People are only just realizing what's in the secret sauce at most burger joints

Fast-food lovers are realizing that this mayonnaise, ketchup and pickle relish salad dressing has long been the 'secret sauce' used at most burger joints in the country. 

While the original story of Thousand Island Dressing is up for debate, its cool, creamy taste has been a favorite for decades for both diners and retailers. 

But eaters are just noticing that this peachy-hued condiment which at times also includes mustard, vinegar, cream, chili sauce, olive oil and Tabasco sauce has been around for decades by different names. 

Thousand Island Dressing has been strongly inspired by a Russian dressing - which has been a longtime staple in the corned beef Reuben sandwich. 

While the original story of Thousand Island Dressing is up for debate, its cool, creamy taste has been a favorite for decades for both diners and retailers

Unlike its counterpart, Thousand Island does not have horseradish as an ingredient which makes it the perfect sauce for burgers and fries. 

Back in 1968, McDonald's debuted its Big Mac sandwich - a double-decker sandwich made with two beef patties, shredded lettuce, cheese, pickles, minced onions. 

At the time, owners advertised the dressing as the 'secret sauce' that was dripping from the bulky burger. 

Originally sold for 45 cents and advertised with the tagline 'a meal disguised as a sandwich', the Big Mac has now become McDonald's most popular menu item and ingrained itself into American culture. 

Originally sold for 45 cents and advertised with the tagline 'a meal disguised as a sandwich', the Big Mac has now become McDonald's most popular menu item and ingrained itself into American culture

But in recent time, health experts have said Thousand Island is one of the unhealthiest dressings ever created

Other joints such as In-N-Out, Shake Shack and Big Boy also quickly decided to make their own 'secret sauces' and released their versions of the dressing. 

While eateries such as In-N-Out added a bit of sugar to the dressing to use in their 'animal-style' burgers and fries, others such as Big Boy decided to make their own version by adding lemon juice and garlic powder. 

As the sauce's popularity rose with time, it soon became an American household staple. 

But in recent time, health experts have said Thousand Island is one of the unhealthiest dressings ever created. 

While eateries such as In-N-Out added a bit of sugar to the dressing to use in their 'animal-style' burgers and fries, others such as Big Boy (pictured) decided to make their own version by adding lemon juice and garlic powder

As the sauce's popularity rose with time, it soon became an American household staple

Well Choices' nutritionist Elizabeth Keller told SheFinds that while the dressing's unique combination may taste incredible, it is also quite high in sugar content. 

'Thousand Island dressing typically contains a combination of ketchup, mayonnaise, and sweet relish, all of which contribute to its high sugar content. 

'The mix of sugars from these ingredients can lead to blood sugar spikes. Over time, those blood sugar spikes can result in a range of issues including problems with your heart and kidneys, weight gain and more,' she told the blog. 

Jamie Allers, a Hartford HealthCare’s Digestive Health Institute dietician also supports Keller's theory. 

This salad dressing is also a terrible option for those trying to lose weight due to its sugar, sodium and saturated fat content

'It's important to look out for added sugars in any dressing. And when it comes to hidden sugars, be particularly careful with low fat dressings. These tend to make up for the lost fat by adding extra sugar for flavor.' 

About two tablespoons of the dressing contains 4.6 gm of sugar and zero percent of Vitamin C, Vitamin D, Vitamin B6, calcium and magnesium. 

This salad dressing is also a terrible option for those trying to lose weight due to its sugar, sodium and saturated fat content. 

Charlotte Martin, a registered dietitian explained: 'Thousand island is one dressing you probably want to avoid. It's notorious for being high in sodium and added sugar, and sugar is often listed at the top of the ingredient list. 

'Added sugars in salad dressings increase calorie content and make it hard to lose weight.'