Understanding Macronutrients and Micronutrients

Posted on Mar 8, 2025 in Human Nutrition and Dietetics

Carbohydrates: Importance and Impact

Carbohydrates Importance:

  • Energy Production: Carbohydrates are the primary, most readily available, and most economical source of energy for the body.
  • Macronutrient Sparing Effect: Consuming at least 100g of carbohydrates per day prevents protein catabolism and excessive lipolysis (ketogenesis).
  • Structural Function: Carbohydrates participate in the structure of essential molecules like ATP, DNA, RNA, NADP, CoA, connective tissue, and nerve tissue.
  • Regulation of Bowel Function: Fiber, a non-digestible carbohydrate, is crucial for healthy bowel function.

Problems with Carbohydrate Consumption:

  • Carbohydrate Intolerance: This can be congenital (present from birth) or a consequence of other diseases or intestinal infections, leading to intolerance or malabsorption.
  • Obesity: Excessive energy intake, often from hidden sugars, is a significant risk factor for obesity and related diseases like diabetes and cardiovascular issues.
  • Cardiovascular Disease: While sucrose has a contradictory effect on lipid levels, complex carbohydrates can be beneficial substitutes for saturated fatty acids.
  • Dental Caries: Simple sugars, especially those with high adhesion, contribute to dental caries, with the frequency and duration of consumption playing a key role.
  • Cholelithiasis: Formation of gallstones in the gallbladder.

Lipids: Importance and Recommendations

Lipids: These compounds are insoluble in water but soluble in organic solvents, including triglycerides, phospholipids, and sterols.

A minimum of 3% of total dietary intake should be lipids, increasing to 4.5%-7% during pregnancy and lactation. It’s impossible to live without lipids because they:

  • Provide a concentrated source of energy.
  • Have a plastic function, forming cell membranes and walls.
  • Provide insulation and help maintain body temperature.
  • Serve as a vehicle for fat-soluble vitamins and essential fatty acids.
  • Have a metabolic function, acting as regulators.

Recommendations:

  • Reduce total fat intake to no more than 30% of total calories.
  • Reduce saturated fat intake (found in meat and meat products).
  • Increase the proportion of mono- and polyunsaturated fatty acids (maintain or increase fish consumption).
  • Preferentially use olive oil over seed oils.
  • Do not exceed 300 mg/day of cholesterol.

Vitamins: Types and Functions

Water-Soluble Vitamins: Thiamin (B1), Riboflavin (B2), Niacin (B3), Pantothenic Acid (B5), Pyridoxine (B6), Biotin (B8), Folic Acid (B9), Cyanocobalamin (B12), Ascorbic Acid (C).

Fat-Soluble Vitamins: A, D, E, and K.

Fat-Soluble Vitamins Characteristics

  • Composition: C, H, O.
  • Sources: Provitamins; found in some foods.
  • Physiological Action: Do not form part of organic structures.
  • Absorption: Complex, requires fats.
  • Storage: Stored in fatty deposits in the body. Risk of hypervitaminosis.
  • Excretion: Feces.
  • Stability: Stable during cooking; lost in frying oil.

Water-Soluble Vitamins Characteristics

  • Composition: C, H, O, N, S, Co.
  • Sources: No provitamins; universally distributed.
  • Physiological Action: Act as coenzymes (energy transport).
  • Absorption: Simple, dissolved in water.
  • Storage: Usually not stored, but some reserves exist.
  • Excretion: Urine.
  • Stability: Lost in cooking water.

Food Composition Tables and Nutritional Requirements

Food Composition Tables: These tables list the values of different nutrients in foods, considering the edible portion of each, and organize foods into groups. Ideally, dietary analysis would involve direct biological (physiological) analysis, but these tables are used for analyzing individual foods and performing chemical analysis of proteins, fats, carbohydrates, and mineral salts.

Recommended Intake: National or international guidelines provide estimated nutrient intake levels for maintaining health. These are collective recommendations for population groups, considering various physiological conditions (age, sex, pregnancy, lactation). They are guidelines; malnutrition will not necessarily occur if they are not met. They aim to meet the needs of at least 97-98% of the population, often including a surplus to ensure coverage.

Nutritional Requirements: The amount of each nutrient that *each individual* needs for optimal health. This is an individual characteristic.