There has been a lot of talk on the internet from people concerned that they are 'Storing' vitamin d and what problems this might cause. Now, I’m not sure where people have got the idea that storing vitamin d is something that is worrisome or something harmful, but let me set the record straight that you should not worry if you store vitamin d. Vitamin d is a FAT SOLUBLE vitamin and you do not excrete it through the sweat, urine or stool as you would if it were a Water Soluble vitamin. Vitamins and minerals such as the B vitamins, magnesium and Vitamin C Supplements must be taken on a daily basis because they get excreted if you do not use them in a short period of time (a few hours to a few days depending upon the vitamin). But the fat soluble vitamins like vitamin d are not excreted this way. In fact it is a GOOD thing that you store vitamin d because this was how humans were designed!
When we evolved as humans, we did not always have consistent sunlight and in most parts of the world, vitamin D producing sunlight is only available for 6 months out of the year- and for most populations, sunlight was the only way to obtain vitamin d. Only populations, such as the Inuit and Sami people of the far Northern parts of the world have access to abundant year round vitamin d food sources. And you MUST remember that milk, in its natural form, is NOT a food source of vitamin d, milk that DOES have vitamin D has it ONLY because artificial supplements are added for 'fortification'. So even our herding ancestors would not have had vitamin d except from fish or sun.
Since Vitamin D from sunlight is an inconsistent way to obtain vitamin d, nature designed us to be EXTREMELY efficient at collecting the vitamin d that we do get when we get it. And the way that we do that is to Store Vitamin D when there is an excess of it. And we DO store vitamin d in our fat and it gets ‘time- released’ as we need it. In fact the ‘half-life’ of natural vitamin d from sun or from Vitamin D3 Supplements is a long 3 WEEKS in order to get us through monsoon season or a long and snowy winter. In fact, to illustrate this point, Dr. Robert Heaney, one of the foremost Vitamin D Researchers, found that if you take 2,200 IU per day, you only have about 12 days supply of vitamin D in your body. “What this indicates,” he explained, “… is that fat reserves of the vitamin are essentially running on empty.” So, according to Dr. Heaney, storing only 12 DAYS of vitamin d is inadequate to really meet your needs.
Sometimes doctors will give extremely large-sounding dosages, up to as much as 600,000 IU’s all at once, and some forums out there are saying, “Oh no, that’s bad because you store the Vitamin D”, there is just simply no worry about this. To store vitamin d when it’s in excess is what our bodies do. While certainly too high of dosages for too long can lead to Vitamin D Toxicity, that is NOT the same thing as storing vitamin d. Too much is TOXIC, but storing vitamin d is a natural healthy body process that no one should ‘Worry’ about.