The Advertising Standards Authority said there was no government recommendation about the amount of wholegrain foods that should be eaten.
A voice-over in the television ad stated: "Experts say you need three servings of wholegrain a day... All of these Nestle cereals have wholegrain guaranteed. Not all cereals do... Look for three-a-day on Nestle cereals."
The ASA upheld seven complaints about the television ad, ruling that the similarity of the "three-a-day" phrase and the Government's five-a-day recommendation for fruit and vegetables could confuse viewers.
Cereal Partners UK, which makes Nestle cereals, said several studies had found a link between wholegrain and prevention against cardiovascular disease, diabetes, obesity and cancer. The US Government also advised that consumers should aim to eat three 16g portions of wholegrain foods each day, the company said.
But the ASA said: "We considered that the ad implied that there was a consensus of opinion among experts regarding the specific quantity of wholegrain foods that should be consumed on a daily basis.
"However, we understood that only some experts had recommended that specific amounts of wholegrain should be eaten on a daily basis, and that others, such as the Food Standards Agency, had made a broader recommendation that people should increase their intake of fibre in general.
"Because of that, and because we considered that the similarity between the 'three-a-day' phrase used in the ad and the Government's 'five-a-day' recommendation for fruit and vegetables could cause confusion among viewers, we concluded that the ad was misleading."
