A New Zealand-made drink company has been forced to publish a notice saying it's made some 'unsubstantiated' claims.

Ārepa calls its product a 'brain drink', but the scientific community has questioned the assertion it boosts mental and athletic performance.

The Ministry for Primary Industries has confirmed the notice the company had put online was compulsory, after an investigation into its labelling and advertising.

Co-founder and co-chief executive Angus Brown says it's tough to balance complex, emerging science with health codes.

"The issue with MPI is in relation to our use of the pre-approved health plans for vitamin C."

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