The excellent review by Al‐Ani et al reflects a consensus approach to management of inflammatory bowel disease during the SARS‐CoV‐2 pandemic that has been established remarkably rapidly by very effective international collaboration.1 Much of the focus has appropriately been on the potential impact of immuno‐modulating therapies. We would also like to highlight the potential importance of nutrition and particularly vitamin D as raised by Panarese and Shahini.2

There are marked variations in mortality from COVID‐19 between different countries. It is becoming clear that countries in the Southern Hemisphere are seeing a relatively low mortality (Figure 1 and Table 1).2, 3 It could be argued that the virus spread later to the Southern Hemisphere and that countries there are simply behind those in the Northern Hemisphere but as time goes by this argument looks increasingly weak. In Australia, 100 cases were reported by 10th March, 1000 by 21st March; in the UK, the first 100 had been reported by 5th March and the first 1000 by 14th March, just 1 week earlier. If one compares the mortality (68 per million) in the UK by 3rd April with the mortality (2 per million) in Australia by 10th April, there is still a huge discrepancy.

FIGURE 1 Open in figure viewer PowerPoint 3 r = 0.53, P < 0.0001 by Spearman's rank correlation Correlation between mortality from COVID‐19 per million by country and latitude. All countries with >150 cases included. Data are from https://www.worldometers.info/coronavirus/ accessed 15th April 2020. Latitude is for capital city. It can be seen that mortality is relatively low at latitudes less than 35 degrees North, the point below which adequate sunlight is likely to have been received to maintain vitamin D levels during the winter. Correlation between mortality and latitude= 0.53,< 0.0001 by Spearman's rank correlation

TABLE 1. Comparison between latitude (of capital city in each country) and mortality from COVID‐19 per million population—as per Panarese et al, with further analysis and updated 15th April 2020 from https://www.worldometers.info/coronavirus/ Countries Latitude degrees Total cases (N) Total deaths (N) Deaths/Million population Iceland 64 1720 8 23 Faeroe 62 184 0 0 Norway 60 6740 145 27 Finland 60 3237 64 12 Sweden 59 11 927 1203 119 Estonia 59 1400 35 26 Latvia 57 666 5 3 Russia 56 24 490 198 1 Denmark 56 6681 309 53 Lithuania 55 1091 29 11 Belarus 54 3728 36 4 Isle of Man 54 256 4 47 Ireland 53 11 479 406 82 Germany 52 132 321 3502 42 UK 52 93 873 12 107 178 Netherlands 52 28 153 3134 183 Poland 52 7408 268 7 Belgium 51 33 573 4440 383 Czechia 50 6151 163 15 Luxembourg 50 3307 67 107 Ukraine 50 3764 108 2 France 49 143 303 15 729 241 Channel Islands 49 445 13 75 Austria 48 14 321 393 44 Slovakia 48 863 6 1 Switzerland 47 26 336 1221 141 Moldova 47 1934 43 11 Hungary 47 1579 134 14 Kazakhstan 47 1290 16 0.9 Croatia 46 1741 34 8 Slovenia 46 1248 61 29 Serbia 45 4873 99 11 Canada 44 27 063 903 24 Romania 44 7216 362 19 Bosnia and Herzegovina 44 1110 41 12 San Marino 44 372 36 1061 Bulgaria 43 735 36 5 Kyrgyzstan 43 449 5 0.8 Italy 42 162 488 21 067 348 North Macedonia 42 974 45 22 Andorra 42 659 31 401 Montenegro 42 288 4 6 Georgia 42 306 3 0.8 USA 41 614 246 26 064 79 Turkey 41 65 111 1403 17 Uzbekistan 41 1275 4 0.1 Albania 41 494 25 9 Spain 40 177 633 18 579 397 China 40 82 295 3342 2 Azerbaijan 40 1253 13 1 Armenia 40 1111 17 6 Portugal 39 18 091 599 59 S. Korea 38 10 591 225 4 Greece 38 2170 101 10 Algeria 37 2070 326 7 Iran 36 76 389 4777 57 Japan 36 8100 146 1 Malta 36 399 3 7 Cyprus 35 695 12 10 Afghanistan 35 784 25 0.6 Pakistan 34 5988 107 0.5 Tunisia 34 747 34 3 Lebanon 34 658 21 3 Iraq 33 1400 78 2 Israel 32 12 200 126 15 Morocco 32 1988 127 3 Jordan 32 397 7 0.7 Palestine 32 308 2 0.4 Egypt 30 2350 178 2 India 29 11 555 396 0.3 Kuwait 29 1405 3 0.7 Saudi Arabia 25 5862 79 2 Qatar 25 3711 7 2 Bahrain 25 1671 7 4 Taiwan 25 395 6 0.3 UAE 24 4933 28 3 Bangladesh 24 1231 50 0.3 Cuba 23 766 21 2 Hong Kong 22 1017 4 0.5 Oman 21 910 4 0.8 Reunion 21 391 0 0 Vietnam 21 297 0 0 Mexico 19 5399 406 3 Dominican Republic 19 3286 183 17 Brazil 16 25 758 1557 7 Guatemala 16 180 5 0.3 Philippines 15 5453 349 3 Senegal 15 314 2 0.1 Martinique 15 158 8 21 Thailand 14 2643 43 0.6 Niger 14 570 14 0.6 Honduras 14 419 31 3 Burkina Faso 12 528 30 1 Djibouti 12 363 2 2 Costa Rica 10 618 3 0.6 Guinea 10 404 1 0.1 Venezuela 10 197 9 0.3 Panama 8 3574 95 22 Ivory Coast 8 638 6 0.2 Nigeria 7 373 11 0.05 Sri Lanka 7 235 7 0.3 Ghana 6 636 8 0.3 Colombia 5 2979 127 2 Cameroon 5 848 17 0.6 Malaysia 3 5072 83 3 Singapore 1 3252 10 2 Ecuador −1 7603 369 21 Kenya −1 225 10 0.2 DRC −4 241 20 0.2 Indonesia −6 5136 469 2 Peru −12 10 303 230 7 Mayotte −13 217 3 11 Bolivia −19 397 28 2 Mauritius −20 324 9 7 Chile −31 7917 92 5 South Africa −33 2415 27 0.5 Australia −35 6447 63 2 Argentina −35 2443 108 2 Uruguay −35 492 8 2 New Zealand −37 1386 9 2

When mortality per million is plotted against latitude, it can be seen that all countries that lie below 35 degrees North have relatively low mortality. Thirty‐five degrees North also happens to be the latitude above which people do not receive sufficient sunlight to retain adequate vitamin D levels during winter. This suggests a possible role for vitamin D in determining outcomes from COVID‐19. There are outliers of course—mortality is relatively low in Nordic countries—but there vitamin D deficiency is relatively uncommon, probably due to widespread use of supplements.4 Italy and Spain, perhaps surprisingly, have relatively high prevalences of vitamin D deficiency. Vitamin D deficiency has also been shown to correlate with hypertension,5 diabetes,6 obesity7 and ethnicity8—all features associated with increased risk of severe COVID‐19.

There are considerable experimental data showing that vitamin D is important in regulating and suppressing the inflammatory cytokine response of respiratory epithelial cells and macrophages to various pathogens including respiratory viruses.9 Evidence that vitamin D might protect against infection is modest but it is important to note that the hypothesis is not that vitamin D would protect against SARS‐CoV‐2 infection but that it could be very important in preventing the cytokine storm and subsequent acute respiratory distress syndrome that is commonly the cause of mortality.10

Research is urgently needed to assess whether there may be a correlation between vitamin D status and severity of COVID‐19 disease. Meanwhile, the evidence supporting a protective effect of vitamin D against severe COVID‐19 disease is very suggestive, a substantial proportion of the population in the Northern Hemisphere will currently be vitamin D deficient, and supplements, for example, 1000 international units (25 micrograms) per day are very safe. It is time for governments to strengthen recommendations for vitamin D intake and supplementation, particularly when under lock‐down.