The press ad, created by Lowe London, received a single complaint from a reader who challenged whether the product had a detoxifying effect and whether it contained more antioxidants than five average portions of fruit and vegetable a day.
The ad was headed "Acai comes from a tree, not a laboratory" and text at the bottom included: "We blended acai with equally incredible pomegranates and blueberries to produce a recipe that contains even more antioxidants than the average five a day".
Innocent said that its Superfoods Smoothie contained pomegranates, blueberries and acai berries which contain high levels of antioxidants which "neutralised the free radicals that could damage the body's cells".
Innocent also said it had no plans to use the ad again or to use similar claims in the future.
The ASA upheld the complaint and said that it did not consider Innocent had provided evidence to prove their product removed toxins from the body. The watchdog also noted that accepted nutritional advice was that fruit juice and smoothies could count towards only one of the recommended five portions of fruit and vegetable per day, no matter how much was consumed.
The ASA said that it welcomed Innocent's assurance that it had no plans to use the ad again and told it to delete the claims and to ensure it could provide suitable evidence to back up any future claims.
In a statement on its website, Innocent said: "Although we provided evidence, [the ASA] didn't agree with the study we used to back up our antioxidant message. They also think that the word detox should only ever be used about things that can prove they actively remove toxins from the liver, whereas we've always thought that detoxing naturally is about making sure you get the good stuff to balance out the bad stuff."