What do we eat?

We are constantly bombarded with terms and phrases not to mention conflicting reports when trying to understand nutrition. Here we try to explain the basics of the food we eat, broken into six categories detailed below. The first three are known as macronutrients, vitamins and minerals are known as micronutrients the difference being size.

Carbohydrates (CHO)

Energy-yielding nutrients providing an efficient fuel for maintaining the body's energy systems allowing us to move our muscles and general physiology. CHO have sub-categories: 1. Simple = sugars, 2. Complex = Starches and Fibres. Beginning in the mouth, complex CHO is broken into smaller parts then absorbed further down the digestive tract. (The GI diet rightly promotes eating predominantly complex CHO to reduce the speed of the absorption process and minimise the negative effect of fast absorption). Simple CHO are absorbed quickly so should be reduced in the diet due to their high absorption rate. No suprise then that simple sugars are found in high quantities in confectionery, biscuits, cakes and most fast foods. A healthy diet should be high in complex CHO including whole wheat bread and cereals, oat based foods like porridge, quality grains like barley and brown pasta and rice. Careful though, too much CHO in the diet will be converted and stored as adipose tissue (fat)!

. Lipids (fats)

Lipids include triglycerides (fats & oils) which can be saturated or unsaturated (depending on chemical structure), phospholipids & sterols. Triglycerides are the main form of lipid in the diet and stored as adipose tissue when we eat triglyceride rich foods like butter, cream, fatty meats and processed foods. Lipids do have important functions in fuel provision, as starting blocks for important nutrients and other functions, however we all tend to eat too much of them and incorrectly proportioned to other nutrients. Fat is absorbed within the intestinal tract and transported to where its needed or stored. Diets high in saturated fat will do two things: 1. make you store any excess not used for fuel, 2. increase the negative transport of fat in the body increasing ill health. A condition we are all susceptible to is arteriosclerosis (thickening of the arteries) which is accelerated by a high saturated fat diet, smoking, low activity, etc. Reduce saturated fat foods in exchange for unasturated fat foods like oily fish, nuts and seeds. Beneficial lipids include oily fish like mackerel and salmon and leafy vegetables, nuts and grains.

Proteins

Proteins are the building blocks for many body tissues including muscle, bones and teeth, however they do have many other functions such as transport of other molecules and catalysing (facilitating) reactions. Proteins are composed of many smaller units (called amino acids) linked to form chain-like stuctures. Proteins are split into two sub-groups:

1. non-essential amino acids and 2. essential amino acids. The simple difference is that group 1 do not need to be consumed in the diet due to our body's ability to manufacture them, whereas group 2 cannot be made by the body so must therefore be consumed in the diet. Contrary to popular opinion, good quality protein is not only found in foods such as steak, foods such as poultry, fish, milk, eggs, legumes, grains and vegetables also provide adequate protein and in many cases are low in saturated lipids unlike red meat. Too much protein in the diet will be converted and stored as lipid in adipose tissue (fat)!

Vitamins

The vitamins are organic compounds required in the body in minute amounts to perform specific functions such as growth, reproduction and physiology maintenance. Vitamins are individual units unlike the macronutrients, they also differ in the fact that they do not yield energy when broken down. Their function is to assist in reactions, for instance helping the enzymes which break down food to releases energy. The main types are the B-vitamins of which there are 8 and vitamin C. Another important category of vitamins occurs in those which are lipid soluble and those which are water soluble. The former are found in meat, fish, dairy, nuts, seeds and vegetables, they are stored with adipose tissue and therefore they are not needed in the diet so readily. The later are not stored so must be taken through the diet from the five food groups regularly. Most vitamins have a corresponding medical deficiency related illness showing their necessity to health, however these are uncommon in the 1st world. Vitamins are toxic in high doses therefore it is prudent to supplement carefully if at all. In fact, proportionally the micronutients are best consumed from a diet high in fresh, natural fruits and vegetables, diary, fish and meat.

Minerals

These are inorganic elements required in small amounts through the diet for good health. They are split into two further categories, 1. major minerals which are those found in the human body in greater quantities than 5g per 500g and 2. trace minerals, those found at less than 5g per 500g in the body. Both these groups are vital for health. Minerals have important functions in fluid balance, digestion, facilitating reactions, transmission of neural signals, structural and more. Minerals are contained in dairy, fresh fruit, vegetables, legumes, meat and fish. Processed foods generally contain less minerals than fresh, natural types.

Water

As we know water constitutes a large proportion of the human body and is an essential nutrient needed in every body cell to perform a variety of functions including: transport of nutrients and waste products, maintenance of structural properties, important in chemical reactions, lubricates and regulates. Many factors such as environment and activity level influence the amount of water intake needed but generally an average adult needs around 2 litres a day.