Vitamin D and Mood: Shedding Light on Anxiety and Depression

✍️Elena Dennis | MSc Neuroscience graduate and aspiring medical writer

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As the evenings get darker in winter, it's common for the 'winter blues' to kick in. Winter depression is referred to as Seasonal Affective Disorder (appropriately called SAD for short). So, is there a link between sunshine, vitamin D, and mood disorders? Can we boost our mood with sunshine or with Vitamin D supplements?

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What is Vitamin D?☀️

Vitamin D is an essential vitamin which our bodies produce when ultraviolet radiation (UV) from the sun hits our skin. Its roles include helping the body absorb calcium as well as reducing inflammation.

Vitamins are 'micronutrients', essential compounds which our bodies require in relatively small quantities. We can obtain vitamin D through diet: oily fish such as trout, tuna, and salmon are naturally high in vitamin D. Egg yolks, some cheese, and some mushrooms can also provide us with vitamin D. However, 80% of our vitamin D is synthesised by our bodies using sunlight. We need UV-B radiation, which is slightly shorter wavelength and higher energy than other UV radiation, and is mostly blocked by glass. This means that UV-B can't reach us through windows, so you need to feel the sunlight directly on your skin to allow your skin cells to produce vitamin D.

What is the benefit of Vitamin D?

We require vitamin D for the absorption of calcium, which keeps our bones healthy and prevents bone weakness or osteoporosis. Vitamin D is also an antioxidant: it helps prevent oxidation of our cells (the equivalent of rust inside our bodies) therefore reducing cell damage and reducing inflammation.

Am I getting enough?

If you live in Europe, probably not. Recent research showed that 40% of Europeans are vitamin D deficient. In winter, sunlight includes very low levels of UV-B so we are unable to synthesise much vitamin D on sunny winter days.

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Is Vitamin D and Depression Linked?😔

What is depression?

Depression is a common mental illness involving persistent feelings of sadness or lack of pleasure in usual activities. Symptoms include disrupted sleep and eating habits, tiredness and reduced ability in concentration

With rates of depression increasing in winter months, it seem logical that sunlight or vitamin D may link to mood. However, research into vitamin D and depression is conflicting.

Supporting evidence 📝

One study into older adults found a correlation between vitamin D deficiency and low mood and cognitive impairment. Another study found that daily vitamin D supplements reduced negative emotions, especially in patients with major depression.

There are vitamin D receptors present in brain areas which could link to depression, such as the prefrontal cortex and the hippocampus (which have roles in decision making, concentration and memory). There are also vitamin D-related enzymes found in the amygdala, a brain area responsible for negative emotions and fear. These could explain how vitamin D mediates mood and symptoms of depression.

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Is Vitamin D and Anxiety Linked?😟

What is anxiety?

Anxiety is a common type of mental illness involving frequent feelings of unease and worry. There are many different anxiety disorders, such as generalised anxiety disorder, phobias, social anxiety, and OCD.

Supporting evidence 📝

Research found that one third of people with Vitamin D deficiency had anxiety. Another study found significantly lower vitamin D levels in both people with depression and people with anxiety. One study found that vitamin D supplementation reduced anxiety symptoms but not depression. Research using mice showed that lacking vitamin D receptors caused signs of anxiety.

As already mentioned, there is a link between vitamin D activity and the prefrontal cortex and the amygdala, two brain areas likely to influence anxiety due to their roles in impulse control, fear and worry.

Criticisms 🤔

One issue is that much of the research linking vitamin D deficiency to depression and anxiety is correlational so it is difficult to infer cause and effect. We can't be sure low vitamin D causes mood disorders just because people with depression and anxiety have low vitamin D. Some studies have contradicted this idea, such as a Chinese study which concluded no significant association between low vitamin D and mood disorders once all other factors were taken into account.

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Is Vitamin D and Inflammation Linked? 😳

Inflammation is part of our bodies' immune response to deal with injury or illness. This makes us go red, swell up, with a goal to help us heal. However, too much inflammation is damaging and causes illness. Various studies have linked high inflammation with both depression and anxiety, with patients showing high levels of inflammation-linked chemicals in their blood.

Vitamin D might protect brain health with its antioxidant activity, which reduces inflammation and oxidative stress (again, the equivalent of rust in our bodies which can damage or kill our cells). Vitamin D reduces oxidation and boosts other antioxidants, which has been suggested to reduce cancer and diabetes, as well as potentially depression and anxiety, which have been linked to inflammation in the brain.

What can I do to boost my mood?💊

Research suggests that vitamin D supplementation might reduce negative emotions and symptoms of anxiety and depression. We are recommended 10 µg per day, so it may be a good idea to take supplements during autumn and winter when your sun exposure is reduced.

Aim to eat vitamin D-containing foods, such as fish and mushrooms, to boost your levels. Control inflammation with an anti-inflammatory diet, high in fruits and vegetables and low in processed foods, to help reduce low mood.

Many studies have linked exercise to a reduction in mood disorders, so including regular exercise should help boost your mood.

What conclusions can be made about Vitamin D use? ☀️

Vitamin D is an essential chemical which reduces inflammation in our bodies and therefore reduces illness. During winter, we are unable to synthesise much vitamin D, and we are unable to absorb sufficient vitamin D from our diets. Several studies have linked low vitamin D to mood disorders such as anxiety and depression, and some studies have shown an improvement in mood when taking vitamin D supplements. Overall the research is not 100% conclusive, but taking vitamin D supplements might boost your mood and reduce symptoms of mental illness.

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Edited by: Olivia Laughton | Content Editor | BSc Microbiology, University of Leeds

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