Depression causes feelings of sadness and/or a loss of interest in activities you once enjoyed (3).

Other symptoms may include changes in appetite, not sleeping enough or sleeping too much, feeling tired, difficulty concentrating, and sometimes thoughts of suicide.

Groups, such as the elderly, adolescents, the obese, and people with chronic illnesses, are at increased risk for vitamin D deficiency and depression.

Research clearly shows a relationship between vitamin D and depression, but it’s not clear exactly how that relationship works.

While people with depression may have lower levels of vitamin D, research has not shown that vitamin D deficiency caused them to develop depression.

Here is some of the research about vitamin D and depression:

Staying indoors, social withdrawal and isolation, and a poor diet may cause people with depression to have lower vitamin D levels.

So, getting outside, socializing, eating a healthier diet, and taking a vitamin D supplement recommended by your doctor may raise your vitamin D levels and improve your symptoms of depression.

Seasonal affective disorder (SAD) is a type of depression that comes and goes with the seasons (8).

Usually, people with seasonal affective disorder have depression-like symptoms in the winter when there are fewer daylight hours.

Vitamin D could play a role in seasonal affective disorder.

Fewer daylight hours can lead to lower vitamin D levels, which could contribute to SAD symptoms.

Ask your doctor to check your vitamin D levels and recommend a vitamin D supplement dosage to start in early fall to make sure you have good vitamin D levels in the winter.

Anxiety can be a normal response to stressful situations, but people with anxiety disorders often have intense and excessive worry and fear that interferes with their life (9).

Anxiety disorders include generalized anxiety disorder (GAD), obsessive-compulsive disorder (OCD), panic attacks, social anxiety disorder, separation anxiety disorder, and various phobias.

Research also shows a link between vitamin D and anxiety:

You can get vitamin D from exposing your skin to the sun (without sunscreen), from eating foods high in vitamin D, or from a vitamin D supplement.

Vitamin D deficiency is common in the United States, especially in people with darker skin.

Research estimates that up to 42% of Americans have a vitamin D deficiency, but 82% of black Americans and 69% of Hispanic Americans are deficient (13), (14), (15).

The only way to know if you have a vitamin D deficiency is to ask your doctor to measure your vitamin D level with a blood test.

Your vitamin D blood level should be at least 30 ng/ml (75 nmol/l) (16).

Only a few foods are naturally rich in vitamin D.

They include cod liver oil, salmon, tuna, sardines, beef liver, egg yolks, mushrooms, and vitamin D-fortified milk, orange juice, and breakfast cereal.

If you don’t eat lots of fatty fish or don’t spend a lot of time in the sun (without sunscreen), you should consider a vitamin D supplement.

Vitamin D3 is the best choice for a vitamin D supplement because vitamin D3 raises vitamin D levels in the blood higher and keeps them there longer than vitamin D2 (17).

There are many causes and symptoms of depression and anxiety, and no single drug, vitamin, or treatment can make them disappear.

But studies show that keeping your vitamin D at a good level may provide some relief from your symptoms of depression and anxiety.