LONDON — PepsiCo Inc. and its Naked brand of juice products once again have run foul of regulatory officials — this time in the United Kingdom. A little more than six months after being told to remove the phrase “all natural” from the labels of its Naked juices in the United States, PepsiCo on Jan. 7 was informed by the Advertising Standards Authority (A.S.A.) that the wording on Naked’s U.K. web site as it related to “antioxidants” was not specific enough and “must not appear again in its current form.”

A complainant challenged whether the claims “antioxidant” and “antioxidant family Juice Smoothies loaded with nature’s elite fighting force to defend your body against free radicals (those nasty little molecules that attack your cells and could have an impact on your overall health)” were authorized on the E.U. Register of Nutrition and Health Claims for Foods.

In making its case for allowing the wording on its Naked web site, PepsiCo said that in the absence of direct guidance, the term “antioxidant” was a non-specific, general health claim, and therefore permissible to use — provided it was accompanied by a specific health claim that was authorized on the E.U. Register. PepsiCo said two Naked products — Green Machine and Mango Machine — contained vitamin C in amounts high enough to allow claims that the product contained vitamin C, along with any associated authorized health claims for vitamin C.

But the A.S.A. concluded that the wording exaggerated the authorized health claim and therefore breached the Committee of Advertising (CAP) Code.

“We noted that health claims could only be made for the nutrient, substance, food or food category for which they had been authorized, and not for the product itself, because the authorized claim described the particular health relationship that E.F.S.A. said had been substantiated by scientific evidence,” the A.S.A. said. “We noted that neither claim included any reference to vitamin C as the nutrient which conferred the health benefit referenced in the authorized claim. We therefore concluded that the claims also breached the code in that regard.”

The A.S.A. said the ad must not appear again in its current form.

“We told Naked Juice to ensure that they retained the meaning of, and did not exaggerate, any authorized health claims if they reworded them to aid consumer understanding, and to include the name of the nutrient, substance, food, or food category for which a claim had been authorized,” the A.S.A. said.

As of Jan. 8, the wording on the Naked web site had been changed to “Antioxidant: Juice smoothies loaded with Vitamin C, which contributes to the protection of cells from oxidative stress.”