Generally speaking, the nutritional information on an Australian product contains the following components required by AU Law:
I am unsure about the specifics of Australian product labelling laws and what other information is required under what circumstances.
The nutritional information is divided into two major sections:
Nutritional Panel - Details the amount of each component within the product
Ingredients - Details the type of each component within the product
Let's begin with the nutritional panel.
Beginning with sodium, this is a mineral (a micronutrient). An abundant source of sodium is your table salt (sodium chloride). We do require sodium to function...but only in small amounts. There's evidence to suggest that excessive sodium intake over an extended period of time promotes the likelihood of various diseases, particularly cardiovascular disease. Processed foods are commonly high in sodium and this is often best avoided from a health standpoint.
Fat, carbs and proteins are macronutrients. They are all of different chemical structure and perform different tasks within our body. All three are required nutrients for our bodies to function effectively.
Proteins are chains of amino acids - the building blocks of cells. Our body can only manufacture a certain number of amino acids, others have to be obtained through our diet. The long-term health effects of a high protein diet are still inconclusive, but many practitioners believe it could lead to osteoporosis (due to inhibited calcium absorption) and renal disease.
Carbohydrates are required to maintain blood glucose and muscle glycogen levels. We need these for energy and will not function efficiently if our diet is lacking carbohydrates. There are two types - sugars (simple) and complex carbohydrates. All this means is that sugar molecules are shorter in length and complex molecules are longer.
The breakdown of carbohydrates on a nutritional panel means very little. Of more concern is the glycemic index (GI) - how quickly the carbohydrate is utilised by the body. High GI will be absorbed rapidly, whereas a low GI product will be utilised over an extended period of time. High GI is a useful tool for recovery after exercise when your body needs nutrients quickly. However a diet that heavily relies on high GI foods promotes the risk of diabetes, obesity and various other diseases. Unfortunately GI is not currently a requirement under Australian law.
Fats assist the transport of fat-soluble nutrients around the body. There are many different types of fats which makes life a bit confusing. Omega-3 fats are your 'healthy' fats and should be included in your typical diet. Diets high in saturated and trans fats can lead to an whole array of problems later down the track including heart attacks, elevated cholesterol, cancers and aneurysms.
The energy value is a result of your three macronutrients (fat, carbs, protein) along with any other energy containing components (eg. glycerine). This will tell you how many calories/kilojoules are in that product. It is an excellent tool for monitoring your daily caloric intake.
Ingredients is extremely important to determine the quality of the macronutrients within a product. For example, a product with a high percentage of a grain as opposed to a meat will have a low quality protein component. Similarly olive oil is generally a healthier fat-containing ingredient than butter. The ingredients are listed in order of abundance.