Why Your Vitamin D Level Matters More Than You Think

A practitioner’s guide to understanding your blood test score

Over the past few years, working closely with many clients — especially those dealing with immune challenges and cancer — one thing I keep seeing again and again is low vitamin D. It’s one of the most important markers I look at on a blood test. Yet many people don’t realise just how powerful vitamin D is for protecting their health. When you next go for a blood test please ask your doctor to check for this as well. I wanted to write a simple guide to help you understand:

• what vitamin D actually does

• why your level matters

• what a good level really looks like

• and what to do if yours is low

Vitamin D and Your Immune System

Vitamin D is absolutely essential for immune health. Alongside zinc, it is one of the two most important nutrients for supporting your immune system properly. The reason is simple: Vitamin D works independently to help your immune system move into what I call surveillance mode. This means your body can:

• recognise harmful bacteria

• identify viruses early

• detect abnormal cells

• destroy pathogens before they become a bigger issue

When vitamin D is low, the immune system often shifts into survival mode instead. In survival mode, your body reacts after problems appear rather than preventing them in the first place. I often explain it like this to clients:

‘Your immune system should be acting like a security guard on patrol — not a firefighter waiting for the alarm to sound.’

Vitamin D helps keep that patrol active.

Vitamin D Works as Part of a Team

Vitamin D not only works independently but also works as a team player. It works closely with other nutrients including:

• Zinc

• Vitamin C

• Magnesium

• Vitamin K2

• Calcium

If one of these is missing, the system becomes less effective.

For example:

Low vitamin C can reduce immune resilience

Low magnesium can prevent vitamin D activation

Low zinc weakens the defence against nasties that enter the body.

This is why I always look at the whole nutritional picture, not just one number on a blood test.

Vitamin D and Bone Strength

Another critical role of vitamin D is maintaining strong bones and joints.

Vitamin D works in partnership with:

• Calcium

• Magnesium

• Vitamin K2

Together they form what I often describe as a nutritional marriage.

Vitamin D helps regulate how calcium moves around the body.

If vitamin D levels are low:

The body may pull calcium out of the bones instead of placing it where it should go.

Over time this can contribute to:

• osteopenia

• osteoporosis

• joint weakness

• increased fracture risk

• reduced bone density

Historically, sailors developed rickets when they spent long periods without sunlight. Their bones became soft and weak — a clear example of vitamin D deficiency.

Where Does Vitamin D Come From?

The main source of vitamin D is sunlight ☀️

Your skin produces vitamin D when exposed to UVB rays.

Small amounts can also be found in foods like:

• mushrooms

• oily fish

• egg yolks

However, food alone rarely provides enough.

Some people also genetically struggle to produce or absorb vitamin D from sunlight, which surprises many clients. In some cases, some of us also fail to absorb it effectively enough in tablet or even liquid form. This is definitely not a one size fits all situation and as such we need to do our own investigations as to what the best sources of vitamin D are for us personally.

I actually discovered this myself through my own blood testing.

Despite working abroad in sunny environments and being very conscious about supplementation, my vitamin D levels were still dangerously very low. This has solidified to me how important regular testing really is. I have since found my father and brother, do not absorb it well either. My mother on the hand is absolutely ‘on the money’ with her vitamin D!

Does Vitamin D Effect Mind and Mood?

There’s a strong relationship between low vitamin D levels and Seasonal Affective Disorder (SAD), especially here in the UK where sunlight exposure drops significantly during autumn and winter. Vitamin D acts more like a hormone than a vitamin and plays an important role in supporting mood-regulating brain chemicals such as serotonin. When sunlight exposure falls, vitamin D production in the skin drops — and this can contribute to symptoms like low mood, fatigue, reduced motivation, poor concentration and disrupted sleep. Clinically, I often see clients with winter low mood improve when their vitamin D levels are brought into the functional range of around 100–120 nmol/L, particularly when combined with magnesium, zinc and regular morning daylight exposure.

Supporting vitamin D levels through testing and targeted supplementation can therefore be a simple but powerful step in protecting mood resilience through the darker months or for those who don’t genetically absorb vitamin D from the sun well.

Why I Often Recommend Liquid Vitamin D?

Vitamin D supplements come in many forms. But not everyone absorbs tablets effectively. This is especially true for those who have digestive issues, low stomach acid, taking a PPI (like omeprozol or lanzoprazol) or are highly stressed.

For this reason, I often recommend liquid vitamin D, which can be absorbed through the tissues of the mouth (sublingually) to reach their blood stream regardless of what is happening from their stomach down. I recommend a functional dose 4000 IU per day.

If you are really low, I would encourage having a vitamin D injection to boost levels pronto and then move to liquid supplements for support.

Vitamin D and Cancer Support

Over the last two years working closely with cancer clients, one pattern has stood out very clearly:

Low vitamin D appears again and again. One theory is straightforward:

If the immune system is weakened, it is less able to detect abnormal cell behaviour early. Vitamin D plays a central role in immune surveillance.

For this reason, keeping levels optimal is something I personally take very seriously — both professionally and for my own health. With these finding I feel it is a very sensible idea to manage your vitamin D levels as part of any preventative/longevity protocol 🤔

What Is a Good Vitamin D Level?

This is where things often get confusing.

Most laboratory “normal ranges” are based on averages from the general population of quite sick people — this is not optimal health.

Typical lab reference range: 50–300nmol/L

But what I consider the functional optimal range for immune protection, bone strength and a happy brain is 100–120 nmol/L

Dosage & Action

< 25 nmol/L: Severe deficiency — urgent correction needed with Vitamin D injection initially and retest for weeks later.

25–50 nmol/L : Insufficient — immune function and bone signalling compromised. Vitamin D injection and retest 4 weeks later.

50–75 nmol/L: Technically “adequate” (NHS range), but not optimal for prevention work. Consider vitamin D supplements mention or liquid vitamin D and retest 4 weeks later.

75–100 nmol/L : Good functional baseline for most adults, support with standard daily dose of liquid vitamin D (1000iu/day)

100–120 nmol/L ⭐

Excellent target for:

• immune surveillance

• cancer-risk reduction strategies

• autoimmune support

• winter resilience

• bone remodelling signalling

Continue what you are doing 👍

120–150 nmol/L : Still safe for many people but monitor cofactors (magnesium, K2, calcium balance).

>150 nmol/L : Usually where I begin reassessing dosing strategy.

Why You Should Never Guess Your Vitamin D Dose

It’s important not to self-prescribe large doses without testing.

Too little vitamin D isn’t ideal — but neither is too much. Levels above 150 nmol/L may place stress on the liver and calcium regulation pathways. This can cause irreparable damage on the liver!

That’s why my approach is always:

Test → Supplement → Retest → Adjust

Never guess.

When Should You Retest After a Vitamin D Injection?

If you receive a vitamin D injection:

Levels take approximately 4 weeks to reach their peak.

I always recommend retesting at the 4-week mark and decide where to go from this point.

This allows us to see:

• How well your body responded

• whether another injection is needed

• whether your level is now in the optimal range

My Personal Approach to Vitamin D Monitoring

Because I discovered I don’t absorb vitamin D efficiently from sunlight, I now:

• monitor my levels regularly

• supplement strategically

• use injections when needed

• retest at appropriate intervals

It’s something I take seriously — especially after seeing how commonly low vitamin D appears in people facing immune challenges.

How I can help?

If you’d like support interpreting your vitamin D result or creating a safe plan to optimise your levels, I’m always happy to help please arrange a Free discovery call with me today.

As a practitioner I have been struggling to find local providers for vitamin injections and IV vitamin Drips. I have now found an excellent Doctor who currently works as as an anaesthetist within the NHS. Needless to say she’s excellent with needles!

She will be visiting the Preston area once a month to do a Day Clinic for my clients.

We are doing our first Day Clinic this coming Tuesday 21st May, in just afew days time. Dr.Debs is doing a variety of Vitamin injections and IV drips.

Message or call me to book if you know you require an injection and have been struggling to find somewhere. Monthly dates will be shared on my newsletters for the coming months shortly