Well, it’s that time of year again. The clock rolled back and we (everyone except Arizona) got a fabulous extra hour of sleep. But, we also now have to deal with the reality of a morning and evening commute in the dark. This fact can be a little depressing on its own but this lack of daylight really may contribute to depression on a biochemical level. As you probably already know we need sunlight to produce Vitamin D, which is actually really a hormone. It is a hormone whose widespread duties in our body are still being discovered. Interest in the connection between low Vitamin D levels and depressed mood is growing, especially in light of statistics that show that a full 1/3 of Americans have insufficient levels of Vitamin D.
Many studies including this meta-analysis from researchers in Canada show that there is a correlation between low Vitamin D levels and depression. Studies showing the nature of that relationship in terms of direct causation are lacking, but definitely needed.
Low Vitamin D levels have also been linked to many other chronic illnesses. This prospective population study out of the United Kingdom followed a group of people over a period of 13 years and found decreased all cause mortality, decreased incidence of cardiovascular diseased, decreased incidence of respiratory disease and decreased incidence of fractures in those who had higher Vitamin D levels. Those with the lowest risk had Vitamin D levels over 90 nmol/L.
There are many reasons why so many of us have inadequate levels of Vitamin D. We spend much more time inside than our ancestors ever did. And no, the sun that you get while you’re driving in your car doesn’t count as we don’t synthesize Vitamin D from sunlight through glass. We also, especially women, wear sunscreen and other beauty products with high SPF.
There are several ways to up your Vitamin D levels this winter. One is to try to spend some time outside during the day. Another is to consider starting a daily vitamin D3 supplement. The third, which is in line with our mission, is to think about getting that nourishment through your food. The best source of Vitamin D is in fatty cold water fish, such as wild caught salmon and tuna. There are concerns about the mercury levels of such large fish that are at the top of the food chain. Other cold water fish to try that may be a little safer are fish such as herring, anchovies and sardines. Eggs yolks, especially those from pasture-raised eggs have a good amount of vitamin D. If you’re up for it liver, either in the form of cod liver oil or eating beef liver, has high levels of vitamin D. Fortified foods such as milk and cereals advertise that they have vitamin D but it is mostly in the form of D2, which is less usable by your body. I would also in general encourage getting nutrients from whole foods rather than fortified processed foods.
Many call vitamin D our most important micronutrient. Whether you’re feeling depressed or not, I highly recommend getting your vitamin D level checked, in the form of 25-hydroxyvitamin D or 25(OH)D, and trying to get good forms of vitamin D into your diet this winter.