Helmet might save your life, it might not....depends on the incident. It certainly won't save your limbs, torso, neck or face.
Cyclists greatest threat from injury on the road is from motorists, wearing a helmet doesn't change this, it may change the severity of the injury in SOME incidents, not the frequency of incidents....
What will reduce your risk of injury is removing incompetent drivers who are not just a danger to cylcists, but pedestrians, other car drivers, themselves and their own passengers, or getting motorists to switch to cycling.
+1 couldn't have put it so well myself