'Unnecessary and disgusting'
Twitter user '_ayrtonnn' uploaded a photo of the product's ingredient list, captioned: "Eww look! Kellogg's UK Frosted Wheats have beef gelatin added to them! Be careful, they are not suitable for veggies/vegans! Why!? So unnecessary and disgusting!"
The tweet, which attracted hundreds of likes and more than 50 comments, saw many vegans outraged at Kellogg's decision to use gelatin - an ingredient made from boiling animals' skin, cartilage, and bones.
"Oh FFS! That's just ridiculous. Thanks for pointing this out. I check cereals for milk—nicely highlighted in bold—but never occurred to me to scan for gelatin!" another Twitter user complained.
The company, who committed to ending animal testing after 65 years earlier this year, also came under fire for fortifying its cereal with Vitamin D, sourced 'from a non-vegan origin'.
The company does, however, sell vegan products as part of its plant-based range 'W.K Kellogg's' - all of which aren't fortified with Vitamin D.
"We recognize that consumers tastes are changing and that people want more choice at breakfast, such as organic and vegan, so these are areas we will continue to explore," Kellogg's state on its website.