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Should you be taking vitamin D?

Have YOU started taking your vitamin D supplement? Approximately one out of every six adults and nearly 20% of children in the UK have vitamin D levels that fall below the government’s recommended guidelines.1https://www.gov.uk/government/news/new-review-launched-into-vitamin-d-intake-to-help-tackle-health-disparities#:~:text=Around%201%20in%206%20adults%20and%20almost%2020%25%20of%20children,levels%20lower%20than%20government%20recommendations.

Reported cases of vitamin D deficiency have been increasing and Public Health England now recommends that everyone should supplement their diet with vitamin D between October – April. The risk of deficiency increases during these darker winter months when the UK sun is playing hide-and-seek with us!

Why is vitamin D deficiency such a problem? Vitamin D is now known to be involved in almost every aspect of health2https://pubmed.ncbi.nlm.nih.gov/25774604/. Unlike most other essential nutrients, vitamin D is not typically supplied by a healthy balanced diet.

The main source of vitamin D is bare skin contact with sunshine, and when sunlight is scarce, deficiency risk starts to soar. To put it simply – we don’t get enough exposure to the sun in the UK! On top of that, we have factors such as working and playing inside, covering up, travelling in cars and liberal use of sunscreen.

So why should you be concerned? Here are just some of the roles vitamin D plays in our health: 

Immune health

The immune system can be divided into 2 vital parts –

  1. The innate immune response can be likened to first responders at the scene of a crime. Innate immune responses are non-specific and include physiological responses such as inflammation, fever, the release of antimicrobial chemicals and the arrival of phagocytic white blood cells that engulf and digest foreign entities. Vitamin D is essential for the innate immune system to function optimally.
  2. The adaptive immune response is more like the specialist team working behind the scenes and recruited a bit further down the line. This specialist team are particularly helpful as they remember previously encountered criminals! Adaptive immune responses are more specific, take time to appear and generate immunologic memory which improves with every encounter. Adaptive immune responses include lymphocytes, memory cells and antibodies. Vitamin D is crucial for the optimal function of the adaptive immune system.

Without sufficient vitamin D, many aspects of innate and adaptive immune function may be compromised. At this time of year, it is vital to keep your immune response strong! A large 2017 study published in the British Medical Journal found vitamin D to be effective for preventing colds and flu3https://pubmed.ncbi.nlm.nih.gov/28202713/. So it’s worth having your levels checked this autumn!

For extra support in strengthening your immune system, try our immune-boosting smoothie recipes!

Bone health

One of the many roles of vitamin D is to support bone health4https://doi.org/10.1093/jn/126.suppl_4.1159S. Calcium is required for normal growth, development and maintenance of the skeleton, where it provides strength and structure. Vitamin D boosts calcium absorption from the intestines and its re-absorption from the kidneys. This is how vitamin D greatly enhances levels of available calcium within the body. Check out our article Unleash your inner strength: 8 reasons you should be strength training for more tips on improving your bone health!


Low vitamin D is commonly associated with elevated levels of C-reactive protein (CRP) – a marker of systemic low-grade inflammation. Inflammation is the main driver behind many diseases including rheumatoid arthritis, dementiaParkinson’s, IBD, heart disease, MS, type 2 diabetes, and obesity. Research has confirmed that correction of low vitamin D status may reduce chronic inflammation.5https://pubmed.ncbi.nlm.nih.gov/35579027/


The days are getting darker, but your mood doesn’t have to! Research has shown that vitamin D might play an important role in regulating mood and decreasing the risk of depression6https://pubmed.ncbi.nlm.nih.gov/32365423/

In 2022, researchers investigated the efficacy of vitamin D in reducing depressive symptoms among adults. The researcher’s results “suggest that vitamin D supplementation has beneficial effects in both individuals with major depressive disorder (MDD) as well as in those with milder, clinically significant depressive symptoms”.7https://pubmed.ncbi.nlm.nih.gov/35816192/

Another study identified low vitamin D levels as a risk factor for more severe fibromyalgia symptoms, anxiety, and depression8https://pubmed.ncbi.nlm.nih.gov/32022867/. Vitamin D is also important for muscle function, growth and development, and reducing autoimmune risk. 

Who is at risk of deficiency?

• Pregnant women, breastfed babies and all children under the age of 5*.
• Elderly adults – the body’s ability to make vitamin D falls by at least half between the ages of 20 – 80 years.
• Limited time outside – housebound, hospitalised or living in a care home.
• Obesity & underweight – both can increase deficiency risk.
• Darker skin tone– African & Asian populations have in-built sun protection and require at least 3-5 times longer sun exposure.
• Liberal use of sunscreen or extensive skin covering – such as for religious or other reasons.
• Genetic factors – common genetic changes are known to affect deficiency risk.
• Where you live / time of year – risk increases the further away from the equator you live & during autumn & winter.

Public Health England – latest vitamin D advice

Public Health England responded to growing concerns around high levels of vitamin D deficiency by recommending that everyone should now supplement with vitamin D daily, not just at-risk groups.

Adults and children aged 5 and upwards should consider taking a daily supplement containing 400 IU vitamin D.
People who are at higher risk of deficiency, including babies under 1, and all children up to the age of 5 are advised to supplement all year round*.
• However, many people are already low or deficient in vitamin D so you need to supplement with higher levels to get your levels back up to scratch if you’re starting point is low or deficient. Your GP can do a simple blood test to find out.

*Exceptions are babies receiving 500ml or more fortified formula milk daily, or breastfed babies where mum is certain that her breast milk contains optimal daily amounts. Getting enough vitamin D via breast milk is a challenge however and for most breastfed babies, a daily supplement will be required.

Test, don’t guess!

Whilst it’s a good idea to supplement with a daily maintenance dose to keep your vitamin D levels topped up, the best way to evaluate your supplement requirements is with a test. Your GP can check your vitamin D status, or alternatively, there are many private companies offering vitamin D tests with a simple at-home finger-prick testing kit. If you do test, it is important that you work with a healthcare professional to evaluate your optimal daily dose. Ideally, everyone should test twice yearly; at the end of summer and at the end of winter, to keep a close eye on any changes.

To learn about how the weather can also affect your mood, check out our article Can the weather REALLY affect your mood?.

Any questions? Contact one of our Nutritional Therapists via live chat, weekdays from 8 am to 8 pm.

Advice given is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always check with your GP for interactions with medications/health conditions before starting supplements.


Questions? Talk to a Nutritional Therapist on live chat!

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