28/04/2026
Why Take Vitamin D Through Winter
🎁 And why we're including a free bottle of Vitamin D with every order until May 31st!
It’s a stunning autumn day in Dunedin, but last week’s inclement weather had me bringing out my winter boots and feeling the reality of a southerly blast.
For most New Zealanders, autumn means warmer layers, soup season, and a few months of not much sunlight. What it should also mean is a check-in with your vitamin D levels.
Many older New Zealanders are low in vitamin D over winter. We sit at the high-latitude end of the world. Dunedin is at 45°S, almost the same line as parts of southern Patagonia!
From May through August, the angle of the sun means our skin can't make much vitamin D, even on a clear day.
Confirming this, a major international consensus statement was published in Endocrine Reviews last year, pulling together 27 of the world's leading vitamin D researchers. They reviewed everything we currently know.
Special Offer
To help our Zestt community get through winter well, we're including a free bottle of Vitamin D3 with every Zestt order over $40 for the next month, while stocks last.
Here's why it matters.
Vitamin D is not just a bone vitamin
Vitamin D receptors live in nearly every cell type in your body.
Vitamin D is important for bones: Vitamin D + Calcium reduces hip and other fractures in older adults, particularly those starting from a low baseline.
Good vitamin D levels are also linked to:
Immune function
Type 2 diabetes risk
Cardiovascular health
Inflammatory pathways
Autoimmune disease risk
The correlation of vitamin D with the onset of multiple sclerosis (MS) is a striking example. MS is more common in people who live at high latitudes than near the equator, the so-called "latitude gradient of MS." Vitamin D deficiency is more common in places with long winters and low sun exposure.
"But aren't supplements just expensive urine?"
You might have heard that supplementation is a waste of money, and all you are left with is expensive urine. The challenge with research into vitamin and mineral supplementation is that the studies are often epidemiological, population-based, with few controls, or they are short and narrow. This makes it more challenging to capture the complexities and variations of humans at different ages and stages. Vitamin and nutrient deficiencies develop slowly. Your needs shift as you age.
Vitamin D in winter is one of the most justifiable supplementation needs because the underlying problem is geographical rather than dietary. Remember, you don’t get vitamin D from food; you make it from exposure to the sun. You can't fix New Zealand's winter UV levels with kale 🥬
Who's most at risk?
The consensus paper outlines clear risk groups. You may be more vulnerable to winter deficiency if you:
- Spend most daylight hours indoors: office, factory, shift work, or driving for a living
- Have darker skin, which needs more UVB exposure to produce the same amount of vitamin D
- Are over 65, as skin synthesis becomes less efficient with age
- Have a higher BMI, as vitamin D gets sequestered in fat tissue
- Have a digestive condition affecting absorption, such as coeliac disease, IBD, or post-bariatric surgery
Take certain medications that accelerate vitamin D breakdown; your GP or pharmacist can advise.
What form, and how often?
Oral cholecalciferol, vitamin D3, is the preferred form for the general population (that’s the form we have for Zestt Vitamin D). It's safe, well-tolerated, and converts efficiently into the active forms your body uses.
Daily dosing is more effective than the occasional very large dose favoured by older protocols.
Our winter offer
⭐️ For the next month, every Zestt order over $40 ships with a complimentary bottle of Vitamin D3.
This is our way of helping you bridge the seasonal gap. Whether you're stocking up on Zestt Breathe+ for the cooler months, restocking your daily essentials, or trying us for the first time, the free Vit D goes in your parcel automatically at checkout.
Terms: Minimum spend $40. One bottle per order. While stocks last.
