overcoming deficiency status to achieve optimal vitamin d levels

by nutritionist Maxine Sheils BSc (Hons) 

Like all vitamins, vitamin D is essential to life, yet 50% of the UK adult population are estimated to have insufficient levels (1), with lower concentrations found in followers of vegetarian and vegan diets. (2) Whilst most vitamin D is produced via skin exposure to the sun, UV rays are not adequate to maintain sufficient status year-round in the UK; further, most food sources are of animal origin, leaving vegans in the UK at a higher risk of deficiency status.  

Vitamin D supports the health of bones, teeth, muscles and more

The literal meaning of vitamin is ‘vital – amine’ indicating a substance that is vital for life, and yet the role vitamin D plays in the body is actually one of a hormone rather than a vitamin. It is, though, just as essential for life as any other vitamin, performing numerous roles in the body, such as supporting the body in its ability to absorb and use calcium and phosphorous, which in turn supports normal blood calcium levels. Vitamin D supports the maintenance of bones, teeth and muscle function within the body. Looking specifically at bone health, both rickets and osteoporosis can occur when the balance of vitamin D and calcium is no longer optimal, leading to both softening and weakening of bones in the case of osteomalacia or the breakdown of bone leading to ‘porous bones’ in osteoporosis. Vitamin D has a direct effect on the health of muscle mass in that it supports cell differentiation, allowing muscle tissue to build whilst also exerting an indirect effect on muscle tissue via its ability to handle calcium, which is required to support muscle contraction, with contraction facilitating movement.

The beneficial effects vitamin D has in maintaining calcium balance not only serves an advantage to the functioning of muscles but also on the central nervous system, the immune system, as well as vital organs such as the heart, brain and lungs. It is no wonder, therefore, that low vitamin D status is now linked to such a wide range of health conditions including cardiovascular disease, autoimmune conditions, neurodegenerative diseases and type 2 diabetes. (3)  

The role of the British weather and dietary sources of vitamin D in maintaining healthy levels

Daily sun exposure supports optimal vitamin D levels

Whilst the main source of vitamin D synthesis is skin exposure to the sun, there are many barriers to maintaining an optimal vitamin D status relying solely on this method. Given the climate in the UK, UV rays are not strong enough between the months of October and March to support vitamin D synthesis within the skin. Furthermore, cloud coverage, sunscreen use and clothing can all provide barriers to the skin’s natural production of vitamin D from UV exposure, even during the summer months. Finally, the skin’s production of vitamin D as a result of UV exposure is also affected by melanin levels in the skin, with darker skin tones requiring longer ‘unprotected’ exposure to the sun than lighter skin tones in order to achieve the daily requirement for vitamin D.

Vitamin D can also be obtained in food items such as salmon, sardines and tuna, cow’s milk, eggs and shiitake mushrooms. Whilst mushrooms provide the only plant-based food source of vitamin D, you would need to eat the equivalent of 20 cups of shiitake mushrooms just to obtain the recommended daily intake of vitamin D for one day, which is not really feasible. 

The current dietary reference value (DRV) of vitamin D is 400IU (or 10µg) per day. This can be achieved with the equivalent of 10-15 minutes sun exposure for those with lighter skin tones, 120 minutes sun exposure for those with darker skin tones, 20 cups of shiitake mushrooms, 1 portion of salmon, or by simply supplementing with vitamin D. If baseline levels are below optimal, higher amounts of vitamin D may be required to increase vitamin D levels to an optimal status. Studies suggest that 800IU can increase vitamin D levels from a deficiency status to a sufficient status, and 1000IU or more of vitamin D can increase levels to an optimal range. (4, 5, 6, 7) 

Correcting a deficiency status becomes more challenging when relying on sun exposure and food sources alone. Firstly, assuming the sun is not shielded by cloud, it is recommended to use sunscreen to protect skin from over-exposure to the sun’s UV rays due to the risk of skin cancer, but as sunscreen obstructs the skin’s ability to produce vitamin D from UV exposure, it may not be practical to rely on the sun for vitamin D synthesis. Also, you would need to consume 2 portions of salmon, 4 portions of sardines, 1.5 litres of cow’s milk or 50 cups of shiitake mushrooms in order to obtain roughly 1000IU of vitamin D from food sources per day, which may not form a very well balanced diet.  

Pure & Essential Vitamin D3 range

To address the need for vitamin D supplementation in the general population, Igennus launched Pure & Essential Daily Vitamin D3 in 2017 and whilst it has been approved by Vegetarian Society, its benefits could not be taken up by our vegan customers because of its source. Vitamin D exists in two forms, as ergocalciferol (vitamin D2), or cholecalciferol (vitamin D3). Vitamin D3 is the form naturally produced in the body when the skin is exposed to UVB rays, converting 7-dehydrocholesterol within the skin to pre-vitamin D3. It is this form that is also found in oily fish. Vitamin D2 is also obtained from exposure to UVB light but as a consequence of irradiation of ergosterol, a compound present in fungi, thus making mushrooms a plant source of vitamin D.

Whilst vegan vitamin D supplements can be obtained from mushrooms to provide D2, vitamin D3 is more potent and longer-lasting than D2 in its ability to increase levels of calcifediol – the active form of vitamin D. (8) As with all supplements in the Igennus Healthcare Nutrition range, the aim is to provide a supplement with high bioavailability for greater benefits to consumers, hence the sourcing of Pure & Essential Daily Vitamin D3 from lanolin, providing the more active vitamin D3 form.  

Mushrooms are not a good way to achieve optimal vitamin D levels

Introducing Pure & Essential Vegan Vitamin D3

Until recently, those following a vegan diet have been restricted in their ability to obtain a more potent form of vitamin D; however, recent discoveries about lichens provide a solution for followers of a vegan diet. Lichens arise from fungi and grow on rocks and trees in parts of North America where they are able to survive extreme climates and accumulate nutrients for survival, including vitamin D. Pure & Essential Vegan Vitamin D3 is sourced from lichens, providing 1000IU of vitamin D3 per capsule, providing an easy solution for vegans to correct deficient vitamin D levels, as well as maintain optimal levels year round to support the healthy balance of calcium in the body, and the health of bones, muscles, the immune system and so much more.

Pure & Essential Vegan Vitamin D3 is safe to provide to children aged 6 years and above, as well as for use in pregnancy and lactation, with 1 bottle providing a 1 year supply.

If you are concerned about your current vitamin D levels, please consult your GP or local healthcare practitioner who will be able to advise you further on testing.


  1. Pearce S.H.S. & Cheetham T.D. (2010). ‘Diagnosis and management of vitamin D deficiency’, The BMJ, 340, pp. 142-147.
  2. Spiro A. & Buttriss J.L. (2014). ‘Vitamin D: An overview of vitamin D status and intake in Europe’, Nutrition Bulletin, 39, pp. 322-350.
  3. Berridge M.J. (2015). ‘Vitamin D: a custodian of cell signalling stability in health and disease’, Biochemical Society Transactions, 43 (3), pp. 349-358
  4. Nelson M.L., Blum J.M., Hollis B.W. et al. (2009). ‘Supplements of 20 microg/d cholecalciferol optimised serum 25-hydroxyvitamin D concentrations in 80% of premenopausal women in winter’, Journal of Nutrition, 139 (3), pp. 540-546.
  5. Gallagher J.C.. Sai, A., Templin T., et al. (2012). ‘Dose response to vitamin D supplementation in postmenopausal women: a randomised trial’, Annals of internal medicine, 156 (6), pp 425-437.
  6. Kennel K.A., Drake M.T. & Hurley D.L. (2010). ‘Vitamin D deficiency in adults: when to test and how to treat’, Mayo Clinic Proceedings, 85 (8), pp. 752-757.
  7. Shab-Bidar S., Bours S.P., Geusens P.P., et al. (2013). ‘Suboptimal effect of different vitamin D3 supplementations and doses adapted to base line serum 25(OH)D on achieved 25(OH)D levels in patients with a recent fracture: a prospective observational study’, European Journal of Endocrinology, 169 (5), pp. 597-604.
  8. Trang H.M., Cole D.E., Rubin L.A., et al. (1998). ‘Evidence that vitamin D3 increases serum 25-hydroxyvitamin D more efficiently than does vitamin D2’, American Journal of Clinical Nutrition, 68 (4), pp. 315-323.

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