Vitamin D Deficiency: What It Means and How to Supplement It Through Your Diet

Vitamin D, often called the “sunshine vitamin”, plays a vital role in maintaining healthy bones, supporting the immune system, and helping the body absorb calcium. 

Yet, many people in the UK are deficient in it, especially during the autumn and winter months when sunlight is scarce. 

A lack of vitamin D can lead to issues such as fatigue, bone pain, muscle weakness, and even increased susceptibility to infections.

Why Vitamin D Deficiency Happens

In the UK, sunlight isn’t strong enough from October to March for our skin to make adequate vitamin D. 

This is especially true for people who spend most of their time indoors, wear clothing that covers most of their skin, or have darker skin (as more melanin reduces the skin's ability to produce vitamin D from sunlight).

Diet alone is unlikely to provide enough vitamin D, but it can help maintain levels, especially when supported with supplements.

Signs You Might Be Deficient

Some common signs of vitamin D deficiency include:

Frequent illnesses or infections

Tiredness or fatigue

Bone and back pain

Depression or low mood

Impaired wound healing

Muscle pain or weakness

If you’re experiencing these symptoms, it’s worth speaking to your GP or pharmacist. A simple blood test can confirm whether your vitamin D levels are low.

Foods That Are Naturally High in Vitamin D

To help boost your intake, include these foods in your diet:

Oily fish (e.g. salmon, sardines, mackerel, trout)

Cod liver oil

Egg yolks

Red meat (especially liver)

Fortified foods such as:

Breakfast cereals

Plant-based milks (soya, oat, almond, etc.)

Margarine and some dairy products

Orange juice (check the label)

Mushrooms exposed to sunlight (labelled as "UV-exposed") are also a vegan-friendly option that naturally contains vitamin D2.

Should You Take a Supplement?

Public Health England recommends that everyone over the age of 1 should consider taking a 10 microgram (400 IU) vitamin D supplement daily during the autumn and winter. People at higher risk of deficiency (e.g. those who are housebound, elderly, or have darker skin) are advised to consider supplements year-round.

Vitamin D supplements are widely available in pharmacies, supermarkets, and health food shops. You can find it as:

Vitamin D2 (ergocalciferol) – plant-based

Vitamin D3 (cholecalciferol) – usually from animal sources or vegan-friendly lichen

A Note on Safety

Avoid taking high doses of vitamin D for prolonged periods unless advised by a healthcare professional. While toxicity is rare, extremely high levels can cause health problems such as kidney damage.

In Summary

Vitamin D is essential, especially for people living in northern climates like the UK. You can top up your vitamin D through oily fish, fortified foods, and safe sun exposure when possible — but during the darker months, a daily supplement is often the most practical way to keep your levels healthy.

Have you checked your vitamin D levels recently? It might be worth adding a little sunshine to your routine — even if it's in tablet form.