gogul: No. It doesn't. That would be totally illegal, and anyone caught poisoning waste food would be subject to criminal prosecution.

Yes alot of food is wasted, this is due to food safety and that much food is imported out of season to the UK's own calender, but at the same time if you shop wisely you can use the sell by system to your advantage. It is possible to buy food at a fraction of the original selling price!! All then you need (if you are going to consume it that day) is a freezer. Especially handy with meat products

And there are some stores that offer to sell to charitable people of the 'soup kitchen' ilk at a very reduced cost rather then waste it.

I do admit some of the 'sell by' dates are stupid in regards to products that never go off (eg honey) ... but if you are friendly (like we are) with local stores, then they'll just bung it to you with your regular goods rather than it be wasted... free of charge!