On the chart, the figure to the left of the food shows the amount of the nutrient that is present in 100 grams of the food. The bar which extends to the left allows comparison at a glance of the nutrient content of the food. The longer the bar, the greater the amount of nutrient in 100 grams of the food. The bar quickly allows you to identify foods that are high or low sources of a given nutrient.

When you know your serving size you can work out your nutrient intake. An average serving of boiled rice, for example, would weigh 160 grams. 100 grams of boiled rice contain 125 kilocalories of energy, so 160 grams would contain (125 ÷ 100) x 160 which is 200 kilocalories. If your serving size is very different from the average size, you will need to take this into account.

While it is interesting to calculate the values of your food intake in order to inform yourself about nutrient values, you will probably find that, as you learn, you will need to do calculations less often. You can look forward then to quick, informal scans, which just con firm what you thought - that spinach does contain lots of nutrients, or that 3 slices of that delicious salami will contain 490 kilocalories or about one quarter of your daily energy allowance.

The amount of nutrient or food component is given as grams, milligrams, micrograms, kilocalories or kilojoules per 100 grams of food. (Some nutrients are only present in very small amounts.)

1 ounce = 28 grams

1 pound = 454 grams

1 milligram = 1/1000 gram

1 microgram = 1/1000 milligram

1 kilojoule = 1/4 kilocalorie

1 kilocalorie = 4.2 kilojoules (approximately 4)

1 millilitre (ml) approximately weighs 1 gram

1 pint = 568 millilitres