There are guidelines on the recommended amounts of vitamins and minerals a person needs every day to maintain a healthy diet. These have changed from RDA (recommended daily allowance) to nutrient reference value (NRV).

NRVs are based on estimates of the daily amount of energy and nutrients needed by different groups of healthy people in the population. They represent the best estimate of the amount of a nutrient that is enough for about 97 per cent of people in a group. The NRV is the total dietary intake from all sources (dietary and supplements). Therefore, someone who is taking a 100 per cent NRV supplement will be consuming more than the NRV if they are also consuming this vitamin or mineral in their food.

It is safe to exceed the NRV of most vitamins and minerals, as long as the safe upper level (SUL) or guidance level (GL) is not exceeded.

The current guidelines in the form of SULs and GLs are under review. SULs and GLs provide a guide to the maximum amount of a nutrient that it is safe to take as a supplement every day for long-term use. In 2003, the Food Standards Agency set SULs (how much can be consumed every day as a supplement without risk to health) for eight vitamins and minerals, and GLs (where there is limited evidence to set a SUL) for a further 23. Often, the SULs are more than the NRVs, but this amount is still safe to take.

Note that SULs refer to the amounts taken in from supplementation or food fortification, not through normal dietary intake.

Always check the SUL/GL if customers are buying more than one product containing the same ingredients.