Australia. One of the sunniest countries on the planet. And yet, research suggests that a significant number of Australian children have inadequate vitamin D levels. It sounds counterintuitive, but when you understand how vitamin D actually works, it starts to make a lot more sense.
The reality is that sunscreen (which we absolutely need in Australia), more time indoors, darker skin tones and limited dietary sources all contribute to a situation where many children aren't producing or consuming enough of this critical nutrient. And vitamin D does so much more than just support strong bones.
80%+
of our vitamin D comes from UVB exposure to the skin, not from food. But glass, sunscreen and clothing all block UVB radiation, which is why indoor time significantly reduces production.
Why vitamin D matters for growing kids
Vitamin D supports:
Immune function: It helps activate and regulate immune cells, supporting your child's ability to fight off infections. Studies suggest that deficiency increases the risk of acute respiratory infections in children. Bone and skeletal health: Vitamin D is essential for calcium absorption. Without it, calcium can't be properly used for bone building. Mood and mental health: Emerging research links low vitamin D to an increased risk of depression and mood disorders, including in children and postpartum women. Muscle function: It supports healthy muscle development and strength.
Why are Australian kids low?
It comes down to a few factors working together:
Sunscreen use. We need sunscreen in Australia (our UV levels are among the highest in the world), but it blocks the UVB radiation that triggers vitamin D production in the skin. This is a genuine catch-22 for parents.
Indoor lifestyles. More screen time, more structured indoor activities, less unstructured outdoor play. Many children spend the peak UVB hours (roughly 10am to 3pm) either inside or covered up.
Skin colour. Children with darker skin tones require more UVB exposure to produce the same amount of vitamin D as lighter-skinned children. This is a significant factor in multicultural Australia.
Limited food sources. Very few foods naturally contain significant amounts of vitamin D. Oily fish, egg yolks and some mushrooms are the main dietary sources, and these aren't exactly toddler favourites.
How much do kids need?
Infants and children (0 to 18 years): 5μg (200 IU) per day as the adequate intake
Many health professionals suggest higher intakes may be beneficial, particularly during winter months or for children with limited sun exposure. A blood test for 25-hydroxy vitamin D is the best way to check levels.
Best food sources of vitamin D
Cod liver oil, salmon, mackerel, herring, trout, sardines, fish roe, tuna, egg yolks, beef liver, and mushrooms (particularly shiitake and those exposed to UV light).
It's worth noting that plant-based sources of vitamin D are extremely limited, which is why we chose to include vitamin D from organic shiitake mushroom powder in Kids Immune Protein. Each serve provides 2.5μg (50% of the adequate intake), making it a meaningful contribution alongside sun exposure and dietary sources.
Practical tips for supporting your child's vitamin D
Get outside early. Brief periods of skin exposure before 10am (when UV levels are lower) can support vitamin D production with less burn risk. Even 10 to 15 minutes of morning sun on arms and face can help.
Include oily fish where you can. Even once or twice a week makes a difference. Salmon, sardines and trout are the richest sources. Tinned salmon on crackers is an easy lunchbox option.
Eggs are your friend. The yolk contains vitamin D. This is one of the reasons I'm such a fan of eggs for kids (they're also one of the best food sources of choline).
Consider testing. If your child has any risk factors (limited sun exposure, darker skin, very restricted diet, or symptoms like frequent illness or fatigue), ask your GP to check their 25-hydroxy vitamin D level. It's a simple blood test.
Why we use shiitake mushroom powder (not synthetic vitamin D)
When formulating Kids Immune Protein, I wanted every ingredient to come from a real food source where possible. Shiitake mushrooms naturally produce vitamin D when exposed to UV light, similar to how our own skin works. Using organic shiitake mushroom powder gives us a wholefood-derived vitamin D source that aligns with our philosophy: nutrients from food, not a lab.
