SELECT count(*) FROM Has_allergy AS T1 JOIN Allergy_type AS T2 ON T1.allergy  =  T2.allergy WHERE T2.allergytype  =  "food"
How many students are affected by food related allergies?
SELECT count ( * ) FROM Has_allergy AS T1 JOIN Allergy_type AS T2 ON T1.allergy = T2.allergy WHERE T2.allergytype = `` food ''
select count ( * ) from has_allergy as t1 join allergy_type as t2 on t1 . allergy = t2 . allergy where t2 . allergytype = value
How many students are affected by food related allergies ?