Nutrition Basics

What is Nutrition?

Nutrition is the science of how organisms obtain and utilize nutrients from food to support growth, maintenance, repair, and energy for all biological processes. Understanding nutrition helps explain why different foods affect the body differently.

Energy and Calories

Calories represent units of energy provided by food. Different nutrients provide different amounts of energy: proteins and carbohydrates provide 4 calories per gram, while fats provide 9 calories per gram. The human body requires consistent energy for metabolic processes, physical activity, and maintaining body temperature.

Macronutrients in Detail

Proteins

Proteins are composed of amino acids, organic compounds that form the building blocks of tissues, enzymes, hormones, and immune system components. The body requires amino acids continuously for tissue maintenance and repair.

• Complete proteins contain all nine essential amino acids (found in animal products and some plant combinations)
• Incomplete proteins lack one or more essential amino acids (found in individual plant sources)
• Daily protein requirements vary but generally range from 0.8 to 2.2 grams per kilogram of body weight depending on activity level

Carbohydrates

Carbohydrates are the body's preferred energy source, particularly for the brain and muscles during physical activity. They exist in two primary forms: simple carbohydrates (sugars) and complex carbohydrates (starches and fiber).

• Simple carbohydrates provide quick energy but can cause rapid blood sugar fluctuations
• Complex carbohydrates provide sustained energy and include fiber for digestive health
• Fiber aids digestion, supports gut health, and helps maintain stable blood sugar levels

Fats

Fats serve multiple critical functions beyond energy provision. They enable absorption of fat-soluble vitamins (A, D, E, K), support hormone production, maintain cell membranes, and protect organs.

• Saturated fats are solid at room temperature; moderate intake is appropriate
• Unsaturated fats are liquid at room temperature and include beneficial omega-3 and omega-6 fatty acids
• Trans fats should be minimized as they offer no nutritional benefit

Micronutrients Overview

Vitamins and minerals are required in smaller quantities than macronutrients but are essential for virtually every biological process. Deficiency in any micronutrient can impair health and function.

Vitamins

Vitamins are organic compounds produced by plants or animals. The body cannot synthesize most vitamins and must obtain them from food or sunlight exposure.

• Fat-soluble vitamins (A, D, E, K) are stored in body fat and require fat for absorption
• Water-soluble vitamins (B-complex, C) are not stored and must be consumed regularly

Minerals

Minerals are inorganic substances essential for bone structure, nerve function, muscle contraction, fluid balance, and enzyme activity. Major minerals include calcium, phosphorus, potassium, sulfur, sodium, chloride, and magnesium.

Digestion and Nutrient Absorption

The digestive system breaks down food into absorbable components. This process begins in the mouth and continues through the stomach and small intestine, where nutrients cross the intestinal wall into the bloodstream for distribution throughout the body.

Factors Affecting Absorption

• Nutrient interactions: Some nutrients enhance absorption of others (e.g., vitamin C enhances iron absorption)
• Food combination: Pairing foods strategically improves nutrient bioavailability
• Individual digestive health: Gut health and digestive function affect nutrient extraction from food
• Cooking methods: Some nutrients are better absorbed after cooking, while others are preserved better raw

Balanced Nutrition

A balanced diet includes appropriate proportions of macronutrients and sufficient micronutrients to support all bodily functions. While specific proportions vary by individual and context, general guidance emphasizes:

• Varied whole foods over processed alternatives
• Adequate protein, moderate healthy fats, and appropriate carbohydrates
• Abundant vegetables and fruits for micronutrient density
• Consistent hydration with water
• Mindful portion control aligned with individual activity and health goals