by Dr Jess Braid

now more than ever, this shouldn’t be overlooked!

Jess says: The benefits of optimum vitamin D levels are now indisputable, particularly in light of the Covid-19 pandemic. Vitamin D is definitely in my top three supplements.  

I recommend that all UK adults* take a vitamin D supplement through the winter months (October to March) of 2000-4000IU (50-100μcg), preferably alongside vitamin K2. If you have any health conditions which could benefit from vitamin D or have a darker skin tone, it may be worth getting a test to check your levels. If you are an indoor worker, or wear high-factor sunscreen you may wish to consider taking the supplement year-round. 

Children should take at least 20μg (800IU), and up to 100μg (4000IU) after the age of nine. Many doctors (including myself) believe we should aim for blood test levels of 70nmol/L for optimum health, rather than the minimum 50nmol/L recommended by the NHS.

*Do not take vitamin D without talking to your healthcare provider if you have high vitamin D levels, primary hyperparathyroidism, hypercalcaemia, tuberculosis, sarcoidosis, or are in kidney failure.

Vitamin D is an essential fat-soluble vitamin, that is important not only for our bones, but our whole body. It is unique, as much of it comes from sunlight and there are only small amounts contained in our food.

60% of the UK population has insufficient vitamin D levels. There has been an alarming rise in Vitamin D deficiency, particularly in children, where rates of deficiency were 15 times higher in 2014 than they were in 2000.1  This might be due to increased testing, as it becomes clearer how important vitamin D is. It may also be due to spending less time outdoors, and the increased use of sunscreen.

Children, elderly people (particularly those in care homes) and those with darker skin tones are particularly at risk of being vitamin D deficient.2

90% of vitamin D is from sunlight


To raise the amount of vitamin D found in the blood to over 50nmol/L (the bare minimum for good health), white British people require 13 minutes of skin exposure to midday summer sun at least three times a week.2 Two of the highest food sources of vitamin D only just provide the minimum adult RDA. It takes 100g of cooked Sockeye salmon to provide 526IU (13.1μcg) and a whole can of tuna contains only 154IU (3.9μcg). The exception is cod liver oil, which provides 1360IU (13.1μcg) per tablespoon.3

for six months of the year, UK daylight doesn’t give us enough vitamin D. During winter months in the UK, there is not enough UVB light for vitamin D synthesis2 and we have to use our body’s stores of vitamin D that we created during the summer, or we need to use supplements. The NHS now recommends that everybody considers taking a vitamin D supplement, particularly children, over 65’s, those with darker skin tones, pregnant women and babies who are breast fed.4

low levels can cause bone problems. Vitamin D is needed along with calcium, magnesium and vitamin K2 for healthy mineralisation of our bones. It is also needed for bone growth and health, and to prevent and help fractures.5 Vitamin D deficiency can cause rickets in children, and osteomalacia in adults. Vitamin D helps to protect adults from osteoporosis.6

vitamin D deficiency can cause increased infections. Vitamin D deficiency not only increases your risk of catching an infection – it also increases your chance of that infection being more serious (including sepsis and likely COVID-197) and also your chance of dying from it.8

deficiency can cause pain and muscle weakness. Vitamin D helps to maintain muscle mass and strength, as well as bone strength.9 Small studies have shown that vitamin D supplements can improve musculoskeletal pain10 and osteoarthritis knee pain.11

deficiency can lead to poor growth and seizures in children. Vitamin D deficiency can cause hypocalcemic tetany (low calcium, from low Vitamin D), leading to seizures.12 It is also linked to growth problems, heart problems, autoimmune disease and ADHD in children.13

vitamin D supplements may help improve mood. Many people feel their mood drop during the darkest months of winter. If this is you, consider taking a vitamin D supplement. Low vitamin D levels have been found to increase the risk of depression and anxiety14 and supplements may improve symptoms of depression.15

vitamin D is critical to the immune system

Immune system cells have specific receptors for vitamin D to activate it, showing how important this vitamin is to our immune system. Vitamin D helps maintain a healthy immune system, protect against infection and autoimmune diseases, and regulates cell growth. It could also protect against cancer.16 More recently, research suggests that low Vitamin D levels may contribute to food allergies,17 possibly through its role in gut health.

vitamin D is important for memory and brain function. Vitamin D can protect against Alzheimer’s and dementia and is important for our brain function and memory.18

vitamin D has a role in gut and heart health. Vitamin D helps to reduce inflammation in the gut and is important in reducing the risk of inflammatory bowel diseases like Crohn’s.19 Vitamin D helps to support heart health, lower high blood pressure and reduce atherosclerosis20 (although it should be taken with vitamin K2 for maximum benefit.)21

how do you get more vitamin D?

vitamin d

go outside! Modern life makes us more and more likely to stay indoors, but the benefits of being outdoors are incredible! As well as being the best way to get vitamin D, sunshine itself promotes lower blood pressure and heart rate, the air quality is better and even the trees around us can reduce stress.

eat oily fish. Tuna, mackerel and salmon are all good sources of vitamin D.

drink organic raw milk. A great source of vitamin D – choose a good supplier.

organic egg yolks. Egg yolks are a great part of your diet, and a good source of vitamin D.

egg yolk

take a vitamin D supplement. Get your vitamin D levels checked with your healthcare provider if you need to. Your results should ideally be over 70nmol/L and under 200nmol/L. Generally, a daily maintenance dose of 800i.u(10-20μg) daily for children and 2000-4000i.u. (50-100μg) for adults is safe and beneficial.

vitamin d supplement


I’ve always believed that I should wear sunscreen at all times when outside. Are you saying this isn’t true?

This very much depends on your sun exposure or skin type. We would encourage a healthy approach for sun exposure, depending on how easily you burn. You can generally expose your skin to sunlight without concern between October and March in the UK (unless the weather is unusually warm). Between March and October, sun cream should be used on sunny days in the UK when you will be spending prolonged periods in the sun, especially between 11am and 3 pm. However, short periods of 10-15 minutes of sun on your skin, alternating with time inside and in the shade can be beneficial without suncream, to raise vitamin D and experience the many benefits of sunlight. Many daily weather apps also include a UV reading, so if the UV levels are high, then use sunscreen. 

If you are abroad on holiday, sunlight can be much stronger and you may need to apply sunscreen much more frequently. We would encourage the use of a natural sunscreen without the many harmful chemicals. We like Green People Organic (the children’s version is good), Aloe Pura and Jason and Badger brands.

I’m vegan. What are the best natural vitamin D-rich foods I should eat?

Mushrooms are the only vegan source of vitamin D and it is in the form of vitamin D2, rather than the optimal form of D3. D2 may not be as available for the body to use. We would suggest that you get your vitamin D levels checked by your medical provider or with a home testing company like Medichecks (you can do it using a finger prick sample). Aim for the optimal range of 70-120 nmol/L and supplement, if your levels are below 70. Cytoplan is a good brand of vegan vitamin D and consider also adding a vitamin K supplement.  



  1. Basatemur E, Horsfall L, Marston L, Rait G, Sutcliffe A. Trends in the Diagnosis of Vitamin D Deficiency Pediatrics. 2017;139(3):e20162748. doi:10.1542/peds.2016-2748
  2. Vitamin D position statement
  3. Vitamin D – Health Professional Fact Sheet
  4. Vitamins and minerals – Vitamin D
  5. Salamon A, Hepp B, Mátrai A, Biró C, Agota K, Fata E, Lőcsei Z, Toldy E. [Vitamin D supply of patients with hip fracture] Orv Hetil. 2014 Apr 27;155(17):659-68. Hungarian. doi: 10.1556/OH.2014.29878. PMID: 24755448.
  6. Tanzy ME, Camacho PM. Effect of vitamin D therapy on bone turnover markers in postmenopausal women with osteoporosis and osteopenia . Endocr Pract. 2011 Nov-Dec;17(6):873-9. doi: 10.4158/EP10339.OR. PMID: 21550960.
  7. Mercola J, Grant WB, Wagner CL. Evidence Regarding Vitamin D and Risk of COVID-19 and Its Severity. Nutrients. 2020 Oct 31;12(11):3361. doi: 10.3390/nu12113361. PMID: 33142828; PMCID: PMC7692080.
  8. de Haan K, Groeneveld AB, de Geus HR, Egal M, Struijs A. Vitamin D deficiency as a risk factor for infection, sepsis and mortality in the critically ill: systematic review and meta-analysis Crit Care. 2014 Dec 5;18(6):660. doi: 10.1186/s13054-014-0660-4. PMID: 25475621; PMCID: PMC4277653.
  9. Rizzoli R, Stevenson JC, Bauer JM, van Loon LJ, Walrand S, Kanis JA, Cooper C, Brandi ML, Diez-Perez A, Reginster JY; ESCEO Task Force. The role of dietary protein and vitamin D in maintaining musculoskeletal health in postmenopausal women: a consensus statement from the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis (ESCEO) Maturitas. 2014 Sep;79(1):122-32. doi: 10.1016/j.maturitas.2014.07.005. Epub 2014 Jul 17. Erratum in: Maturitas. 2015 Mar;80(3):337. PMID: 25082206.
  10. Le Goaziou MF, Kellou N, Flori M, Perdrix C, Dupraz C, Bodier E, Souweine G. Vitamin D supplementation for diffuse musculoskeletal pain: results of a before-and-after study Eur J Gen Pract. 2014 Mar;20(1):3-9. doi: 10.3109/13814788.2013.825769. Epub 2013 Sep 9. PMID: 24576123.
  11. Glover TL, Horgas AL, Fillingim RB, Goodin BR. Vitamin D status and pain sensitization in knee osteoarthritis: a critical review of the literature Pain Manag. 2015;5(6):447-53. doi: 10.2217/pmt.15.43. Epub 2015 Sep 24. PMID: 26399462; PMCID: PMC4895921.
  12. IBasatemur E, Sutcliffe A. Incidence of hypocalcemic seizures due to vitamin D deficiency in children in the United Kingdom and Ireland  J Clin Endocrinol Metab. 2015 Jan;100(1):E91-5. doi: 10.1210/jc.2014-2773. PMID: 25279499.
  13. Drury R, Rehm A, Johal S, Nadler R. Vitamin D supplementation: we must not fail our children! Medicine (Baltimore). 2015 May;94(18):e817. doi: 10.1097/MD.0000000000000817. PMID: 25950689; PMCID: PMC4602533.
  14. Bičíková M, Dušková M, Vítků J, Kalvachová B, Řípová D, Mohr P, Stárka L. Vitamin D in anxiety and affective disorders Physiol Res. 2015;64(Suppl 2):S101-3. doi: 10.33549/physiolres.933082. PMID: 26680471.
  15. Shaffer JA, Edmondson D, Wasson LT, Falzon L, Homma K, Ezeokoli N, Li P, Davidson KW. Vitamin D supplementation for depressive symptoms: a systematic review and meta-analysis of randomized controlled trials Psychosom Med. 2014 Apr;76(3):190-6. doi: 10.1097/PSY.0000000000000044. PMID: 24632894; PMCID: PMC4008710.
  16. xTrochoutsou AI, Kloukina V, Samitas K, Xanthou G. Vitamin-D in the Immune System: Genomic and Non-Genomic Actions Mini Rev Med Chem. 2015;15(11):953-63. doi: 10.2174/1389557515666150519110830. PMID: 25985946.
  17. Suaini NH, Zhang Y, Vuillermin PJ, Allen KJ, Harrison LCImmune Modulation by Vitamin D and Its Relevance to Food Allergy . Nutrients. 2015 Jul 27;7(8):6088-108. doi: 10.3390/nu7085271. PMID: 26225992; PMCID: PMC4555110.
  18. van der Schaft J, Koek HL, Dijkstra E, Verhaar HJ, van der Schouw YT, Emmelot-Vonk MH. The association between vitamin D and cognition: a systematic review Ageing Res Rev. 2013 Sep;12(4):1013-23. doi: 10.1016/j.arr.2013.05.004. Epub 2013 May 29. PMID: 23727408.
  19. Ghaly S, Lawrance I. The role of vitamin D in gastrointestinal inflammation Expert Rev Gastroenterol Hepatol. 2014 Nov;8(8):909-23. doi: 10.1586/17474124.2014.925796. Epub 2014 Jul 22. PMID: 25047396.
  20. Dong J, Lau CW, Wong SL, Huang Y. Cardiovascular benefits of vitamin D Sheng Li Xue Bao. 2014 Feb 25;66(1):30-6. PMID: 24553867.
  21. Shioi A, Morioka T, Shoji T, Emoto M. The Inhibitory Roles of Vitamin K in Progression of Vascular Calcification. Nutrients. 2020 Feb 23;12(2):583. doi: 10.3390/nu12020583. PMID: 32102248; PMCID: PMC7071387.