Hot dogs have become the quintessential summer cuisine, with hot dog producers estimating to average 38 percent of their sales between Memorial Day and Labor Day. In fact, 10 percent of annual sales are made during the month of July alone, which is why America has designated it as National Hot Dog Month. But the hot dog of today has gone through numerous transformations to become the current meat product in your bun.

Historians have traced the origins of the hot dog back to the Roman emperor Nero’s cook Gaius, the first sausage linker. At the time, it was customary to starve the pig before it was slaughtered, cleaned, and cooked. One day, a pig entered into Gaius’ kitchen cooked and not cleaned. Seeing as it wasn’t fit to eat for the emperor, Gaius cut into the roast and found the empty intestines when a creative idea struck him — to stuff the intestines with ground meats, spices, and wheat.

The sausage became a delicacy and traveled across Europe and eventually to present-day Germany. Frankfurt says it invented the frankfurter over 500 years ago, while Vienna claims to be the true inventor of the wienerwurst. Despite the discrepancy, most historians will agree that it was German immigrants who began to sell the first wieners in New York City in the 1860s. By 2014, New Yorkers spent more money on hot dogs in retail stores than any other market in the country, with a total of $121.6 million in sales.

If you reach for a dog today, most are created with vacuum-sealed cellulose casings, which are later removed, but other brands will use a natural, more expensive, and edible casing, according to the National Hot Dog and Sausage Council. Within the casing, ground meat, processed chicken trimmings, food starch, salt, water, corn syrup, and other flavorings are added depending on what region it’s sold in. The most controversial of ingredients are the nitrates added to preserve the hotdog in its plastic casing because they’ve been linked with cancer.

In 2009, the American Institute for Cancer Research (AICR) issued a report linking hot dogs to an increased risk of cancer based on more than 7,000 scientific studies. Since then, many hot dog companies have removed nitrates and replaced it with natural preservatives such as celery. Regardless, health warnings have not slowed the consumption of hot dogs, with the average person consuming 50 hot dogs every year.

New ingredients have been added inside and outside of the hotdog, creating jalepeño, bacon, and cheese-flavored products with toppings that go far beyond mustard and ketchup. In fact, the popularity of high protein foods coupled with consumer interest in natural and organic products has only increased sales expectations.