Just to add a bit to this discussion. There is food additives and there is food additives.. Some of them are added to make food more appealing - colours, taste enhancers, etc and I do agree that we can do without them. Others do very much serve a purpose. Take for example nitrites which are added to prevent the growth of clostridium botulinum, a very nasty bacteria, which can produce toxins that kill in a very unpleasant way at minute quantities. And going on to pesticides - almost all crops are affected by different species of funghi. Some of them produce toxins, one of which is amongst the most toxic substances known to man. I think there is a general misconception amongst people that all that is natural is healthy and safe, when actually almost all of the most toxic substances are found in nature.
I entirely agree that one should avoid processed foods, but mainly because of the amount of fats, sugars and salt added to these and the low conent of nutrients. If you have a varied diet and get enough fruit, veg and fibre into you, you should be ok. The body is like a machine, if you give it the best fuel, it does the job.