The agency's laboratory analysed 55 products sold in 18 gyms around the country at the beginning of the year. Almost half (26) showed levels of vitamins, minerals, fatty acids or other nutrients that were either higher or lower than indicated in the labelling, with ingredients like caffeine, colours or genetically modified ingredients often not even mentioned on labels.
The survey also found seven products containing pharmaceutical drugs or 'high levels of vitamins or minerals typically found in medicines', and two products classified as medicines.
The National Food Agency has asked the local food authorities to contact the importers or the manufacturers and to check that the products are altered. The regulatory body also plans to increase scrutiny of such outlets, expanding the pilot project into a national control project, to be carried out in the next few months.
It is aiming to encourage gym operators to monitor the conformity of the products they sell.
The food agency also found four companies making claims in their marketing material referring to the prevention, treatment or cure of diseases. It examined the advertising brochures and websites for 77 products in total.
The country's food authority said it has taken action to eliminate unsubstantiated claims from the marketing material. Products in which drugs listed in the compendium of pharmaceuticals or high medicine-like levels of vitamins were found have been sent to the National Agency for Medicines to check their status.
The results of the pilot project and other material related to the gym project can be found on the National Food Agency's wwebsite.