This time of year, as the days become shorter and the sun is lower in the sky, many people start to suffer from Seasonal Affective Disorder (SAD). Depression, low energy and social withdrawal are all symptoms associated with SAD. Sometimes, it can turn into long-term depression.
Recommended treatments for those afflicted with SAD include taking long walks during daylight hours and staying socially active, even if this requires some effort. Light therapy, using a special light with a very bright fluorescent lamp that mimics sunlight, may also be helpful. This latter treatment should only be done in accordance with your doctor’s instructions.
Exactly why SAD occurs and how increased exposure to sunlight or artificial light can help alleviate the condition is not fully understood. But biomedical research is starting to indicate a connection to vitamin D.
One respect in which vitamin D is quite unusual is that most people’s diets do not provide it in adequate amounts; very few foods naturally contain this vitamin. Instead, unless one takes a vitamin supplement or eats foods fortified with vitamin D, nearly all of it in the body is made by our skin when it is exposed to sunlight. Thus, vitamin D’s nickname is the “sunshine vitamin.” Once it is made, the body modifies the vitamin into a steroid hormone. Such hormones have powerful effects on human physiology, and this probably explains vitamin D’s seemingly broad benefits.
Biomedical evidence is accumulating for vitamin D’s crucial importance in maintaining human health in a variety of ways. In addition to its well-known ability to help build and preserve strong bones (by facilitating calcium absorption), it has also shown signs recently of counteracting cancer, heart disease, autoimmune disease, the flu, high blood pressure and Parkinson’s disease, to name a few. This all seems credible given that we now know vitamin D influences a wide range of cellular functions by binding to vitamin D receptors, specialized proteins found on surfaces of cells throughout the body.
In recognition of the growing body of data indicating vitamin D’s importance, one year ago, the US Institute of Medicine (IOM) adopted higher recommendations for vitamin D intake from 200 to 600 international units (IUs) per day for adults up to age 70 and 800 IUs for people over 70. Not to be outdone, the Endocrine Society, the world’s largest and oldest scientific group focused on hormone research, recently called for vitamin D intake two to three times higher than even the IOM’s new recommendations.
These are important developments, because according to the National Center for Health Statistics, many of us are vitamin D deficient. The reason for this is clear enough. Whereas our ancient ancestors spent a lot of time in the sun hunting and gathering, or later farming, now most people live and work indoors, and thus receive comparatively little exposure to the sun. The higher the latitude at which a person lives, the worse this problem can become, especially in winter when sunlight is in short supply and the harsh weather necessitates full-body protection.
According to Nathan Seppa, a biomedicine staff writer for the magazine Science News, many studies have linked vitamin D deficiency with depression. Moreover, Seppa has also reported that a 1999 US study showed that a large increase in vitamin D intake improved the depression scores in people with SAD.
What’s the best way to increase one’s vitamin D levels? Taking vitamin pills can help, but spending more time in the sun may be the safest practice, as “overdosing on vitamin D from the sun appears impossible,” according to Seppa. Not only that, but sunlight is extremely effective in causing vitamin D synthesis by the skin, and the form of the vitamin made by our skin is superior to the form sometimes found in pills.
Of course, the risk of skin cancer from sun exposure must always be kept in mind, and sunburn should be strictly avoided. However, Science News also reported that as little as a brief five- to 10-minute tan on the arms and legs can produce upwards of 2000 IUs of vitamin D. We are lucky here in Southern California, because such exposure to sunlight is often possible even in the middle of winter.
So, “let the sunshine in” and help yourself to a free dose of vitamin D several times a week! You may have nothing to lose but your SAD.
John Grula, PhD, is affiliated with the Southern California Federation of Scientists.