2000ui/day is quite a lot. Most supplements are 10ug / 400iu. Especially as it's a 5 year study.
With 4000ui per day being the safe limit for someone who's not monitoring levels. (Too much vitamin D is pretty grim because of the effects on calcium levels).
Once you get into checking levels you lose all benefits of a simple intervention.
>Most supplements are 10ug / 400iu. Especially as it's a 5 year study.
That's because an error was made when the RDAs were initially assessed. 400 IU is going to have no effect. I believe in the above link if the sunlight study they even mention that interventions below 1500 IU/day have no effect.
>Too much vitamin D is pretty grim because of the effects on calcium levels
Sure, but I wonder about this 4000 IU limit. Experts also royally screwed up last time with their suggestions that have had an impact for years . This was such a monumental screw up that somehow took decades to address:
>A statistical error in the estimation of the Recommended Dietary Allowance (RDA) for Vitamin-D was recently discovered, indicating that 8895 IU/day are needed for 97.5% of individuals to achieve values ??50 nmol/l, analyzing correctly the same data used by the Institute of Medicine. [0]
>Since all-disease mortality is reduced to 1.0 with serum vitamin D levels ≥100 nmol/L, we call public health authorities to consider designating as the RDA at least three-fourths of the levels proposed by the Endocrine Society Expert Committee as safe upper tolerable daily intake doses. This could lead to a recommendation of 1000 IU for children <1 year on enriched formula and 1500 IU for breastfed children older than 6 months, 3000 IU for children >1 year of age, and around 8000 IU for young adults and thereafter. [0]
That being said, I'm unsure if I would supplement 8000 IU either, but 2000 a day for a study still seems low.
Apparently it's not that easy to get vitamin D toxicity:
>A total of 127,932 serum/plasma 25(OH)D measurements were performed on 73,779 unique patients. Of these patients, 780 (1.05%) had results that exceeded 80 ng per mL and 89 patients (0.12%) had results that exceeded 120 ng per mL. Only 4 patients showed symptoms of vitamin D toxicity. Three of these cases involved inadvertent misdosing of liquid formulations. [1]
Although, it's important to keep in mind that others could've had problems, but just not shown identifiable symptoms.
With 4000ui per day being the safe limit for someone who's not monitoring levels. (Too much vitamin D is pretty grim because of the effects on calcium levels).
Once you get into checking levels you lose all benefits of a simple intervention.