Todays newspapers carry a story about a meta-analysis, a statistical analysis of lots of studies either recommending people eat more omega 3 rich food, or take omega 3 rich supplements. A typical headline says 'omega 3 pills not the answer for heart disease'. Many say ' instead of taking supplements eat oily fish twice a week'. The strange thing is that this isn't what the study's statistics suggest.
Those studies that compared dietary counselling to increase omega 3 from food show no benefit. However, if you look at only those studies giving supplements of omega 3s (Figure 2 in the paper) the overall results of 13 studies shows 11% less risk for heart attack; the overall results of 7 studies shows 13% less risk of sudden death; 13 studies show 9% less risk of cardiac death; 17 studies overall show less risk of death from any cause. Only for stroke, the overall effect of 9 studies shows a 5% increased risk. I am deeply suspicious of 'meta-analyses' because they often merge studies with varying doses, varying patient types, and ignoring whether a person is selected on the basis of likely benefit, as well as issues of competing medication. It's a blunt instrument unless you are looking at studies that are very similar in design.
If, for example, you've had a cardiovascular event, and are at increased risk of another, then the evidence suggests you will benefit from omega 3 supplementation (average dose given was around 1.5g - e.g. between one and two fish oil capsules), especially if you are not in the habit of eating lots of oily fish. The slight negative on strokes doesn't surprise me because many people who've suffered a stroke are on blood-thinning medication. Omega 3 does the same thing and, if you over thin the blood you can cause a stroke (cerebral haemorrhage).
Meanwhile, a new study published in the journal of the Public Library of Sciences (not a statistical analysis of previous studies) finds that giving children the omega 3 fat DHA improves reading in those who aren't doing so well. Dr Alex Richardson, a senior research fellow at the Centre for Evidence-Based Intervention at Oxford University, said: ‘Our results showed that taking daily supplements of omega-3 DHA improved reading performance for the poorest readers (those in the lowest fifth of the normal range) and helped these children to catch up with their peer group.’
Paul Montgomery, Professor of Psychosocial Intervention at the Centre for Evidence-Based Intervention at Oxford University, said: ‘Previous studies have shown benefits from dietary supplementation with omega-3 in children with conditions such as ADHD, Dyslexia and Developmental Coordination Disorder, but this is the first study to show such positive results in children from the general school population.’ The researchers worked with Oxfordshire County Council’s Education Department to identify 362 healthy children from mainstream state schools in Oxfordshire, aged between seven and nine, who underperformed on a standardised reading test. They were given 600 mg/day of omega-3 DHA for 16 weeks.
Although no significant treatment effect on reading was found in the overall study sample (children whose initial reading placed them in the lowest third of the normal range), supplementation with DHA did significantly improve the reading of children whose initial performance fell within the lowest fifth of the general population range. In these children the imporvement in reading was 20 percent greater than would normally be expected. In the subgroup of 105 children, the bottom 10 per cent of readers, the improvement in reading was nearly 50 percent greater than would be expected. The study also found an improvement in behaviour in the children who received the DHA supplement, with parents reporting significantly less hyperactivity and defiant behaviour than parents of children in the control group.
While the omega 3 fat DHA is most important for building the brain (I prefer to give children more DHA than EPA) EPA has consistently proven more effective for reducing heart disease risk, as well as mood and joint pain. DHA appears more effective for reducing memory loss. Overall, I prefer to give most adults a bit more EPA than DHA. (DPA, the third type of omega 3, can be converted into either DHA or EPA as needed.)