This page on the NHS England website claims that eating fish oils (long chain Omega-3 I assume rather than any Omega-3) help prevent depression. It says:
Omega-3 fatty acid
Research has shown a link between the amount of a fish people in different countries eat and the level of depression. In Japan, where people eat on average 70kg (150lbs) of fish a year, the rate of depression is 0.12%. Whereas in New Zealand, where people eat only 18kg (40lbs) of fish a year, the rate of depression is almost 50 times higher.
It is though that a chemical found in fish – omega-3 fatty acid – may help your brain work more efficiently, so serotonin (which can boost your mood) has more of an effect on you.
Fish that contains a lot of omega-3 fatty acid includes salmon, sardines and mackerel. Vegetarian alternatives include walnuts and tofu, and omega-3 food supplements are also available over the counter (OTC) from health shops.
I don’t think this would get through on Wikipedia. “Research has shown” are weasel words if you don’t say who’s research and where. This is a shame because on the same site is a well balanced report on a reasonable study of whether a mediterranean diet prevents depression. The contradiction between these articles is interesting.
To show how ridiculous the fish oil claim – that people in Japan are less depressed because they eat more fish – real is consider the graph below (taken from the EqualityTrust.org.uk site – a great site go and donate now).
It shows that there is a correlation between mental health and inequality and that New Zealand is a ‘worse’ place than Japan for mental health ‘because’ NZ is a more unequal society. Is there are causal link between fish consumption and income inequality I wonder?
Given the choice between depression being caused by a chemical imbalance and depression being caused by a more complex set of social (even ethical or religious) conditions it is easy to see which the market would prefer to respond to. Eat more fish! Take these supplements!
I have a load of material on the fish oil ‘conspiracy’ that I’ll have to find time to post. In the mean time if anyone has actual scientific research showing that eating fish makes people happy (other than just because they like the taste) I’d love to see it.
There is a lot of literature on Omega-3 and mental health. Check PubMed.
What is the income inequality within the population of Japanese Americans?
See also http://en.wikipedia.org/wiki/List_of_countries_by_suicide_rate
Thanks for your interest. There are indeed many papers in PubMed on this but none that show there is any advantage to healthy people’s mental health to consume Omega-3 and, I would contend, no evidence to show that even un-healthy people benefit. Most studies that look like they were well carried out end with statements like this “However, existing studies on omega-3 fatty acids in depression have limitations such as small sample sizes and a wide variance in study design, and results regarding efficacy are mixed.” (http://tinyurl.com/ykv7guo) or “In the studies that demonstrated statistical significance, improvement in depression rating scale scores for omega-3 fatty acids was comparable to placebo.” (http://tinyurl.com/yewxdkh).
Omega-3/6/9 supplementation studies should be easy to carry out – you just give people pills or placebo or nothing.
Don’t know about Japanese Americans. That would be way to complex a study.
Suicide is one of the things that isn’t effected by income inequality. It is in the Spirit Level book but not on their website. Generally people in stressed situations (e.g. war zones of violent suburbs) don’t kill themselves – these things are more complex.
Looking at the wikipedia suicide rate page natural oily fish eating nations such as Finland have higher suicide rates than places like New Zealand which would directly contradict the original NHS web page.
My point is that these simple links between one dietary component and mental health are probably nuts!
Eating fish does make me happy, actually. Though I guess it depends with whom I share the meal.