Vitamin D - We all should be supplementing!

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The current guidance in the UK on vitamin D is that we should all supplement with 400 IU (10 μg) to prevent deficiency although babies up to 1 year may need a different dose.  Here’s why:

Vitamin D is vital for the health of our bones and teeth but is increasingly thought to play a role in regulating our immune system, cell division, muscle function and in preventing respiratory infections. Low levels of vitamin D have been associated with poorer outcomes for those who develop COVID-19 symptoms and this has thrust the “sunshine vitamin” into the spotlight.

We already know of a clear association between users with vitamin D deficiency and a poorer diet, but also that users without a vitamin D deficiency are more likely to report feeling happier.

While we know a lot about vitamin D, a large proportion of people in the UK still have insufficient levels due to their lack of exposure to sunlight, diet, DNA, obesity and ethnicity. A quarter of Afro-Caribbean people, and a third of Asians are believed to have insufficient levels.

However, we know that many don’t supplement and others are taking supplements in far higher doses so who is right and what’s right for you?

If you have any underlying health conditions, you should seek advice from your GP before taking any supplements.

Sources of Vitamin D: Where does our vitamin D come from?


Our primary, and best source of vitamin D is produced when sunlight acts on our skin. However, most of us simply don’t get the exposure to sunlight we need to have an optimal level, especially in the northern hemisphere. The sun must be high in the sky and this doesn’t happen in the UK between October and March. Even in the summer months, the increased use of sunscreen to protect us from skin cancer also reduces our vitamin D levels. Clearly we must continue to use sunscreen to protect ourselves from sunburn, but we should also consider how we replace the lost vitamin D this causes.

☀️ Remember! Winter sun in the UK does not provide us with any vitamin D.


Vitamin D is found in foods like oily fish, egg yolks, mushrooms, liver and red meat. It is added to some products like cereals and fortified milk as well as being in fish oil supplements like cod liver oil. However, it’s unlikely to be in sufficient quantities in most diets to provide what we need.  The table below shows you the levels in what are considered vitamin D rich foods. Vegan diets particularly are likely to be low in vitamin D.  

Factors that make vitamin D deficiency more likely


There is a well established relationship between ethnicity and vitamin D levels. Put simply, the darker your skin, the longer you need to spend outside to produce optimal levels of vitamin D. Vitamin D levels are also linked to how much skin is exposed to the sun. Those who cover their skin, for any number of reasons, will also reduce their vitamin D level.

Genetics & Age

We know that some people are genetically pre-disposed to have low levels of vitamin D. A DNA test will help you understand whether you fall into this category. We also know that our ability to produce vitamin D declines with age so the elderly are more prone to being deficient.


Pregnancy places additional demands on a woman’s body. This means that pregnant women have a greater chance of being deficient in vitamin D. Once the baby is born, there is also a risk that breast milk will not contain sufficient levels of vitamin D. However, new born babies are advised to have supplements.


Those with a high BMI are more likely to have insufficient levels and will need higher doses of supplements to correct them.

Health conditions

People are more likely to be vitamin D deficient if they take certain medications such as steroids or drugs to combat epilepsy. Also, if you have illnesses that interfere with the absorption of your food, such as Crohn's. Other illnesses make you more sensitive to vitamin D, such as TB or lymphoma. Kidney disease, which is common, can also mean that you may need a LOWER dose than other people.

COVID-19 and vitamin D

Researchers are urgently trying to understand why certain groups of people are disproportionately affected by COVID-19. That’s people with obesity, high blood pressure, diabetes, the elderly and those from ethnic minority groups. One national intensive care report showed 35% of critically ill patients in the UK came from Black and Minority Ethnic backgrounds -  a population that are particularly prone to vitamin D deficiency.

Low vitamin D levels are also being reported as a common feature that often goes hand in hand with very severe illness. We should stress that it’s too early to say whether the links are causal but we hope the Evergreen Life community might be able to help some shed some light on this.

So what should YOU do? How to get more Vitamin D:

Supplement the minimum

The most important message here takes us back to the UK guidance that everyone over 1 year old should take a minimum supplement of 400 IU of vitamin daily. However, many clinicians agree that 1000 IU would be safe for the majority of people. Vitamin D supplements are measured in either International Units (IU) or micrograms (μg). The guide amount of 400 IU daily has been calculated to prevent deficiency for the whole population. It’s a blunt tool that’s not designed to provide a personalised optimal dose for good health, or to correct an existing deficiency.

💊 Good to know: Vitamin D supplements for pregnant women and babies are available free-of-charge to low-income families on the Healthy Start scheme.

Get outside more & change your diet

If it’s possible to safely expose your skin to more natural sunlight, without the risk of burning, then this is nature’s way of “supplementing” your vitamin D.

The table below is a guide to help you understand your skin type and to strike a balance between being safe in the sun and getting enough vitamin D. Please note in the UK the sun is only high enough to help our skin absorb Vitamin D between April and September.

💡 Remember! Sitting inside a sunny window doesn't work because windows filter out the UV light that we need to create vitamin D.

Equally, if you can, add in vitamin D rich foods to your diet  like egg yolk, oily fish, red meat or mushrooms, then you should.  However, this might not be possible and is still likely to only be a small percentage of what you need.

However, there is more you can do…

Understand your vitamin D

To make a well-informed decision about if and how you should be supplementing, you really need to know your vitamin D level. If you are worried that you might have low vitamin D levels, you should speak to your GP who may arrange a test which measures your vitamin D from a blood sample. If you can’t get a test from your GP, you can also arrange your own.

There are a number of private suppliers of vitamin D tests in the UK which cost around £35, such as Medichecks which you can purchase here.

If you choose to do a private test or haven’t linked to your GP record, please record your results in your personal health record found within the ‘Records’ section of your Evergreen Life app.

If you have been to your doctor they will recommend the appropriate level of supplement if you need one. If you have done your own test, you should receive advice with the test results which may help you make your own decision. The right dose for you is based on all the factors described above and any pre-existing medical conditions, so we simply can’t tell you what’s right for you.

Test results are described using the catchily named nanomoles per litre (nmol/L) or nanograms per millilitre (ng/ml).

There is a general consensus that a level of under 50 nmol/L (20 ng/ml) is insufficient and 25 nmol/L (10 ng/ml) is deficient. If your level is under 50 nmol/L, you should speak to your GP for advice.

Typically, it takes up to three months to see the full effect of a vitamin D supplement, though the levels of vitamin D in your blood should increase within a few weeks. If you supplement to remedy a deficiency, or achieve an optimal level, you may need to adjust your dose over time. The only way to know how you’re getting on is to re-take a vitamin D test either through your GP or privately. However, it’s worth being aware of how you’re feeling and record any changes in your Sense of Wellbeing check in the Evergreen Life app.

📲 Not got the app? With Evergreen Life, you can measure and track your wellbeing and also receive tips on how to improve other areas such as diet, sleep and happiness. Download the app here and take your available questionnaires to start your wellness journey.

How much is too much?

There is much debate about the highest safe dose. A quick search online will find recommendations for doses ranging from 400 IU through to as high as 4000 IU and beyond.

Supplementing with very high doses over a long period of time can cause build-up of calcium in your body which can weaken bones and damage the kidneys and the heart. It’s good to know that we can’t get too much vitamin D from sunshine though. The European Food Standards agency say that supplementing up to 4000 IU a day is considered safe but if you wish to consider supplementing at that level, you should consult with your GP and test regularly.

💡 It would be wise to consider regular blood tests or consult your GP if you intend to take a supplement any higher than 1000 IU per day.

The takeaway

The optimal level of vitamin D is how much you need personally for a healthy lifestyle and there is far less agreement about what an optimal level should be. The reality is that we are all different, so we need to base our decisions on our personal risk factors and a blood test if you have one.

Spread the word

Our goal is to make sure that everybody has the right information at the right time to make the right decisions about their own health and wellbeing. We hope you’ve found this useful and if you have, please share with anybody you feel would benefit.

Written by
Nicky Verity

Meet Nicky Verity, wellbeing researcher at Evergreen Life. A former clinical pharmacist, Nicky is passionate about empowering others to help themselves.

Article updated:
June 21, 2021
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