A.2.2.2 Micronutrients and their role in energy transfer and tissue synthesis (HL) Notes

Micronutrients and their Roles

1. Unlike macronutrients (such as proteins, fats, and carbohydrates), micronutrients do not provide energy (calories) but are crucial for numerous metabolic processes.
2. Micronutrients are required in small amounts. Despite being needed in smaller quantities, they are vital for good health.
3. These nutrients facilitate critical functions such as immune defense, cell function, and energy metabolism.

Types of Micronutrients

Micronutrients can be broadly categorized into two main groups:

Vitamins

1. Fat-soluble vitamins: These are stored in the body's fat and liver. Examples include vitamins A, D, E, and K.
2. Water-soluble vitamins: These are not stored in the body and are excreted in urine. Examples include vitamin C and the B-vitamins (B1, B2, B3, B6, B12, folate, etc.).

Minerals

1. Major minerals: Required in larger amounts, including calcium, phosphorus, magnesium, sodium, potassium, and chloride.
2. Trace minerals: Required in smaller amounts but still crucial for health, including iron, zinc, copper, iodine, and selenium.

General Functions of Micronutrients

Facilitate Energy Transfer

1. Micronutrients, particularly B vitamins, are essential for converting food into usable energy.
2. They act as coenzymes in metabolic pathways such as glycolysis, the citric acid cycle, and oxidative phosphorylation.

Support Tissue Synthesis and Maintenance

1. Vitamins like Vitamin A and C, as well as minerals such as calcium, are involved in tissue growth and repair.
2. Vitamin A is essential for maintaining the health of epithelial tissues (e.g., skin, mucous membranes), and Vitamin C is needed for collagen synthesis, aiding in the repair of tissues after injury.

Maintain Bodily Functions

Micronutrients regulate various body functions, including immune response, bone health, blood clotting, and fluid balance.

Key Micronutrients and Their Roles

Iron

1. Iron is a crucial mineral involved in the transport of oxygen throughout the body. It is a key component of hemoglobin, a protein found in red blood cells, and myoglobin, a protein in muscle cells.
2. Iron binds to oxygen in the lungs, allowing hemoglobin to transport it to tissues, and myoglobin stores oxygen in muscles, releasing it during physical activity.

Iron in Hemoglobin and Myoglobin

1. Iron binds to oxygen in hemoglobin, forming oxyhemoglobin, and releases it at tissues where oxygen is needed.
2. In muscles, myoglobin also binds to oxygen and releases it during intense exercise.
   1. Hemoglobin: Carries oxygen to body tissues and returns carbon dioxide to the lungs.
   2. Myoglobin: Provides a reserve of oxygen for muscle contractions.

Calcium

Role in Bone and Connective Tissue

1. Calcium is a major mineral component of bones and teeth.
2. It plays a vital role in bone formation and maintenance, providing structural strength.
3. Calcium is continuously deposited and withdrawn from bones to maintain bone density.
4. Calcium contributes to the rigidity and strength of bones and teeth.
5. It also helps in maintaining bone density, reducing the risk of fractures.

Muscle Contraction

1. Calcium is involved in muscle contraction.
2. It is released from the sarcoplasmic reticulum in muscle cells when a nerve impulse triggers a contraction.
3. Calcium ions bind to proteins on the actin filaments in muscles, facilitating the sliding of actin and myosin, which leads to muscle contraction.
   1. Skeletal Muscle Contraction: Calcium enables the actin-myosin cross-bridge to form, allowing muscle fibers to contract and perform movements.
   2. Cardiac and Smooth Muscle: Calcium also helps regulate contraction in cardiac and smooth muscles, supporting heartbeat and digestive functions.

Other Functions

1. Calcium also plays a role in nerve impulse transmission, enzyme activation, and regulating the permeability of cell membranes.
2. It is integral in maintaining proper cellular function.

Deficiency Impact

1. A lack of calcium can result in conditions such as osteoporosis, characterized by weak, brittle bones that are more prone to fractures.
2. It may also cause muscle cramps, nervous system dysfunction, and impaired muscle contractions.

Sodium

1. Sodium is predominantly found in extracellular fluid and is crucial for regulating blood pressure, nutrient absorption, and maintaining the balance of fluids in and out of cells.
2. It is also involved in nerve transmission and muscle function.
   1. Water Balance: Sodium helps retain water in the body and maintain normal blood pressure.
   2. Nerve Function: Sodium ions play a critical role in transmitting nerve impulses.

Potassium

1. Potassium is mainly located in intracellular fluid and works in balance with sodium to maintain proper nerve and muscle function.
2. It helps regulate fluid balance and is essential for muscle contraction and maintaining the electrical potential across cell membranes.
   1. Muscle Function: Potassium helps muscles contract, and it plays a role in maintaining normal heart rhythms.
   2. Electrical Potential: Potassium helps regulate the electrical charge across cell membranes, which is crucial for nerve signaling and muscle contractions.

Chloride

1. Chloride works alongside sodium to maintain fluid balance and plays a role in regulating the pH of the blood.
2. It also supports nerve function, similar to sodium and potassium.

Vitamins and Their Role in Metabolism

1. Vitamins are essential organic compounds that the body requires in small quantities to support a variety of functions, including tissue synthesis, growth, immune function, and energy metabolism.
2. Unlike macronutrients (carbohydrates, proteins, and fats), vitamins do not provide energy directly, but they are crucial for enabling biochemical reactions that facilitate the utilization of energy from food.

Water-Soluble Vitamins

1. Water-soluble vitamins dissolve easily in water and are not stored in the body, meaning they must be consumed regularly in the diet.
2. These vitamins are absorbed directly into the bloodstream during digestion and are excreted in the urine when in excess.
3. Because the body does not store these vitamins, toxicity is rare.
4. However, large doses can still lead to discomfort (e.g., gastrointestinal issues) or interfere with other metabolic processes.

Examples of Water-Soluble Vitamins:

1. Vitamin C: Involved in collagen synthesis (important for skin, blood vessels, and connective tissues), acts as an antioxidant, and enhances iron absorption.
2. B Vitamins: A group of vitamins, including B1 (thiamine), B2 (riboflavin), B3 (niacin), B6 (pyridoxine), B9 (folate), B12 (cobalamin), and pantothenic acid, which all have varying roles in metabolism, including converting food to energy, nerve function, and red blood cell production.

Fat-Soluble Vitamins

1. Fat-soluble vitamins dissolve in fat and are stored in adipose tissue and the liver.
2. Because they are stored, excessive intake over time can lead to toxicity.
3. These vitamins are absorbed along with dietary fat in the intestines and transported through the lymphatic system before entering the bloodstream.

Examples of Fat-Soluble Vitamins

1. Vitamin A: Necessary for maintaining healthy vision, immune function, and skin integrity. It also plays a critical role in cellular differentiation and reproduction.
2. Vitamin D: Regulates calcium and phosphorus levels in the blood, facilitating bone mineralization and immune function.
3. Vitamin E: Acts as a potent antioxidant, protecting cells from oxidative damage and supporting immune function.
4. Vitamin K: Vital for blood clotting and bone health, as it activates proteins that help in coagulation and bone mineralization.

Balanced Diet

1. A balanced diet is essential for maintaining optimal health, supporting growth, and promoting recovery and performance.
2. It consists of various food components, each serving a distinct role in the body's function.
3. A well-balanced diet provides all the essential nutrients, maintaining the correct proportions to support bodily processes and fuel performance.

Dietary Guidelines and Nutrient Intake Recommendations

1. Dietary guidelines are structured recommendations based on scientific research, often formulated by health organizations to promote general health and reduce the risk of chronic diseases.
2. They give clear advice on the proper quantities of food and nutrients necessary to maintain optimal health.
3. Recommended Nutrient Intake (RNI): These levels guide how much of each nutrient is needed for the body to function optimally. They vary for different populations based on factors like age, gender, activity levels, and health status

Cultural and Religious Dietary Influence

1. Cultural and religious practices significantly impact dietary choices, leading to variations in the types of food consumed.
2. These factors must be taken into consideration when planning nutrition for diverse populations.
3. Some cultural practices, such as vegetarianism or veganism, can offer health benefits but require careful planning to ensure adequate intake of all essential nutrients.

Factors Influencing Nutritional Needs

Age

1. The nutrient needs of children, adolescents, adults, and elderly individuals differ as their growth, development, and metabolism rates change.
2. For instance, adolescents require more protein and energy for growth, while older adults may need more calcium and vitamin D to maintain bone health.

Sex

Males and females have different nutritional needs, with women requiring more iron during menstruation and pregnancy, while men may require higher amounts of certain nutrients like zinc.

Physical Activity Level

1. Athletes and physically active individuals need higher energy intake, particularly carbohydrates, for fuel during exercise.
2. Active individuals may also require more protein for muscle repair and growth.

Pregnancy and Lactation

1. Nutritional requirements increase during pregnancy and breastfeeding to support fetal development and milk production.
2. This includes increased intake of calories, protein, iron, calcium, and folic acid.

Energy Needs and Macronutrient Distribution

1. Energy needs are based on the amount of energy the body requires to perform essential functions and physical activity.
2. These needs can be measured in kilocalories (kcal) and are determined by factors such as basal metabolic rate (BMR), activity level, and overall health.
3. The three macronutrients, carbohydrates, proteins, and fats play specific roles in providing energy and supporting bodily functions.

1. Carbohydrates (55–75% of total energy):

1. The primary source of energy, especially during exercise.
2. Carbs are stored in muscles and the liver as glycogen and are the body’s main fuel source during physical activity.

2. Proteins (10–15% of total energy)

1. Essential for tissue growth, muscle repair, and the production of enzymes and hormones.
2. They are also used for energy when carbohydrate stores are low.

3. Fats (15–30% of total energy)

Provide a concentrated source of energy and are crucial for cellular structure, hormone regulation, and fat-soluble vitamin absorption.

International Dietary Guidelines

1. Different countries offer guidelines on the optimal intake of nutrients to promote health.
2. These international recommendations, provided by organizations like the World Health Organization (WHO) or national health bodies, ensure that dietary patterns across the world help reduce the prevalence of lifestyle diseases like obesity, heart disease, and diabetes.
3. The WHO recommends that fat intake should make up no more than 30% of total energy intake to prevent chronic diseases.
4. The USDA’s MyPlate emphasizes balancing food groups, encouraging consumption of vegetables, fruits, grains, and proteins.

WHO/FAO Recommendations

1. Total Fat: 15-30% of total energy intake
2. Saturated Fat: Less than 10% of total energy intake
3. Carbohydrates: 55-75% of total energy intake
4. Protein: 10-15% of total energy intake
5. Sodium (Salt): Less than 5g per day
6. Fruits and Vegetables: At least 400g per day for optimal health

The Role of Nutritional Ergogenic Aids

1. Nutritional supplements are widely used in sports to enhance performance and recovery.
2. While some are backed by scientific evidence, others lack proven benefits.

The most commonly used performance-enhancing supplements include:

Caffeine

1. Acts as a central nervous system stimulant, reducing perceived exertion and enhancing endurance and strength performance.
2. Recommended Dose: 2–6 mg/kg body mass before or during exercise.
3. Benefits: Improved endurance, increased force production.
4. Potential Side Effects: Insomnia, anxiety, mild diuretic effects.

Creatine

1. Increases muscle creatine phosphate stores, improving short-duration, high-intensity exercise performance.
2. Recommended Dose: 15–20 g/day for 4–7 days (loading phase), followed by 2 g/day maintenance.
3. Benefits: Enhanced power output, increased muscle mass.
4. Potential Side Effects: Weight gain due to water retention.

Bicarbonate

1. Acts as a buffer to reduce muscle acidity, delaying fatigue in high-intensity activities.
2. Recommended Dose: 0.3 g/kg before exercise.
3. Benefits: Improved tolerance to anaerobic exercise.
4. Potential Side Effects: Gastrointestinal discomfort.

While supplements can provide performance benefits, they should be used alongside a well-balanced diet and proper training.