milking clusters in milking parlour© John Eveson/FLPA / imageBROKER/REX/Shutterstock

A poster by vegan campaign group Viva! linking milk to cancer is unsubstantiated, misleading and must not appear again, says the Advertising Standards Authority (ASA).

The advert featured an image of a cow’s udder and included the claim: Milk contains 35 hormones, including oestrogen … some of these are linked to cancer.”

Two complainants contacted the ASA and challenged whether the implied claim was misleading and could be substantiated.

See also: NFU criticises ‘misleading’ vegan dairy adverts

In its defence, Viva! said the claim referred to hormones that were naturally occurring in cow’s milk, which increased during pregnancy and were essential for calf development.

It said its claim did not refer to hormone treatments or artificial hormones – and argued that the advert stated the hormones were “linked to” cancer, rather than that they “caused” cancer.

Complaints upheld

But the ASA upheld the complaints and banned the advert, saying it must not appear again.

It said consumers would interpret the phrase “linked to” to mean that drinking cow’s milk could increase a person’s risk of developing cancer.

It said: “We considered that consumers were likely to understand from the context of the ad as a whole, which focused on calves and pregnant cows, that the claim related to the naturally occurring hormones that were present in cow’s milk.

“We considered that such a claim must be substantiated by robust evidence that demonstrated a link between the naturally occurring hormones in cow’s milk with incidences of cancer in human populations.”

No definitive evidence

Although Viva! submitted various papers to support its claim, the ASA said none included definitive evidence that demonstrated hormones in cow’s milk increased cancer risk.

The ASA said Viva’s claim was unsubstantiated and was therefore misleading.

It said: “The ad must not appear again in the form complained about.

“We told Viva! not to make claims which stated or implied that due to the presence of hormones, drinking cow’s milk could increase a person’s risk of developing cancer.”