Vitamin D
Vitamin D
Vitamin D is a fat-soluble vitamin best known as the “sunshine vitamin,” because your skin makes it when exposed to sunlight. It’s a little different from other vitamins — it behaves almost like a hormone, and your body stores it and switches it into its active form as needed. It comes in two forms: D2 from plants, and D3 from animal foods (and certain lichens, which makes lichen-based D3 a useful vegan option). It’s most famous for keeping bones strong — a serious shortage in children causes rickets — but it also supports your muscles and immune system.
What does vitamin D do?
Helps you absorb calcium, for strong bones and teeth — working alongside vitamin K2 to direct that calcium to your bones
Supports your muscles and movement
Supports the immune system
Where do you get vitamin D?
Sunlight is the main source — your body makes vitamin D when daylight reaches your skin. Food provides only a small share (often just 10–20% of what you need): oily fish (salmon, sardines, mackerel), egg yolks, some mushrooms and fortified foods. Because it’s genuinely hard to get enough from food alone, the rest has to come from sunshine in the brighter months, or a supplement through the darker ones.
Can you have too little — or too much?
Low levels are common, especially through autumn and winter, for people who spend little time outdoors, have darker skin, or are older. In many countries, health authorities suggest considering a vitamin D supplement over the colder months — your doctor can advise what’s right for you, ideally with a simple blood test. Too much only comes from high-dose supplements, never from sun or food, so any high dose is worth checking first.
Common questions
Should I take a vitamin D supplement? Many people, particularly in winter, benefit from one — your doctor can confirm based on your situation.
Can I get enough vitamin D from food? It’s difficult; food covers only a small fraction, so sunlight and supplements do most of the work.
This is general information to help you eat well, not medical advice. If you have a specific concern, your doctor is the best person to help.
