To not eat these yogurts?

[LynetteScavo]

The best before date is 13th August.

They've just been given to me by someone saying "They're fine, it's jsut a best before date"

Yoghurt is fine over the date, particularly if it's plain. If it's still sealed, it just gets - more yoghurty! Obviously, there's going to be a cross-over point where it starts getting noxious, but if it's sealed and a week over, I'd look, sniff and taste. Won't kill you.

You are confusing 'Use By' and 'Best Before' dates which are two different things (although personally, I'm a bit slack on use by dates too .

You can tell if yoghurt has gone off if there is a gas build up under the foil lid, or if it looks mouldy or tastes fizzy. Other than that, it will be fine, even well past the BB date.

Even if it is 'off' it's unlikely to do you any harm - too much live bacteria. The stuff you really need to worry about is cooked rice, cooked pasta and meat/chicken/shellfish. Most other foods are unlikely to do you any harm, even if they're a bit mouldy (and no, I'm not advocating that you eat mouldy food, just making the point).