Health food is not a drug or medicine, a watchdog said after a major investigation found companies were adding drugs to their products.

The China Food and Drug Administration issued the warning on Friday during a news conference following investigations in 15 provinces that uncovered a widespread presence of drugs in food.

Most of the health food brands claim their products can help stamina, control weight, blood pressure and sugar levels. Sometimes companies add drugs that help them achieve these aims, the investigation found.

Glibenclamide and phenformin, drugs used to treat diabetes, were found in a health food called “ganoderma glycopeptide”.

Two other brands of health food used to control weight were found to contain phenolphthalein and sibutramine, the use of the latter was forbidden by the CFDA in 2010 over fears that it increased the risk of cardiovascular disease.

Also, the CFDA found some health food brands falsely claim they can prevent liver disease and kill bacteria.

The Food Safety Law forbids health food brands to claim they have medicinal effects.