Consumers trying to save money are gambling with their health and risking food poisoning by ignoring use-by dates on food, according to research published by the government's food watchdog.

In an effort to spend less and make their food go further, many are also keeping leftovers for longer than the recommended limit of two days in the fridge.

The poll by the Food Standards Agency (FSA) showed that most of those questioned (97%) believed the cost of their typical shopping basket had gone up significantly in the past three years, with half (47%) trying to make better use of leftover food.

The research reveals that people are also risking food poisoning by disregarding use-by dates more than they used to. The use-by date is considered the most important on the food label, and more meaningful than "best before" or "display until". It is used on foods that can rapidly become unsafe such as chilled or ready-to-eat foods.

At the start of Food Safety Week, the FSA is reminding people not to take risks with food safety, even as budgets are squeezed.

Bob Martin, a food safety expert at the FSA, said: "With most of us seeing our weekly shopping bills increase over the last few years, we are all looking for ways to get the most out of our shopping budget. Using leftover food is a good way of making our meals go further. However, unless we're careful, there's a chance we can risk food poisoning by not storing or handling them properly."

There are around a million cases of food poisoning every year in the UK. The levels increase during summer months, with around 120,000 extra cases from June to August. One reason is warmer temperatures causing any germs present to multiply faster, which underlines the importance of getting leftovers into the fridge quickly.

Researchers found that a third of people were more likely to judge when food was safe to eat by its smell, look or how long it had been stored than by its use-by date.

Martin added: "It's tempting to just give your food a sniff to see if you think it's gone off, but food bugs like E coli and salmonella don't cause food to smell off, even when they may have grown to dangerous levels. So food could look and smell fine but still be harmful. These dates provide helpful information on how long food will stay safe for, so it's very important you stick to the use-by date. Other dates marked on foods focus less on food safety. The 'best before' date relates to food quality and can be treated more flexibly, while 'display until' dates are there to help shop staff to manage stock."

Sainsbury's said in February it would change its longstanding advice to customers to freeze food on the day of purchase, in an effort to cut down on waste. Labelling now tells shoppers to freeze food as soon as possible up to the product's use-by date.

UK health watchdogs have been reminding people to wash fruit and vegetables after investigating earlier this year whether a salmonella outbreak in which 35 people in the UK were known to have been infected was linked to watermelons.

The FSA has also announced a crackdown on unlicensed vans selling burgers, hot dogs and fish and chips to the millions of visitors to the 2012 Olympic Games in an attempt to protect them from food poisoning and from being ripped off by rogue operators.

© Guardian News and Media 2012

[Expiration date on milk via planet5D LLC / Shutterstock]