Let's Talk Vitamin D

Vitamin D, also known as the sunshine vitamin, is essential for good health. Despite this, vitamin D deficiency is common in the UK. In this article, we take a look at the role of vitamin D in health, the different types of vitamin D, and how to make sure you’re getting enough.

What are the benefits of vitamin D?

Vitamin D benefits are numerous. It helps to control the amount of calcium we absorb and therefore is important for developing and maintaining strong bones and teeth. It also contributes to the normal functioning of the immune system and the inflammatory response (1) (2) (3). People with too low vitamin D are at risk of developing conditions like rickets, osteomalacia, cardiovascular disease and high blood pressure. (1)  Other symptoms of vitamin D deficiency include fatigue, mood changes/ low mood, muscle weakness or aches and hair loss/ thinning hair. (19)

Vitamin D in food

Vitamin D sources include a small number of animal foods and vitamin D supplements. It’s mainly found in animal products like eggs, oily fish, red meat, and liver. It's hard to get the required amount through food alone. (18)

We can also get vitamin D from the action of sunlight on our skin (2) - hence the term “the sunshine vitamin”, however, this can be difficult for people who have limited exposure to sunlight, especially during gloomier winter months in the UK (and even during the rainy summer spells!) (2). You may not be surprised to learn that one in five adults in the UK are vitamin D deficient (4)

Groups at risk of a vitamin D deficiency include:

    • Those who spend a lot of time indoors (5)
    • People who cover their skin for cultural reasons (5)
    • People who follow a vegan diet (6,7)
    • People with darker skin tones, as more melanin in the skin reduces the absorption of vitamin D from the sun (5)

The UK government recommends that adults should take a daily vitamin D supplement throughout the autumn and winter months (1). Those at risk of deficiency are encouraged to take a supplement throughout the year (1) (2).

Vitamin D Daily Dose 

In the UK, the recommended daily intake (RDA) of vitamin D is 400 IU. It is worth noting that RDA’s are the absolute minimum levels to prevent deficiency and many experts believe the guidelines are far too low. (11)

To reach Vitamin D blood levels linked to health benefits, many studies have shown that you need to consume more vitamin D than the guidelines recommend. (11) (12)

A Vitamin D deficiency is generally classed as blood Vitamin D levels below 30 nmol/L. (13)

According to an expert panel of 48 scientists, researchers and doctors, the optimal blood level of vitamin D is between 100-150 nmol/L. (14)

A study found supplementing with 2000 IU per day achieved vitamin D blood levels of 85 nmol/L whereas 400 IU per day achieved only 63 nmol/L. (14) The Vitamin D society therefore recommend that healthy adults take 2,000 IU of vitamin D daily, but more than this if you get little or no sun exposure. (14)

Based on current research, it seems that consuming 1,000–4,000 IU (25–100 mcg) of vitamin D daily should be ideal for most people to reach healthy vitamin D blood levels.

Can you take too much Vitamin D? 

A daily intake ranging from 40,000–100,000 IU (1000–2500 micrograms), for one to several months, has been shown to cause toxicity in humans. (15) (16)

Doses up to 10,000 IU have not been shown to cause toxicity in healthy individuals (10), The Institute of Medicine has set the safe upper level of daily vitamin D intake at 4000 IU. (17) Don’t take more than 4000 IU without consulting a doctor.

The difference between Vitamin D2 and D3

Vitamin D comes in two main forms:

  • Vitamin D2 (ergocalciferol) - derived from mushrooms or made synthetically (8)
  • Vitamin D3 (cholecalciferol) - derived from animal products including eggs, red meat and liver. Vitamin D3 supplements are derived from sheep’s wool (lanolin), unless the label specifically states that it’s vegan. (8)

Vitamin D2 vs D3? – Which is better?

Vitamin D3 is the type your skin produces when it’s exposed to sunlight (8). A similar process takes place in plants when they’re exposed to light, resulting in the formation of vitamin D2 (8).

When vitamins D2 and D3 are consumed, they’re converted in the liver to calcitriol (8). This is the active form of Vitamin D, which means it can enter your bloodstream and be used around the body (8).

Multiple studies have found that vitamin D3 is more bioavailable in the body than vitamin D2, producing significantly more calcitriol. Another Vitamin D3 benefit is that it remains in the body for longer, providing longer lasting health effects  (8). So where possible, it’s recommended to choose sources of vitamin D3.

However, this can be challenging for vegans and people who avoid animal products, as most vegan supplements only contain vitamin D2. The good news is that Botanycl supplements contain vitamin D3 (the most bioactive form of vitamin D). And while most Vitamin D3 supplements are made from sheep’s wool, our Botanycl Vegan Vitamin D3 supplement is made from lichen, one of the only known plant sources of vitamin D3 (9).

As vitamin D is fat-soluble, supplements that contain oil help to increase absorption of the vitamin into the body (10). Botanycl Vegan Vitamin D3 supplement uses a coconut oil base, ensuring that you receive maximum health benefits.


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    1. SACN vitamin D and health report [Internet]. GOV.UK. 2021 [cited 1 August 2021]. Available from: https://www.gov.uk/government/publications/sacn-vitamin-d-and-health-report
    2. Vitamins and minerals - Vitamin D [Internet]. nhs.uk. 2021 [cited 1 August 2021]. Available from: https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/
    3. Chang S, Lee H. Vitamin D and health - The missing vitamin in humans. Pediatrics & Neonatology. 2019;60(3):237-244.
    4. NDNS: results from Years 5 and 6 (combined) [Internet]. GOV.UK. 2021 [cited 1 August 2021]. Available from: https://www.gov.uk/government/statistics/ndns-results-from-years-5-and-6-combined
    5. PHE publishes new advice on vitamin D [Internet]. GOV.UK. 2021 [cited 1 August 2021]. Available from: https://www.gov.uk/government/news/phe-publishes-new-advice-on-vitamin-d
    6. G. Engel M, J. Kern H, Brenna J, H. Mitmesser S. Micronutrient Gaps in Three Commercial Weight-Loss Diet Plans. Nutrients. 2018;10(1):108.
    7. Vici G, Belli L, Biondi M, Polzonetti V. Gluten free diet and nutrient deficiencies: A review. Clinical Nutrition. 2016;35(6):1236-1241.
    8. Tripkovic L, Lambert H, Hart K, Smith C, Bucca G, Penson S et al. Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis. The American Journal of Clinical Nutrition. 2012;95(6):1357-1364.
    9. Björn LO, Wang T. Vitamin D in an ecological context. Int J Circumpolar Health. 2000;59(1):26-32.
    10. Grossmann R, Tangpricha V. Evaluation of vehicle substances on vitamin D bioavailability: A systematic review. Molecular Nutrition & Food Research. 2010;54(8):1055-1061.
    11. Bischoff-Ferrari H, A. Giovannucci E, Willett W, C. Dietrich T, Dawson-Hughes B. Estimation of optimal serum concentrations of 25-hydroxyvitamin D for multiple health outcomes. The American Journal of Clinical Nutrition. 2006;84(1):18-28.
    12. Vieth R, Bischoff-Ferrari H, Barbara J Boucher B J. Dawson-Hughes B, Garland C F. Heaney R P, et al.The urgent need to recommend an intake of vitamin D that is effective. The American Journal of Clinical Nutrition. 2007;85(3):649-650.
    13. Amrein K, Scherkl M, Hoffmann M, Neuwersch-Sommeregger S, Köstenberger M, Berisha A T. Vitamin D deficiency 2.0: an update on the current status worldwide. European Journal of Clinical Nutrition. 2020;74:1498-1513.
    14. New Study Reveals How Vitamin D Prevents Disease. [Internet]. VITAMINDSOCIETY.ORG. 2013 [cited 1 August 2021]. Available from: https://www.vitamindsociety.org/press_release.php?id=19
    15. Vieth R. Vitamin D toxicity, policy, and science. Journal of bone and mineral research. 2007;22(2):64-68.
    16. Klontz K C. Acheson D W. Dietary supplement-induced vitamin D intoxication. The New England Journal of Medicine. 2007; 357(3): 308-309.
    17. Hathcock J N. Shao A, Vieth R, Heaney R. Risk assessment for vitamin D. The American Journal of Clinical Nutrition. 2007;85(1):6-18.
    18. Vitamin D. Vitamins and Minerals. [Internet]. NHS.UK. https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/ 
    19. Vitamin D Deficiency. [Internet]. CLEVELANDCLINIC.ORG. https://my.clevelandclinic.org/health/articles/15050-vitamin-d--vitamin-d-deficiency 
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