Most people think of vitamin D as a vitamin. But here's the thing — it's actually a hormone. It acts as a signalling molecule throughout the body, regulating a remarkable range of physiological processes. And during menopause, when your hormonal landscape is already shifting significantly, getting your vitamin D right isn't optional. It's essential.

I include vitamin D3 with K2 in my Daily Menopause Support formula for exactly this reason — and the K2 is just as important as the D3. Here's why.

Vitamin D Is a Hormone

Unlike true vitamins, which must be obtained entirely from food, vitamin D is synthesised in the skin in response to sunlight and then converted into its active hormonal form — calcitriol — by the liver and kidneys. It binds to receptors found in virtually every cell in the body, influencing gene expression, immune function, inflammation, and hormonal balance.

In the UK, most of us are deficient for at least half the year. And deficiency doesn't just affect bones — it affects mood, immunity, hormonal regulation, and long-term disease risk in ways that are only now being fully understood.

How Vitamin D Impacts Your Hormones

Oestrogen & Testosterone

Vitamin D receptors are present in the ovaries, and research has found that adequate vitamin D levels support healthy oestrogen and testosterone production. Low vitamin D has been linked to lower levels of both hormones in women — which matters enormously during perimenopause and menopause, when oestrogen is already declining.

Insulin & Blood Sugar

Vitamin D plays a direct role in insulin secretion and sensitivity. Low levels are associated with insulin resistance and an increased risk of type 2 diabetes — a risk that rises after menopause as oestrogen's protective metabolic effects diminish. Supporting vitamin D levels is one of the most straightforward things you can do to support healthy blood sugar regulation.

Parathyroid Hormone (PTH) & Calcium

When calcium levels in the blood drop, the parathyroid glands release PTH to compensate — which can draw calcium from bones. Vitamin D increases calcium absorption from the gut, reducing the need for this compensatory mechanism and protecting bone density. This is particularly critical during and after menopause, when bone loss accelerates.

FSH, LH & the Menstrual Cycle

Low vitamin D has been linked to elevated levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) — the hormones that drive the menstrual cycle and whose dysregulation is central to menopausal symptoms. By supporting healthy levels of these hormones, vitamin D may help moderate some of the hormonal turbulence of perimenopause.

Vitamin D & Menopause: Why It Matters So Much

Bone Health

Oestrogen plays a key role in maintaining bone density. As oestrogen declines during menopause, bone loss accelerates — and the risk of osteoporosis rises significantly. Vitamin D is essential for calcium absorption and bone mineralisation, making it one of the most important nutrients for menopausal women. But vitamin D alone isn't enough.

Why K2 Is Non-Negotiable

This is where most vitamin D supplements fall short. Vitamin D increases calcium absorption — but without vitamin K2, that calcium can end up deposited in arteries and soft tissue rather than directed into bones where it belongs. K2 activates the proteins that transport calcium to the skeleton and keep it out of the bloodstream. D3 and K2 work together as a system — which is why I include both in my Daily Menopause Support formula. Taking D3 without K2 is, in my view, an incomplete approach.

Mood & Depression

Vitamin D receptors are found throughout the brain, and low levels are strongly associated with depression, anxiety, and low mood — all of which are common during menopause. Studies have found that supplementing vitamin D can improve mood and reduce depressive symptoms, particularly in those who are deficient.

Inflammation

Menopause is associated with increased systemic inflammation, which raises the risk of heart disease, cognitive decline, and metabolic dysfunction. Vitamin D has well-documented anti-inflammatory effects, helping to modulate the immune response and reduce inflammatory markers.

How Much Do You Need?

The UK government recommends 400 IU daily — a figure most experts now consider far too low, particularly for menopausal women. Many functional medicine practitioners recommend 2,000–4,000 IU daily, ideally tested and adjusted based on blood levels. If you haven't had your vitamin D tested recently, it's worth doing — it's one of the most actionable things you can find out about your health.

My Daily Menopause Support includes vitamin D3 with K2 alongside a comprehensive blend of nutrients specifically chosen to support women through perimenopause and menopause. If you'd like personalised guidance on what you need, I also offer 1-1 Personal Health Consultations.