Anaemia is a nasty thing. Two Indian researchers found that it severely damages the IQ of schoolgirls and impairs their educational capacity.
Source: Monika Jain, Shalini Chandra
One more thing. If you look at the map, you will notice that countries such as Syria, Irak, Yemen, Pakistan, Nigeria, Sudan, Eritrea, and many other problem states suffer from iron deficiency. Maybe at least one beef steak a week would improve the IQ of jihadists or mujaheeds to the point they would abandon their vicious faith and the urge to fight for it.