tuna sub
Julie Hambleton
Julie Hambleton
May 11, 2024 ·  2 min read

Lab Analysis Of Subway Tuna Sandwiches Fails To Identify Tuna DNA. What does this mean?

The popular fast-food sandwich chain Subway has had a rough year. The Irish court ruled that the chain couldn’t legally call their bread “bread” in the country due to its high sugar content. In January, two women from California launched a lawsuit against the company, claiming the Subway tuna sandwiches didn’t contain real tuna as they promised. And recently, a reporter from The New York Times investigated, and this is what they found.

Subway Tuna Sandwiches: Real Tuna Or Not?

When the story originally broke at the beginning of the year, media outlets worldwide began reporting that Subway tuna sandwiches didn’t contain any real tuna meat. This is because the two women who were launching the lawsuit did DNA testing on the sandwiches, which didn’t find any tuna fish DNA.

A New York Times reporter decided to do her own investigation to determine if the allegations were true or not. Naturally, the sandwich chain denied the allegations. She purchased 60 subway tuna sandwiches, removed the tuna, froze it, and shipped it to a DNA company specializing in fish.

The company tested for the two types of tuna fish that Subway claims make up their 100% tuna sandwiches. Just as the women in California found, they found zero tuna fish DNA. That being said, another journalism outlet, Inside Edition, also tested some Subway tuna sandwiches. They did find tuna DNA. So what’s the deal?

Read: Do you prefer self-serve checkouts?

It All Has To Do With Cooking

Canned tuna is cooked, as I’m sure we are all aware. However, according to the New York Times reportonce the fish is cooked, the proteins are denatured. These denatured proteins make it next to impossible to identify the fish via DNA.

“In the defense of Subway, or quite a lot of these fishmongers, the further you get the fish from the bone, the harder it is to recognize what that fish is,” explained Peter Horn, director of the Ending Illegal Fishing Project at the Pew Charitable Trusts.

Source: NYT

Subway’s Response

Of course, Subway has denied these allegations from the beginning. They stated that the claims made by the Californian women were not only false but damaging to the Subway brand.

“Unfortunately, various media outlets have confused the inability of DNA testing to confirm a specific protein with a determination that the protein is not present,” explained a Subway spokesperson. “The testing that the New York Times report references does not show that there is not tuna in Subway’s tuna. All it says is that the testing could not confirm tuna, which is what one would expect from a DNA test of denatured proteins.”

Source: Business Insider

So, in the end, likely Subway tuna sandwiches do contain real tuna. While there may be other reasons to limit your intake of Subway food and food from other fast food establishments, fake tuna is not one of them.

Keep Reading: McDonald’s Replaces Some Drive-Thru Workers With AI


  1. The Big Tuna Sandwich Mystery.” NY Times. Julia Carmel. June 19, 2021.
  2. Is Subway’s Tuna Sandwich Actually Made of Tuna?Youtube. Inside Edition. February 11, 2021.
  3. Subway says the drama surrounding the New York Times’ tuna story is based on a misunderstanding.” Business insider. June 23, 2012.