Nutrition Overview and Macronutrients

Nutrition Overview

• Nutrition is the study of food and its impact on health, focusing on how nutrients contribute to body growth, development, and maintenance.
• A nutrient is a chemical substance found in food that supports the body.
• Macronutrients - provide energy:
  • Carbohydrates: 4 calories per gram
  • Proteins: 4 calories per gram
  • Fats: 9 calories per gram
• Micronutrients - do not provide energy:
  • Vitamins
  • Minerals
  • Water
• Good nutrition is essential for optimal growth and overall health.

Factors Influencing Nutrient Needs

• Age
• Gender
• Activity Level
• Climate
• Health Status
• Nutritional Status

Carbohydrates

• Primary energy source (4 calories per gram).
• Required for fat oxidation and the synthesis of non-essential amino acids.
• Three main sources: starches, sugars, and cellulose.
• Human body stores carbohydrates as glycogen.
• If dietary carbohydrate intake is insufficient, the body utilizes protein and glycerol to maintain glucose homeostasis.
• Carbohydrates are carbon compounds with numerous hydroxyl groups, containing either an aldehyde or ketone group.

Carbohydrate Functions

• Energy source.
• Contribute to the structure of glycoproteins and glycolipids found in cell membranes and receptors.
• Pentose sugars (ribose and deoxyribose) are components of nucleic acids, free nucleotides (ADP and ATP), and coenzymes (NAD and FAD).

Carbohydrate Classification

• Monosaccharides: Single polyhydroxy aldehyde or ketone unit (e.g., glucose, fructose).
• Disaccharides: Two monosaccharide units linked together (e.g., sucrose).
• Oligosaccharides: 3 to 10 monosaccharide units (e.g., raffinose).
• Polysaccharides: Long chains of monosaccharide units, either straight or branched (e.g., cellulose, glycogen, starch). They are not reducing sugars.

Proteins

• Complex organic nitrogenous compounds (4 calories per gram).
• Composed of monomers called amino acids.
• Contain sulfur, and sometimes phosphorus and iron.
• The human body utilizes approximately 20 different amino acids.
• 8 amino acids are considered "essential" as they cannot be synthesized by the body and must be obtained from dietary sources.
• Protein nutrition status is assessed through serum albumin concentration, which should be above 3.5 g/dl.

Protein Classification

• Animal Proteins: Obtained from animal sources (e.g., eggs, milk, meat, fish). Considered higher quality due to a complete profile of essential amino acids.
• Plant Proteins: Derived from plant sources. Lower quality due to a limited content of one or more essential amino acids.

Amino Acids

• Essential Amino Acids:
  • Histidine
  • Isoleucine
  • Leucine
  • Valine
  • Lysine
  • Methionine
  • Threonine
  • Tryptophan
  • Phenylalanine
• Non-essential Amino Acids:
  • Alanine
  • Aspartate
  • Cysteine
  • Glutamate
  • Proline
  • Glycine
  • Serine
  • Tyrosine
  • Ornithine
  • Arginine
  • Asparagine

Protein Functions

• Provide nitrogen, sulfur, and some vitamins.
• Formation of hemoglobin, enzymes, protein hormones, and antibodies (immunoglobulins).
• Structure of supporting tissues such as bone, cartilage, skin, nails, hair, and muscles.
• Contribute to the blood buffer system.
• Plasma proteins transport hormones, minerals, and lipids (as lipoprotein complexes).

Protein Types

• Simple Proteins: Consist solely of amino acids.
• Conjugated or Complex Proteins: Composed of simple proteins in association with a non-protein prosthetic group (e.g., metal or compound).
• Derived Proteins: Derivatives of proteins resulting from heat, enzymes, or chemical reagents.

Fats (Lipids)

• Large molecules containing carbon, hydrogen, and oxygen (9 calories per gram).

Lipid Classification

• Simple Lipids: Esters of fatty acids with alcohols.
  • Fats: Esters of fatty acids with glycerol (oils are liquid fats).
  • Waxes: Esters of fatty acids with higher molecular weight monohydric alcohols.
• Precursor and Derived Lipids: Substances derived from simple and compound lipids through hydrolysis (e.g., fatty acids, alcohols, mono- and diglycerides, steroids, terpenes, carotenoids).
• Complex Lipids: Esters of fatty acids containing additional groups (e.g., phosphate residue, nitrogen containing bases).
  • Phospholipids: Contain fatty acids, an alcohol, and a phosphate residue (e.g., glycerophospholipids, sphingophospholipids).
  • Glycolipids: Contain a fatty acid, sphingosine, and carbohydrate.
  • Other Complex Lipids: Include sulfolipids and aminolipids; lipoproteins can also be classified here.

Lipid Functions

• Provide energy (stored efficiently as ATP).
• Act as a thermal insulator.
• Support and cushion organs and bones.
• Essential for the absorption of fat-soluble vitamins.
• Cholesterol and phospholipids are crucial for cell membrane structure and function.

Recommended Blood Lipid Levels

• Total cholesterol:
  • (Provide specific recommended levels based on the available information)

This quiz explores the fundamentals of nutrition, including the role of macronutrients and micronutrients in health. It covers factors influencing nutrient needs and the importance of carbohydrates as a primary energy source. Test your knowledge on how nutrition impacts growth and overall well-being.