In short is suggests that you need around 10KIUs of D3 to get just 20ng/ml for 97.5 individuals - with supplementation. Diet and sun exposure will add to this.
The RDA is specified as the range of 400-600IUs. They got this RDA figure by aggregating x10 D3 dosage studies and out of those studies they extracted 32 study averages. They did this in winter months above the 50th parallel to remove the confounding issues of creating D3 from the skin.
From this dataset they regressed the line and found the IUs required for 50nmolL (20ng/ml).
This paper suggests that the data was misinterpreted resulting in the 600UIs being miscalculated suggesting you need more than the recommended 600IUs.
It states the following:
The correct interpretation of the lower prediction limit is that 97.5% of study averages are predicted to have values exceeding this limit. This is essentially different from the IOM’s conclusion that 97.5% of individuals will have values exceeding the lower prediction limit. To illustrate the difference between the former and latter interpretation, we estimated how much vitamin D is needed to achieve that 97.5% of individuals achieve serum 25(OH)D values of 50 nmol/L or more. For this purpose we reviewed each of the 10 studies used by the IOM. Eight studies reported both the average and standard deviation [2,5–11]. These eight studies had examined a total of 23 supplementation doses [2,5–11]. For each of these 23 study averages we calculated the 2.5th percentile by subtracting 2 standard deviations from the average (depicted by yellow dots in Figure 2). Next, we regressed these 23 values against vitamin D intake to yield the lower prediction limit (red line in Figure 2). This regression line revealed that 600 IU of vitamin D per day achieves that 97.5% of individuals will have serum 25(OH)D values above 26.8 nmol/L rather than above 50 nmol/L which is currently assumed. It also estimated that 8895IU of vitamin D per day may be needed to accomplish that 97.5% of individuals achieve serum 25(OH)D values of 50 nmol/L or more. As this dose is far beyond the range of studied doses, caution is warranted when interpreting this estimate. Regardless, the very high estimate illustrates that the dose is well in excess of the current RDA of 600 IU per day and the tolerable upper intake of 4000 IU per day [1].
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MrG68
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I checked my Vitamin D3 bottle & it says 5000iu once day. However I believe it is of not much use by itself. Take with vit K2 it should help with bone health.
Depending on what you read, some suggest that 20ng/ml is deficient, others say 30ng/ml.I personally aim to have the minimum of 50ng/ml.
The 600IUs RDA as shown in the regression line will not get most people anywhere near the 20/30 mark. You will get some outliers who will perform better than others.
I will say though, that I didn’t investigate the 10 studies they used for their data. But from this paper it’s apparent that the 600IUs they decided on is too low. These 10 cases are what they used to decide the 600IUs.
I think the real issue with vitamin D3 is this fear of toxicity. I’ve already commented on why I believe the existing RCTs dosages are low in the past. If you have a look at the 2nd (corrected) regression line you’ll see that toxicity is actually difficult to do. The curve for D3 isn’t linear (not the regression line). It plateaus at the higher and lower ranges. This is with the exception of one having some condition. Some people can reach toxicity easier than others. I don’t take a calcium supplement with D3 because D3 increases your calcium absorption.
Personally, I don’t want to be near the deficient end of the curve. 50+ you’re not.
how bizarre, I opened that as I was taking my D3+k2!
I got an ‘urgent’ callback from my doctor a while back. Had to phone her immediately. The bloodwork showed an elevated level of D3 and calcium and she needed to run further tests for calcium. Turns out my calcium levels were fine. I was confused because this is what she said the issues were. Turns out she didn’t know anything about the level of calcium. Had to later confer with another doctor who said there wasn’t an issue. So basically she implied the level would be too high without really understanding it.
My article and study reading says that high D3 intake can be dangerous without Calcium. And K2 helps it go to the bones. Since I am on Lupron/Abiraterone/Prednisone which reduce bone at a fast pace I am also on Prolia. Calcium 1200 mg and 2000IU D3 (taken 1/2 with breakfast and 1/2 with dinner), and K2 (100 mcg of Mk-7 and 50000 mcg of Mk-4) with lunch.
The best part is there may be anti-cancer effects from D3. GLTA
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