Sunday, December 27, 2015

2909 IU of Vitamin D3 per Day - That's What Mr. Average Needs | What Do You Need? 3094, 4450, or 7248 IU/day?

Your BMI or rather the associated level of inflammation and bodyfatness determines your D3 requirements.
I know that I have previously written about estimated vitamin D requirements, but in contrast to previous articles that were based only on 1-3 studies, today's article about the purported vitamin D requirements of the average Westerner, however, is based on the same previous 108 published estimates and new calculations based on the vitamin D status of 13,987 individuals in various studies Veugelers, Pham and Ekwaru used as the observational database for what is a of now probably the most tangible vitamin D recommendation in their recently published study in Nutrients (Veugelers. 2015).
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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).
As a SuppVersity reader you will be aware that normal-, overweight and obese subjects will need different amounts of supplemental vitamin D3 to achieve these "optimal" levels. To accomdate for these differences and to provide adequate estimates for normal weight, overweight and obese participants, Veugelers et al conducted separate analysis and used suitable logistic regression models to identify the log term of supplementation that provides the best fit. Needless to say that this sub-analysis was conducted based only on those studies that either included exclusively normal-, overweight or obese subjects or distinguished between the three of them yielded. It is thus only logical that this analysis yielded different results of which the 3094 IU/day, which is the suggested daily amount of vitamin D3 to maintain optimal vitamin D levels for normal-weight individuals, is yet pretty much identical to the previously cited "optimum" for Mr. Average Joe.

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.
So what's the verdict, then? While the study at hand certainly provides the hitherto best estimate of our individual vitamin D3 requirements, I still wouldn't put blind faith into the results of Veugelers' model calculation. To be sure you're not too extra-ordinary to be average, I would suggest you test your 25OHD levels after 6 months on the suggested dosage. If you're "in the zone", everything is fine. If not, adjust appropriately.

Fat loss will trigger decent increases in vitamin D, but vitamin D will not trigger significant fat loss | more
Apropos adjusting, as the authors point out, the previously discussed figures may not even be the most practically relevant result of the study. Rather than that, it is the "large extent of variability in 25(OH)D concentrations" of which the authors rightly say that it "makes a RDA for vitamin D neither desirable nor feasible" (Veugelers. 2015) that's the most relevant results of the study.

And yes, you've read that right. The 400, 600 and 1000 IU/day RDA you will find in different countries all over the world is total bogus, not just because it is too low, but because stating a recommended daily allowance based only on the age, not the weight, or rather inflammatory status of an individual, is absolute bogus | Comment on Facebook!
References:
  • 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.