The Problem of Vitamin D Scarcity: Cultural and Genetic Solutions by Indigenous Arctic and Tropical Peoples

Abstract

Vitamin D metabolism differs among human populations because our species has adapted to different natural and cultural environments. Two environments are particularly difficult for the production of vitamin D by the skin: the Arctic, where the skin receives little solar UVB over the year; and the Tropics, where the skin is highly melanized and blocks UVB. In both cases, natural selection has favored the survival of those individuals who use vitamin D more efficiently or have some kind of workaround that ensures sufficient uptake of calcium and other essential minerals from food passing through the intestines. Vitamin D scarcity has either cultural or genetic solutions. Cultural solutions include consumption of meat in a raw or boiled state and extended breastfeeding of children. Genetic solutions include higher uptake of calcium from the intestines, higher rate of conversion of vitamin D to its most active form, stronger binding of vitamin D to carrier proteins in the bloodstream, and greater use of alternative metabolic pathways for calcium uptake. Because their bodies use vitamin D more sparingly, indigenous Arctic and Tropical peoples can be misdiagnosed with vitamin D deficiency and wrongly prescribed dietary supplements that may push their vitamin D level over the threshold of toxicity.

Meta-Analysis of European Clinical Trials Characterizing the Healthy-Adult Serum 25-hydroxyvitamin D Response to Vitamin D Supplementation

“…Within Europe, serum 25(OH)D levels are higher in northern Europe, which may be related to traditionally higher consumption of fatty fish and cod liver oil, whereas low serum 25(OH)D levels in southern European countries may be due to greater skin pigmentation and sunshine-avoiding behavior [ 78 ]. We agree with Frost [ 79 ] that metabolic processes are affected by natural selection. In consequence, humans living at higher latitudes may have adapted to reduced synthesis of vitamin D. These adaptions may include higher uptake of calcium from the intestines, a higher rate of conversion of vitamin D to its active forms, stronger binding of vitamin D to carrier proteins in the bloodstream, and greater use of alternative metabolic pathways for calcium intake.…”

Long-Term Prognosis in Relation to Vitamin D Status in Pediatric Solid Tumor Patients

“…Vitamin D levels are naturally lower in darker-skinned populations, who have adapted to lower levels by using Vitamin D more sparingly and more efficiently. This is notably the case with South Asian populations, from whom the Romani are derived [58]. Since the Romani have poorer health outcomes due to a variety of socioeconomic factors, our findings may be an artefact of such factors.…”

“…As data on childhood cancer survival are limited in terms of the pre-diagnostic Vitamin D level of patients, further investigation is required on the topic, with larger sample sizes and even throughout therapy and later, during the survival period. Moreover, the authors would like to underline the importance of identifying the ethnic origins of future patients, particularly those from darker-skinned or Arctic populations that have adapted to lower levels of Vitamin D over tens of thousands of years [58].…”

Genetic Determinants of 25-Hydroxyvitamin D Concentrations and Their Relevance to Public Health

“…This was also a relatively small study ( n = 10 to n = 36 per treatment group), so further trials with appropriate controls and a larger sample are required to examine possible benefits and effective approaches for personalized vitamin D supplementation. Given more profound genetic adaptations to differences in vitamin D intakes (‘vitamin D scarcity’) are possible, more research is also needed to establish target levels reflecting ‘optimal’ 25(OH)D concentrations and supplementation approaches for specific population groups, including indigenous Arctic and Tropical peoples [ 90 ].…”