Dear Editor,
The current SARS‐CoV‐2 pandemic has mandated significant isolation measures. Streets
in affected countries are mostly empty, and many individuals spend several consecutive
days at home to reduce the risk of infection. While determinant for pandemic control,
home reclusion may have a significant toll on the health of individuals.
One relevant area where we are yet to see proper discussion and strategies pertains
to vitamin D deficiency.
Vitamin D is a fat‐soluble hormone that plays a significant role in calcium‐phosphate
metabolism, in addition to intervening in cell metabolic activity, immune regulation,
among other functions.
Vitamin D is synthesized in skin epithelium under ultraviolet B (UVB) radiation. It
then undergoes two successive hydroxylations in the 25‐ and 1‐ carbons, in the liver
and in the kidney, respectively, to yield the active form, calcitriol. A minor portion
of vitamin D is obtained from alimentary sources.
The time of exposure to solar radiation sufficient to produce the necessary daily
amounts of vitamin D is yet matter of discussion, as it depends heavily on the incident
radiation (thus varying according to season, latitude and hour of the day), as well
as on individual characteristics such as age, clothing, sunscreen use or skin phototype.
Modern life has significantly reduced daily exposure to solar radiation, as most activities
are carried indoors. It comes as no surprise that vitamin D deficiency is common in
Western countries. Nationwide data from the United States of America suggests 40%
of adults may have vitamin D deficiency.
1
While this prevalence may be higher at nursing homes,
2
prevalence of about 10% and 60% has been found in paediatric age
3
and free‐living healthy young adults,
4
respectively.
Home reclusion in the context of social isolation measures to fight SARS‐CoV‐2 pandemic
may lead to a surge in vitamin D across the world, causing significant harms.
The consequences of vitamin D deficiency have been extensively reviewed,
5
,
6
,
7
but are important to be highlighted in the current context. Vitamin D deficiency has
been associated with developing both type 1 and type 2 diabetes, cognitive decline,
malignant neoplasms, autoimmune diseases, cardiovascular diseases, osteoporosis, risk
of fall in the elderly and overall mortality. The risk of fracture may further be
heightened in elderly patients as daily physical activity may be diminished during
lockdown, as may physical therapy and rehabilitation treatments. This leads to reduction
the beneficial mechanical stimulus that promotes bone mineralization, as well as loss
of physical strength, coordination and balance that may predispose to falling and
bone fractures. Furthermore, it may be an independent risk factor for infection, severe
sepsis and mortality in critically ill patients,
8
thus raising the possibility of contributing towards worse outcomes in the event of
COVID‐19 infection.
The fight against SARS‐CoV‐2 is far from over and will significantly impact society
over the coming months. As such, it is paramount that we identify rising problems
and address them as soon as possible to prevent dire complications. Regarding vitamin
D deficiency, simple measures can be adopted to prevent, identify and treat this condition.
Solar exposure could be recommended as a general advice for the entire population.
While individuals should avoid breaking confinement, solar exposure of the face and
bare upper limbs over a window or on a balcony may suffice to produce the necessary
amounts of vitamin D. Patients should be informed that glass blocks UVB transmission
and as such direct solar exposure is necessary. Caution should also be heeded to avoid
excessive solar exposure as this may carry unwanted harms. While precise recommendations
on ideal time of exposure cannot be offered due to the abovementioned variability,
a sensible total exposure of 20‐40 minutes, divided in two periods across the day
may be adequate to prevent significant vitamin D deficiency.
Increased intake of vitamin D through diet could also be recommended. Egg yolks, oily
fish, dairy products and mushrooms are generally good sources for vitamin D, and their
intake may be preferred over other low‐vitamin D food. However, increasing natural
intake of vitamin D may not be easy during isolation, as commerce is running slowly
and people avoid frequent shopping, thus preferring long shelf‐life foods over fresh
produce.
Global supplementation has not been advocated under normal circumstances. However,
under the current pandemic, further thought should be given to this matter, particularly
if home confinement is prolonged over the coming months, considering the low toxicity
of these supplements when administered at standard dosage. Evidence shows vitamin
D supplementation significantly reduces the risk for respiratory infections, particularly
in those with deficiency
9
and has been advocated for COVID‐19.
10
Additional consideration should be given to the elderly, as the risks for bone mass
imbalance is higher in this age group. The daily requirements for vitamin D vary according
to age and preexisting conditions, but intake up to 4000 UI/day in adults and elderly
seems to be safe, posing no risk of adverse effects.
11
Thus, 400‐2000 UI of vitamin D3 supplementation could assist in preventing vitamin
D deficiency during lockdown, without significant risk for harms.
Serum vitamin D dosing should be offered to all individual at high risk for vitamin
D deficiency during or immediately after this crisis, to identify those at need for
treatment. If vitamin D deficiency is diagnosed, treatment should be conducted according
to international guidelines, based on age and comorbid conditions.
Vitamin D deficiency may become a significant public health issue as consequence of
lockdown measures implemented to fight SARS‐CoV‐2. Sensible solar exposition over
open windows or on balconies may suffice to prevent over vitamin D deficiency. As
food availability is also limited during this crisis, supplementation should be administered
particularly to those at highest risk for complications. Global supplementation should
be considered as a public health policy, as the risks of such an intervention are
minimal. Testing may be advised in high‐risk individuals, where prophylactic supplementation
may not be sufficient to solve previously established deficiencies.
Yours sincerely
CONFLICT OF INTEREST
None declared.