Silversurfer
New Member
Hi Weight lose Pilgrims Of recent there has been a lot of talk about nutrition, protien and what foods are good and bad, so with the help of my dietician and with his consent i've cobbled this information below together which might help those struggling to understand the 5 basic food groups and why each has its importance !
No-nonsense nutrition – the basics
You do not need to be an expert on nutrition to manage your weight effectively. However, a little background knowledge is essential if you are to make informed food choices. There are hundreds of books available on the subject of nutrition, but for everyday, practical purposes, most of what you need is here.
There are 5 basic food groups:
1. Proteins
Proteins are required for the maintenance and repair of all body tissues. Major dietary sources of protein are meat, fish, shellfish, eggs, milk, cheese, lentils, peas, beans, nuts, bread and cereal grains.
2. Fats
Three types: saturated, monounsaturated and polyunsaturated.
They all contain the same number of calories and are all composed of fatty acids.
Each fatty acid is made up of a chain of carbon atoms, which are joined to each other by a single or a double chemical bond. The fatty acids can be saturated or unsaturated depending on whether they have one or more than one double bond.
Saturated fatty acids have no double bond in the carbon atom chain
- C – C – C – C – C – C – C – C –
Unsaturated fatty acids can be either mono-unsaturated or poly-unsaturated.
Monounsaturated fatty acids have 1 double bond;
- C = C – C – C – C – C – C – C
Polyunsaturated fats have more than one double bond:
- C = C – C – C – C = C – C – C
The number of bonds in the structure determines the physical properties of the fats. Saturated fats tend to be solid at room temperature, whereas unsaturated fats tend to be liquid. There are about 20 different fatty acids in food and they all have different properties. It is the relative proportion of the different fatty acids in a fat or oil which makes it a solid or liquid, healthy or unhealthy.
Saturated fats
Examples of fats and oils which are saturated are:
Dairy fats - butter, cheese, cream etc.
Meat fats – beef, mutton, pork, lard, dripping, suet etc.
Plant fats – coconut oil, palm oil, sunflower oil.
Processed fats – fats used in industry to make cakes, biscuits, pies, snacks, sausages and some blended vegetable oils and margarines.
Saturated fats are important because they tend to increase blood cholesterol levels and are strongly associated with the development of heart and circulatory diseases.
Monounsaturated fats
The main monounsaturated fatty acid in the diet is oleic acid, the main constituent (more than 70 per cent) of olive oil. Monounsaturated fats – far from increasing the risk of heart attack – actually protect the heart by reducing cholesterol levels and by making the blood less sticky and hence less likely to clot. Major sources are olive oil, canola oil, peanut oil, nuts and margarine. Monounsaturated oils are liquid at room temperature, but start to solidify at refrigerator temperatures.
Polyunsaturated fats (PUFA)
Polyunsaturated fats tend to be a liquid consistency whether at room or refrigerator temperature. There are two large families of polyunsaturated fatty acids (PUFA) in the diet: the Omega 6 and the Omega 3.
Omega 6 fatty acids are found in vegetable sources such as sunflower, corn, safflower and Soya oils and margarines, grape seed oil and sesame seeds.
Omega 3 fatty acids are found in oily fish, such as mackerel, trout, tuna, salmon and pilchards. Studies show that regular consumption of oily fish rich in Omega 3s reduces the risk of a heart attack. Fish consumption may also reduce the risk of sudden cardiac death by protecting against dangerous disturbances in heart rhythm (arrhythmia).
Trans-fats
We saw above that saturated fats have no double bonds in their structure, whereas unsaturated fats may have one (monounsaturates) or more than one (polyunsaturates).
One of the characteristics of saturated fats is that they prolong shelf-life and improve food texture. This is why manufacturers use so much saturated fat in food processing. To prolong the life of unsaturated fats, manufacturers use a process called hydrogenation. In essence, this involves adding hydrogen and converting the double bonds (in mono- and polyunsaturates) into single bonds. In other words, converting unsaturated into saturated fats. This obviously has implications for heart health since saturated fats tend to increase levels of cholesterol in the blood and the risk of heart problems.
Some of the hydrogenated (saturated) fats are of a special type – called trans fats. It turns out that these trans fats have an even more detrimental effect on heart health than ordinary saturated fats. Indeed, recent US research had linked a 2% increase in the energy intake from trans fats to a 23% rise in coronary heart disease rates.
Pick up almost any box of snack foods or prepared products from the supermarket shelf and you will see that partially hydrogenated vegetable oil is one of the ingredients. This should alert you to the fact that trans fats are lurking inside.
limit your intake of trans fats by:
Avoiding hard (stick) margarine, fried foods, cakes, pastries, biscuits and savoury snacks that are often high in trans fats.
Choose soft margarine labelled ‘trans free’.
Avoid food items which have ‘partially hydrogenated vegetable oil’ as a major ingredient on the label i.e. near the top of the list
3. Carbohydrates
Carbohydrates (sugars and starch) are the dietary sources of glucose and come in two main forms, i.e. simple sugars or complex carbohydrates (or starches).
Simple Sugars
Sugars are the simplest form of carbohydrates. Chocolate and confectionery continue to make a large contribution to the national diet, though much of our sugar come “hidden” in things such as tinned soups, sauces, pickles, cereals and pizza. Indeed most processed foods contain some sugar. Simple sugars cause rapid changes in blood sugar levels and also stimulate the release of insulin – the effect of which is to make you feel hungry again, very soon!
It is better to opt for whole grain carbohydrates in the form of starches (see below) which avoid rapid changes in blood sugar and insulin and help to make you feel fuller for longer.
Starch (Complex Carbohydrates)
Refined carbohydrates such as white bread or rice and potatoes tend to cause rapid changes in blood sugar and insulin. Better to choose whole grains such as brown rice and pasta, wholemeal bread, oatmeal biscuits, beans, lentils, sweet potato, etc.
4. Dietary Fibre
Fibre is a special form of carbohydrate which used to be called ‘roughage’. It forms the cell walls of plant foods and is, therefore, the main structural component of all plants, vegetables, fruit, seeds etc. Fibre is the part of out food not digested by the body.
Two basic forms: those that are soluble in water, and those that are not:
Insoluble fibre: required for a normal, smooth and regular bowel movement. It helps to promote the growth of bacteria, and makes a soft bulky stool. Breakfast cereals, whole grain breads (e.g. wholemeal), nuts, brown rice and bran products, are good sources of insoluble fibre.
Soluble fibre: found particularly in oat products, e.g. oatmeal (porridge), oat bran, beans, lentils and peas, apples, citrus fruits, banana and some vegetables. Soluble fibre dissolves in water and forms a gel in the gut, and may help lower levels of blood cholesterol.
5. Vitamins and Minerals
These are sometimes known collectively as micronutrients. There are more than 30 micronutrients essential for health.
Vitamins, minerals and trace elements help your body to use food effectively. They do this by assisting with the absorption and breakdown of various dietary components and also the repair and rebuilding of body tissues. The main micronutrients are shown below.
Vitamins Minerals
Fat-soluble - Calcium
Retinol and carotenoids (Vitamin A) - Chlorine
Calciferols (Vitamin D) - Magnesium
Tocopherols (Vitamin E) - Phosphorous
Phylloquinones (Vitamin K) - Potassium
Sodium
Sulphur
Water-soluble
Thimin (Vitamin B1) - Trace elements
Riboflavin (Vitamin B2) - Chromium
Nicotinic Acid - Copper
Pyridoxine (Vitamin B6) - Fluorine
Cobalamins (Vitamin B12) - Iodine
Folic Acid - Iron
Biotin - Manganese
Ascorbic acid (Vitamin C ) - Molybdenum
Selenium
Zinc
Calorific value of Macronutrients
The calorific value of the three main macronutrients + alcohol is shown below:
Macronutrient Calories/gram
Protein - 4
Carbohydrates - 4
Alcohol - 7
Fats - 9
