|Your BMI or rather the associated level of inflammation and bodyfatness determines your D3 requirements.|
Now, as the headline already tells you, their analysis of said data lead the researchers to conclude that "2909 IU of vitamin D per day is needed to achieve serum 25‐hydroxyvitamin D (25(OH)D) concentrations of 50 nmol/L or more in 97.5% of healthy individuals" (Veugelers. 2015). To get to this value, the researchers from the University of Alberta used quantile regressions to
"model the effect of vitamin D supplementation on the 2.5th percentile, the median and the 97.5% percentile of serum 25(OH)D concentrations [and an] exponential model [and] logistic regression [for the estimates and] to estimate the probability of having serum levels above a lower and below an upper serum 25(OH)D concentration, [respectively]" (Veugelers. 2015).In that it is important to know that in this model the limit of the 'normal' vitamin D concentrations (58-171 nmol 5(OH)D/L) was defined in accordance with the values Luxwolda et al observed in traditionally living populations in East Africa who have mean serum 25‐hydroxyvitamin D concentration of 115 nmol/l or more (Luxwolda. 2012). So, we are not talking about absolute minimum levels, but rather about levels many researchers would call "optimal".
|Figure 1: Plot of the results of the model calculations (left) and my visualization (right) of the calculated vitamin D requirements in IU/day for normal-weight, overweight and obese individuals (Veugelers. 2015).|
Against that background, it is yet all the more important to note that the average overweight or obese Westerner will yet need significantly more vitamin D3, 4450 IU/day and 7248 IU/day, to be precise, to keep his / her labels stable. Based on what you should remember from the role of 25OHD as an anti-inflammatory acute phase reactant (Waldron. 2014), though, this is not really surprising.
- Luxwolda, Martine F., et al. "Traditionally living populations in East Africa have a mean serum 25-hydroxyvitamin D concentration of 115 nmol/l." British Journal of Nutrition 108.09 (2012): 1557-1561.
- Veugelers, Paul J., Truong-Minh Pham, and John Paul Ekwaru. "Optimal Vitamin D Supplementation Doses that Minimize the Risk for Both Low and High Serum 25-Hydroxyvitamin D Concentrations in the General Population." Nutrients 7.12 (2015): 10189-10208.
- Waldron, Jenna Louise, et al. "Vitamin D: a negative acute phase reactant." Journal of clinical pathology (2013): jclinpath-2012.