If you are unsure if a food is healthy or not just use these criteria:

1. If you can't pronounce the ingredients, don't eat it.

2. If it wasn't here 10,000 years ago, don't eat it.

3. If it has a shelf life of more than 5 days, don't eat it.

4. If it's heavily marketed, don't eat it.

5. If it's man-made, don't eat it.

The most widely used sweetener in the world, found in fizzy drinks and sweets, is being made using a secret genetic engineering process, which some scientists claim needs further testing for toxic side-effects.

The use of genetic engineering to make aspartame has stayed secret until now because there is no modified DNA in the finished product. Monsanto, the pioneering GM food giant, which makes aspartame, insists that it is completely safe. But some scientists fear that not enough is known about the process of making it. One of the two elements that make up the sweetener can be produced by genetically engineered bacteria, and scientists say that they cannot rule out toxic side-effects.