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Richardson Trial Edit

In a widely cited 2006 study, the Richardson group ran a six month randomized controlled trial of Omega 3 supplementation [1] in children between the ages of 5 and 12. They administered 170 mg of DHA, 560 mg of EPA and 60 mg γ-linoleic acid daily, through an 80-20% mix of fish oil and evening primrose oil. The active group received this treatment for 6 months, while the placebo-crossover group received placebo for 3 months, then the active treatment for 3 months. They observed significant improvements in reading, spelling and behaviour testing in the active treatment group after 3 months, and in both groups after 6 months, although no effect on motor skills was observed. On this basis they say that "The findings ... suggest ... that fatty acid supplements of this type may be a safe, tolerable, effective treatment for improving academic progress and behavior among children with DCD."

Capsules vs. Bottled Fish Oil Edit

Nutritional Info Imgur

Comparison of EPA/DHA levels and Vitamin D, in bottled fish oil (Seven Seas 'Ocean Gold', left) and capsule fish oil (Extra high strength one-a-day capsules, right). For 100% Recommended Daily Allowance of Vitamin D, left provides 2300 mg of EPA/DHA, right provides 360 mg, which compares to the 730 mg dose in the Richardson trial

The Richardson study gave participating children 6 tablets per day, which would be clearly problematic as a long term therapy. Although the amount of EPA and DHA can usually be seen on the side of fish oil product packaging, so that daily treatment can be matched to the levels administered in the trial (which had a combined EPA/DHA treatment of 730 mg/day), some products have high concentrations of Vitamin D, which can be dangerous above the Recommended Daily Allowance. See figure, right. Other factors to take into account are the taste of liquid fish oil (which may be a particular problem for young children) and the cost of capsules vs. bottled oil.


Concerns about contamination of fish oils Edit

There have been concerns raised about the contamination of fish oils with dioxins, PCBs, and Mercury. The British Foods Standards Agency has published surveys to investigate:


PCBs/Dioxins Survey[2]

In this case, the concerns were somewhat vindicated. As against a Tolerable Daily Intake of 2 picograms per kilogram (body weight) per day (pg/kg bodyweight/day), they found exposure levels of 0.02-1.7 in various capsules, and 0.3-7.1 in various bottled oils. This difference may simply be because the bottled oil daily dose is higher. But these figures indicate a need to carefully select a product which has undergone a high level of filtering and safety testing. For UK based consumers, the Seven Seas(TM) products demonstrated consistently lower dioxin concentrations, with the "Ocean Gold Ultra Pure" product giving the lowest concentration for bottled pure fish oil.

Mercury Survey[3]

Here, the results were reassuring:

"Only nine of the 100 samples were found to contain mercury above the limit of detection of 0.0014 milligrams/kilogram. Over 500 of the tablets with the highest concentration of mercury would need to be consumed per person per day, in addition to the rest of the diet, to exceed the Provisional Tolerable Weekly Intake (PTWI) for methylmercury (equivalent to 0.23 micrograms per kilogram bodyweight per day), set by the Joint FAO/WHO Expert Committee on Food Additives (JECFA)"

  1. Richardson et al, 2006, http://pediatrics.aappublications.org/content/115/5/1360.long
  2. FSA, 2002, http://food.gov.uk/multimedia/pdfs/fishoil_table.pdf
  3. FSA, 2005, http://www.food.gov.uk/multimedia/pdfs/fsis8005.pdf