Carbohydrates

Carbohydrates are the body’s preferred fuel. Its primary role is to supply the body’s cells with glucose for energy. Apart from being an excellent source of energy, carbohydrates feed the working body with fibre, vitamins, minerals, protein and water and are mainly found in cereals, grains, fruits, vegetables and milk. Carbohydrates come in two basic forms: complex and simple. Complex carbohydrates are made up of hundreds or thousands of glucose units, linked together in single molecules. Simple carbohydrates, on the other hand, are no more than three units of sugar. Taste is the easiest way to determine which sources of carbohydrates are simple or complex. Simple carbohydrates are sweet, while complex carbohydrates – take a potato for example – are pleasant to the taste buds but not sweet. There are two groups of complex carbohydrates: high fibre and low fibre. The healthiest source of high-fibre carbohydrates are vegetables, with studies showing the intake of such foods lower the risk of hypertension, cancer, arthritis and diabetes. Meanwhile, simple sugars and lower-fibre carbohydrates can pose a health risk if consumed inappropriately. Three types of complex carbohydrates are important in nutrition: glycogen, starch, and the fibres. Glucose plays a central role in carbohydrate metabolism, while starch is the main contributor to the body’s glucose supply. Sugars and starches replenish working muscles after exercise by restoring depleted glycogen levels. If consumed appropriately after exercise, carbohydrates can also accelerate the recovery process. Some people do not, however, satisfy their body’s energy requirements. To keep providing glucose to replenish glycogen stores, a person has to eat dietary carbohydrates frequently, after all, glycogen stores only last for hours, not days. To maintain energy levels at an adequate level, health experts recommend a minimum carbohydrate intake of 100 grams per day. Although it is important to include carbohydrates in your daily diet, it shouldn’t be abused. The result of excessive carbohydrate intake can cause generalised vascular disease. A high-carbohydrate diet causes the pancreas to produce large amounts of insulin, and if the diet is ongoing for many years in a genetically predisposed person, the insulin receptors throughout the body may become resistant to insulin, resulting in chronic hyperglycemia and hypertension.

Protein is the body’s building blocks. From the moment of conception, protein is involved in growing, repairing and replacing of muscle tissue in the human body. For example, to build a bone or a tooth, cells lay a matrix of the protein collagen, filling it with crystals of minerals including calcium, phosphorus and fluoride. Also made of collagen are scars that knit the separated parts of torn tissues together. Protein’s versatility allows it to either facilitate or regulate, while in other instances it becomes part of the structure.

Protein is also the basis the body’s organs, hormones, enzymes and antibodies to fight infection. Excellent sources of protein include meat, fish, poultry, eggs, cheese, milk, vegetables, grains and legumes. Plant proteins are usually preferable to animal proteins – a higher intake of soy and other plant proteins aid in the building of stronger bones, may prevent osteoporosis and help lower blood cholesterol.

Protein can act as an emergency supply of energy in the absence of carbohydrates and fats. However, excessive intake of protein can lead to health risks. In the case of an athlete, a diet high in protein and fat can significantly lower their performance and endurance. Not only must protein intake be looked at, but also the energy intake. If your energy intake is inadequate and you are consuming the RDA for protein, the body will automatically use the protein to meet energy needs rather than to replace and repair muscle cells.

The Recommended Dietary Intake (RDI) for proteins follows:

Excess protein in an individual’s diet will not increase muscle size. Instead, the protein is converted to and stored as fat and can also strain the kidneys which excrete the waste products of protein metabolism. Protein found in animal foods, such as meat, tend to be rich in saturated fats. Therefore, there is a correlation between a high protein diet and heart disease and high cholesterol. The risk of colon and kidney cancer also surface with high meat (red) and high protein foods.

Protein rich-foods are often fat-rich foods, thus contributing to obesity with its accompanying health risks. With this in mind, weight loss gimmicks that encourage high-protein diets are rarely useful, diets providing adequate protein, minimal fat, and sufficient carbohydrates are much better for overweight people.

Sodium is a mineral element mostly found in salt (sodium chloride), and may also be found naturally in very small amounts in water and in plant and animal foods. Sodium helps balance the amount of fluid in our tissues and blood by acting as a sponge, attracting and holding fluids in body tissue. Sodium is also essential for nerve transmission and muscle contraction.

Diets rarely lack sodium, that is why no recommended dietary allowance (RDA) is set, however, there is an 'adequate intake' recommendation for adults of460-920 milligrams per day. Sodium is absorbed into the intestinal tract and travels freely in the blood. The kidneys are responsible for filtering sodium out of the blood, however, the sodium returns to the blood in great precision with the exact amount the body requires. Thirst is a good indicator that sodium levels have risen in the body, signalling to drink until the appropriate sodium-to-water ratio is restored.

It is important to maintain your sodium intake at a healthy level, ideally less than 2300mg (one teaspoon of salt contributes 2000mg sodium) – although many Australians consume twice this amount. Excessive intake of sodium can cause water retention and increase the risk of hypertension. A very high intake of salt can also increase the risk of stomach cancer.
It is estimated that one in three people are salt-sensitive. Assume you are a salt-sensitive person if there is a history of hypertension in your family. Hypertension occurs in people when their kidneys do not flush out the excess sodium, instead retaining the excess sodium (which could result in a daily sodium intake above 3000mg). For this reason, people with hypertension or kidney ailments are usually restricted to as little as 1600mg sodium intake per day. While salt avoidance will prevent hypertension in salt-sensitive individuals, it will not lower blood pressure.

On the other end of the spectrum, too little sodium can cause low blood pressure, known as hypotension, and decrease blood flow to the heart, brain and kidneys – especially during exercise. Vomiting, diarrhoea or heavy sweating can lead to sodium deficiency and both sodium and water must be replenished immediately.

Be wary of finding hidden sodium in foods, largely in processed foods. It is estimated that less than 15 per cent of our sodium intake comes via the salt shaker, 10 per cent from natural salts in fresh foods, with the rest – a staggering 75 per cent – deriving from salt added by the manufacturer. Processed foods do not always taste salty, largely because they may contain sodium with chloride. For example, 1¼-cup serving of corn flakes contains more sodium than 1¼-cup of salted peanuts.

The discovery of the GI Factor or Glycaemic Index of foods has changed the way we view the effects of sugars and complex carbohydrates on blood sugar and health. Carbohydrates are not equal in terms of digestion and absorption and those digested slowly have been found to have some startling health benefits.

Hailed as “the glucose revolution” by the discoverers – Associate Professor Jennie Brand-Miller and Kaye Foster-Powell from the University of Sydney – the GI has changed the way we think about food and health. In their research Foster-Powell and Brand-Miller found it made an enormous difference to the diet and lifestyle of diabetics. They also believe it can help improve general public health by assisting in weight loss and protecting against heart disease.

What is the GI Factor of Foods?
The old way of classifying carbohydrates as either 'simple' or 'complex' is now more intricate and precise. The GI factor is used in the ranking of foods based on their immediate affect on blood sugar levels. Carbohydrate foods, which break down quickly during digestion, have the highest GI factors because blood sugar or glucose increases quickly. Conversely, carbohydrates that break down slowly and release glucose more gradually in the bloodstream have the lowest GI factors.

The Glycaemic Index of glucose is set at 100 and all other foods are ranked on a scale from 0 to 100 according to their affect on blood sugar levels. Scientists have tested the GI values of hundreds of foods and compiled tables for various foods and recipes.

When it comes to food, fat isn’t the ugly word it used to be. There is a lot of good in some fats and once you know the difference, it’s easier to ensure a life of healthy eating – not to mention the occasional guilt-free treat.

• Saturated Fat
Saturated fat is the dietary bad guy. Experts agree that most of us should cut down on the total amount of fat that we eat, particularly saturated fat. This fat is generally found in animal foods including dairy, although it is also contained in coconut and palm oil. Too much saturated fat contributes to health problems like heart disease because it raises the level of LDL or bad cholesterol in your blood.

• Unsaturated Fats
Not all unsaturated fats are good. The main ones are monounsaturated, polyunsaturated and Trans fats.

• MONOUNSATURATED FATS
Found in olive and canola oil, avocados and many types of nut. These fats can reduce the level of LDL or bad cholesterol and thus may help reduce heart disease risk.

• POLYUNSATURATED FATS
Mainly found in plant oils such as sunflower and safflower oils. Oils in margarines are mostly polyunsaturated, and nuts such as peanuts, walnuts and hazelnuts are good sources — as are most fish. Polyunsaturated fats also help lower cholesterol but unlike the monos they reduce both good and bad cholesterol in your blood.

• TRANS FATS
Unsaturated fats are mainly formed when vegetable oils are hydrogenated to make margarines. Trans fats act more like saturated fats in the body and can raise the level of bad cholesterol. Australian margarines generally contain only small amounts of trans fats. Some processed foods maybe made using trans fats – for example biscuits, pastries and cakes.

• THE OMEGA STORY
Omega-3 and Omega-6 fats are polyunsaturated fats that have been found to be beneficial in many areas of human health, including heart disease, inflammatory disease and the development of vision and brain function in babies.

Polyunsaturated margarines and seed-based cooking oils are the major sources of Omega-6 fats in the Australian diet. Other good sources include sunflower, sesame and pumpkin seeds, walnuts and oats. Omega-3s are mainly found in fish and other seafoods, and canola oil. Green leafy vegetables, linseed, soy and walnut oils are moderate sources of omega-3 fats.