Vitamin D and depression

The Link Between Vitamin D and Depression

There is an association between low vitamin D levels and mood disorders, especially depression.

Although researchers have yet to conclude exactly how vitamin D impacts mood, there are extensive vitamin D receptors located throughout the nervous system and brain and there is a wide consensus that low vitamin D levels are connected to depression.

How is vitamin D made?

Vitamin D production is initiated by the skin being exposed to UV light which begins the process of converting inactive vitamin D into an active form of vitamin D that the body can use.

With the increased awareness surrounding being sun safe and reducing skin cancer risk, we often don’t get the adequate 30 minutes of full-body sun exposure that would render sufficient vitamin D levels during the summer months.  Moreover, UK weather can be unpredictable, and we can go for weeks and weeks without seeing the sun! As we head into the darker months of autumn and winter, vitamin D levels can become further depleted.

Although it is also possible to get some vitamin D from foods, this is not such a rich source.

Vitamin D and mood

Acting like a hormone, vitamin D has many important roles in the body, including regulating the immune system, promoting bone health, and balancing mood.

There are several different potential theories as to why low vitamin D is implicated in depression:

Neurotransmitters: Vitamin D is involved in the production of neurotransmitters, such as the contentment neurotransmitter serotonin. One of the theories of depression is insufficient serotonin levels and this is often the target of antidepressant medication.

Stress Response – Vitamin D plays a role in the regulation of the body’s stress response, enabling a better-regulated stress response that can promote improved resilience to daily stress. Stress is a close relation to depression and anxiety – chronic stress often precedes bouts of dysregulated mood.

Anti-inflammatory – Vitamin D is recognised as possessing strong anti-inflammatory properties and it is thought that it may play a role in preventing brain inflammation. A leading, modern theory of depression is low-grade brain inflammation.

Brain adaptation and development – vitamin D plays a role in promoting brain plasticity, which involves brain repair, the growth of new brain cells, and neural connections, enabling adaptation to environmental situations. This adaptability helps us to form appropriate responses and have a degree of resilience, something that we often lack when experiencing low mood and anxiety.  

Risk Factors for low vitamin D

Some people are more likely to be low in vitamin D. Risk factors include:

Being overweight or obese – vitamin D can become stored away in fatty tissue, rendering the body unable to access and utilise it, therefore being overweight or obese can directly lead to a vitamin D deficiency.

Having a darker skin tone – people with darker skin tones have a higher proportion of melanin, which limits access of UV light, and therefore, vitamin D production in the skin. This can especially be an issue for those living in an area of less natural sunshine, such as the UK.

Gut issues – gut issues that impact nutrient absorption, such as inflammatory bowel disease, can impair the body’s ability to absorb vitamin D, both from dietary sources and its converted active form from UV light.

Kidney and Liver issues – the kidneys and liver are directly involved in the process of activating vitamin D from UV light, therefore those with impaired function of either of these organs are also at risk of deficiency.

The importance of vitamin D testing

The NHS currently recommends supplementing with 400iu vitamin D a day during the autumn and winter, but this is usually insufficient to correct a deficiency. It is dangerous, however, to supplement with higher levels of vitamin D without ascertaining existing levels via a blood test. This is because too much vitamin D can be as harmful as too little. I therefore almost always recommend testing a client’s vitamin D levels, so that I can ensure accurate and targeted dose rates to see marked improvements more rapidly.

Food sources of vitamin D

Although sunshine exposure is the best natural provider of vitamin D, it can also be found in some foods. However, it is only really possible to gain around 10% of vitamin D requirements from food compared to sunshine.

Vitamin D can be found in the following sources:

  • Oily fish – such as salmon, mackerel, and sardines
  • Eggs
  • Liver
  • Fortified foods – such as breakfast cereals and milk
  • Mushrooms (when grown under UV light)

Take home point:

If you are experiencing low mood, it is important that you get your vitamin D levels tested, especially if you also have a risk factor for low levels. Low levels are easily rectified but it is dangerous to do so without testing.

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