Nutrition
It is important to have a varied menu. Ideally, we should eat all sorts of fruits meats and vegetables on a regular basis. That is not always possible, so that we have to try to do as much variation as we can, staying within our limits (financial and geographical)
Vitamins are called micronutrients, because they are needed in very small amounts. From a full meal, you only get fractions of a gram of vitamins. The bulk of the food is composed of carbohydrates, fats, fibre ,minerals and proteins.
Vitamins are usually large and complex molecules. To hold such structure, they often have a metal atom in its center. For instance the vitamin B12 , also called cobalamin, has an atom of cobalt in its center. That is why we also need a variety of minerals, all in very small quantities.
Fibre is a different matter, because it is totally excreted . It's job is only to assist to push the food through the digestive tube. It is composed of cellulose - cell walls(read above) -.
Proteins are found in meat and eggs . Not all vegetables can provide a comparable amount of protein. The leguminosae, like beans, lemtilss, peas,soya etc, are plants that produce a lot of protein. They are the main source of protein used by vegans.
Carbohydrates are formed of hydro –which means water (word root) and carbon.
They include the sugars. Although some people may think that sugar is only the one you put in tea, it is important to know that it is a class of compounds. There are a lot of different sugars and their names always end in -ose. For instance, glucose, fructose, lactose, etc...
Main sources of carbohydrates are potato, pasta, rice,
Fats are found mainly in oils, butter and margarine. Vegetable oils are made of various seeds,like sunflower, peanut, soya ,rape seed, as well as olives.
There are also other fruits that contain a lot of fat, like avocado for instance.
Meat can also contain a lot of fat.