Human Nutrition and Biochemical Parameters

Human Nutrition & Biochemical Parameters of Nutrition

• This presentation covers human nutrition and the biochemical parameters associated with it.

Science of Nutrition

• The science of nutrition focuses on qualitative and quantitative aspects of diet.
• It also looks at the utilization of dietary components for maintaining health.

Major Components

• Major components for human nutrition include carbohydrates, proteins, lipids, minerals, trace elements, vitamins, and fiber.
• These components are well-defined biochemically.

Essential Nutrients

• Essential nutrients, those not synthesized in the body, are provided through diet.
• Essential amino acids and fatty acids fall under this category.
• Water-soluble and fat-soluble vitamins (A, E, K) are essential. Vitamin D is essential for children but not adults.

Essential Amino Acids

• A table of essential, nonessential, and conditionally essential amino acids is included.
• The conditionally essential amino acids are needed in young people and/or during illness.

Essential Fatty Acids

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

Variation in Nutrient Requirements

• Nutrient needs change based on age, sex, reproductive status, and health conditions (disease, injury, or treatment).

Energy Requirement

• The recommended energy intake, according to WHO, balances energy expenditure, body size, and body composition for optimal long-term health.
• In children and pregnant/lactating women, energy requirements include those associated with tissue development and milk production.
• Energy balance occurs when energy intake equals expenditure plus changes in stored energy.

Basal Metabolic Rate (BMR)

• BMR is the resting energy expenditure.
• It accounts for about 60-70% of daily caloric expenditure.
• BMR considers processes like heart function, cell proliferation, respiration, temperature regulation, circulation, and nutrient processing.
• BMR is influenced by age, weight, height, gender, environmental temperature, diet, and exercise.
• Direct and indirect calorimetry methods are used to determine BMR.

Nitrogen Balance

• Nitrogen balance measures the balance between the intake and excretion of nitrogen, and is an indicator of endogenous energy use.
• A positive nitrogen balance is essential for growth in children and during pregnancy and lactation.

Excessive Nutrients

• Excess nutrients are often stored as fat, potentially leading to obesity.
• When nutrients are insufficient, stored fats and muscle proteins provide energy sources.

Starvation and Hypermetabolic States

• Starvation is a severe caloric deficiency.
• It can cause permanent organ damage and death.
• Starvation involves an imbalance between energy intake and expenditure.
• Hormones and cytokines trigger hypermetabolic situations following injuries or infections.
• In hypermetabolic states, muscle tissue plays a significant role in gluconeogenesis.

Observation of Hypermetabolic States

• Signs of hypermetabolic states include fever, increased basal metabolic rate, increased nutritional needs, 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; contributing 50-60% of total calories.
• Excessive carbohydrate intake can lead to weight gain.
• Insufficient carbohydrate intake can trigger fat mobilization, resulting in ketosis and electrolyte imbalances.
• One gram of carbohydrate provides 4 kcal (1kJ) of energy.

Protein Requirement

• Dietary protein provides amino acids for tissue protein.
• The quality of protein depends on its essential amino acid content.
• Infants, children, and adults have different essential amino acid requirements (43%, 36%, and 10%, respectively).
• Good-quality protein is vital to replace losses due to stress, injury, and conditions like fever.
• Protein restriction may be required in diseases like acute liver failure and end-stage renal disease.

Nitrogen Balance Studies

• Nitrogen balance assesses the use of dietary amino acids and the balance between anabolic and catabolic processes.
• Accurate nitrogen output assessment needs accurate dietary records, plus measurement of fecal and urinary nitrogen levels, including correction factors.
• Urine urea nitrogen (UUN) measures total urinary nitrogen (TUN).

Positive vs. Negative Nitrogen Balance

• Positive nitrogen balance (protein intake > protein loss) is a sign of healthy growth, development, and pregnancy.
• Negative nitrogen balance (protein intake < protein loss) during starvation, cachexia or hypermetabolic conditions necessitates medical intervention for nutritional support.

Protein Synthesis

• Protein synthesis depends on the protein levels in the blood along with patient conditions.

Levels of Proteins

• Short-lived proteins are useful in tracking the responses to nutritional supplementation.
• Prealbumin and RBP levels predict improvements in the patient's nutritional state.

Lipids

• Lipids are the most energy-dense macronutrients, providing 9 kcal/g.
• A typical American diet contains 35-45% calories from fat.
• The American Heart Association recommends reducing fat consumption below 30% of total caloric intake.

Minerals and Trace Elements

• A table of minerals, and trace elements, needed by the human body, is presented.

Fiber

• Fiber, containing plant components, is indigestible.
• Insoluble fiber like cellulose and lignin aids colon health.
• High fiber diets can hamper the bioavailability of certain minerals (calcium, iron, zinc).

Malnutrition

• Malnutrition encompasses deficiencies, excessive intake, and imbalances of nutrients (essential nutrients).
• The prevalence includes undernutrition (wasting, stunting, underweight, micronutrient deficiencies), overweight, and obesity.
• Malnutrition causes many diseases and complications.

Types of Malnutrition

• Protein-energy malnutrition (PEM) derives from insufficient protein and energy.
• Micronutrient deficiencies derive from insufficient vitamins or minerals.
• Obesity originates from taking in more calories than the body needs and leads to fat accumulation.

Protein Malnutrition (Kwashiorkor)

• Kwashiorkor is a severe protein deficiency, typically found in developing countries.
• It affects breast-fed infants when switched to carbohydrate-rich diets, impacting children under 5.

Protein-Energy Malnutrition (Marasmus)

• Marasmus is a severe overall deficiency in both calories and protein.
• It induces signs of starvation (loss of subcutaneous fat and muscle mass), affecting the overall appearance and requiring glucose synthesis from muscle proteins.

Degrees of Protein-Energy Malnutrition

• Protein-energy malnutrition (marasmus) is classified based on BMI (kg/m²).

Undernutrition

• Undernutrition involves insufficient nutrients impacting health but not considered severe PEM.
• It's a leading cause of child mortality in developing countries (50%).

Micronutrient Deficiency

• Micronutrient deficiency arises from insufficient vitamins and minerals.
• It leads to various health impacts, including increased infection severity, blindness, impaired immunity, and stunted intellectual and physical development.

Obesity

• Obesity is defined as a body mass index (BMI) of 30 or higher.
• While protein-calorie malnutrition remains a major issue in developing countries, obesity is increasing in affluent societies worldwide.

BMI

• BMI (body mass index) is a measure of an adult's nutritional status.
• The calculation involves dividing weight in kilograms by the square of height in meters (kg/m²).
• BMI categories include underweight, normal weight, pre-obesity, and different obesity classes.

Therapeutic Nutrition Support

• Nutritional intervention is crucial in PEM, undernourishment, and specific nutrient deficiencies.
• This involves various methods to support malnourished patients, such as enteral feeding and parenteral nutrition.

Enteral Feeding

• Enteral feeding involves introducing nutrients directly into the stomach via tubes.
• Enteral formulas prepared to meet individual needs are preferred to other options, whenever possible.

Parenteral Nutrition

• Parenteral nutrition (PN) is the intravenous delivery of nutrients in cases where oral or enteral routes are not feasible.
• It includes lipid emulsions, glucose, amino acids, electrolytes, and micronutrients to meet nutritional needs.

Biochemical Parameters to Monitor Nutritional Status

• Biochemical parameters are used to monitor nutritional status and guide therapeutic interventions.

General Detection & Monitoring of PEM

• Assessing PEM in hospitalized patients or those who are aging involves using anthropometric measurements, physical evaluations, and laboratory tests to evaluate the nutritional status.

Lab. Tests to Monitor Nutritional Status

• A table lists various tests, such as urine urea nitrogen (UUN), for monitoring nutritional status.

Urinary Urea Nitrogen (UUN)

• UUN (urinary urea nitrogen) helps estimate nitrogen balance based on intake and 24-hour excretion.
• It is used to estimate total urinary nitrogen (TUN) which corresponds to 80-90% of total nitrogen output.