UPDATED: Observer plugs fish oil for concentration, ADHD and depression

I was surprised to see the usually excellent Guardian Science tweeting that “Fish oil helps schoolchildren to concentrate”. This linked to Denis Campbell’s Observer article, reporting that

Fish oil helps schoolchildren to concentrate
US academics discover high doses of omega-3 fish oil combat hyperactivity and attention deficit disorder
Children can learn better at school by taking omega-3 fish oil supplements which boost their concentration, scientists say.

Boys aged eight to 11 who were given doses once or twice a day of docosahexaenoic acid, an essential fatty acid known as DHA, showed big improvements in their performance during tasks involving attention.

Dr Robert McNamara, of the University of Cincinnati, who led the team of American researchers, said their findings could help pupils to study more effectively and potentially help to tackle both attention deficit hyperactivity disorder (ADHD) and depression.

Unfortunately, the Observer’s claims about fish oil are not evidence-based.