May a biology graduate offer a few words of wisdom? Old food that looks and smells OK isn't necessarily safe to eat. There are plenty of microorganisms that alter the smell, taste and appearance of food, but you could still eat it without coming to harm, though you probably wouldn't enjoy it. Conversely, the dangerous bacteria may not affect the eating quality, and are often undetectable except by lab tests. There's a difference between a "best before" and a "use by" date. The first refers to eating quality, the second to safety. Some "best before" dates are clearly daft, for instance, my supermarket sells kiwis as hard as bullets, and they don't ripen until the "best before" date is history.
The retailers add on a margin to cover their own backs, so it may be safe to go a day or two over a "use by" date, but it's unwise to ignore them and rely on your nose, especially with meat. (Vegetarians rarely get food poisoning!)
Same goes for medicines. They don't remain stable for ever, and can undergo changes which, at best, make them less effective, and at worst could make them harmful. Out of date medicines, whether prescribed or over-the-counter, should always be taken to the pharmacy for safe disposal, never put into landfill or flushed down the toilet.
I applaud the comments about supporting poor farmers in developing countries, and a good way to do this is to buy goods with the Fairtrade logo. If you have a bit of money to spare, think about buying some Fairtrade groceries to donate to a food bank. That way, you benefit two lots of needy people with the same money.