If I were you, I would try a few helmets to find the most suitable. The best for me was Gonex Wind, but it’s expensive . Firstly I had some troubles with a proper size, but it’s really comfortable. U can try to find something on http://bestadviser.net/mountain-bikes/top-mountain-bikes-helmets-and-clothing-review/. There is a nice top of the helms, so all of them are pretty good.