The Super Water Protein range, which comes in flavors including orange and passion fruit and watermelon, contains four percent 'Hydrolysed Beef Collagen' according to the ingredients list.
Collagen is a protein which makes up connective tissue including tendons and bones. It is found in all animals. According to Heathline, when collagen is hydrolyzed, it's broken down into smaller, easy-to-process particles.
Vegans on social media
Twitter user Vegan4Eva shared an image of the drinks, writing: "Dear @marksandspencer, why on earth is there beef collagen in these fruit juices."
Many people responded, with one saying: "That is revolting. Been shopping in M&S recently as I’ve been enjoying the Plant Kitchen range. But this is a step backward in my opinion. Grim and completely unnecessary."
The images have also circulated in various vegan Facebook groups.
"There's growing demand for protein-based drinks that offer added vitamins and benefits," an M&S spokesperson told the Daily Mail.
"In response, we've launched two new Super Waters containing a natural source of collagen, which is a widely used ingredient.
"The drinks are clearly labeled with their ingredients on the pack, however we are looking into how we can make this clearer for our vegan and vegetarian customers."
Marks & Spencer vegan
The collagen-containing drinks seem particularly surprising to some consumers as the British high street store has taken many strides forward in recent times when it comes to catering to vegans. In January, it launched a major new vegan range, called Plant Kitchen, featuring more than 60 meals, snacks, and ingredients. It includes BBQ Pulled Jackfruit Pizza, No Pork Sausages, Cauliflower Popcorn, and Rainbow Veg Sushi Wrap among other items.
"Some people think meat-free food is boring but that couldn't be further from the truth, it's experimental – and it's delicious," Claire Richardson, who developed the range alongside a team of food experts, said in a statement.
"We've created a collection that will appeal to everyone – whether you're a longstanding vegan, want to lead a more flexitarian lifestyle or you love meat but think cauliflower popcorn sounds amazing. It's all about delicious tasting food first - and plant-based second."