Why we need Vitamin D for mental health

In this article I’ll outline what Vitamin D is, how we get it and what it does. I’ll then looks at why there is a big problem with deficiency, the evidence for mental health improvement, and my own clinical experience and practice for helping people with mental health problems with low vitamin D.

Photo by Pixabay: https://www.pexels.com/photo/abstract-beach-bright-clouds-301599/

What is a Vitamin?

Vitamins aren’t just things that your mum used to make you take as a kid as you didn’t eat broccoli.  They are essential chemicals that your body and mind need to function effectively.  You can’t make them yourself, although your body can manipulate them a bit if it has the basic chemical building blocks.

Why do we need Vitamin D?

Vitamin D has multiple key roles in you which include effective functioning of bone, muscle, brain, immune system.  Other roles include regulating inflammation regulation, immune function, blood sugar control.  Furthermore, if you are very  deficient, serious bone diseases such as rickets can occur, or you may get tetany (muscle cramping).

Deficiencies in Vitamin D are associated with multiple chronic diseases & cancers, ans also long-COVID.  Also, other symptoms can be vague including recurrent viral illnesses, fatigue, anxiety, depression, slow wound healing, hair loss, muscle pain.

How do we get Vitamin d?

Let’s start by Taking a look at the diagram which explains the processes involved. 

Firstly, Vitamin D is largely made in the skin by absorbing UV rays from sunlight.  It changes in our liver and kidney to Vitamin D2, then Vitamin D3 (the active, effective form). 

Secondly, It is also available in our diets as oily fish as D3, like salmon, mackerel, anchovies, sardines, herring.  A good way to remember this is SMASH.  It is also in some fortified foods like cereal. 

Thirdly, Increasing numbers of people take supplements – tablets of Vitamin D3, or Fish liver oils (most well known is cod liver oil).

Credit: Ed Rainbow

Why are people deficient?

Sadly, there is a pandemic of Vitamin D deficiency currentlyIt won’t surprise you to learn that lack of sun exposure  due to living in northern latitudes with less sunlight, living inside, and lifestyle restrictions due to COVID-19 are a big part of this.  Other lifestyle factors include the use of suncream, which stops 97% UV absorption UV light.  Those with darker skin, or who wear covering clothing year round also will produce less. 

In addition, where oily fish would have been fished and eaten previously, our diet has changed to eat less of these.  Finally, medications play a big role.  As Vitamin D is contained in dietary fats, so Statins (which 8 million adults  in the UK use) & fat losing drugs like Orlistat could lead to deficiencies.  Finally, medication including antiepileptics and steroids can also affect levels adversely.

What is a normal level?

Let’s pause to consider the Units of measurement. They can be are confusing  and there are two measurements in use.  They are: nmol/L (nanomoles per litre of blood) and ng/mL (nanograms per mililitre of blood).  In the UK we use nmol/L. For reference, 1 nmol/L = 0.4ng/mL, 1ng/mL = 2.5 nmol/L

A frank deficiency is thought to be <30nmol/L, or and those potentially at risk if 30-50nmol/L.  A Level of >75nmol/L is needed for effectiveness of bodily functions.  There is a Potential risk of toxicity >125nmol/L.  To conclude, the effective range for most people is 50-80nmol/L

Supplementation – what should I do?

Nature’s way is always best.  A good starting point is Ideally get more sunlight & eat more oily fish.  White skin types should aim for 10-15mins/day from March – September, whilst darker skin should aim for 25-40 mins/day.  Oily fish recommendations are for 1 portion (140g) per week.  There are benefits beyond this, which include getting Omega 3 in your diet,which is good for multiple body systems.

What about tablet supplementation, how do we go about this?   

Firstly, let’s take a moment to understand the three different measurements.   Number one is  the NRV (Nutritional Reference Value) is 400 IU/day.  This is the level thought to prevent the occurrence of bone diseases like Rickets and osteomalacia.  I find this has little practical value. The other two that useful are IU (international units) and mcg (micrograms)

To convert between the three values – 1,000 IU (international units) = 25mcg (micrograms) = 500% NRV (nutrient reference value) I tend to use IU values.

One more thing to note, is that supplementation should be in the active form, Vitamin D3 (also know by two names: cholecalciferol-D3 / alfacalcidol)

Do I need Vitamin D to improve my mental health?

This is a complicated question to answer.

Whilst the evidence of supplementation is clear for some diseases, for example, there’s evidence showing supplementation that it can improve life expectancy in people with cancers, this isn’t so clear cut for Vitamin D.  This summary of studies tells us that Vitamin D supplements are unlikely to improve mental health problems on their own.

A reason for this is unfortunately, the few studies that have been done in this area are of mixed quality, use different doses and outcomes.  Whislt some of the studies show some benefit, and the authors acknowledge that doing this alongside areas with stronger evidence like exercise and diet improvement is more likely to be beneficial.  Similarly, Seasonal affective disorder and Vitamin D studies have the same conclusion.

However, Lifestyle Medicine looks at the whole picture, not just the numbers on a chart. We know that often there are multiple areas in mental health, particularly sleep and stress management which are important to address aso. Also, We know that having a healthy level of vitamin D is important for functioning of multiple body systems.  Furthermore, it’s also very important for effective absorption of other key minerals like alcium, phosphate and magnesium.  Magnesium in turn, is involved in regulating this absorption and production of the active end product

My experience of Vitamin D and mental health management

In my NHS work I’m fortunate enough to be able to measure Vitamin D, which I know that not all colleagues are able to do.  I find it’s valuable to check in those with mental health issues.  In fact, I find nearly everyone with a mental health issue I test is deficient (<30nmol/L), and I advise patients to correct this as per UK guidance (5,000 IU/day for 2 months), and then moving to a maintenance dose of 1-2,000 IU/day . It’s also important to note some people are poor absorbers / poor converters, so you won’t know if you don’t test & retest after treatment.  Furthermore,  I explain clearly this won’t act as a cure, but may help alongside  multiple areas of lifestyle change.   

Personally, as I have darker skin, work largely inside and have had mental health problems in the past, I take 1-2,000 IU/day.  I believe personally it’s important to keep this in the healthy range for my mental health and functioning.

I have a mental health problem and I also think I have Vitamin D deficiency.  What should I do?

A good place to start would be with your GP, who can assess both of these areas, and make sure you’re safe..

If you’d like to take a holistic approach to your mental health, please book a call so we can discuss further.  I look forward to hearing from you.

This article is just for information.  Always consult your doctor before starting a new vitamin supplement.  Do not stop or change any medications without consulting your doctor


Vitamin D – National Institute of Health [Accessed June 2022]


Vitamin D Deficiency Management, National Institute of Clinical Excellence  [Accessed June 2022]


Is Sunlight Exposure Enough to Avoid Wintertime Vitamin D Deficiency in United Kingdom Population Groups?


MF, Binkley NC, Bischoff-Ferrari HA, Gordon CM, Hanley DA, Heaney RP, et al. Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab 2011;96:1911-30. [PubMed abstract]

Rosen CJ, Abrams SA, Aloia JF, Brannon PM, Clinton SK, Durazo-Arvizu RA, et al. IOM committee members respond to Endocrine Society vitamin D guidelines. J Clin Endocrinol Metab 2012;97:1146-52. [PubMed abstract]

Association between Vitamin D Supplementation and Mental Health in Healthy Adults: A Systematic Review


Association between vitamin D supplementation and mortality: systematic review and meta-analysis


The Vitamin D Deficiency Pandemic and Consequences for Non Skeletal Health: Mechanisms of Action


The Vitamin D Deficiency Pandemic: a Forgotten Hormone Important for Health


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