This is your sign to take a daily vitamin D supplement now

vitamin d
Why you should take a vitamin D supplementTanja Ivanova - Getty Images

It’s November, which means it’s officially winter and everyone – yes, everyone (including pregnant and breastfeeding women) – should consider taking a daily vitamin D supplement.

Why? Most of our vitamin D comes from sunshine, so in the autumn and winter months, both the Government and the NHS advise that in the UK individuals should supplement with vitamin D – because we simply don’t make enough vitamin D from sunlight. But do we really need these pills? And do they even work?

The recommended daily amount is 400 IU or 10mcg (µg) for adults.

Meet the experts: Dr Federica Amati, Head Nutritionist at ZOE, the personalised nutrition company and author of Recipes for a Better Menopause. Tina Lond-Caulk, nutritionist, Revive Active brand ambassador and author of Eat Well and Feel Great. Kim Pearson, Harley ­Street-based nutritionist.

Why do our bodies need vitamin D?

‘Vitamin D is the sunshine vitamin,’ says Tina Lond-Caulk, nutritionist, Revive Active brand ambassador and author of Eat Well and Feel Great – aka the Nutrition Guru. ‘Our bodies need it for so many reasons, and during our winter months in the UK, it becomes even more crucial.’

‘Vitamin D impacts every tissue in our body,’ adds Dr Federica Amati, Head Nutritionist at ZOE and author of Recipes for a Better Menopause. ‘It’s essential for immune system function and bone health.’

While the body is able to produce it through sun exposure and also source it from our diet (think: oily fish, mushrooms and fortified cereals), at this time of year – due to the lack of sunlight – vitamin D cannot be produced in our body (and, actually, most of us don’t obtain much vitamin D from our diets compared to what we need for our health).

‘Unfortunately, there are few good quality, natural food sources of Vitamin D,’ says Harley ­Street-based nutritionist Kim Pearson. ‘And due to our increasingly indoor lifestyles and unpredictable UK weather, this puts many of us at risk from deficiency.’

But our bodies need vitamin D, Dr Amati says, and its role extends well beyond bone health. ‘Vitamin D, in partnership with vitamin A, fine-tunes the immune response,’ she explains.

‘Immune cells are equipped with vitamin D receptors, allowing them to interact directly with the vitamin. These cells can even produce the active form of vitamin D, which in turn modulates their activity.’

Vitamin D really is a key player in terms of so many aspects of our health, says Lond-Caulk, who describes vitamin D as ‘like a hormone’ since it regulates various body functions and gene expressions.

‘It plays several crucial roles in the body. First up it helps regulate the immune system, helping our body fend off infections and illnesses. It can have a huge impact on our mood and mental health and help prevent things like seasonal affective disorder (SAD). Another of its main jobs is to help our bodies absorb calcium and promote strong, healthy bones,’ she says.


The benefits of vitamin D

  • Helps fight colds and flu

  • Promotes healthy bones and teeth

  • Regulates blood sugar levels

  • Plays an important role in regulating mood and warding off depression

  • Reduces the risk of allergies


What are the symptoms of low vitamin D?

‘There are many common health symptoms associated with deficiency,’ says Pearson. ‘These include; suffering with frequent coughs and colds, fatigue, low mood and depression, lower back pain and muscle weakness. However, it’s common to have suboptimal levels of the vitamin and experience no symptoms at all. The only way to know for sure is to test your levels.’

How would someone know if they're low in vitamin D? A 25-hydroxy D blood test is the best way of actually measuring your vitamin D status, but this is a proxy measure – which means it gives you an idea of how your body is breaking vit D down, but it doesn't necessarily tell you how it's being used or what effects it's having.

Why should we consider taking a vitamin D supplement?

‘It’s recommended to take a supplement for all the months with an R in from September to the end of April when we cannot make efficient Vitamin D from sunlight in the UK,’ says Lond-Caulk.

But the body’s vitamin D level is affected by various factors beyond seasonal changes, adds Dr Amati. ‘The use of sunscreen, while protective against UV damage, can significantly reduce the skin's ability to produce vitamin D, which requires UVB radiation for synthesis. Skin pigmentation also plays a role; melanin acts as a natural sunscreen, and more melanin can decrease vitamin D production.’

As we age, our skin’s capacity to generate vitamin D from sunlight diminishes, she says. ‘Additionally, body fat impacts vitamin D status since it is fat-soluble; higher body fat levels can trap vitamin D and restrict its circulation in the bloodstream.’

‘Genetic factors also contribute, with certain genetic variations, including Single Nucleotide Polymorphisms in vitamin D-related genes, potentially altering vitamin D levels and associated disease risk.’

So who should take a vitamin D supplement all year round?

  • People with dark skin from African, African-Caribbean and South Asian backgrounds.

  • Older people, especially those who live in care homes or spend long periods indoors.

  • People who are frail or housebound.

  • Those who cover most of their skin when outside – especially for cultural and/or religious reasons.

Is there any downside to taking vitamin D supplements?

There have been several trials where people have been given more than 400 IU per day – up to 5,000 – which have shown that having vitamin D injections or large amounts via mouth led to increased fractures and increased falls.

It's worth noting that vitamin D doesn't just get peed out like some other B vitamins. So, if you overdose, you'll end up with a build-up, which can cause nerve problems and muscle problems.

Do not take more than 100 micrograms (4,000 IU) of vitamin D a day as it could be harmful.

What are the different vitamin D supplements out there?

‘Supplements are available in two forms,’ says Pearson. ‘Vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol).’

‘Most experts agree that D3 is the preferred form – humans synthesise vitamin D3 in response to sunlight and therefore it is the most natural form to supplement,’ she says. ‘Vitamin D3 is more bioavailable and significantly more effective at increasing blood levels than vitamin D2.’

Just be cautious of the dose –and make sure you're getting the 400 international unit – which is equivalent to 10 micrograms.

The best vitamin D supplements on the market

So what sort of supplement should you look for? Lond-Caulk recommends choosing a Vitamin D3 and K2 supplement together ‘as they are the preferred choice at effectively raising your levels of Vitamin D, making it a dynamic duo,’ she says.

Why? ‘Because the Vitamin K2 directs the calcium from your bloodstream to your bones and teeth and ensures it doesn’t accumulate in the arteries,’ she explains.

Best vitamin D spray

Best vitamin D drink

Best vitamin D capsules

Best vitamin D sachet

Best vitamin D gummies

Best vitamin D supplement for vegans



  • If you’re concerned you don’t have a ‘normal’ vitamin D level, chat with your GP and/or dietitian.

  • Always check with your GP or a healthcare professional before trying any new supplements, treatments or remedies. Food supplements must not be used as a substitute for a varied and balanced diet and a healthy lifestyle.


More in Nutrition

Cut through the noise and get practical, expert advice, home workouts, easy nutrition and more direct to your inbox. Sign up to the WOMEN'S HEALTH NEWSLETTER

You Might Also Like