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Most North Americans are familiar with the term "winter blues and some are affected by the decreased daylight hours of winter. This condition is known as Seasonal Affective Disorder (SAD).

Most North Americans are familiar with the term "winter blues" and some are affected by the decreased daylight hours of winter. This condition is known as Seasonal Affective Disorder (SAD).

A SAD diagnosis is made when the following symptoms occur during two or more autumn/winter seasons and resolve themselves during the spring and summer:


  • sadness
  • irritability
  • anxiety
  • increased appetite (strong craving for carbohydrates)
  • lethargy
  • increased sleep

What's Your Latitude?

Research shows that SAD is strongly influenced by latitude. The northern regions report higher rates of SAD versus regions closer to the equator. This could be because there are more defined season changes. Family and twin studies also indicate that SAD is influenced by genetics. Latitude and genetics are, however, not the only influences.

Eat More Fish

New research indicates that nutritional influences over SAD may be underappreciated. Despite latitude, rates of SAD are much lower in Japan and other areas of Europe versus North America. Incredibly, SAD is virtually unknown in Iceland despite its extreme seasonal changes. These regional differences were recognized by researchers from the US National Institutes of Health (NIH) who made a strong connection between low national SAD rates and high fish consumption. They published their research in the American Journal of Psychiatry (February, 2001), finding that Japan and Europe consume considerably more fish than North Americans.

Similar studies have connected national fish consumption rates and protection against non-seasonal, bipolar, and postpartum depression. The NIH researchers also suggested that maintaining a traditional high fish diet is protective against SAD when Icelanders immigrate to Canada. This means that dietary omega-3 fatty acids from fish may have the potential to trump genetics and latitude.

Further support for the omega-3 connection is based on new research which shows rapidly escalating rates of SAD among traditional communities in polar (Arctic) regions. The typical Western diet high in simple carbohydrates and saturated fats has steadily replaced the traditional high seafood diets among the Arctic peoples. As a result, omega-3 intake has declined. Researchers from the University of Alaska, Institute of Arctic Biology, have pointed to this declining omega-3 intake as a contributing factor in the alarming increase in SAD and other conditions such as depression and anxiety in these Arctic communities.

A number of studies show that blood and fat (adipose) levels of omega-3 components eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are low in non-seasonal depression. Experi-mental research shows that omega-3 deficiency and omega-6 (corn, safflower, sunflower) excess can cause changes to brain physiology and structure that are strikingly similar to depression. Because eating enough fish is not always possible or healthy due to mercury contamination, turning to omega-3s in supplement form is a safe and convenient option.

Fish consumption and fish-oil supplementation is not a substitute for appropriate mental health evaluation and care. However, fish and omega-3 supplements have other health benefits, particularly in cardiovascular health. In addition to standard care, increasing fish consumption and incorporating an EPA-rich fish oil supplement should be a consideration for those experiencing the symptoms of SAD.

Fish Consumption

The NIH found that Iceland consumes approximately 225 lbs of fish per person per year while Japan consumes 147 lbs. In North America the consumption is lower; Canadians consume 51 lbs per person, and the US consumes 48 lbs.



Your winter wellness game plan

Your winter wellness game plan

Stay healthful when the weather outside is frightful

Joshua Duvauchelle

Joshua Duvauchelle