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What Do They All Do?
Carbohydrates - are an ideal source of energy for the body. This is because they can be converted more readily into glucose, the form of sugar that's transported and used by the body, than can proteins or fats.
Complex Carbohydrates:
Complex carbohydrates are often referred to as starch or starchy foods. They are found naturally in foods and also refined in processed foods.
Complex carbohydrates as natural starches are found in:
-
Bananas
- Barley
- Beans
- Brown rice
- Chickpeas
- Lentils
- Nuts
- Oats
- Parsnips
- Potatoes
- Root vegetables
- Sweet corn
- Wholegrain cereals
- Wholemeal breads
- Wholemeal cereals
- Wholemeal flour
- Wholemeal pasta
- Yams
Complex carbohydrates as refined starches are found in:
- Biscuits, pastries and cakes
- Pizzas
- Sugary processed breakfast cereals
- White bread
- White flour
- White pasta
- White rice
Simple Carbohydrates:
Simple carbohydrates are also known as sugars. They also exist in either a natural or refined form.
Natural sugars are found in fruit and vegetables.
Refined sugars are found in:
- Biscuits, cakes and pastries
- Chocolate
- Honey and jams
- Jellies
- Brown and white cane sugar
- Pizzas
- Prepared foods and sauces
- Soft drinks
- Sweets and snack bars
Simple carbohydrates (sugar) cause tooth decay.
The difference between complex and simple carbohydrates:
All carbohydrates form glucose when digested. Glucose is transported around the body via blood and taken into cells to be converted into energy.
The pancreas gland in your abdomen secretes the hormone insulin which controls the uptake of glucose by your cells.
If you have any excess glucose, this is converted into glycogen which is stored in the liver or in fat around the body.
When your body needs more energy, a second hormone called glucagon is secreted by the pancreas. This converts the glycogen back into glucose, which is then released into your bloodstream for your cells to use.
This means the body's glucose (sugar) metabolism is a cycle of glucose, insulin and glucagon reactions.
The slower the release of glucose and hormones, the more stable and sustainable the energy levels of the body.
The more refined the carbohydrate, the faster the glucose is released into your blood. This can cause peaks and drops in your blood sugar level, and less stable energy levels in the body.
Complex carbohydrates provide a slower and more sustained release of energy than simple carbohydrates.
In their natural form they contribute to long-term good health, appetite control and sustained energy levels.
Proteins -
Protein is the building block of all life and is essential for the growth of cells and tissue repair.
All proteins are made up of different combinations of 20 compounds called amino acids.
Depending on which amino acids link together, protein molecules form enzymes, hormones, muscles, organs and many other tissues in the body.
There are two types of amino acids:
- Non-essential amino acids can be made by the body
- Essential amino acids cannot be made by the body and must be got from food. There are nine essential amino acids.
Types of Protein:
Animal Protein -
Animal proteins contain all the essential amino acids. This type of protein is found in:
- Meat
- Poultry
- Fish
- Eggs
- Dairy products
Oily fish (salmon, sardines, trout, tuna) is a good source of protein. It has the added advantage of being high in types of fatty acid that provide protection against heart attack and to some extent strokes.
Oily fish contain up to eight times as much omega-3 and omega-6 fatty acids as lean fish (cod, haddock, skate).
Plant Protein:
Plant protein contains many amino acids, but no single source contains all of the essential amino acids. This type of protein is found in:
- Legumes (peas, green beans)
- Cereals
- Beans
- Pulses
- Grains
- Nuts
- Seeds
- Soya products
- Vegetable protein foods such as Quorn or veggie mince.
You need to combine different plant proteins to make up the complete range of amino acids needed by your body. In practice this is achieved without any special effort, for example by eating baked beans with bread (toast) or using milk on cereal.
Plant Versus Animal Proteins:
In terms of healthy eating, you should aim to eat a diet with a higher proportion of plant proteins than animal ones.
Fats:
Some fat is essential in everyone's diet.
Fats provide a source of concentrated energy as well as the fat-soluble vitamins A, D, E and K. Fat transports these vital nutrients around the body.
We also need fat for hormone metabolism, healthy skin and hair, tissue repair, protecting the internal organs and to prevent excessive loss of body heat.
There are two main types of fat: saturated and unsaturated.
Saturated Fat:
Excessive amounts of fat are found in saturated animal fats and trans-fatty acids. These types of fat raise cholesterol levels and increase your risk of many chronic diseases such as heart disease, strokes and certain cancers.
Saturated fats are solid at room temperature and are found mainly in the following animal and dairy products:
- Meat
- Butter
- Cream
- Cheese
- Eggs
- Lard
- Full fat milk
- Suet and dripping
- Full fat yoghurt
Saturated fats are also found in hard margarines that are formed by the 'hydrogenation' of vegetable oils.
Hydrogenation increases the shelf-life of food, but it also creates trans fats (trans-fatty acids) that are harmful for health.
Hydrogenated margarine or butter is often used for making cakes, biscuits and pastry.
Unsaturated Fat:
Unsaturated fats are generally liquid at room temperature.
They come from vegetable sources and are also found in oily fish and in soft margarines labelled 'high in polyunsaturates'.
Unsaturated fats contain essential fatty acids that cannot be manufactured by the body. This means you need to get them from food.
Good sources of unsaturated fats include:
- Avocados (one quarter of an avocado contains 5g of unsaturated fat)
- Unsalted nuts (cashew, brazil, pecan, walnut)
- Seeds (pumpkin, sunflower, sesame).
Omega-3 and omega-6 essential fatty acids play an important role in the functions of the body that promote health and wellbeing.
In particular, studies have shown that omega-3 fatty acids protect against heart disease. Oily fish is the best source of omega-3:
- Salmon
- Tuna
- Trout
- Sardines
- Mackerel
- Pilchards
- Herring
Current advice is to eat oily fish two to three times a week. While oily fish is the best source of essential fatty acids, other omega-rich foods are:
- Corn oil
- Flaxseed oil
- Nut oil
- Safflower oil
- Sunflower oil
- Virgin olive oil
Tips For Healthy Living
We tend to eat a lot of fat, so aim to include some essential fatty acids in your daily diet and reduce yourintake of saturated fats. Below are a few ways to improve your diet.
Swap saturated fat for unsaturated
- Cook with vegetable oil instead of lard, butter or margarine, and use sparingly. Sesame seed oil is a good choice for stir-frying
- Pour warmed virgin olive oil on bread instead of butter or margarine
- Replace the meat in your Sunday roast with salmon or trout
- Dress your salads with virgin or nut oils instead of mayonnaise
- Instead of reaching for crisps or chocolate, try one of these: pumpkin seeds, sunflower seeds, unsalted nuts or raw vegetables.
Get The Most From Your Food
- Check food labels for fat content before you put something in your trolley. It can be surprising how much (and how little) fat some foods contain. Knowing what food contains means you can find a healthier, tasty alternative
- Poach or lightly grill your oily fish to maintain the essential fatty acid content
- Purchase and store your vegetable oils in dark frosted glass bottles. Light and heat can easily destroy the oils' nutrients
Make Healthier Choices
Choose lean meat or poultry and remove the excess fat before cooking. This means the skin on chicken breasts, the rind on bacon, the crackling on pork
- Avoid margarine that contains hydrogenated oil. This will be stated onthe packaging, so check your favourite brand. Margarines made without hydrogenated oil include Clover, Biona and Olivio
- Choose your dairy products carefully. You won't compromise your calcium intake by opting for lower-fat yoghurts and skimmed or semi-skimmed milk
- Keep frying and roasting to a minimum. Better choices are to bake, grill, steam or stir-fry
- Make biscuits, cakes and pastry an occasional treat. They are high in saturated fats and are likely to contain hydrogenated vegetable oil
Remember, as a member of the Science Bus Club you can ‘Ask Albert’ a question about any of the topics. So if you’re not already a member join today!!
