Is it safe to eat food that's past its 'use by' date? Experts weigh in.

Food has been marked with "use by" dates for over half a century, but there's still no consensus among consumers about whether these dates are a hard and fast rule or simply a suggestion. Do use by dates indicate a date by which a food needs to be eaten? Or are the dates printed on the foods we eat merely a general idea of when we should consume them by?

Kathryn Butler tosses any food in her kitchen when its use by date arrives because she "lives in fear of [her] children vomiting." Butler, who worked in the restaurant industry and attended several food safety trainings, recalls learning how much can go wrong if food goes bad. "The points about mold spores in things like expired flour really stuck with me," she says. Her training in food safety, coupled with concern for her children's well-being has led to what she calls "some healthy food caution."

Chaunie Marie Brusie, on the other hand, is much less cautious. "I once ate a whole piece of toast before I realized the loaf was moldy," she says, explaining she goes "by the smell and look [of food] more than the … [use by] date."

Some families are divided over use by dates. Ruth Dawkins says her husband will "toss stuff on the day of the 'best before' without even checking, rather than using his eyes and nose to actually decide if it's OK."

"Drives me wild," she says. "I hate the waste."

Kathy Meyer Larson and her husband often argue over the use by date concept. "He is a strict by-date thrower-outer and I am not. At all," she tells Yahoo Life. She confesses her husband has "no idea how many times" she's served her family food that's hit its use by date. Though Larson says her husband thinks she's going to "poison" their kids if she serves them food past its use by date, she's certain no one in her family has gotten sick from eating anything she's served them, even after years of ignoring use by dates. "As long as it smells fine … waste not, want not," she says.

Why the confusion?

There's a good reason for the confusion around use by dates. According to Hilary Walentuck, a registered dietitian with New England Dairy, "date labels are not safety labels," but consumers are often unaware of this fact.

"They're used to indicate quality," she says of use by dates.

Joan Salge Blake, a nutrition professor at Boston University and host of the Spot On podcast, explains that consumers are routinely "misinterpreting" these dates and "inadvertently tossing good food into the trash."

"This is causing Americans to needlessly throw away about one third of the foods they are purchasing and waste over $160 billion on food that could be safely consumed," says Salge Blake. She believes use by date confusion is costing consumers money and causing harm to the environment.

Why do use by dates exist?

Chef Chris Hughes says prior to the ’70s, some food manufacturers used an opaque system of marking packaging so they'd know when an item expired. However, the public had no way to decipher this system and consumers demanded more transparency regarding food safety. "The theory was this would reduce the amount of spoiled food that was sold," says Hughes.

It didn't turn out that way. In fact, marking foods with use by dates led to more food going to waste. Walentuck says an astounding 40% of food in the U.S. today goes to waste and a "a key cause is confusion caused by 'best by,' use by and 'sell by' labels."

What do use by dates mean?

There are three types of dates consumers in the U.S. see on food: best by, use by and sell by. Less commonly, consumers may see food marked with an expiration date.

According to Walentuck, best by and use by dates "represent a manufacturer's estimate on when their food's taste and texture will start to degrade." She warns the dates do not tell a consumer anything about whether the food is safe to eat.

These dates are particularly misleading when it comes to shelf-stable foods, like canned goods that can last for years past the marked date "as long as the can looks in good condition and does not contain dents, bulges or rust," says Hughes.

A best buy date indicates the manufacturer's "recommended date for best flavor or quality" and is most often found on products like crackers and chips, Walentuck explains. "Even if the best if used by date has passed on a food you have at home, it should be safe if stored and handled properly," she adds.

A use by date is like a best by date, but more precise. This is "the last date recommended for use of the product at peak quality, according to the manufacturer," Walentuck says. She explains "while this isn't always black and white, it's best to stick to this date with products like meat."

"But with products like dairy," she adds, "your slightly sour milk doesn't always need to go down the drain."

A sell-by date tells retailers "how long to display items, but doesn't denote when the food will go bad," Walentuck says. Sell by dates are most often found on products like eggs, dairy and meat. "Often products can be eaten days, weeks or even months after those dates, depending on the product," she says.

When it comes to expiration dates, however, consumers should be more cautious: An expiration date does indicate when a product will go bad, according to Walentuck. Baby formula and baby food are the items most commonly marked this way.

How can consumers tell if food has spoiled?

Since the best by, use by and sell by dates don't tell consumers whether their food is safe to eat, they should rely on their five senses to tell them if their food has gone bad, says Walentuck. "Use your best judgment and check for signs of spoilage," she advises. Walentuck recommends examining food to see if it has mold, a "different texture than you would expect," "smells off" or has an "unpleasant taste."

Walentuck explains if a food shows no signs of spoilage, it's likely nothing bad will happen if you eat a food past the marked date. However, "eating spoiled food is not only unpleasant but can also be dangerous and put you at risk for food poisoning," she says, adding that it's a good idea to check a food that is past its use by date just to be sure.

"Use your nose and eyes to determine if a food is spoiled," says Blake. "When in doubt, throw it out."

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