How do I know if I have a vitamin D deficiency?

The most reliable way to check is a simple blood test called a 25-hydroxyvitamin D test, which your GP can order. Common symptoms include persistent fatigue even after adequate sleep, unexplained bone and joint pain, frequent colds or infections, low mood or anxiety, and muscle weakness. However, many people with low vitamin D have no obvious symptoms at all, which is why testing is important — especially for women over 50 who are at higher risk.

How much vitamin D should a woman over 50 take daily?

Most health guidelines recommend 600–1000 IU daily for adults over 50, but many healthcare professionals now suggest 1000–2000 IU, particularly during autumn and winter or if you spend most of your time indoors. If your blood test shows a significant deficiency, your doctor may prescribe a higher therapeutic dose (e.g., 5000 IU daily) for several weeks to bring your levels up. Always check with your GP before starting high-dose supplementation.

Can you get enough vitamin D from food alone?

It’s very difficult to get adequate vitamin D from food alone. The best dietary sources are fatty fish (salmon, sardines, mackerel), egg yolks, and UV-exposed mushrooms, but you’d need to eat large amounts daily to meet your requirements. Most of our vitamin D comes from sunlight exposure. If you’re over 50, live in a cooler climate, or spend limited time outdoors, a supplement is usually the most practical and reliable option.

Does vitamin D deficiency get worse during menopause?

Yes, menopause increases the risk of vitamin D deficiency for several reasons. Dropping oestrogen levels reduce your body’s ability to activate vitamin D. Your skin also becomes less efficient at producing vitamin D from sunlight as you age. Additionally, vitamin D is crucial for calcium absorption, and without adequate levels, the bone density loss that accelerates during menopause becomes even more pronounced. This is why testing and supplementation are especially important during and after menopause.

What is the best form of vitamin D supplement to take?

Vitamin D3 (cholecalciferol) is the most effective and well-absorbed form. It’s the same type your body produces naturally from sunlight. Vitamin D2 (ergocalciferol) is plant-derived and less potent. Look for D3 supplements, ideally combined with vitamin K2, which helps direct calcium to your bones rather than your arteries. Take your supplement with a meal containing fat (like avocado, nuts, or olive oil) as vitamin D is fat-soluble and absorbs much better with dietary fat.

5 Warning Signs of Vitamin D Deficiency After 50

Vitamin D is often called the “sunshine vitamin” — and for good reason. Your body produces it when your skin is exposed to sunlight. But after 50, your skin becomes less efficient at making vitamin D, and many of us spend more time indoors than we realise.

The result? An estimated 1 in 4 Australian adults is vitamin D deficient, and the risk climbs significantly after menopause. Low vitamin D doesn’t just affect your bones — it impacts your energy, mood, immunity, and muscle strength.

Here are five warning signs that your vitamin D levels might be too low.

1. Constant Fatigue

If you’re getting 7–8 hours of sleep but still dragging yourself through the day, low vitamin D could be a factor. Research shows that vitamin D plays a key role in energy production at the cellular level. Women with deficiency often describe a “bone-deep” tiredness that coffee can’t fix.

What to do: Ask your GP for a 25-hydroxyvitamin D blood test. Optimal levels are between 50–100 nmol/L.

2. Bone and Joint Pain

Vitamin D is essential for calcium absorption. Without enough of it, your bones can’t mineralise properly, leading to aching bones and joints — especially in your lower back, hips, and legs. This is often dismissed as “just getting older,” but it’s a treatable deficiency.

What to do: If you’re experiencing unexplained bone pain, mention vitamin D testing to your doctor. Supplementation can make a dramatic difference.

3. Low Mood and Anxiety

Vitamin D receptors are found throughout the brain, including areas that regulate mood. Studies have linked low vitamin D to increased rates of depression and anxiety, particularly in women over 50. Seasonal changes (less sunlight in winter) can make this worse.

What to do: While vitamin D isn’t a replacement for professional mental health support, correcting a deficiency often helps lift the fog.

4. Frequent Illness

Catching every cold, flu, or bug that goes around? Vitamin D is a critical player in your immune system. It helps activate T-cells — the “soldier cells” that fight off infections. Low levels mean your immune defences are compromised.

What to do: If you’re getting sick more than 2–3 times per year, consider having your levels checked. Many healthcare professionals now recommend a daily supplement of 1000–2000 IU, especially during autumn and winter.

5. Muscle Weakness

Struggling to get up from a chair, climb stairs, or carry groceries? Vitamin D deficiency can cause muscle weakness that’s often mistaken for general deconditioning. Your muscles have vitamin D receptors, and without adequate levels, they simply can’t function at their best.

What to do: Combine vitamin D supplementation with regular strength training for the best results. The two work together to keep your muscles and bones strong.

How to Get More Vitamin D

Sunlight: 10–15 minutes of midday sun on your arms and face, several times a week (without sunscreen). Be sensible — don’t burn.
Food sources: Fatty fish (salmon, sardines), egg yolks, mushrooms exposed to UV light, and fortified foods.
Supplements: Vitamin D3 (cholecalciferol) is the most effective form. Most adults over 50 benefit from 1000–2000 IU daily, but check with your GP for the right dose.

The Bottom Line

Vitamin D deficiency is common, underdiagnosed, and completely fixable. If any of these symptoms sound familiar, a simple blood test is all it takes to find out. Don’t write off fatigue, aches, or low mood as “just part of ageing” — your body might be trying to tell you something. ☀️