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Vitamin D, the “sunshine vitamin,” has often been linked to a change in mood. The lack of sunlight in winter can cause lower mood, ranging from a mild droop, to severe seasonal depression.

Although there are Vitamin D supplements that are relatively inexpensive and safe to use, depression is much too complicated to have a singular, curable cause. As a result, finding ways to treat depression can be an arduous task. So, what does the evidence say when it comes to vitamin D? Can it cure depression at all?

How Does It Work?

Vitamin D can be ingested (vitamin D2 and vitamin D3) as well as synthesized by sunlit skin (vitamin D3). As a result, receptors for vitamin D can be found all over the body. Therefore,  its effects on mood are numerous, depending on how much vitamin D is ingested/produced and where it is absorbed into the body. For example, vitamin D is used to regulate your testosterone levels, which can cause a drop in mood if it is too low.

However, although studies may show a correlation between mood and vitamin D, it does not prove that low vitamin D causes depression. Someone who is depressed may go outside less, leading to less exposure to sunlight, thus lowering vitamin D levels – depression is the cause of low vitamin D, rather than the other way round.

Another way in which vitamin D and depression can be linked are by considering the amount of someone’s exercise. By not going out as much it is fair to assume that a person is getting less exercise. With less exercise, a drop in someone’s mood is more likely, as well as less sleep. In this case, a person may develop low mood and low vitamin D, even though neither are the cause or the effect of the other.

Therefore, it is almost impossible to prove whether a singular factor is affecting a person’s mood or vitamin D production, as several factors are likely to be at play. 

Who Lacks Vitamin D?

It may seem surprising, but vitamin D deficiency could be affecting as much as 50% of the population worldwide. In the UK it is believed that 1 in 5 people suffer from vitamin D deficiency. By looking into different ethnic groups, it is evident that certain groups are prone to vitamin D deficiency more than others. According to some reports, over 50% of Asian people living in the UK suffer from the condition, with approximately a third of the black community suffering from it too.

Overall, a lack of sunlight is blamed as the main cause, mostly due to the UK’s longer winter months and fewer people spending time outside. However, for those with darker skin; their higher melanin levels, which cause pigmentation, prevent the skin from synthesising vitamin D as easily as those with lighter skin. Together these two factors combine, contributing to a higher chance of vitamin D deficiency for those in the Asian and black communities.

It can still affect people with lighter skin, however. Ignoring how much sunlight or dietary vitamin D you get could lead to weaker bones. This is due to the vitamin D hormone’s relation to calcium regulation in the blood, which helps to increase bone strength.

If you wonder where you fall on the scale, getting a test twice a year during midsummer and midwinter – the longest and shortest days of the year – will let you know how your vitamin D levels are affected seasonally.

What Does The Evidence Say?

Several studies between 2015 and 2017 suggest that there is some correlation between the level of vitamin D and depression. However, some of these studies have raised issues with bias and methodology. For example, some of the individuals tested in these studies were found to have low levels of depression with sufficient levels of vitamin D (before supplements were taken).

If a test subject had higher levels of depression or insufficient levels of natural vitamin D production, then the results might be more significant with regards to whether supplements help or not. Therefore, it can’t be ruled out that those with greater depression or less vitamin D production could benefit from taking supplements.

So, if you considered only the studies whose subjects had insufficient levels of vitamin D, but were given enough to reach a sufficient level throughout the trial, then supplements were almost as effective as antidepressant medication.

What does this really mean though? Well, it seems that, due to the complexity of depression and its numerous causes and triggers, vitamin D is not a definitive cure (nor is it likely to be). There are simply too many factors at play as to why someone is depressed or why someone’s vitamin D levels are low. It is an issue that is far from binary. However, if you do need vitamin D supplementation, they are easily obtainable for you to boost your vitamin D3 levels.

Primal Bite

Vitamin D is actually a hormone rather than a vitamin, which can be both ingested or produced via exposure to sunlight.

Approximately 50% of the world’s population suffer from a vitamin D deficiency.

Studies have shown very few beneficial effects of vitamin D supplementation, but further studies are required to help understand this more.