McDonald’s has introduced kale salad to its US menu – but the fast food giant’s health kick may not be quite as virtuous as you think it is.

For rather than offering a low-calorie, low-fat and low-sodium alternative, the leafy green combo actually contains more salt, fat and calories than a Double Big Mac.

Health experts say that while kale – which is full of useful vitamins – is in itself a good ingredient, once it appears alongside crispy chicken and an Asiago Caesar dressing, as it does in the “Keep Calm, Caesar On” chicken salad, it rockets up the cholesterol charts.

According to the McDonald’s nutrition centre, which is accessible via their website, the salad contains 520 calories, 31g of fat and 1,140 milligrams of sodium.

But when you add in the Asiago Caesar dressing, it rockets up to 730 calories, 53 grams of fat, and 1,400 milligrams of sodium – whereas the Double Big Mac rings in at 680 calories, 38g of fat and 1,340 milligrams of sodium.

According to CBC News, who spoke to Toronto-based dietician, Shauna Lindzon, it amounts to “a fat and sodium overload”.

“By eating that salad, you’re getting your sodium for the day,” she said. “Putting kale into the menu doesn’t mean you’re getting a healthy choice.”

You would have to eat the equivalent of three McDonald’s regular hamburgers to ingest the same number of calories, she said.

Similarly, the lightest chicken kale salad offered by the firm, when added with a Greek feta dressing – weighing in at 420 calories, 26g of fat and 1,080 milligrams of sodium – gives it the same ratings as eating a Double Cheeseburger.

Ms Lindzon recommends using only half the dressing to slash the fat and calorie count, and taking away the feta which is high in salt content.

A McDonald’s spokesman said however that customers have a choice when it comes to modifying menu items.

“[They] have the choice to have a salad with or without dressing, select a burger without the bun, choose their chicken protein crispy or grilled,” Adam Grachnik told CBC News.

Last year the burger giant made headlines when it announced it would be introducing kale into its menu.

New CEO Steve Easterbrook said he planned to turn them into a “modern, progressive burger company”, following news of dropping sales.

But the superfood is not currently available in the UK – meaning we’ll have to keep waiting for that particular naughty treat.