Last partial update: July 2016 - Please read disclaimer before proceeding.
Dietary nutrient groups
The nutrients in food are divided into two main groups; those present in large amounts, called macronutrients, and those in small amounts, called micronutrients. The macronutrients consist of carbohydrates, fats, fibre and protein, while the micronutrients consist mainly of vitamins and minerals. The table below indicates the energy content and functions in the body of each of these groups. The roles nutrient groups play in causing and preventing illness in Western society are discussed in detail throughout this book. It needs to be emphasized that the majority of Australian diets are not nutrient deficient. In fact, most Australian diets contain too much energy and too much fat. There are, however, a few groups of people who are likely to have micronutrients deficiencies. This issue is discussed in the sections on micronutrients, vegetarian diets, and osteoporosis. The role of antioxidants in disease prevention is also discussed later in this section.
Function and energy content of nutrient groups
|
||||
Nutrient |
Foods sources |
Energy content |
Function / use |
|
cal |
kJ |
|||
Fat - Fatty acids |
Mainly animal sources and vegetable oils. |
9 |
37 |
Mostly stored as fat for later energy use by the body when needed. Also an integral part of cell membranes. |
Fat - Cholesterol |
Lambs brains, liver, eggs and some seafood. |
Synthesis of body compounds including cell membranes and body chemicals, such as steroid hormones. |
||
Alcohol |
Alcoholic beverages |
7 |
29 |
Used for energy. Alcohol is not converted to fat but is metabolized to provide energy before fat and thus reduces the rate of fat breakdown. |
Protein |
Meats, fish, poultry, eggs, milk products, cereals, nuts and legumes, including soy beans, lentils, beans and peas |
4 |
17 |
Mostly used in the synthesis of body components. Only rarely used as an energy source, such as in starvation. |
Carbohydrate - Starches (complex carbohydrates) |
Pasta, potato, breads, cereals, fruit, legumes |
4 |
16 |
Provides energy for the body’s functions and some energy storage. It is usually stored as glycogen in the liver (and the muscle) but may be converted to fat if consumed in excess. (Glycogen is just many glucose molecules joined together.) The sugar that circulates in the blood and provides energy for the body is glucose. The brain relies almost solely on this glucose for energy and thus it is very important for blood glucose levels to be maintained. |
Carbohydrate - Simple sugars (sucrose, glucose, fructose, lactose) |
Fruit, honey and other sweet syrups |
|||
Fibre |
Bread, cereals, vegetables, fruit. |
0 |
0 |
Fibre keeps the bowel functioning normally and has a role in protection of the bowel from cancer causing substances. Soluble fibre can reduce blood cholesterol levels. |
Vitamins and minerals |
A wide variety of foods is needed, especially vegetables, fruit, low-fat dairy and lean meat. |
0 |
0 |
They are essential for the synthesis of many body components, especially enzymes. These nutrients have no significant energy function. Some are also important antioxidants. |
Water |
Fluids, fruit and vegetables |
0 |
0 |
70% of the body is composed of water. |
The major groups listed in the above table (and other nutrition topics) are dealt with in detail in other sections of this web site. (Links to these sections are listed below.)
Major dietary health dilemmas
a. Body energy imbalance and obesity - Australians eat too much
One of the major problems associated with our modern, technologically-based society is that it has dramatically altered our body’s energy balance, unfortunately for the worse. We are doing less physical activity and have less time to prepare nutritious foods, relying instead on prepared food that usually has a high energy content. This combination of using less and consuming more energy means that many people have an energy intake in excess of their needs and this excess energy intake is stored as fat. And excess body fat (i.e. obesity) causes about 7.5% of all illness in Australia.
The contribution made by the different nutrient groups to this energy imbalance varies according to their energy content, with dietary fat being the main culprit. Table 8 shows that fat and alcohol have significantly higher energy content (per unit weight) than carbohydrate and protein. In addition to having a lower energy content, carbohydrates use up more body energy in the processes of being digested, stored (as fat or glycogen in the liver), and released for use in the body than fat does. It is an easy and efficient process for the body to store excess energy from dietary fat as fat in the body. The equivalent of only about 3 per cent of the energy provided by dietary fat is used in its storage as body fat. In contrast, about 25 per cent of the energy contained in the carbohydrate is used up in the process of converting it to stored fat. This is a much less efficient process and means that less fat will be created if excess energy is consumed in the form of dietary carbohydrate rather than dietary fat.
While alcohol is generally not stored as fat, the energy it provides means that less energy from dietary fat or dietary carbohydrate is needed for the body’s immediate energy demands, resulting in more being available for fat storage. Protein is rarely used to supply body energy. Starvation is one such time.
In an optimum diet, carbohydrate, mostly in the form of starch, contributes about 55 to 60 per cent of dietary energy intake and fat about 25 to 30 per cent. The other 15 per cent comes from protein. The contribution from alcohol varies according to consumption. Unfortunately, in modern western diets, the energy contribution from fat is more in the region of 35 per cent and the overall energy intake from all nutrients is excessive.
Reversing this energy imbalance is a major preventative health dilemma facing many Australians. It is dealt with in Part 5, Obesity and Physical Inactivity.
b. Lack of fruit and vegetables
Fruit and vegetables are an important source of many nutrients, including vitamins, minerals and antioxidants.
The recommended daily intake for Australian adults is five servings of vegetables and two servings of fruit and unfortunately few Australians achieve this aim. Lack of fruit and vegetables causes about 2.1% of all illness in Australia, mostly by increasing heart disease. (Two-thirds of this illness occurs in men as they eat less fruit and vegetables and have more heart disease.)
Another important benefit from vegetables is that many have a low energy content and substituting these for high energy foods in main meals can significantly reduce energy consumption and thus weight. For example, substituting potatoes rice and pasta (high energy foods) with carrots, broccoli and peppers will reduce the energy content of a meal without reducing food quantity.
Source – Adapted from Australian Institute of Health and Welfare: Begg, S. et al: 2007. |
c. Consuming too much fat and the wrong type of fat
Australians, in general, consume too much fat in their diet. Fat is an energy dense nutrient and its excessive consumption increases weight / obesity risk.
Australians also consume too much saturated fat. This mostly comes from animal sources of fat, although there are some non-animal sources. (e.g. coconut, hazel nuts) Saturated fat raises blood cholesterol and also causes inflamation in the body, both of which cause illness. The effect that saturated fat has on raising cholesterol has in the past led it to being seen as a cause for cardiovascular disease (heart attaks and strokes). While this is still the view of the National Heart Foundation there is some disagreement as to whether saturated fats do directly cause heart disease. However, there is general agreement in the medical community that the best type of diet for your health is a Mediterranean diet that is relatively low in saturated fat and high in mono-unsaturated fats and poly-unsaturated fats.
Medical authorities also agree that trans-fats are deleterious for your health and should be avoided.
See the section on Fat in the Diet for more information about the types of fat Australians consume.
Suggested food components in a healthy diet
There are many nutritional factors that require consideration in formulating a healthy diet and these will be discussed in the rest of this section. Below is a table summarising what most nutritionists and dietitians would consider a healthy diet.
Recommended food intake for a healthy diet low in fat
|
|
Bread, pasta, potatoes (prepared without fat), grains
|
Meat, fish, chicken, eggs, legumes: Meat must be lean with all visible fat removed and chicken should be skinless.
|
Vegetables
|
Fruit
|
Nuts
|
Milk products
|
Fats and oils
|
Indulgences
|
Fluids
|
Consumer food information
Almost all packaged foods in Australia have a nutrition label. It shows the ingredients and the presence of common food allergens. It also provides information about the nutritional contents, including energy, fat, protein, saturated fat, sugars and sodium. This is expressed as the amount in a usual serving of the product and in 100g of the product.
By looking at the content of total fat, saturated fat, energy and sodium, people will be able to determine whether the food is detrimental or beneficial addition to their diet. Hopefully, where appropriate, many packaged foods will also provide the fibre content and the glycaemic index on their labels to aid in purchasing decisions. With regard to unlabeled foods, food nutritional guides, together with the comments on the fat and energy content of foods in this book, should enable an informed judgement regarding the food’s nutritional value.
An example of a typical nutritional label appears below and, as stated above, the nutrients, such as saturated fat, are shown as two different amounts. Different food items in the same group of foods will often have different serving sizes and the best way to compare nutritional values in similar items, such as butter and margarine, is to look at the quantity of the nutrient in 100g of the product.
The amount of in a typical serving is there to help people calculate how much of the ingredient they will consume when eating a typical serving. The quantity of product in a typical serving is also stated. It is important to recognize that the typical servings quoted are only a guide, as your portion size may vary significantly from this level. (Some manufacturers suggest unrealistic portion sizes to hopefully increase consumption of their product.) People need to weigh the portion on their plate to calculate its energy and fat contents accurately.
Example of an Australian food label
Nutritional information |
||
|
Quantity |
Quantity |
Energy |
608kJ |
405kJ |
Ingredients: Whole milk, concentrated skim milk, sugar, strawberries (9%), gelatine, culture, thickener (1442). |
||
PRODUCT OF AUSTRALIA |
||
Best before 1 APR 10 |
||
Food shopping
There are now well over 15,000 different food items available at a large supermarket store and making choices while ‘strolling the isles’ can be very difficult.
Here is some advice.
- Plan ahead. Planning the week’s meals ahead allows people to go to the supermarket with a list of what they need and means unhealthy food choices can be eliminated before going to the store. It helps to have a range of main meals to choose most meals from, say at least 20, and then perhaps have one or two days a week where something different is tried.
- Try to avoid buying prepared foods when ever possible. Making sauces etc from scratch makes them tastier and is usually not too difficult.
- Do not be tempted by displays and advertising in the store. They are mostly unhealthy foods.
- Avoid buying unhealthy drinks. These include soft drinks and juices with added sugar. (All juices have some sugar and should be had in moderation.) Preferred drinks should be water and low-fat, calcium-enriched milk.
- Avoid buying problem ‘treat’ foods for the pantry. These include confectionary, cakes, biscuits, and most energy / fruit bars. This does not mean no treats. It just means that treats should be just that; something bought (or made at home) occasionally.
- When choosing between similar items, such as brands of tinned tomatoes or margarines, use the product information label to help in making the most nutritious choice. (See above.)
Further information
Nutrition Australia
www.nutritionaustralia.org
A non-government, non-profit, community-based organisation that has offices in all states and territories. It aims to promote the health and well-being of all Australians.
Food Standards Australian & New Zealand (FSANZ)
www.foodstandards.gov.au
Provide current recommendations regarding food standards in Australia. Lots of good information.) Ph 02 - 6271 2222
OzFoodnet
http://www.ozfoodnet.gov.au
A health network designed to enhance the surveillance of food-borne diseases in Australia.
Further information on food allergies
FARE - Food allergy Research and Education
www.foodallergyalliance.org
Australasian Society of Clinical Immunology and Allergy
www.allergy.org.au