RDI - What does it mean?

RDIs indicate the average quantities of key nutrients that children and adults should obtain from their food every day to achieve and maintain long-term health. RDIs are the same in both countries. They are often quoted on food labels; for example, the amount of iron in a typical serving may be shown as a percentage of the RDI for iron.

• RDIs are different for men, women and children, for different age groups and for pregnant and breast­feeding women. Where RDIs apply to an 'average adult', they are meant only as a rough guide to healthy eating.

• Deficiencies resulting from getting too little of a given nutrient, and any adverse effects from getting too much, are also indicated when they are known.

Are they enough?
It's important to remember that the RDIs are recommendations - not requirements - for large groups of people. The levels are those assumed to supply the nutrient needs of most peo­ple, plus a generous margin of safety. Many experts, however, think that current RDIs (especially those for vitamins) are still much too low for maintaining optimal health or for treating certain diseases.

While RDIs vary according to age and sex, the values can't take into account such variables as smoking, alcohol consumption, exposure to pollu­tants and medication use, all of which can interfere with nutrient absorption. Nor do they allow for indi­vidual differences in nutritional needs according to occupation, weight and other factors, such as emotional stress or illness.