Vitamins D is vital for maintaining good health. It is possible to get all you need from sunshine and good food. But because we get relatively little sun in the UK and not everyone eats perfectly, the health authorities recommend we all take Vitamin D supplements from October to April and eat Vitamin D rich foods such as oily fish and eggs all year round.

The recommended supplement amount is set quite low, at 10ug or 400iu (except for babies who consume 500ml plus of infant milk formula as these include Vitamin D). However, since everyone’s Vitamin D absorption, synthesis and storage capacity differs, that doesn’t fit everyone. This is partly why Vitamin D supplements vary so considerably with their dosages and can be 10x the RDA at 4,000iu during the winter months.

We all store Vitamin D at different rates, and therefore levels vary from person to person. For instance, people with darker skin, and those who keep out of the sun or wear lots of sun cream in the summer, may need to take additional vitamin D all year round.

How much Vitamin D should you have in your blood?

There is currently no global definition of an ‘optimal’ blood level of vitamin D. However, the NHS says that a level below 30 nmol/L is ‘deficient’, an “adequate” level is 50 nmol/L), and more than 75 nmol/L is “optimal”, with an upper limit of 220 nmol/L.

However, the government also recognises that there may be additional benefits if you have levels between 90 -100 nmol/L and some research has suggested 100/110 nmol/L may be a better level for people suffering from chronic health conditions including inflammatory or autoimmune illnesses.

But you should know that your level will vary through the year, as you top it up in sunny times, storing it in your fat, from where it will be released over time when you’re not getting enough. This means that while you might have super levels in the summer, by February, your reserves might be running low.

I would recommend targeting 75 nmol/L to 100 nmol/L all year round. During winter and spring, this is likely to need more supplementation than the rest of the year.

Implications of different Vitamin D levels
Vitamin D level Vitamin D status Health effect
<30 nmol/L Deficient Rickets, Osteomalacia
30 – 50 nmol/L Insufficient Associated with disease risk
50 – 75 nmol/L Adequate Healthy
>75 nmol/L Optimal Healthy
Source: NHS

How can you measure how much vitamin D you have in your blood?

This is carried out through a blood test called 25 (OH) D and measures how much Vitamin D you have in your blood. But it is usually quite hard to persuade your GP to test your Vitamin D levels if you do not have a specific deficiency flag. As a result, many people are left in the dark on how effective their supplements are, and have to make an educated guess to how much Vitamin D they should be taking.

This is why we suggest a simple home testing blood prick test that helps you to monitor your vitamin D levels so you can adjust your intake and optimise your blood levels. We recommend you do this test every few months for a while, to gauge how your Vitamin D levels vary from season to season.

What affects how much extra Vitamin D you need?

There are lots of risk factors for people who may struggle to generate enough Vitamin D, or need extra. They include:

  • Living in high latitude countries
  • Time of year
  • Pigmented skin
  • If you don’t get outside much
  • If you cover your skin with clothes or sunscreen
  • Elderly
  • Infants & children under 5
  • Pregnant or breastfeeding women
  • Vegan/Vegetarian
  • Certain medical conditions affecting absorbtion
  • Obesity
  • Genetic differences

How can genetics affect how much Vitamin D we need?

More recent research into Vitamin D genetic SNPs finds that there are three genes (GC, CYP27B1 and VDR) which can affect how much Vitamin D we need and how high our blood levels need to be to feel well and protect our bones.

These genetic variances can significantly influence vitamin D availability and our response to it. They do not tend to alter how much vitamin D is detected in the blood, but how much of it is utilised. Which means it is thought that those who carry these genes probably need to aim to have their vitamin D blood levels closer to 100, rather than 75 to get the benefits.

Genetic testing is much more accessible now these days and as you can see can drill down much further into why a person may not feel the benefits from their Vitamin D supplementation. This genetic testing needs to be done privately and is something that can be arranged through our NatureDoc clinical team.

What about Vitamin D for Covid-19?

There is evidence on the benefits of Vitamin D in the context of Covid-19, showing an association between vitamin D deficiency and greater incidence or severity of Covid-19 infection. While this research is somewhat inconsistent, and does not meet the threshold for NHS recommendation, there is a wide consensus that as Vitamin D is low-cost and generally safe, there is very little to be lost in being generous with supplementation, and a group of doctors have been calling for 4,000 IU per day to be recommended a safe and reasonable amount in the absence of testing.

So how much Vitamin D should you take?

There’s no single answer, and this is why testing is helpful. If your test comes back a long way below where you’d like it to be, then you can take extra for short periods of time.

Here are some common Vitamin D strengths:

  • 400iu – this is the RDA set by the NHS and is the minimum amount that everyone in the UK should take over the winter months
  • 1,000iu – if your toddler’s Vitamin D blood test shows they have less than adequate or optimal amount of vitamin D then step up to 1,000iu daily for 6-8 weeks and retest
  • 2,000iu – if your child aged 4+ has less than adequate or optimal vitamin D, then increase intake of Vitamin D to 2,000iu for 6-8 weeks and retest
  • 3,000iu – teens and adults ages 12+ who are below the adequate or optimal level for Vitamin D can take 3,000iu daily for 6-8 weeks and then retest
  • 4,000iu – adults whose Vitamin D levels are below the adequate or optimal level for Vitamin D and need to raise their levels slightly higher due to autoimmunity/inflmmatory conditions may well benefit from 4,000iu daily for 6-8 weeks. Again, retest at this point.

In the absence of a known deficiency, we generally recommend 400iu for children below 12, and for adults there is no real “wrong” amount. But if you choose to aim for the higher end of the scale, then 4,000iu would be for people who are not taking any other supplements or multivitamins containing Vitamin D, and otherwise, 3,000iu is probably better.

Lucinda Recommends

NHS Vitamin D Blood Test
BetterYou D3000 Vitamin D Daily Oral Spray
BetterYou D400 Junior Vitamin D Oral Spray


Share This