Nutrients are the life sustaining substances found in food.
- Necessary for growth, maintenance, and repair. 

There are 6 nutrients:
 - Vitamins
 - Minerals
 - Carbs
 - Lipids
 - Proteins
 - Water

A macronutrient is a nutrient the body requires in large quantities, whereas a micronutrient is a nutrient the body requires in small quantities.

| Macronutrients | Micronutrients |
| -------------- | -------------- |
| Carbs          | Vitamins       |
| Lipids         | Minerals       |
| Proteins       |                |

Nutrients are used for:
- Growth and development
- Energy
- Regulation of processes

## Essential Nutrients
A nutrient is classified as essential if:
- It must be supplied by food, because the body cannot create it in sufficient quantities
- If the nutrient is missing, it results in a deficiency disease
- When added back to the diet, the disease corrects
- Explanation exists as to why the abnormalities occurred when the substance was missing.

## Phytochemicals
Phytochemicals are substances in plants that *may* have healthful benefits. Examples of phytochemicals include:
- Caffeine
- Beta-carotene
- Nicotine

## Calories
In nutrition, the term Calorie typically refers to a kilocalorie, or 1000 calories, where a calorie is the amount of energy needed to heat up one gram of water one degree Celsius.

# Definitions
| Term               | Definition                                                                                                                                                                                                    |
| ------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Nutrients          | The life sustaining substances found in food. Necessary for growth, maintenance, and repair.                                                                                                                  |
| Nutrition          | The study of how nutrients affect our body.                                                                                                                                                                   |
| Diet               | A person's usual pattern of food choices. Everyone has a diet, and you don't begin and end diets, you just make changes to your existing diet.                                                                |
| Lipid              | Fat                                                                                                                                                                                                           |
| Organic            | An organic substance contains *carbon*, and can be degraded.                                                                                                                                                  |
| Essential nutrient | A nutrient is considered *essential* if it *must* be supplied by food, because the body cannot create it in sufficient quantities. If an essential nutrient is missing, it results in a *deficiency disease*. |
| Deficiency disease | A deficiency disease occurs when an essential nutrient is missing. Examples include anemia (iron) and scurvy (vitamin c)                                                                                      |