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Carbohydrates

Carbohydrates

Carbohydrates are one of the most important sources of energy for our bodies and are mainly found in plants (fruits, vegetables, grains & legumes) or in foods made from plant sources.

Carbohydrates take two forms namely starches (such as potatoes, cereals, bread, and pasta) and sugars such as table sugar (sucrose), milk sugar (lactose), and fruit sugar (fructose).

When digested, the starches and sugars in carbohydrates are broken down into millions of glucose molecules which are released into the bloodstream. When blood glucose levels rise, your body releases a hormone called insulin, which allows glucose to enter cells. Insulin also plays a key role in fat storage: when insulin levels rise, our cells are forced to burn glucose rather than fat.

Carbohydrates are important as they are:

  • A universal fuel for most organs and tissues in our bodies.
  • The only fuel source for our brain, red blood cells and a growing fetus.
  • The main source of energy for our muscles during strenuous exercise.

Carbohydrates are also used for:

  • structural components of cell walls.
  • genetic material. Sugars form the structural framework of RNA and DNA (ribonucleic acid and deoxyribonucleic acid).
  • giving certain proteins their functionality. For example, glycoproteins, are proteins with carbohydrate attached, which then allow cells to communicate with each other.
  • Adding taste, texture and colour to foods and drinks.  For example, fructose gives fruits their sweet taste and sucrose is commonly used as table sugar in baking.

Carbohydrate-rich foods can be found in every food group.

The Australian Guide to Healthy Eating depicts the 5 core food groups needed in a healthy diet and relative proportions to achieve the optimal balance of nutrients, vitamins and minerals.

 

  • Most Grainy Foods are rich sources of carbohydrates.  This food group includes breads, cereals, rice and pasta.
  • While non-starchy vegetables like green vegetables and salad are low in carbohydrate, starchy vegetables can be rich sources.  Starchy vegetables include potato, sweet potato and corn.
  • Most fruits contain carbohydrates except for limes, lemons, rhubarb & avocado.
  • Dairy foods, like milk and yoghurt contain carbohydrates due to the lactose content.  Cheese is an exception because it contains little to no lactose.
  • Most protein foods are low in carbohydrate. However nuts and legumes like kidney beans and chickpeas, contain carbohydrates.
  • The ‘Sometime foods’ group is not a core food group as these foods are often high in kilojoules, low in nutrition and therefore not required for good health and should therefore be limited.  This group includes cakes, biscuits, takeaway foods, processed meats and alcohol. Many of these foods are high in refined carbohydrates and sugar, which are both sources of carbohydrate.

Carbohydrate recommendations

In Australia, the National Health and Medical Research Council set the recommendations for carbohydrate at between 45-65% of total energy intake.  This aligns with the Institute of Medicine and the World Health Organisation.  This equates to approximately 225 to 325 grams of carbohydrates/day for an 8,700 kJ or 2000 calorie diet.

At the low end of this carbohydrate range, it becomes difficult to meet the recommendations for fibre intake. Alternatively, at the high end of the range, overconsumption of carbohydrates may result in high blood triglyceride levels and low HDL cholesterol levels. Over-consuming carbohydrate may also mean other nutrients are either under-consumed, which can lead to protein, vitamin or mineral deficits, or energy requirements are exceeded, which may lead to weight gain.

The Australian Health Survey.

The Australian Health Survey 2011-13 (AHS)  was conducted to provide a better understanding of the health of people living in Australia. We commissioned further sub-analysis of the survey to examine the dietary glycemic index (GI) and glycemic load (GL) of Australian adults and children. We also investigated what changes occurred in the dietary GI and GL in Australian adults from 1995 to 2012.