Vitamins and Minerals 2

An essential nutrient is a nutrient required for normal body functioning that either cannot be synthesized by the body at all, or cannot be synthesized in amounts adequate for good health (e.g.niacin, choline), and thus must be obtained from a dietary source.

Essential nutrients are also defined by the collective physiological evidence for their importance in the diet, as represented in e.g. US government approved tables for Dietary Reference Intake.^[1]

Some categories of essential nutrients include vitamins, dietary minerals, essential fatty acids, and essential amino acids.

Different species have very different essential nutrients. For example, most mammals synthesize their own ascorbic acid, and it is therefore not considered an essential nutrient for such species. 

It is, however, an essential nutrient for human beings, who require external sources of ascorbic acid (known as Vitamin C in the context of nutrition).

Vitamins and minerals

Main articles: Vitamins and Minerals

Vitamins are materials required for normal metabolism but which the body cannot manufacture itself and which must therefore come from soil. Vitamins come from a number of sources including fresh fruit and vegetables (Vitamin C), carrots, liver (Vitamin A), cereal bran, bread, liver e ( B vitamins), fish liver oil (Vitamin D) and fresh green vegetables (Vitamin K).

Many minerals are also essential in small quantities including iron, calcium, magnesium and 

sulphur; and in very small quantities copper, zinc and selenium. The micronutrients, minerals, and vitamins^[6] in fruit and vegetables may be destroyed or eluted by cooking.

Vitamin C is especially prone to oxidation during cooking and may be completely destroyed by protracted cooking.^[7]