A new US National Research Council report, requested by the Food & Drug Administration's Center for Veterinary Medicine, assesses whether the addition of three dietary supplements - lutein, evening primrose oil and garlic - to the diets of horses, dogs or cats may cause significant adverse health effects.

The committee that wrote the report said because of inadequate data, it could not clearly define a safe upper limit for lutein, evening primrose oil or garlic, but it could cite historical safe intakes and estimate presumed safe intakes based on available research findings.

The committee added that current regulations addressing animal dietary supplements are in "disarray".

The report stressed that clear and precise regulations need to be established so "only safe animal dietary supplements are allowed on the market".

An improved adverse event reporting system for animal dietary supplements would help because existing systems have various deficiencies, including limited public access, passive rather than active solicitation of adverse events and unclear discrimination of minor versus serious adverse events, it noted.