Vitamin D is activated when sunlight hits our skin, that’s why it’s called ‘the sunshine vitamin’. This makes Vitamin D an interesting and unique nutrient. We get a whopping 80-90% of our Vitamin D from sunlight - if we can catch enough rays. The sun’s UVB light converts D to its active form, Vitamin D3 (Cholecalciferol). In fact, studies show that sunlight is a better source than diet for Vitamin D. Spend a lot of time indoors or in the shade lately? Thankfully there's a lot of options to support healthy Vitamin D levels.
So, should we watch our Vitamin D levels during cooler months?
Short answer, yes.
Scientists found a direct link - the less sun exposure we have, the higher our likelihood of a Vitamin D deficiency. Here in NZ that’s May to September especially. In colder months the sun’s UVB rays are less intense (lower UV index), also we’re often indoors and more rugged up so our skin sees less sun.
Could you be deficient?
It’s a fairly common deficiency in New Zealand. A recent study showed around 30% of Kiwi adults have sub optimal levels, that’s a lot of people. Also considering how important Vitamin D is for us (more on this later), it’s quite a big deal.
So many factors influence our Vitamin D levels, like:
- Time of year – less sun exposure in winter
- UV index – how strong UVB rays are on a particular day and time of year
- Closeness to the equator - South Islanders are further away so more likely to be low
- Melanin levels – more melanin means better UV protection for darker skin, but less Vitamin D activation
- Age – our efficiency at converting Vitamin D goes down as our age goes up
- Diet – how much oily fish we eat
- Exclusively breastfed babies - breastmilk is a not a rich source of Vitamin D
How do I up my Vitamin D?
Getting enough sunlight is a great way to up your D levels. There’s also a range of high-quality Vitamin D supplements to support healthy Vitamin D levels, which can be especially useful during winter months.
Is there a Vitamin D - sunlight sweet spot?
Keeping in mind that we need to protect our skin from UV rays, it can be a delicate balance. At this stage, there aren't set guidelines due to all the factors above. In NZ the amount needed is as little as 6 minutes in the height of summer and up to 97 minutes in the depths of winter. So, it’s not a one-size-fits-all, which is unfortunate, because imagine having a prescribed amount of daily sunshine...it might encourage us to leave the office for a healthy sunshine break more often.
Safe sun for Vitamin D
There are some general sun smart guidelines for sunlight and Vitamin D. Sunblock reduces our activating ability, but it doesn’t block it altogether, so no need to skip the sunscreen in favour of Vitamin D. We only need about 20% of our skin to be exposed and short bursts are better than extended exposure.
Interesting fact - outdoor sun exposure is best because UVB rays don’t pass through glass. Sunning ourselves by a sun-drenched window is delightful, but it won’t activate our Vitamin D.
Vitamin D benefits
Vitamin D plays a pivotal role in healthy bone mineralisation, the process that keeps our bones strong and hard. It helps the body absorb calcium (our number one bone mineral). Vitamin D (along with Calcium) is especially important after menopause when bone mineralization naturally declines.
Our nervous system needs Vitamin D - we have Vitamin D receptors in our brain. Healthy Vitamin D levels have been linked with healthy mood and feelings of happiness.
Cells in our immune system use Vitamin D for healthy defenses against winter ills and chills (which can be a catch 22 because winter offers less D activating sunlight).
Adequate Vitamin D levels are needed for healthy fertility for all genders as well as healthy pregnancy and breastfeeding for both mum and baby.
Vitamin D foods
As mentioned earlier, sunlight is a better source of D than food, because very few foods naturally contain Vitamin D and they don’t yield high amounts.
- Egg yolk: 0.73 mcg
- Cod liver oil: 10 mcg per 5ml
- Oily fish: 1-10 mcg per 100g serve
See below for how much Vitamin D you should be getting per day.
Where you can, try and go for sustainably caught, oily fish options like, Mullet, Blue Mackerel, Sardines and Kahawai.
Signs you're deficient in Vitamin D
If you have sub optimal levels, you might not have noticeable signs. Here are some key Vitamin D deficiency signs.
- Low or flat mood
- Getting sick often
- Bone weakness
- Joint stiffness
If you think you might be deficient, it’s best to talk to your health professional.
How much Vitamin D per day?
Your ideal Vitamin D amount depends on your individual needs. Here’s how much we need every day to avoid deficiency.
- Babies & kids: 5mcg (200 IU)
- Adults: 5-15 mcg (200-600 IU)
- Pregnant & breastfeeding mums: 5 mcg (200 IU)
It’s important to note that recommended dietary intake is often based on the amount you need to consume in order to prevent a deficiency rather than the ideal amount needed for optimal health.
Can you have too much Vitamin D?
Yes, the upper tolerable limit is 80 mcg or 3,200 IU daily. The max recommended amount in supplements is 25 mcg or 1,000 IU daily, we don’t recommend people take above this. Vitamin D is fat soluble and stored in our fat cells. And don’t worry, we can’t get too much Vitamin D from the sun, because the body is onto it - it regulates how much it converts.
What to look for in your Vitamin D supplement
If you’re thinking about taking a Vitamin D supplement it makes sense to choose the active D3 (Cholecalciferol) form rather than D2. It’s in a more useable form for the body. Looking for a Vitamin D the whole family can take? To keep things nice and simple, choose a kids Vitamin D and then adjust the dose for adult family members. There are plenty of options to suit your needs - capsules, tablets, liquid sprays, drops, dissolvables, and chewables.