It looks so pure, white and harmless next to the pepper pot on your dining table but do you realise the dangers that lurk in your salt cellar?

While we are often urged to cut down on alcohol and fatty foods because of the harm they cause to our health, we hear less often about another killer in our kitchen - humble sodium chloride.

Too much salt in your diet can lead to high blood pressure, heart disease and narrowed arteries it has also been linked to osteoporosis, stomach cancer, fluid retention, asthma and the ear disease menieres.

The Foods Standards Agency (FSA) has launched a campaign urging us to cut down on the white stuff with a reminder that the recommended daily allowance (RDA) is six grammes - about a teaspoonful. On average, women consume 8.1g a day and men 11g.

We sprinkle it on our meals and add it to the pan as we cook. Chips wouldn't seem the same without it.

But the real danger is there's a huge amount of salt already hidden in our foods.

Consensus Action on Salt and Health (CASH) examined 3,000 foods and found in some cases there was up to a 30-fold difference between the most salty and least salty foods.

Three-quarters of the salt we eat comes from processed food such as cereals, crisps, bread, biscuits and sauces.

So, even if you think you're eating healthily, a closer look at the nutritional labels will probably reveal you're not.

But standing in the supermarket and comparing the levels of salt on labels is tedious and time-consuming. That's why we have done the job for you.

Salt is made up of sodium and chloride and it is the sodium part which is the danger.

On a calculator, type in the amount of sodium per 100g which is usually (not always) printed on the packet, multiply it by 2.5, divide that figure by 100 and then multiply that figure by the portion you will be eating in grammes.

To work out what percentage of your RDA it is, divide that figure by six and multiply it by 100.

If you are short of time and want to work it out back home, you can use the FSA's salt calculator on its web site.

This useful tool works out the sum for you if you give it the sodium per 100g and the portion in grams you will be eating.

We worked out the figures for our products and also compared them to the amount of salt in a snack in a 100g pack of salted peanuts.

The results make scary reading if you thought just cutting out crisps and nuts was the best way to a low-salt diet.

There can be as much salt in a ready-made lasagne as in two and three quarter bags of nuts. There can be as much in a serving of baked beans as two bags of nuts and as much in a bowl of cornflakes as one and a half bags of nuts.

But a bit of shrewd shopping can make a difference to your salt intake without having to miss out on your favourite foods.

Simply by changing brands or switching to the healthy eating alternative of your favourite meal can drastically reduce the salt in your diet.

But don't spoil all that good work by then pouring lashings of salt over your meal. Instead, throw that salt cellar away or, if you really must use salt, opt for LoSalt which contains one third the sodium of common salt.

For the salt calculator and further information, log on to www.salt.gov.uk