Seasonal Affective Disorder .Every year, as the days get shorter and the weather gets , colder millions of people (particularly in the northern climates) are affected by a condition known as SAD or Seasonal Affective Disorder. About a third have the actual SAD, as it is clinically defined, while the rest can be lumped into the winter blues category, which many of us can identify with.
Natural light and Tryptophan
There are many theories as to why this condition exists and trying to isolate a single causal factor is unlikely. Many feel that SAD is likely due to an imbalance of the neurotransmitters melatonin and erotonin. Production of both of these neurotransmitters, which are made from the amino acids trytophan, is controlled by the pineal gland located in the brain, which is sensitive to natural light. Currently exposure to full-spectrum light remains the most widely used therapy today. Natural sources of trytophan can be readily found in foods like turkey but youre going to need the carbohydrate from the mashed potatoes to get it into the brain. The word Comfort food certainly applies in this case.
Vitamin D , a very powerful pro-hormone, has also been implicated in SAD since production is also determined by natural light exposure. Studies have been able to show improvement in those individuals with depressive symptoms given adequate dosing of this vitamin. How much to take is a matter of some debate but for those living in the northern latitudes like Canada a reasonable amount to supplement would be between 3000 and 7000 IU per day depending on your current vitamin D status. To keep this in perspective it is estimated that for those with fair skin the body will make approximately 20,000 IU in one half hour of full body sun exposure . As one researcher put it worrying about a vitamin D overdose is like worrying about drowning when you are dying of thirst in the middle of the desert! A simple blood test called a 2-5 OHD test can easily determine this. The ideal range should be between 35-55 ng/ml. This writer would argue that one should aim for the upper limit, as this is what one would achieve naturally by being in the sun. Nature has conveniently put a physiological limit as to how high our levels can get by breaking down vitamin D after a certain period of sun exposure.
Lastly, one cannot ignore the pivotal role that essential fatty acids play in moderating and alleviating symptoms of mild depression. Numerous studies have found a positive effect on mood by the addition of Omega 3 Fatty Acids in the diet. But please remember it is the long chain fatty acids EPA/DHA most easily found in marine sources that are providing the benefits. Those oil blends with a higher EPA to DHA ratio seem to provide better support for mood elevation than oils with near equal amounts of EPA/DHA.
P.S. Some have noted that the Icelandic population suffers from a lot less SAD than one would expect from those living at such high latitude. Could it be the vitamin D rich fish oil in the Cod? I wonder?