A practical guide for navigating sun exposure, supplements, and bone health in Aotearoa.

What Is Vitamin D—and Why Does It Matter?

Vitamin D plays a vital role in keeping your bones strong, muscles working well, and immune system resilient. One of its key jobs is helping your body absorb calcium—essential for maintaining healthy bones throughout life.

Your body naturally produces Vitamin D when your skin is exposed to sunlight. You can also get small amounts from food sources like oily fish, egg yolks, liver, and fortified foods such as some milks or cereals.

In Aotearoa New Zealand, most of us get enough sun during summer to replenish our Vitamin D levels—but by late winter or early spring, mild deficiency is common, especially in people with low sun exposure. In some cases, supplements may be recommended.

Who Might Benefit from Vitamin D Supplements?

You may benefit from a Vitamin D supplement if you:

☀️ Get little sun exposure

• You spend most of your time indoors
• You wear clothing that covers most of your skin
• You are careful to avoid the sun due to skin cancer risk
• You live in areas with long winters or low UV

🧬 Have darker skin

• People with darker skin tones require more UV exposure to produce the same amount of Vitamin D.

🩺 Have certain medical conditions:

• Chronic kidney disease
• Malabsorption (e.g. coeliac disease, Crohn’s, gastric bypass)
• Liver disease

💊 Take certain medications:

• Anticonvulsants
• Glucocorticoids (e.g. prednisone)
• HIV medications

When Should You Take a Supplement?

Vitamin D supplements are generally recommended if you’re at risk of deficiency due to one of the above reasons.

🧪 Routine blood testing for Vitamin D is not necessary for everyone, and usually not needed before starting a standard supplement dose—unless you have specific medical conditions.

How Much Vitamin D Should You Take?

Recommended dosages vary based on individual needs:

Group	Suggested Dose
At-risk adults	800–1000 IU (20–25 mcg) daily
Maintenance (once levels are normal)	400–800 IU (10–20 mcg) daily

⚠️ What about high-dose Vitamin D?

High doses (e.g. 50,000 IU weekly or monthly) should only be taken under medical supervision—typically for a short period to correct a significant deficiency.

Too much Vitamin D over time can lead to:

• High calcium levels
• Kidney stones
• Nausea, confusion, or other complications

Can You Get Enough From Food?

Vitamin D is found in only a few foods. Helpful sources include:

• Salmon, sardines, mackerel
• Egg yolks
• Fortified milk, plant milks, or cereals
• Liver (only occasionally, due to high vitamin A levels)

While these foods contribute to your intake, it’s difficult to meet your full requirement from diet alone.

What About Sunlight?

Most New Zealanders get enough Vitamin D through everyday incidental sun exposure during the warmer months.
As a guide, 5–30 minutes of sunlight on bare skin (arms, legs, or face) a few times a week is often sufficient for healthy people.

☀️ But balance is key—prolonged sun exposure increases the risk of skin cancer, so sun safety still matters.

Why Does My Bone Density Report Say to Stop Taking It?

We’re often asked about this. Bone density reports sometimes include a general recommendation to stop Vitamin D supplements—but this advice is intended for the general population, not for those with specific risk factors.

You may still benefit from Vitamin D supplementation if you:

• Have limited sun exposure
• Have darker skin
• Have a relevant medical condition or take certain medications
• Have had documented low vitamin D

Need a Supplement? Check In With Your Clinician

If you’re unsure whether Vitamin D is right for you—or how much to take—have a conversation with your GP or specialist.
They can help determine if testing is needed and recommend a safe, appropriate dose based on your overall health and lifestyle.

References and Guidelines

• NZ Ministry of Health: Vitamin D Advice for Healthcare Professionals
• Endocrine Society Clinical Practice Guidelines (2011)
• National Osteoporosis Foundation
• RACGP: Preventive Activities in General Practice
• Institute of Medicine (IOM) Dietary Reference Intakes (2011)