Winter Vitamin Supplements You Might Need: Why Vitamin D, B12 & Omega-3 Matter

As the nights draw in, Vitamin D, B12 and Omega-3 become harder to get from diet and daylight alone. This guide covers what each one does, how much you need, and when a quick blood test can tell you for sure. 

Winter vitamin supplements you might need

As the colder months and shorter days set in, adjusting your vitamin intake can help you stay healthy and energised throughout winter. Below, we explore the three most recommended winter supplements (plus three more nutrients worth knowing about this winter):

  • Vitamin C
  • Vitamin D
  • Vitamin B12
  • Omega‑3 fatty acids, why they matter, and how to use them safely, by our private online GP service to support your health and wellbeing.
  • Iron
  • Zinc

Why take vitamin supplements in winter?

Even with a healthy lifestyle, winter can present unique challenges. The UK's darker days can lower energy levels, contribute to the ‘winter blues’, and make it harder to stay active. Limited sunlight, colder weather, and changes in routine often leave our bodies lacking essential nutrients.

Winter vitamin supplements like Vitamin D, Vitamin B12, and Omega-3 fatty acids can help keep you feeling your best. From boosting energy levels to supporting brain function, these supplements offer essential benefits when you need them most.

1. Combat fatigue & support energy with vitamin B12

What does vitamin B12 do?

Vitamin B12 is essential for:

  • Releasing energy from food
  • Producing red blood cells

Without sufficient B12, you may feel fatigued, weak, or lethargic. A deficiency can also impact mental health, with low B12 levels linked to depression in some cases. Correcting this deficiency may help improve mood and energy levels.

Food sources of vitamin B12:

Vitamin B12 is found in:

  • Milk and cheese
  • Eggs
  • Meat and fish

Since B12 is not naturally found in fruits, vegetables, or grains, it’s particularly important for vegetarians and vegans to consider supplementation.

Recommended intake

The NHS advises adults to consume up to 1.5 micrograms of Vitamin B12 daily. If your diet doesn’t provide enough, a supplement is a great option to ensure you meet your needs.

2. Stay strong with vitamin D

What Does Vitamin D Do?

Known as the ‘sunshine vitamin’, Vitamin D is vital for:

  • Healthy bones and teeth
  • Strong muscles

A lack of Vitamin D can lead to fatigue, aches, and serious conditions like rickets in children or osteomalacia (bone pain) in adults.

Food sources of vitamin D:

Natural sources include:

  • Oily fish (e.g., salmon, mackerel, sardines)
  • Egg yolks
  • Liver
  • Red meat

Other Sources - Our bodies create 90% of the Vitamin D we need through exposure to sunlight. However, from September to March, reduced daylight makes it difficult to meet this requirement naturally.

Recommended intake

The NHS recommends taking 10 micrograms of Vitamin D daily during autumn and winter. This ensures your body gets the Vitamin D it needs for optimal health. For more details, visit the NHS Vitamin D page.

3. Boost your brain with Omega 3 fatty acids

What do omega-3 fatty acids do?

Omega-3 fatty acids are crucial for brain health and function. Research by the University of Pittsburgh found that people with lower levels of Omega-3s were more likely to experience mild depression or a negative outlook.

Food sources of omega-3s:

You can find Omega-3 fatty acids in:

  • Oily fish (e.g., herring, sardines, mackerel)
  • Salmon
  • Walnuts
  • Flaxseed

Recommended intake

Experts recommend up to 500 milligrams of Omega-3 fatty acids daily. Look for supplements containing eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) for maximum benefit.

4. Support your immune system with vitamin C

What does vitamin C do?

Vitamin C supports your immune system, skin, and how well your body absorbs iron from plant-based foods. While it’s often marketed as a cold remedy, the evidence for preventing colds is modest — regular supplementation may slightly shorten how long a cold lasts, but starting it once symptoms appear is unlikely to make much difference.

Food sources of vitamin C:

Vitamin C is found in:

  • Citrus fruits (e.g., oranges, lemons)
  • Peppers
  • Broccoli
  • Strawberries

Recommended intake

Adults need around 40mg of Vitamin C a day, which most people get through a varied diet. If you choose to supplement, avoid exceeding 1,000mg daily long-term, as high doses can cause stomach upset.

5. Fight winter fatigue with iron

What does iron do?

If you’ve been searching for why you feel constantly tired this winter, low iron could be part of the answer. Iron is essential for producing haemoglobin, the protein in red blood cells that carries oxygen around your body — without enough of it, you can develop iron-deficiency anaemia, which causes fatigue, weakness, and pale skin.

Who’s most at risk?

Menstruating women, pregnant women, and vegetarians or vegans are most likely to need extra iron, since heavy periods, pregnancy, and plant-based diets can all make it harder to get or retain enough.

Food sources of iron:

Iron is found in:

  • Red meat
  • Beans and lentils
  • Fortified breakfast cereals
  • Dark leafy greens (e.g., spinach)

Recommended intake

Because too much iron can be harmful, it’s best to get a blood test before starting a supplement rather than guessing — your GP can confirm whether you’re actually deficient and recommend the right dose for you.

6. Support immunity with zinc

What does zinc do?

Zinc plays a key role in immune function, and some studies suggest that taking zinc lozenges or supplements at the first sign of a cold may shorten how long symptoms last.

Food sources of zinc:

Zinc is found in:

  • Meat and shellfish
  • Dairy products
  • Bread and cereals
  • Beans and nuts

Recommended intake

The NHS recommends around 9.5mg of zinc a day for men and 7mg for women, available through a balanced diet for most people. Avoid taking more than about 25mg a day long-term, as too much zinc can affect how your body absorbs other nutrients.

Which groups need extra care with winter vitamins?

Some groups are more likely to need particular nutrients than others:

  • Vegans and vegetarians: more likely to need a Vitamin B12 supplement, since B12 is mainly found in animal products.
  • Older adults: at higher risk of low Vitamin D, partly due to spending less time outdoors and reduced synthesis of it in the skin with age.
  • Pregnant women: need both Vitamin D and folate to support their baby’s development.
  • Children: also need Vitamin D to support healthy bone growth.

Should you get a blood test before supplementing?

If you suspect you might be low in Vitamin D, B12, or iron — for example, if you’re feeling unusually tired, low in mood, or have muscle or bone pain — a blood test can confirm whether you actually need a supplement, rather than guessing. This is particularly useful before starting iron, since taking too much can be harmful. Doctor Care Anywhere’s private GP service can arrange a blood test and talk you through your results, so you know exactly what your body needs.

Winter nutrients at a glance

  • Vitamin D: supports bones, muscles and immunity. 10µg (400IU) daily between October and March, from oily fish, egg yolks, liver and red meat. Especially important for older adults, children, pregnant women, and anyone with limited sun exposure.
  • Vitamin C: supports immune function and helps your body absorb iron from plant foods. Around 40mg daily, found in citrus fruits, peppers, broccoli and strawberries. Worth watching if your diet is light on fruit and veg.
  • Iron: prevents the fatigue and anaemia that come with low oxygen-carrying capacity in the blood. Best confirmed with a blood test before supplementing, from sources like red meat, beans, lentils, fortified cereals and leafy greens. Menstruating women, pregnant women, and vegetarians or vegans are most at risk of running low.
  • Vitamin B12: supports energy production and red blood cells. Around 1.5µg daily, from milk, cheese, eggs, meat and fish. Vegetarians and vegans are most likely to need a supplement.
  • Omega-3: supports brain health and mood. Up to 500mg daily (EPA/DHA), from oily fish, walnuts and flaxseed. Worth considering if you rarely eat oily fish.
  • Zinc: supports immune function and may shorten how long a cold lasts. Around 9.5mg (men) or 7mg (women) daily, from meat, shellfish, dairy, beans and nuts. Worth watching on a restricted diet.

Stay healthy this winter with expert support

Winter can be tough on both physical and mental health, but the right supplements can make a big difference.

If you’re unsure which supplements are best for you, our private online GP service is here to help. Available 24/7, our team of GPs and Advanced Clinical Practitioners (ACPs) can offer tailored advice, consultations, and support to keep you and your family healthy throughout the colder months.

How to use supplements safely, winter wellness habits

  • Prefer Vitamin D in the widely recommended 10 µg (400 IU) daily dose in autumn/winter unless a healthcare professional advises otherwise.
  • For B12 — especially if you are vegetarian or vegan — consider a daily supplement if diet doesn’t supply enough.
  • For Omega-3 — aim for supplement forms providing EPA/DHA; take with a meal containing fat to improve absorption.
  • Supplements aren’t a substitute for a healthy lifestyle: a balanced diet, safe sun exposure when possible, physical activity and sleep remain fundamental.
  • If in doubt — especially if you have health conditions or take other medications — consult a doctor or qualified GP before starting supplementation.

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Frequently asked questions

Got questions about winter vitamins? Here's what our GPs get asked most about staying well through the colder months. 

Yes- because in the UK, winter sunlight is rarely strong enough for skin to make sufficient vitamin D. Even a balanced diet often won’t supply enough, so a daily supplement of 10 µg during autumn and winter is widely recommended. 

It’s difficult, because B12 is naturally found in animal-based foods. Without fortified foods or supplements, vegetarians and vegans may risk deficiency.

The standard recommendation is 10 micrograms (400 IU) per day for most people. Higher doses should only be taken under medical advice. 

With a meal containing some fat — this helps absorption. Taking it daily is useful if your diet lacks oily fish. 

For most healthy adults, yes, taken at recommended doses, there’s generally no conflict. But if you have existing health conditions, check with your GP. 

It can be helpful; especially if you suspect deficiency (fatigue, bone/muscle pain, low mood). A blood test gives clarity; for general preventative supplementation, guidelines offer safe baseline doses. 

For most people in the UK, Vitamin D, Vitamin B12, and Omega-3 are the three most commonly recommended daily supplements — Vitamin D because winter sunlight is rarely enough, B12 particularly for vegetarians and vegans, and Omega-3 for those who don’t regularly eat oily fish. See the sections above for full details on each. 

Yes — for most healthy adults, there’s no issue taking all three together. Vitamin D and Omega-3 are fat-soluble, so it helps to take them with a meal containing some fat to improve absorption. If you have an existing health condition or take other medication, check with your GP first. 

Rather than recommending a specific brand, the NHS advises adults take 10µg (400IU) of Vitamin D3 daily between October and March, when sunlight alone isn’t enough. Look for a D3 (rather than D2) supplement, and speak to your GP or pharmacist if you’re unsure which product suits you. For more detail, see the NHS vitamin D page.