When buying your safety helmet, you should definitely pay attention to the VG1 or, even better, the PAS015 standard. This standard states that the minimum safety requirements are met.
But it is only tested once, which is why variations in production quality are not covered. The English PAS015 standard, which tests every helmet at regular intervals, is more precise. The production date, which you can find on a label inside the helmet, is also important. It should not be longer than 2-3 years ago.