Vitamin D in Autumn: What UK Adults Need to Know Before Winter

August 27, 2026

As the days grow shorter and summer gives way to autumn, vitamin D becomes one of the most relevant nutrients to think about in the UK.

Unlike most vitamins, our bodies can make vitamin D when skin is exposed to sunlight. But during the darker part of the year, the UK sun is not strong enough for most people to make sufficient vitamin D this way.

That is why current NHS and UK government guidance recommends that adults and children over four consider taking 10 micrograms (400 IU) of vitamin D each day during autumn and winter.

So when should you start thinking about vitamin D, which foods contain it, and what should you look for when comparing supplements?

Here is a practical guide.

Why Does Vitamin D Matter More in Autumn and Winter?

Between roughly late March or early April and the end of September, most people in the UK can make the vitamin D they need through sunlight on their skin alongside a balanced diet.

From around October to early March, the situation changes.

At this time of year, sunlight in the UK does not contain enough UVB radiation for the skin to make adequate vitamin D. This means we become more dependent on dietary sources and, where appropriate, supplements.

Because naturally occurring food sources of vitamin D are relatively limited, government guidance recommends considering a daily supplement during these darker months.

When Should You Take Vitamin D in the UK?

For adults and children over four, current NHS guidance recommends considering a daily supplement containing 10 micrograms of vitamin D during autumn and winter.

Ten micrograms is the same as 400 International Units (IU).

For most people, this seasonal guidance applies from approximately October until early March.

This includes pregnant and breastfeeding women.

It is important to distinguish this general public-health recommendation from personalised medical advice. Some people may be advised to take a different amount by a doctor or another qualified healthcare professional.

Do Some People Need Vitamin D All Year?

Yes.

Some people may have less opportunity to make vitamin D from sunlight even during spring and summer.

Current UK guidance advises certain groups to consider taking 10 micrograms of vitamin D throughout the year, including people who:

are not often outdoors;
are frail or housebound;
live in a care home;
usually wear clothing that covers most of their skin when outside.

People with dark skin, including people from African, African-Caribbean and South Asian backgrounds, may also not make enough vitamin D from sunlight and are advised to consider supplementation throughout the year.

If you are uncertain which guidance applies to you, ask a pharmacist, GP or another appropriately qualified healthcare professional.

Can You Get Vitamin D From Food?

Vitamin D is found naturally in only a relatively small number of foods.

Sources include:

oily fish such as salmon, sardines, herring and mackerel;
egg yolks;
red meat;
liver;
foods fortified with vitamin D, such as some breakfast cereals and fat spreads.

These foods can contribute to your overall vitamin D intake as part of a varied and balanced diet.

However, UK guidance recognises that it can be difficult to obtain enough vitamin D from food alone during autumn and winter.

That is one reason seasonal supplementation is recommended for consideration.

What Does 10 Micrograms of Vitamin D Mean?

One thing that can make vitamin D labels confusing is that the amount may be expressed in two different units.

You might see:

micrograms (µg or mcg); or
International Units (IU).

For vitamin D:

1 microgram = 40 IU

This means:

10 micrograms = 400 IU

Once you know the conversion, comparing supplement labels becomes much easier.

The key is to look at the amount per recommended daily serving, rather than simply choosing the product with the largest number on the front.

Is More Vitamin D Always Better?

No.

A higher-strength supplement is not automatically more appropriate.

The NHS advises adults not to take more than 100 micrograms (4,000 IU) of vitamin D per day, because taking excessive amounts over a prolonged period can lead to too much calcium building up in the body.

That upper amount is very different from the general autumn and winter recommendation of 10 micrograms.

Some products are intentionally formulated at higher strengths, so it is important to read the label, understand the amount per serving and follow the directions for use. Veldic's Lipo-D3 + K2 Liquid Drop is one example — it provides 100µg (4,000 IU) of vitamin D3 per serving, combined with vitamin K2. That sits within the NHS upper limit, but well above the general 10µg autumn and winter recommendation, so formats like this are typically better suited to people who have been advised by a healthcare professional to take more, or who specifically want a combined D3/K2 formula. If you already take a multivitamin or another supplement containing vitamin D, check the combined total against the 100µg daily limit before adding a higher-strength product.

If a healthcare professional has recommended a particular vitamin D dose because of your individual circumstances, follow their advice rather than general information online.

Vitamin D2 or Vitamin D3: What's the Difference?

Vitamin D supplements commonly contain either vitamin D2 or vitamin D3.

Vitamin D2 is known as ergocalciferol, while vitamin D3 is known as cholecalciferol.

You do not necessarily need to become an expert in supplement chemistry before choosing a product, but checking the ingredient list will tell you which form is present.

Some products also combine vitamin D with other nutrients.

The most important starting point is still to understand the amount provided per serving, follow the label and choose a format that suits your needs.

What Should You Look for When Comparing Vitamin D Supplements?

Supplement shelves can be confusing, especially when products use different serving sizes, units and formats.

A few simple checks make comparison easier.

1. Check the amount per serving

Look at the nutritional information rather than simply relying on the front of the pack.

Make sure you know how much vitamin D the recommended serving actually provides.

2. Check whether the label uses micrograms or IU

Remember:

10 micrograms = 400 IU

This makes it easier to compare two products presented using different units.

3. Check the form

Look at the ingredient list if you want to know whether the supplement contains vitamin D2 or D3.

4. Check the recommended intake

Different products can have very different strengths.

Follow the directions on the individual product rather than assuming all vitamin D supplements are taken in the same way.

5. Check your other supplements

A multivitamin, mineral complex or another daily supplement may already contain vitamin D.

Check all the products you use before adding another source.

A Simple Autumn Vitamin D Checklist

When the days start becoming noticeably shorter, ask yourself:

Am I entering the October-to-early-March period?
Do I already take a supplement containing vitamin D?
Have I checked the amount per daily serving?
Do I understand whether the label is using micrograms or IU?
Do I spend very little time outdoors?
Does government guidance suggest I should consider vitamin D throughout the year?
Have I been given different advice by a healthcare professional?

These checks take only a few minutes and can make supplement choices much easier to understand.

Keep Food in the Picture

Supplements should complement a balanced diet rather than replace one.

Oily fish, eggs and fortified foods can contribute vitamin D, while a varied diet provides many other vitamins, minerals, protein, fibre and essential nutrients.

Vitamin D supplementation during autumn and winter is a specific piece of UK public-health guidance — not a substitute for healthy eating.

The Bottom Line

For most UK adults, autumn is the point when vitamin D becomes particularly relevant.

From around October to early March, the sun is not strong enough for most people in the UK to make adequate vitamin D through their skin.

Current NHS guidance therefore recommends that adults and children over four consider taking 10 micrograms (400 IU) of vitamin D per day during autumn and winter.

Some people are advised to consider the same amount throughout the year because they have limited sun exposure or may make less vitamin D from sunlight.

The important thing is not to assume that the highest-strength product is automatically the best choice.

Understand the guidance, read supplement labels carefully and seek professional advice where your circumstances fall outside general recommendations.

Practical Recommendations

Start with the official guidance. For most adults, the current seasonal recommendation is to consider 10 micrograms of vitamin D per day during autumn and winter.

Check what you already take. Multivitamins and other supplements may already contain vitamin D.

Compare the serving, not just the front label. Look at the amount provided by the recommended daily serving.

Understand micrograms and IU. Knowing that 10 micrograms equals 400 IU makes product comparisons easier.

Do not assume higher strength means better. Different products are designed with different serving strengths and instructions.

Keep your diet varied. Foods such as oily fish, egg yolks and fortified foods can contribute vitamin D alongside other essential nutrients.

If you are comparing vitamin D supplements or other everyday nutrients, Veldic offers a dedicated Vitamins & Minerals range with a variety of supplement formats.

Explore Veldic Vitamins & Minerals

Food supplements should not be used as a substitute for a varied and balanced diet and a healthy lifestyle. Always read and follow the product label. If you have a medical condition, are taking medication, are pregnant or breastfeeding, or are unsure whether a supplement is suitable for you, seek advice from an appropriate healthcare professional.

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