Supplements labelled 'high strength' may contain the same or less omega 3 than cheaper standard versions, Which? Some supplements labelled as ‘high strength’ contained less omega 3 fish oils than the recommended guideline daily amount - and the same as or less than products not labelled ‘high strength’, despite costing more. But Boots' supplement costs 9p per dose and doesn't claim to be high strength, whereas Superdrug’s costs 13p. Holland & Barrett’s 'High Strength' Omega 3 fish oil 1,500mg costs 27p per daily dose but contains just 375mg of EPA and DHA. It means that an omega 3 supplement that contains 1,000mg (1g) of fish oil would only need to contain 7.2mg of omega 3s to be labelled as 'high strength'.