NUTRITION BASICS
So what is nutrition all about? Below is an introduction to basic nutrition. This should help you to understand more about what happens to your food in your body.
Food can be divided into MACRONUTRIENTS and MICRONUTRIENTS.
Macronutrients: Carbohydrate, Protein, & Fat (& Alcohol). Provide energy and are the main components of your diet. Click here if you want more information about energy storage.
Micronutrients: Vitamins and minerals are needed in small quantities for your body to function.
Carbohydrates
Foods like bread, rice, pasta and potatoes contain carbohydrates. Essentially the main purpose of these foods is to supply energy; the brain is largely dependent on carbohydrate, glucose specifically, as its energy source.
There are 2 main types of carbohydrates and many foods contain both:
Simple sugars
Glycaemic carbohydrates are easily digested in the small intestine and are quickly transferred to the blood where they travel to the body tissues requiring energy. Although the amount of glucose in your blood is tightly controlled by insulin in most people, if you have type 2 diabetes you may need to limit foods containing simple sugars.
Dietary Fibre
Fibre rich foods are incredibly important as studies show the more fibre you eat the less likely you are to be overweight and the less likely you are to suffer from constipation and, more seriously, bowel cancer. These foods take more effort to be broken down so travel to your large intestine (sometimes trapping some fat on the way). As they are bulky, they make it easier for your intestines to push them through and so make constipation less likely! They also have another function. You’ve heard all about your good bacteria, well they feed on this material and get out that last bit of energy from your food. Everyone has different types of bacteria in their gut, depending on their diet but they are incredibly important. If you don’t eat enough fibre, the good bacteria don’t have enough food and the more harmful bacteria may become dominant causing discomfort and bloating. A healthy gut flora is also incredibly important for your immunity- and some studies suggest may prevent allergies. These bacteria also produce vitamin K & Biotin, which are essential for blood clotting and cell growth.
Protein
Meat, fish, eggs, pulses and grains are good sources of protein, which is required by every cell in the body for growth, maintenance and repair. Protein is made up of chains of amino acids, as body protein is constantly broken down and replaced there must be a constant supply of amino acids. There are 9 essential amino acids which cannot be made by the body so must be provided in your diet. Only meat and eggs contain all of these essential amino acids so vegetarians or vegans may need to be careful they eat a wide enough variety of protein rich foods to ensure they get all of these essential amino acids.
Most foods contain some protein, and commonly in the UK intake is greater than requirement. In periods of growth, such as during childhood or pregnancy more protein is needed but this is rarely a problem in developed countries.
Fat
Fat is essential in your diet. Not only is it the best source of energy (it contains 9 calories per gram, compared to just 4 calories for both carbohydrate and protein) and makes food taste better, the essential fatty acids - omega 3 & 6 are important for skin, growth and hormones.
No doubt you are aware of the health risks of a high fat diet; obesity, cardiovascular disease and increased risk of some cancers to name a few. To confuse matters, you have probably also heard of the importance of omega 3 fish oil for brain development and maybe you have heard of good and bad fats?
Whilst it is important not to eat too much fat, the type of fat you eat is important. It’s all to do with the effect the different types of fats have on your blood-lipid profile (the fat carried in your blood) which in turn affects your risk of cardiovascular disease.
High levels of LDL cholesterol increase the risk of cardiovascular disease. This is because LDL is more likely to deposit fat in the artery walls and cause a blockage, when this travels to your heart it causes a heart attack or to your brain meaning a stroke.
High levels of HDL cholesterol decrease the risk of cardiovascular disease. HDL cholesterol is carried back to the liver and is used to produce bile salts, decreasing the amount of cholesterol in the bloodstream so reducing the risk of anything being deposited in the arteries.
Bad Fats
Saturated fats found in cakes, pastry, chocolate & animal products increase levels of LDL cholesterol (bad) in your blood and therefore increase the risk of having a heart attack or stroke.
Trans fats are even worse, they not only increase levels of LDL but decrease HDL (good). Trans fats are found in deep fat fried foods and are also common in processed baked products as they extend shelf life.
Good Fats
Monounsaturated fats, found in olive oil, nuts and avocadoes increase levels of HDL (as does exercise).
Polyunsaturated fats (the essential fats - omega 3s & omega 6s) are found in fish, cereals, seeds and nuts - lower LDL & HDL. Omega 3 also effects inflammation and blood clotting and therefore reduces the risk of heart attack or stroke.
Micronutrients: Vitamins & Minerals
Both vitamins and minerals are essential and if they are not eaten in adequate amounts, signs of deficiency occur. This also means that if they are taken in excess, symptoms of toxicity may also occur and this can, in some cases, be equally hazardous.
The table below shows the main functions of each vitamin & mineral and gives examples of good food sources.
Vitamin
|
Essential for
|
Found in
|
| Vitamin A | Growth & Tissue development (particularly important for eyesight). Reproduction & immunity. Antioxidant.
|
Liver, dairy products, orange or red fruits and vegetables. |
| Vitamin C | Collagen production for blood vessels, cartilage, muscle & bone. Strengthens resistance to infection. Aids iron absorption & antioxidant.
|
Citrus fruits, orange juice. Fruit juice & vegetables. |
| Vitamin D | Calcium absorption-bones. Muscle & nerve function. |
Can be made in the skin using sunlight. Present in oily fish, fortified margarine.
|
Vitamin E
|
Antioxidant.
|
Polyunsaturated vegetable oils. |
Vitamin K
|
Blood clotting & bone formation.
|
Synthesised by gut bacteria. Liver, leafy green vegetables. |
B Vitamins
|
Energy metabolism.
|
Wholegrain, dairy products. |
Vitamin B12 & Folate
|
New cell production. | Animal products (B12) & leafy green |
Mineral
|
Essential for
|
Found in
|
Iron
|
Carrying oxygen in the blood & muscles.
|
Red meat, legumes & dried fruit. Fortified bread & cereals
|
Calcium |
Mineralisation of bones & teeth. Muscle contraction, nerve impulses and blood clotting.
|
Dairy products, tofu, green vegetables.
|
| Phosphorus | Mineralisation of bones & teeth. Genetic material & energy metabolism.
|
Animal products, cereals, nuts &
|
| Magnesium | Mineralisation of bones & teeth. Protein synthesis.
|
Wholegrains, nuts, legumes. Dark green vegetables.
|
| Potassium | Maintains fluid balance, nerve impulses & muscle
|
Fruit & vegetables.
|
| Sodium | Maintains fluid balance, nerve impulses & muscle contractions.
|
Various foods and salt.
|
| Chloride | Maintains fluid balance, nerve impulses & muscle contractions.
|
Various foods and salt.
|
| Zinc | Enzymes, genetic material, immunity, taste & foetal
|
Red meat & wholegrains.
|
If you want to check you are getting enough of these nutrients, click here for more details of our Services.
