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Vitamin D in winter: Why you need to pay attention

Updated: Aug 6


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As we hit the cold, dark stretch of winter, many of us cozy up inside, shielding ourselves from the elements. But while we’re staying warm, there’s something important we might be missing—Vitamin D.


Whether you're a busy parent, a weekend warrior, or simply trying to take care of your long-term health, Vitamin D plays a huge role in how your body feels and functions. And in winter? Deficiency is incredibly common.


What Is Vitamin D?

Vitamin D is a fat-soluble vitamin that acts more like a hormone in the body. It's essential for a wide range of functions, including:

  • Calcium absorption and bone strength

  • Immune system support

  • Muscle health and performance

  • Mood regulation (some links to depression and low vitamin D)

  • Hormone balance and reproductive health


Why Are We Low in Vitamin D During Winter?

Vitamin D is known as the “sunshine vitamin” because our bodies can make it naturally—but only when our skin is exposed to UVB rays. In the winter months, especially in places like New Zealand, southern Australia, or Northern Hemisphere regions, the sun sits too low in the sky for us to produce adequate Vitamin D.


Add to that:

  • More time indoors

  • Sunscreen use (which blocks UVB)

  • Bundling up in layers

  • Darker skin tones (which naturally need more sun exposure to make enough)

And you've got the perfect recipe for low Vitamin D levels.


Who Needs It Most?

In truth? Everyone. But certain groups are especially at risk:

  • Infants and young children

  • Pregnant and breastfeeding women

  • Older adults (especially over 65)

  • People with darker skin

  • Anyone who covers most of their skin or wears sunscreen daily

  • People with limited sun exposure or who work indoors

  • Athletes or active individuals under stress


What Foods Contain Vitamin D?

Unfortunately, food isn’t a super-rich source of Vitamin D—though it can help top things up:

Tip: Whole food sources help, but most people need to supplement—especially in winter!

You'd need to eat large amounts of these daily to meet your needs through food alone.

Food

Approx. Vitamin D (IU)

Salmon (100g, cooked)

500–600 IU

Egg yolk (1 egg)

~40 IU

Fortified plant or cow’s milk

~100 IU per cup

UV-exposed mushrooms (100g)

~400 IU

Sardines (2, canned)

~40–60 IU

Fortified cereals (1 serve)

~40–100 IU

Should You Supplement?

In most cases—yes, especially in winter.

General guidelines (always check with your health provider):

  • Adults: 1000–2000 IU/day

  • Children: 400–1000 IU/day (depending on age)

  • Pregnant or breastfeeding women: Often advised to take 1000 IU/day

  • Some people may need higher doses if levels are very low (under guidance)

Look for Vitamin D3 (cholecalciferol)—it's the most effective form for most people.


Testing Your Levels

Want to know where you stand? Ask your GP or health provider for a Vitamin D blood test. Optimal levels are generally considered to be 50–75 nmol/L or higher, depending on guidelines used.


Bottom Line

If you live somewhere with dark winters, you’re likely not getting enough Vitamin D from the sun alone. It’s worth paying attention to—whether that means testing, adding more fatty fish to your plate, or simply supplementing during the colder months.

Your body will thank you with stronger bones, a brighter mood, better immunity, and more energy.


Need help figuring out your vitamin and supplement needs this winter?Book a 1:1 consultation and get personalised support tailored to your age, lifestyle, and health goals.

Let’s fuel your health with evidence-based nutrition—together.


 
 
 

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