Good one ShelL. There is a reason why sunshine produces Vitamin 'D' in virtually every living being, and the winter sun, or those who do not get much sunlight is most often deficient in it. I supplement mine, based on sun cycles to ensure peak optimization. However, usually simple blood tests can determine where you are deficient. Nutritionists too, can help show if you are lacking in certain areas. Diet does affect mood quite often... Just 'food for thought'.
