The research, published Wednesday, shows the deceased were all male.
They include 16-year-old Jaffar Deghayes from Brighton, who reportedly died fighting for Jabhat al-Nusra. The Syrian Islamist group are said to have a shared history with al-Qaeda.
The oldest man to die was 41-year-old Abdul Waheed Majeed.
Majeed was a Crawley-based truck driver who acted as a suicide bomber for Jabhat al-Nusra. He plowed a truck laden with explosives into a prison in Aleppo, Syria, in February 2014.
Jabhat al-Nusra is a militarized group fighting against Syrian President Bashar Assad’s Ba’athist regime. It reportedly seeks to set up an Islamist state in war-torn Syria.