5 min read – fact checked ✔
Today is World Vitamin D day, and there is no better day to raise awareness about this important steroid hormone and its importance to the pathophysiology of diabetes than during Diabetes Awareness month.
Vitamin D plays a crucial role in pancreatic beta cell function (figure 1) as the pancreas expresses high levels of vitamin D receptors involved in insulin release (1). Insulin secretion is a calcium-dependent process, and calcium homeostasis is dependant on sufficient vitamin D levels (1). Additionally, Vitamin D deficiency has been shown in animal and human studies to impair insulin release, and linked to an increased risk of prediabetes, and both type 1 and type 2 diabetes (1).
Most importantly, insufficient Vitamin D levels has been strongly linked to the development of hypertension, hyperlipidemia, metabolic syndrome, obesity and insulin resistance, which are strong risk factors themselves in the development of diabetes (2). These conditions often result in a considerably increased expression of inflammatory mediators, which studies show can interfere with the insulin signalling cascade in peripheral cells impairing glucose uptake (3), worsening or increasing the risk of prediabetes or type 2 diabetes.
Important studies evaluating global Vitamin D status such as the one from Palacios and Gonzalez (2014) (4), evidenced that Vitamin D insufficiency / deficiency is extremely prevalent in all age-groups worldwide (figure 2), and in my subjective experience with local clients, vitamin D insufficiency / deficiency also appears to be quite common. Therefore, knowing your current levels and understanding how it may be contributing to or increasing the risk of prediabetes or diabetes, as well as correcting vitamin D insufficiency / deficiency following a food-first approach is crucial to support optimum health.
Vitamin D is primarily obtained via cutaneous synthesis from UVB exposure, but insufficient sunlight, excessive use of sun creams, dark skin, clothing, age, genetics, latitude, elevation, and even environmental pollution, can impair cutaneous Vitamin D synthesis (5), whilst long-term use of certain medications and other conditions such as cholecystectomy (gall bladder surgery), can impair dietary Vitamin D absorption (6).
Dietary sources of Vitamin D include oily fish, oysters, shrimp, egg yolks, mushroom, fortified foods, and smaller amounts in meats such as liver, and butter (7). Therefore, optimising nutrition with a balanced diet with a qualified nutrition professional is key to regulating vitamin D levels in conjunction with a responsible sun exposure. However, during certain seasons (ie winter) supplementation provides a valuable source of vitamin D levels which is important for proper muscle, bone and immune function. UK Government guidelines recommend supplementing with 10 ug (400 IU) of vitamin D daily (6), unless otherwise recommended by your healthcare provider, particularly during the autumn and winter.
It’s always important to test your levels first, not guess, and avoid self-medicating with vitamin D supplements as it can cause interactions with prescribed medications. Take advice from a qualified healthcare professional, as certain condition such as, those already on prescribed Vitamin D, pregnancy, under 18years of age, impaired kidney function, or those with a family history of kidney stones, vitamin D supplementation may be contraindicated (8) or should be carefully monitored. Excess vitamin D could increase the risks of toxicity, and could also increase intestinal calcium absorption which could lead to undesirable health outcomes. Its also very important to keep supplements away from pets and young children.
I am clinically trained to (legally) recommend supplements (such as Vitamin D) to help support clients optimise their health, or where evidence justifies the use of vitamins for persons experiencing various chronic / metabolic health issues who may or may not be on prescribed medications, in collaboration with other healthcare professionals. I hope you found this blog post interesting, and If you have any further queries do not hesitate to contact me on info@andrewfortuna.com, via phone / WhatsApp (+350) 54084900 or simply use the contact form below. Keep healthy!
1. Memon A, Baig S, Farooqi HA, Habib FZ. Diabetico-protective role of Vitamin D. Pak J Med Dent [Internet]. 2018 [cited 2021 Nov 2];7(4):6–6. Available from: http://ojs.zu.edu.pk/ojs/index.php/pjmd/article/view/150
2. L Bishop E, Ismailova A, Dimeloe S, Hewison M, White JH. Vitamin D and Immune Regulation: Antibacterial, Antiviral, Anti‐Inflammatory. JBMR Plus. 2021 Jan;5(1).
3. Wimalawansa SJ. Associations of vitamin D with insulin resistance, obesity, type 2 diabetes, and metabolic syndrome. J Steroid Biochem Mol Biol [Internet]. 2018 Jan [cited 2021 Nov 2];175:177–89. Available from: https://linkinghub.elsevier.com/retrieve/pii/S0960076016302539
4. Palacios C, Gonzalez L. Is vitamin D deficiency a major global public health problem? J Steroid Biochem Mol Biol [Internet]. 2014 Oct [cited 2021 Nov 1];144:138–45. Available from: https://linkinghub.elsevier.com/retrieve/pii/S0960076013002331
5. Wacker M, Holick MF. Sunlight and Vitamin D: A global perspective for health. Derm Endocrinol. 2013;5(1):51–108.
6. Expert Group on Vitamins and Minerals. Safe Upper Levels for Vitamins and Minerals Expert Group on Vitamins and Minerals Contents. Expert Group Vitam Miner [Internet]. 2003 [cited 2020 Apr 20];(May):1–351. Available from: https://cot.food.gov.uk/sites/default/files/vitmin2003.pdf
7. British Nutrition Foundation. Vital Vitamin D [Internet]. 2019 [cited 2021 Nov 2]. Available from: https://www.nutrition.org.uk/media/gyceqobk/vital-vitamin-d.pdf
8. UK Gov. Vitamin D supplements: how to take them safely [Internet]. GOV.UK. [cited 2021 Nov 2]. Available from: https://www.gov.uk/government/publications/vitamin-d-supplements-how-to-take-them-safely/vitamin-d-supplements-how-to-take-them-safely