Participants
hemochromatosis, Social Dysfunction, Wilson's diseases, intellectual disability, intellectual disabilities
HYPERPARATHYROIDISM, WILLIAMS SYNDROME, HEMOCHROMATOSIS, WILSON'S DISEASE, FISH ALLERGY
Participants were recruited from six care organisations for people with intellectual disabilities in different regions in the Netherlands (i.e., Amarant, Amerpoort, Gemiva‐SVG‐groep, Schakenbosch, 's Heeren Loo and Trajectum). People with borderline intellectual functioning may need similar support as people with mild intellectual disability due to psychological co‐morbidity and deficits in adaptive abilities (Jonker et al., The following inclusion and exclusion criteria were used: Successfully completing the run‐in phase; Age between 12 and 40 years; Receiving care from an intellectual disabilities‐organisation; IQ < 85; Score ≥5 on the Social Dysfunction and Aggression Scale (see Measurements); Not pregnant or breast feeding; Does not have one of the following conditions: Williams syndrome, Wilson's diseases, hemochromatosis or hyperparathyroidism; Not using levothyroxine, methyldopa or levodopa; No fish allergy; Not using dietary supplements with vitamins or minerals for the past 14 days (only vitamin D supplements up to 50 μg per day were allowed).