5.1 Macronutrients and micronutrients

Macronutrients and micronutrients are the building blocks of a healthy diet. Carbs, proteins, and fats fuel our bodies, while vitamins and minerals support vital functions. Understanding their roles is key to optimizing athletic performance and overall health.

For athletes, getting the right balance of nutrients is crucial. Proper intake of carbs, proteins, and fats can enhance energy, muscle growth, and recovery. Meanwhile, adequate micronutrients ensure optimal bodily functions and can prevent performance-hindering deficiencies.

Macronutrients and their roles

Carbohydrates

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• Primary energy source for the body
• Essential for fueling high-intensity exercise
  • Stored as glycogen in muscles and liver (glucose polymers)
  • Rapidly broken down to provide energy during intense activity (sprinting, weightlifting)
• Recommendations for athletes
  • Consume 5-7 g/kg body weight daily for moderate exercise (1 hour per day)
  • Consume 8-12 g/kg body weight daily for high-volume intense exercise (1-3 hours per day)

Proteins

• Essential for building, repairing, and maintaining muscle tissue
  • Composed of amino acids, which are the building blocks of muscle proteins
  • Adequate protein intake is crucial for muscle recovery and growth (hypertrophy)
• Play a role in enzyme and hormone production, immune function, and fluid balance
  • Enzymes catalyze chemical reactions in the body (digestive enzymes)
  • Hormones regulate various physiological processes (insulin, growth hormone)
  • Antibodies are proteins that help defend against pathogens (immunoglobulins)
  • Proteins help maintain fluid balance by controlling osmotic pressure (albumin)
• Recommendations for athletes
  • Consume 1.2-2.0 g/kg body weight daily, depending on training goals and intensity

Fats

• Provide energy, particularly during low-intensity, long-duration exercise (marathons)
• Support cell membrane structure and aid in the absorption of fat-soluble vitamins
  • Phospholipids and cholesterol are essential components of cell membranes
  • Fats facilitate the absorption of vitamins A, D, E, and K
• Play a role in hormone production and insulation
  • Steroid hormones are derived from cholesterol (testosterone, estrogen)
  • Subcutaneous fat provides insulation and helps regulate body temperature
• Recommendations for athletes
  • Consume 20-35% of total daily energy intake from healthy fat sources (nuts, seeds, avocados, fatty fish)

Functions of essential micronutrients

Vitamins

• Organic compounds essential for normal growth, development, and metabolism
• Classified as water-soluble (B-complex and C) or fat-soluble (A, D, E, and K)
  • Water-soluble vitamins are not stored in the body and must be consumed regularly
    • Involved in energy metabolism (B vitamins as coenzymes)
    • Support red blood cell formation (folate, vitamin B12)
    • Maintain nervous system function (thiamine, niacin)
  • Fat-soluble vitamins are stored in the body and can be toxic in excessive amounts
    • Vitamin A is involved in vision, immune function, and cell differentiation
    • Vitamin D is crucial for bone health and calcium absorption
    • Vitamin E acts as an antioxidant, protecting cells from oxidative damage
    • Vitamin K is essential for blood clotting and bone metabolism

Minerals

• Inorganic elements essential for various bodily functions
• Classified as major minerals (calcium, phosphorus, magnesium) or trace minerals (iron, zinc, selenium)
  • Major minerals are required in larger amounts
    • Calcium and phosphorus are crucial for bone health and muscle contraction
    • Magnesium is involved in energy metabolism and muscle/nerve function
    • Sodium, potassium, and chloride regulate fluid balance and nerve impulses
  • Trace minerals are required in smaller amounts
    • Iron is essential for oxygen transport via hemoglobin and myoglobin
    • Zinc supports immune function, wound healing, and protein synthesis
    • Selenium acts as an antioxidant and supports thyroid function
    • Copper is involved in iron metabolism and collagen synthesis

Recommended daily intake of nutrients

Macronutrient recommendations

• Expressed as a percentage of total daily energy intake
• Acceptable Macronutrient Distribution Ranges (AMDR) for adults
  • Carbohydrates: 45-65% of total energy intake
  • Proteins: 10-35% of total energy intake
  • Fats: 20-35% of total energy intake
• Specific recommendations for athletes based on training goals and intensity
  • Higher carbohydrate intake for endurance athletes (7-10 g/kg body weight)
  • Higher protein intake for strength and power athletes (1.6-2.0 g/kg body weight)

Micronutrient recommendations

• Expressed as Recommended Dietary Allowances (RDAs) or Adequate Intakes (AIs)
  • RDAs: Average daily intake level sufficient to meet nutrient requirements of 97-98% of healthy individuals
  • AIs: Established when insufficient evidence to determine RDA; expected to meet or exceed needs of most individuals
• Specific recommendations vary by age, sex, and life stage (pregnancy, lactation)
  • Example: RDA for vitamin C is 90 mg/day for adult males and 75 mg/day for adult females
  • Example: RDA for iron is 8 mg/day for adult males and 18 mg/day for adult females (due to menstrual losses)
• Athletes may have higher micronutrient requirements due to increased energy expenditure and training demands
  • Example: Iron requirements may be 1.3-1.7 times higher in endurance athletes compared to sedentary individuals

Nutrient deficiencies and athletic performance

Macronutrient deficiencies

• Carbohydrate deficiency
  • Leads to reduced muscle glycogen stores and impaired high-intensity exercise performance
  • Can result in fatigue, decreased endurance, and impaired cognitive function
• Protein deficiency
  • Impairs muscle recovery and repair, leading to reduced muscle mass and strength
  • Compromises immune function, increasing the risk of illness and infection
• Fat deficiency
  • Impairs absorption of fat-soluble vitamins (A, D, E, K)
  • Can lead to hormonal imbalances and reduced energy availability

Micronutrient deficiencies

• Iron deficiency
  • Causes anemia, reducing oxygen delivery to muscles and impairing endurance performance
  • Symptoms include fatigue, weakness, and impaired immune function
• Vitamin D deficiency
  • Impairs muscle function, reduces strength, and increases the risk of injury
  • Affects calcium absorption and bone health, increasing the risk of stress fractures
• Calcium deficiency
  • Impairs bone health and increases the risk of stress fractures and osteoporosis
  • Can lead to impaired muscle contraction and nerve function
• Zinc deficiency
  • Impairs immune function, wound healing, and protein synthesis
  • Can result in loss of appetite, fatigue, and impaired growth and development Preventing nutrient deficiencies through a balanced diet and appropriate supplementation (when necessary) is essential for optimizing athletic performance and overall health.