When you wake up and the world feels dim; not sad, not sick, just flat. As though your body is running on 20% battery and no one warned you.
That quiet heaviness can sometimes be low vitamin D.
And here’s the twist: vitamin D isn’t technically a vitamin at all. It behaves more like a hormone a backstage operator quietly directing essential processes in the body.
When sunlight reaches your skin, ultraviolet B rays trigger a transformation. Cholesterol in the skin is converted into cholecalciferol (vitamin D₃), which is then processed by the liver and kidneys into calcitriol the active hormonal form. From there, it acts as a genetic switchboard, influencing hundreds of genes involved in bone strength, immune resilience, inflammation regulation, and even mood stability.
It doesn’t shout. It regulates.
Modern life, however, isn’t designed for optimal vitamin D status. SPF 50 (which we absolutely still need for skin cancer prevention), indoor offices, long commutes, shift work, screen time, and cooler seasons all limit the skin’s opportunity to produce it. While supplements can be useful and sometimes necessary, the body’s preferred source is still safe, sensible sunlight.
What’s recommended?
In Australia, general guidance suggests:
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Adults aged 19–50 years: Around 5–10 minutes of mid-morning or mid-afternoon sun on most days in summer (longer in winter, particularly in southern states).
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Adults over 50: Slightly longer exposure may be needed.
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Darker skin tones: Often require longer sun exposure to produce the same amount of vitamin D.
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Dietary intake: The Australian recommended dietary intake (RDI) is 5 micrograms (200 IU) per day for adults up to 50, increasing to 10–15 micrograms (400–600 IU) for older adults — though sunlight remains the primary source.
If you’re unsure about your levels, a simple blood test — 25-hydroxyvitamin D — provides a reliable snapshot. Generally, levels above 50 nmol/L are considered adequate for bone health, though optimal targets can vary depending on individual health needs.
What foods can help?
When you start wondering if food can fix that 20% battery feeling, vitamin D gets a little humbling.
Although food helps, sunlight remains the primary source of energy.
Oily fish are the true standouts; salmon, sardines, mackerel and tuna deliver meaningful amounts in a single serve. If you’re going to focus anywhere, focus here.
Egg yolks contribute, but modestly. Mushrooms only help if they’ve been UV-exposed. Some milks and cereals are fortified, but amounts vary.
The honest reality? Even with a good diet, it’s hard to reach optimal vitamin D levels from food alone.
So yes, add the salmon. Keep the eggs. Sun your mushrooms.
But if that beige fog lingers, it may be worth checking your levels.
Grilled salmon