There have been countless studies examining the role of fish oil and in particular Omega-3 in relation to brain health. Eating oily fish is part of the Mediterranean diet, a diet that has been shown (again through research) time and time again to assist in promoting brain health and function.
Adverts for fish oil supplements regularly appear in the media, in magazines and on the T.V. Doctors have been recommending fish oil supplementation for a number of health benefits including arthritis and heart health as well as a way to promote memory and cognition.
So, with such a wealth of peer reviewed research and growing acceptance of the use of fish oil supplements, I was somewhat taken aback by the findings of a recent study, a new Cochrane systematic review, which analysed the findings of three large trials and concluded that there was no benefit for cognitive health or dementia prevention in older people (over the age of 60 - now, is that really "older"?) taking omega-3 supplements.
So why would they have come to this conclusion?
The researchers looked at the results of 3536 people aged 60 and older who had taken part in trials comparing the outcome on memory and cognition through the consumption of omega-3 either as capsules, margarine spread, sunflower, olive oil and regular margarine. They found no difference in studies lasting up to 3 1/2 years.
Does this mean we are all wasting our time taking fish oil supplements?
I don't believe so.
Our brain and body requires Omega 3 fatty acids for a number of different and vital roles in ensuring we stay healthy. Our brain is predominantly made up of fat and Omega-3 provides the essential components for maintain a healthy cell membrane around our neurons. A membrane is far more than a simple separation of the inside from the outside. The membrane being flexible has the ability to allow substances to pass across the membrane in both directions, critical for communication between cells and enhancing their longevity.
Frautschy in 2010 advocated the urgent need for dementia prevention strategies that are cheap, effective and affordable.
To say that these trials showed there was no benefit in this age group (60 plus) over this time frame neglects the fact that of course a healthy brain is required from birth and that optimal health covers the entire lifespan.
The three major sources of Omega-3 that we obtain from our diet include:
- ALA (alpha linoleic acid) from seeds and nuts
- EPA (eicosapentoic acid) and DHA (docosahexaenoic acid) from oily fish - salmon, mackerel, sardines.
One of the main areas of research into Omega-3 and the brain has been in relation to prevention or slowing down of dementia such as Alzheimer's disease and vascular dementia. Some of the benefits of DHA are as follows:
- DHA, the Omega-3 fatty acid from fish has been shown to help reduce the production of the protein beta-amyloid. Amyloid is linked to the pathology of Alzheimer's disease.
- DHA has been shown to have a moderating effect of some of the enzymes that lead to a process called hyperphosphorylation, of tau protein. Tau forms part of neurofibrillary tangles also found in Alzheimer's disease.
- DHA is believed to suppress insulin/neurotrophic factor signalling deficits
- It is also thought to suppress neuroinflammation and oxidative damage that can contribute to synaptic loss and neuronal dysfunction in dementia.
- DHA increases levels of BDNF (brain derived neurotrophic factor), and reduces the levels of Omega- 6 fatty acid arachidonate and its associated prostaglandin metabolites which have been implicated in promoting Alzheimer's disease.
Oster in 2010 stated that DHA is "one of the most valuable diet ingredients, whose neuroprotective properties could be crucial for designing nutrition based strategies for preventing Alzheimer's disease".
Another paper contradicting the Cochrane study was published in the highly prestigious Neurology journal in early 2012. Here the authors found that people with lower levels of omega-3 fatty acids had lower brain volumes. In other words their brains had shrunk more.
Those in the lowest quartile of Omega-3 (DHA and EPA) not only had smaller brains they scored lower on test of visual memory and executive functions including problem solving, multitasking and abstract thinking.
The authors concluded that this brain volume loss was equivalent to two years of structural brain ageing.
And finally, just in case you still were unsure whether all this fish oil stuff matters, consider the findings of a study published this month in October 2012 where those who took Omega-3 supplements for four months were shown to alter the balance of their fatty acid composition (Omega-6 to Omega-3 ratio) that helps to conserve your telomeres.
Now this is an anti-ageing effect.
Telomeres are the "shoelace caps" that sit at the end at the end of our chromosomes and help to protect their longevity. The faster our telomeres shorten, the faster we deteriorate! In this study the findings suggest that Omega-3 through its anti-inflammatory effect helps to maintain telomere length in immune cells, but it was the effect of the reduced Omega-6: Omega-3 ratio that was considered most important.
Our typical Western diets are mostly Omega-6 heavy. Omega-6 comes from vegetable oils and as a result some populations have a ratio of 15:1.Taking Omega -3 supplements and eating fish can help to reduce this. Researchers suggest we need to be aiming more for a ration of 4:1 or even 2:1.
So, is fish oil supplementation a red herring?
In a word, no. Whilst it is imperative that all good scientific studies be continually evaluated for validity, this Cochrane study only indicates that short term supplementation of Omega-3 in an older population (and I'm still not happy that 60 is considered older!) does not appear to produce cognitive benefit. Even the researchers themselves hint at the shortcomings of the findings and suggest that fish should be part of a healthy diet "and still support the recommendation to eat two portions a week".
Maybe some nice herring would be a good fish to enjoy this week. Refs:
Emma Sydenham, Alan D Dangour, Wee-Shiong Lim. (2012) Omega 3 fatty acid for the prevention of cognitive decline and dementia. The Cochrane Library, June 13, 2012 DOI: 10.1002/14651858.CD005379.pub3
Z. S. Tan, W. S. Harris, A. S. Beiser, R. Au, J. J. Himali, S. Debette, A. Pikula, C. DeCarli, P. A. Wolf, R. S. Vasan, S. J. Robins, S. Seshadri. Red blood cell omega-3 fatty acid levels and markers of accelerated brain aging. Neurology, 2012; 78 (9): 658 DOI: 10.1212/WNL.0b013e318249f6a9
Janice K. Kiecolt-Glaser, Martha A. Belury, Rebecca Andridge, William B. Malarkey, Beom Seuk Hwang, Ronald Glaser. Omega-3 supplementation lowers inflammation in healthy middle-aged and older adults: A randomized controlled trial. Brain, Behavior, and Immunity, 2012; 26 (6): 988 DOI: 10.1016/j.bbi.2012.05.011