RESUMEN
The concept of the vitamin D response index was developed based on vitamin D intervention studies conducted with Finnish cohorts. In this study, we challenged the concept by performing a single vitamin D3 bolus (80,000 IU) intervention with a cohort of 100 native Saudis. The change of serum levels of the proinflammatory cytokines interleukin 6, interleukin 8 and tumor necrosis factor measured directly before intervention in comparison to samples taken one and thirty days after vitamin D3 supplementation were used as biomarkers for distinguishing low, mid and high responders. Interestingly, we identified 39 % of the study participants as low responders. In contrast, when we used in a subset of 37 study participants whole blood expression changes of seven well-known vitamin D target genes one and thirty days after supplementation as alternative biomarkers, only 9 persons (24 %) were identified as low responders. In conclusion, in Saudi Arabia the rate of low vitamin D responders is equal or even higher than that in Finland. Therefore, similar to Nordic countries also in Saudi Arabia appropriate vitamin D3 supplementation is essential, in order to fulfill the needs of low responders.
RESUMEN
Vitamin D deficiency has increased in the general population and is a public health issue. Vitamin D plays an important role in regulating the immune system, e.g., by modulating the production of inflammatory cytokines. In most countries, the recommended maximal daily dose of vitamin D3 is 4000 IU (100 µg) per day. In this study, we investigated whether a single vitamin D3 bolus can reduce the levels of the inflammatory markers interleukin (IL) 6, IL8 and tumor necrosis factor (TNF) within one month. Fifty healthy Saudi males were recruited from the local community in Jeddah city and were orally supplemented with a single dose of 80,000 IU vitamin D3. Serum samples were collected at time points 0, 1 and 30 days, and serum levels of IL6, IL8 and TNF, parathyroid hormone (PTH), 25-hydroxyvitamin D3 (25(OH)D3), triglycerides, cholesterol, calcium (Ca2+) and phosphate (PO4-) were determined. On average, the vitamin D3 bolus resulted in a significant increase in vitamin D status as well as in a significant decrease in the levels of inflammatory cytokines even one month after supplementation without changing serum Ca2+, PO4- or lipid levels. In conclusion, single high-dose vitamin D3 supplementation is safe for reducing inflammation markers and may lead to an update of current recommendations for vitamin D intake, in order to prevent critical health problems.