Our body uses vitamin D for so many different things. It helps our bones, our immune systems, our growth. But can it affect our mood?

In recent years, this has been an area of interest for scientific studies. With depression being named the leading cause of worldwide disability by the World Health Organization, and the estimated 14.8 million American adults who suffer from it, vitamin D could be an even more helpful supplement to our bodies than previously thought.

What is seasonal affective disorder (SAD)?

Seasonal affective disorder (SAD) is a type of depression that happens around the changing seasons. Most people who experience it notice SAD as fall changes to winter. It manifests itself in a few different ways:

• Feeling extra tired or unmotivated
• Feeling depressed throughout the day, for nearly every day during winter
• Increased cravings for carbohydrates or food in general
• Difficulty sleeping
• General agitation or anxiety
• Decreased sex drive
• Difficulty concentrating

About 10 percent of people living in areas far from the equator suffer from SAD. Yet, it’s not really well understood what causes it, therefore, it’s tough to understand how to treat it.

Vitamin D supplements could help with SAD

One area of study in recent years is the effect low vitamin D may have on SAD. We can get vitamin D from the sun and from our diet. In general, relying on the sun for a vitamin D source is unreliable. Factors like where you live, how long you spend outside, the weather, air pollution, how much skin is visible, even the pigment of your skin, can affect how well your body generates vitamin D when exposed to sunlight.

And in winter months, people may be spending even less time outside. So, using a vitamin D supplement is a reliable way to track how much vitamin D your body is getting. Studies have shown vitamin D deficiency may play a role in depression. In particular, women may have a greater need for vitamin D for their mental and physical health, as SAD is more common in women than men.

Treating SAD with light may be less effective

If our bodies can get vitamin D from sunlight and our diet, is one better than the other? A study that compared light therapy as a possible treatment for SAD found that people who spent an hour getting extra light had fewer symptoms than those who only got 15 minutes. However, a study comparing light therapy to vitamin D supplementation in people with SAD found depression decreased in the supplement group compared to the light treatment group.

In people not suffering from SAD, taking a vitamin D supplement along with vitamin A showed an enhanced positive affect. So, supplementing with vitamin D is a possible strategy for improving mood in healthy people as well as people with SAD.

Should you take a vitamin D supplement for SAD?

In recent years, the amount of vitamin D our bodies need is up for debate. It’s possible the currently recommended daily allowances (600 International Units) are actually quite low. Before starting any type of supplement, you should talk to a medical professional. Since vitamin D benefits so many systems in your body, a vitamin D supplement could be a good idea for your general health. Meanwhile, research will continue to look at the role vitamin D can play to boost your mood and fight depression.