Could Low Vitamin D Be the Missing Link to your Energy, Mood and Immunity?

Do you feel more tired, moody, or run down in the Winter months even when you’re eating well and doing all the right things? You’re not alone. One nutrient could make all the difference - Vitamin D

Why Vitamin D Matters

Let’s face it - we’ve all heard of vitamin D, but few people realise just how powerful it is. Beyond strong bones, this sunshine vitamin plays a vital role in energy production, mood, hormones, immunity, and even how our genes function. Yet, despite its importance, deficiency is surprisingly common - even here in the UK.

What Is Vitamin D?

Vitamin D is a fat-soluble vitamin needed at every stage of life, from new-borns to the elderly. It comes in two forms - D2, found in plants, and D3, which is made by our skin when exposed to sunlight and found in animal foods like oily fish and eggs.

Once produced, it is converted by the liver and kidneys into its active form, known as calcitriol- technically a hormone. Calcitriol helps regulate calcium and phosphorus in the body, supporting bone strength, teeth, and muscle function, but I’s influence extends far beyond that.

A Hormone in Disguise

Here’s when it gets fascinating: vitamin D may not even be a true vitamin but a hormone-like compound. Almost every cell in the body has a receptor for vitamin D (called the VDR), showing just how far-reaching its effects are. These receptors are involved in regulating the immune system, inflammation, cell repair, and even the way our bodies recycle old or unhealthy cells.

It’s also been linked to improved blood pressure, better insulin sensitivity, reduced inflammation, and a lower risk of auto-immune conditions - showing that vitamin D’s impact goes far beyond bones. 

The Team Players: Nutrients That Work with Vitamin D

Vitamin D doesn’t like to work alone. For best results, it needs key cofactors - nutrients that help it do its job properly:

• Magnesium and calcium for bone strength and muscle function

• Zinc for immune balance and repair

• Vitamin A for healthy skin and mucosal barriers

• Vitamin K2 to help calcium get into bones rather than arteries

So, if you’re taking vitamin D, make sure your overall nutrition is well-balanced- otherwise you may not get the full benefits.

How To Know If It Gets Low and Who’s at Risk

Although Rickets is rare today, vitamin D deficiency is still widespread. Signs can include fatigue, low mood, frequent colds, muscle weakness, and joint or bone pain. It is also associated with autoimmune conditions, cardiovascular issues and even anxiety or depression.

Those most at risk include:

• People who get little or no sun exposure

• Those who use sunscreen regularly or cover up their skin

• People living in Northern latitudes (hello, UK!)

• Individuals with darker skin, who need more time in the sun to make vitamin D

How Much Do You Need?

Conventional medicine often considers above 50nmol/L to be sufficient, but as a Functional Nutritionist, I typically recommend aiming for between 75-125nmol/L for optimal health.

Supplement doses vary, but studies suggest 1000 - 4000 IU per day is safe for most adults. It’s always best to test your vitamin D levels first - then supplement according to your results and re-test every 3-6 months. 

Remember vitamin D can be stored in the liver for around 4 months, so if your levels dip in winter, you might start to feel it by February.

Sunlight, Food and Supplementation

Our main source of vitamin D is sunlight, but in the UK, we can only make it between April and October. From October to March, it is almost impossible to synthesize enough, which is why food and supplements are essential.

Good food sources include:

• Oily fish (salmon, sardines, mackerel, tuna)

• Eggs

• Fortified foods

• Mushrooms exposed to sunlight

A simple tip: if your shadow is the same height or shorter then you are making vitamin D. If it is longer - the sun’s rays aren’t strong enough.

The Takeaway

Vitamin D truly is the multitasker of the nutrient world - supporting mood, energy, hormones, immunity, and bone health. Yet so many of us are running low without realising it.

If you’re unsure about your vitamin D status, consider testing your levels and seeking guidance on how to optimise them safely.

Ready to find out if low vitamin D could be affecting your energy, mood or hormones? Book a free 20-minute discovery call and let’s get your levels, and your health back in balance.