketosis and electrolyte imbalance. - One gram of carbohydrate provides 4 kcal of energy.

Protein Requirement

• Dietary proteins supply amino acids, the building blocks of tissue proteins.
• Essential amino acids must be obtained from diet.
• Protein quality is assessed based on the content of essential amino acids.
• Infants, children ages 10-12 years old, and adults require different percentages of essential amino acids in their diets.
• Protein is crucial for replacing losses during hypermetabolic stress (e.g., fever, burns, trauma) but can be restricted for specific health conditions like acute liver failure or end-stage renal disease.

Biochemical Parameters Used to Monitor Nutritional Status

• Anthropometric measurements (body weight, height, body mass index), physical examination, and laboratory tests (e.g., urine urea nitrogen, plasma albumin and other specific proteins) are used to detect and monitor protein-energy malnutrition and other nutritional deficiencies.

Lipids

• Lipids are a highly energy-dense macronutrient, providing 9 kcal per gram.
• A typical American diet contains 35-45% of calories from fat.
• The American Heart Association recommends reducing fat consumption to less than 30% of total caloric intake.

Minerals

• List of electrolytes and trace minerals required in the diet.

Fiber

• Fiber, composed of undigestible plant components, benefits colonic function.
• High-fiber diets bind divalent minerals, potentially reducing their bioavailability.

Malnutrition

• Deficiencies or excesses in nutrient intake or imbalance of essential nutrients, coupled with diet-related noncommunicable diseases, define malnutrition.
• Malnutrition can take several forms, including wasting, stunting, underweight, and micronutrient deficiencies.

Types of Malnutrition

• Protein-energy malnutrition, or PEM, arises from lack of sufficient protein and calories.
• Micronutrient deficiencies involve insufficient vitamins or minerals.
• Obesity is associated with excessive food intake relative to body needs.

Protein Malnutrition--Kwashiorkor

• Kwashiorkor is a severe protein deficiency, typically in undernourished populations where infants are transitioned to high-carbohydrate diets following breastfeeding.

Protein-Energy Malnutrition—Marasmus

• Marasmus is a severe deficiency in both protein and calories, manifest as wasted appearance, due to the breakdown of muscle proteins to produce glucose.

Degrees of Protein-Energy Malnutrition

• Degrees of protein-energy malnutrition are categorized according to BMI.

Undernutrition

• Undernutrition represents insufficient nutrient intake to meet daily requirements, but less severe than PEM.

Micronutrient Deficiency

• Micronutrient deficiencies can impact various aspects of health, including vision, immune function, and disease severity. Deficiencies can hinder cognitive and physical development.

Obesity

• Obesity is defined as a BMI equal to or greater than 30. It's a growing concern in affluent societies despite widespread protein-calorie malnutrition in developing nations.

BMI

• BMI is a widely used tool to assess nutritional status in adults. It is calculated by dividing weight in kilograms by height in meters squared. Different classifications of BMI reflect levels of underweight, normal weight, pre-obesity, and obesity.

Therapeutic Nutrition Support

• Malnourished patients, suffering from protein-energy malnutrition or nutrient deficiencies, may require therapeutic nutritional intervention for treatment.

Enteral Feeding

• Enteral feeding delivers nutrients directly into the stomach through tubes, often preferable to total parenteral nutrition for maintaining healthy gut function.

Parenteral Nutrition

• Parenteral nutrition consists of intravenous administration of nutrient solutions. This is given to patients unable to obtain necessary nutrients through oral or enteral means.

Laboratory Tests to Monitor Nutritional Status

• A wide array of laboratory tests is available to monitor nutritional status, including urine and plasma measurements for specific proteins, electrolytes, and other nutrients.

Urinary Urea Nitrogen (UUN)

• UUN estimations, when combined with dietary nitrogen intake, can assess nitrogen balance. UUN is also used as an indicator of total urinary nitrogen.

Protein Synthesis

• Interpreting plasma albumin and other protein results needs consideration for patient-specific factors, such as alterations in fluid balance, inflammation, and trauma.

Test your knowledge on essential nutrients, basal metabolic rate (BMR), and their roles in human nutrition. This quiz covers key concepts such as energy requirements, physiological functions, and the effects of starvation. Suitable for students studying health sciences or nutrition.