Researchers from the University of Reading examined 39 takeaway meals from 23 food outlets in the British city of Reading and published their findings in PLOS One.
They wanted to determine whether the restaurants' stated salt content matched the actual amount.
The results showed that 47 percent of the meals examined contained more salt than indicated on the menu.
According to the researchers, this is partly because portion sizes, ingredients, and preparation methods can vary from one order to another, ScienceDaily reports.
Also read: Rising sea temperatures could boost harmful bacteria
Large differences
The study also found significant differences between dishes. Meat pizzas had the highest salt content per 100 grams, while curry dishes varied considerably.
Pasta dishes contained an average of 7.2 grams of salt per serving. One dish contained as much as 11.2 grams.
For comparison, adults in the UK are advised to consume no more than 6 grams of salt per day, according to ScienceDaily.
The World Health Organization (WHO) estimates that excessive salt intake contributes to around 1.7 million deaths worldwide each year.
Also read: How diet soda can affect your liver if you drink it every day
An unexpected winner
One of the study's most surprising findings was that fish and chips had among the lowest salt levels.
According to the researchers, this is because salt is typically added only after cooking and only if the customer requests it.
The study therefore concludes that the salt information provided on takeaway menus is not always accurate.
Several of the meals examined contained significantly more salt than the restaurants had stated.
Also read: New sugar patterns may help detect cancer earlier
Also read: New study finds hidden advantage in red hair genes