Why is the EPA to DHA Ratio Important?
You notice I continually refer to “high-EPA fish oil.” By this, I mean a fish-derived concentrate whereby eicosapentaenoic acid is its predominant component. Current research on depression, chronic fatigue syndrome and children’s behavior suggests that not only is it important to have a greater concentration of EPA, but it is equally important to have as little DHA as possible. This is referred to as the EPA to DHA ratio.
States Dr. Malcolm Peet, Consultant Psychiatrist for the United Kingdom National Health Service and former Head of the University Department of Psychiatry, Sheffield, in United States Patent 6689812, “Highly purified ethyl EPA and other EPA derivatives for psychiatric and neurological disorders”:
Conventionally, most studies on the uses of EPA and related fatty acids have used materials partially enriched in EPA but also containing substantial amounts of other fatty acids, especially docosahexaenoic acid (DHA) which is found alongside EPA in most natural oils. The fatty acids have usually been in the triglyceride or ethyl ester forms, and occasionally in the free acid and phospholipid forms. Docosapentaenoic acid (DPA n-3) is also a common component of such materials. The new understanding of possible mechanisms of action of EPA which we have developed has, however, led to the realization that the purer is the EPA the better is likely to be the activity. This is not just a question of dose, although that is indeed a valuable aspect of the application of pure EPA.”
He further states in the same patent:
More importantly, other fatty acids such as AA, DPAn-3, and DHA, which are relatively similar in structure to EPA, but do not share the same spectrum of biological activity, compete with EPA for binding to the active sites of all the relevant enzymes. Thus these other fatty acids will compete with EPA for occupation of these active sites and reduce its activity. The purer the preparation of EPA the more likely is it to occupy the relevant active binding sites, and the more likely is it to be able to have desirable biological effects.
In essence, Peet theorizes that by eliminating DHA, you eliminate the competition for neuronal receptor sites. This apparently allows EPA to “get there first” and do its job.
Other researchers support the notion that the EPA:DHA ratio matters. Writes Håvard Bentsen, MD, PhD of Diakonhjemmet University Hospital in Oslo, Norway in the December 2005 issue of PUFA Newsletter:
…There seems to be a neglect of the difference between the effects of EPA and DHA. In studies of affective disorders, children developmental disorders (like Richardson AJ et al, Pediatrics 2005) and schizophrenia there is a consistent finding that the ratio of EPA to DHA, not only the sum of PUFAs, is important. Put simply, the higher the ratio, the better evidence of effect. DHA alone has not been shown to be efficient, whereas EPA (or ethyl-EPA) has. Also studies of the effect of EPA vs DHA on protein kinases show a markedly stronger effect of EPA than DHA. DHA, on the other hand, seems to have a calming effect (reduces noradrenalin and aggression in human RCT, and anxiety/conditioned fear response in rats). Thus, they may both have beneficial effects, but on partly different phenomena, and this distinction should not be overlooked.”
Professor Basant K. Puri, Consultant at Hammersmith Hospital and Imperial College London, and author of over 100 scientific papers and more than 20 books explains:
In general it has been found that as the ratio of EPA to DHA rises in the supplement used in clinical trials of certain conditions, such as depression and attention-deficit hyperactivity disorder (ADHD), the ability of the supplement to improve the condition also rises.”
And Dr. Alexandra Richardson, Oxford university expert of the effects of fatty acid supplementation in children explains:
Fish oil contains two major omega-3 fatty acids: EPA and DHA. Both are necessary, but until recently, it wasn’t at all clear which of these was more important in producing the benefits reported for ADHD and related conditions. In early life, plenty of DHA is needed for the growing brain – and because this fatty acid is so important for actual brain structure, it was thought that this must be reason for the apparent benefits from fish oil.
However, the latest research makes clear that it is EPA, not DHA, which is more effective in reducing the problems with attention, perception and memory that are associated with ADHD, dyslexia and dyspraxia.
This is probably because EPA plays a more important role in the minute-by-minute functioning of the brain, and also helps to make many other substances (such as prostaglandins) that are crucial for proper signalling between cells.
Of the omega-3 fatty acids, the latest evidence indicates that it is EPA - not DHA - that is likely to be most beneficial for these purposes.”
So what happens if your body needs DHA, you ask? Fortunately, if the body has enough EPA then it can convert it into exactly enough DHA when and where it needs it as it is only two steps down the chain of ecosanoids (hormones which control things like the inflammatory response and blood clotting.) Ω