Written by Aoife Brennan PhD
Sunshine Vitamin D is causing quite a stir at the moment and is omnipresent in the media, with mounting evidence advocating its use in the battle against COVID-19. Dr Anthony Fauci has admitted he supplements daily, some countries are even implementing national supplementation recommendations, while the UK have announced millions of elderly and vulnerable will receive free Vitamin D. Since it is estimated that 1 billion people worldwide are deficient in this ‘steroid hormone’, it is understandable that if Vitamin D plays such a crucial role in immune function, then its deficiency can pack a punch when it comes to global health.
What are some of the factors which contribute to Vitamin D deficiency?
i) Compromised sunshine exposure – through wearing clothes, wearing sunscreen, having darker skin with higher melanin content (which acts as a natural sunscreen), cloudy skies and air pollution, not getting outside due to immobility, working indoors, sedentary lifestyle etc.
ii) Living in a northern latitude – where no solar UVB radiation reaches the atmosphere for 6 months during the winter, resulting in no cutaneous biosynthesis of Vitamin D.
iii) Age – older adults have a reduced ability to synthesise Vitamin D from the sun, with data suggesting a 70-yr old makes four times less Vitamin D than their former 20 year old self.
iv) Obesity – obese individuals have less Vitamin D bioavailability, as this fat-soluble vitamin has greater difficulty being released into the bloodstream.
v) Compromised intestinal absorption – an issue for those with Crohn’s disease, coeliac disease, cystic fibrosis, gastric bypass, gallbladder removal etc.
vi) Magnesium deficiency – research has shown deficiency greatly disrupts the Vitamin D synthesis and metabolism pathway.
vii) Other factors – such as single nucleotide polymorphisms (SNPs) to Vitamin D, vegan lifestyle, certain medications.
What is the difference between the forms and preparations of Vitamin D in supplements?
Vitamin D2 (ergocalciferol), found in UVB radiated fungi, is thought to be less effective than Vitamin D3 in raising 25(OH)D levels.12 Vitamin D3 (cholecalciferol) sourced from lanolin isn’t an option for vegetarians or vegans, but Vitamin D3 can also be sourced from lichen or algae, making it suitable for everyone.
Results from two randomised, placebo-controlled studies showed no significant difference between different preparations of Vitamin D3 (oral sprays and powdered capsules), with regard to absorption at 1000IU or 3000IU, finding all preparations were equally efficacious at raising serum 25(OH)D.13,14
What other nutrients should be considered when supplementing with Vitamin D?
Magnesium deficiency has been linked to Vitamin D deficiency and vice versa. It appears magnesium is initially needed to increase Vitamin D (Vitamin D binding proteins and enzymes in the liver and kidneys are magnesium-dependent), where Vitamin D in turn increases magnesium (by increasing intestinal absorption of magnesium), thus forming a feed-forward loop. Research has suggested that optimal magnesium status may be important for optimal 25(OH)D status.15, 16
Vitamin K works in tandem with Vitamin D in maintaining calcium homeostasis. There is a concern around high-dose Vitamin D resulting in toxicity or hypercalcaemia, which of course could be problematic, but vitamin K (particularly K2) has been shown to mitigate some of these risks. Vitamin K activates Gla proteins such as osteocalcin involved in calcium transport, and it has been suggested that combined supplementation of Vitamin D and Vitamin K might provide more benefit than supplementing with either alone.17, 18, 19
Is there any scientific research on Vitamin D with regard to Covid-19?
Research has shown how Vitamin D influences the adaptive and innate immune system and protects against acute respiratory tract infections.20, 21, 22 Anecdotal reports have suggested a link between lower Vitamin D status and worse COVID outcomes, with a recent retrospective study showing over 80% of hospitalised Covid patients were Vitamin D deficient.23 There have been over 1,500 scientific papers published on the topic since the coronavirus outbreak and over 30 human studies are currently registered with www.clinicaltrials.gov.
The first published randomised controlled trial (RCT) on Vitamin D and Covid-19, reported high-dose Vitamin D administered to hospitalized patients, practically abolished
the need for ICU admission.24 Another recently published observational study also on hospitalised Covid patients, showed modest nutrient doses (1000IU VitaminD3 + 150mg
magnesium + 500mcg VitB12) were correlated with better outcomes regarding admission to ICU for oxygen therapy.25 While observational studies can’t determine causation, the findings along with the RCT, strongly imply an association between supplement administration and outcome.
Conclusion:
As researchers gain a deeper understanding of the pivotal role Vitamin D appears to play in immune health, alongside the possibility that it regulates 5% of the protein-encoding human genome,26 it seems bizarre that something as simple and safe as Vitamin D supplementation isn’t commonplace in a world where its deficiency has been described as being pandemic.27 We know Vitamin D is no panacea, but in the words of one author regarding supplementation ‘although it may not always be helpful, it is unlikely to be harmful’.28 Information used n this blog has been sourced from reputable academic research databases. All references are available upon request.
