Table 3.
CD Epidemiology and the Vitamin D Hypothesis
| Area | CD Epidemiology | Possible Explanation Based on the Vitamin D Hypothesis |
|---|---|---|
| Sweden | 1984 was the inception of the Swedish CD “epidemic.”116 | March 1983 was the inception of mandatory vitamin D supplementation of milk and margarine in Sweden.117 |
| Finland | CD prevalence doubled among Finnish adults between 1978 and 2000 based on serology.6 | Oral vitamin D consumption in Finland increased during this time period primarily due to a significant increase in the proportion of the population using vitamin D supplements.118–120 |
| Nordic countries vs Germany | At least five times greater prevalence of CD in Sweden and Finland than in Germany.6,116,121 | Much greater intake of oral vitamin D in Sweden and Finland than in Germany due to greater use of vitamin D supplementation and fortification in Sweden and Finland than in Germany.76,117,122,123 |
| US | Significant increase in prevalence of CD and CD serology in the US in recent decades.5,8,124 | Increased use of vitamin D supplements, increased doses of vitamin D supplements, and increased levels of vitamin D fortification in the US in recent decades.125–130 |
| Burkina-Faso | No case of CD based on serology among 600 adults in Burkina-Faso, despite wheat consumption by all and some genetic susceptibility.131 | There have historically been no vitamin D supplementation programs or vitamin D fortification programs in Burkina-Faso.132,133 |
| Karelians | Finnish Karelian children have a CD risk that is 2.3 times greater than Russian Karelian children based on serology and 4.6 times greater based on biopsy.134 | Finland fortifies food with vitamin D and encourages vitamin D supplementation in childhood.76,135 Russia has not historically fortified food with vitamin D or provided supplemental vitamin D to its population.136,137 |
| Breastfeeding | Early studies found that breastfeeding decreases risk of CD,138 while more recent studies do not find such an effect.139 | Vitamin D fortification and supplementation in infancy has increased during the last three decades in much of the developed world.76,80,135 Infant supplementation in some countries is focused on breastfed infants.80,140 These effects may outweigh any positive effect of breastfeeding. |
| Constipation and CD in Finland | Between the late 1970s and 2013 in Finland, there was a 500% increase in constipation as a symptom of CD among newly diagnosed children.93 | During this time, vitamin D intake increased significantly in Finland.76,118–120,135 Vitamin D exposure increases risk of constipation.92 If vitamin D exposure increases risk of CD, this change in presentation would be expected. |
| Pregnancy | Greater risk of CD onset during pregnancy and the period immediately following pregnancy.141,142 | Plasma levels of 1,25(OH)2D are elevated during pregnancy and lactation.143 |
| Helicobacter pylori | Significantly decreased incidence of gastric H. pylori infection observed in children with CD.144 | Plasma levels of 1,25(OH)2D are often elevated in those with CD,17,22,23 and 1,25(OH)2D activates a lysosomal degradation pathway that is effective in combatting H. pylori infection.145 |
| African Americans | CD and CD serology is much less common among African Americans than among non-Hispanic White Americans despite some genetic risk.4,146,147 | Vitamin supplementation in general is less common in the African American community than among non-Hispanic White Americans.148 |
| Smoking | Smoking is associated with decreased risk of CD.149 | Vitamin supplementation in general is less common among smokers,150 and plasma levels of 1,25(OH)2D are lower among smokers than non-smokers.151 |
| Socioeconomic | Higher socioeconomic status is associated with increased risk for CD.152,153 | Vitamin supplement use is greater among those of higher socioeconomic status.154 |
Abbreviations: 1,25(OH)2D, 1,25-dihydroxyvitamin D; CD, celiac disease; US, United States; vs, versus.