Monday, May 31, 2010

Are Some People Pushing Their Vitamin D Levels Too High?

by Chris Masterjohn

Has science proven that the minimal acceptable blood level of vitamin D, in the form of 25(OH)D, is above 50 ng/mL (125 nmol/L)? No. If you’ve been trying to maintain your levels this high because you thought this was the case, I’m sorry to break the news. There is, on the contrary, good evidence that 25(OH)D levels should be at least 30-35 ng/mL (75-88 nmol/L). Much higher levels may be better, or they could start causing harm, especially in the absence of adequate vitamins A and K2. Once we leave the land of 30-35 ng/mL, however, we enter the land of speculation.

You can read the full blog over at the Weston A. Price site by clicking here:

Are Some People Pushing Their Vitamin D Levels Too High?

Read more about the author, Chris Masterjohn, PhD, here.


  1. My joints started to crack after taking 10,000 IU of vitamin D for several days. After I supplemented with vitamin A and K2, I had gotten better. This may explain why.

  2. Definitely, thanks for sharing your experience.

  3. Hi Chris,

    In your May 2006 article, you seem more comfortable with higher levels of serum 25 (OH) D. Could you comment on that? I'm wondering what, if anything, has changed for you in the last four years re: optimal levels?


    "...In order to maximize calcium absorption, blood levels of 25 (OH) D need to be maintained at 30 ng/mL, which, in the absence of UV-B light, would require roughly 2600 IU per day of vitamin D. The risk of fracture continues to decline at even higher 25 (OH) D levels because people with higher vitamin D levels actually fall less often, suggesting a neuromuscular benefit to high levels of the vitamin. Even higher levels of 46 ng/mL are needed to maximize the body's ability to regulate blood sugar, and since dark-skinned agricultural workers in the tropics have 25 (OH) D levels of about 60 ng/mL, it's probable that this is closer to the ideal level...."

  4. Jin,

    I think when reading that paragraph that I provided evidence for the mid-40s range.

    I should more cautiously have said that it was "possible" rather than "probable" that the 25(OH)D levels reached in the tropics by some groups with huge amounts of sun exposure(by lifeguards, I believe that should actually say) is optimal.

    I also should have more clearly distinguished between observational and experimental findings. The inverse linear correlation between 25(OH)D and glucose intolerance bottoms out at about 46 ng/mL, but this is a statistical correlation. I should have pointed this out in the original article. Now, however, it has been shown that obesity decreases 25(OH)D levels because bodyfat acts as a "sink" for vitamin D. Since people with glucose intolerance are often overweight, there is even greater reason to be careful of interpreting the statistical correlation than there was when I wrote the article. It has also been shown, on the other hand, that vitamin D supplementation improves glucose tolerance. No one, however, has yet shown that reacing 46 ng/mL improves glucose tolernace more than reaching 30-35 ng/mL.

    That said, I have never seen any evidence that any great harm might come from levels of 46 ng/mL, so I think that aiming for a range between 35-50 ng/mL is probably the most sensible bet.

    Lifeguards have higher 25(OH)D levels but they also have more kidney stones. Maybe if they got plenty of vitamins A and K2, they would not. But this is a gray area right now.

    Hope that helps,

  5. Thanks, Chris, that helps.

    I'm wary of the current trend to push 25(OH)D levels up & up by supplementing with high doses of D3 without balancing the D3 with enough A & K2.

    Ideally (?), we'd all be getting sufficient amounts of the important fat soluble vitamins through real foods. In reality, few people seem to be eating those powerhouse foods on a regular basis, myself included.

    With that in mind, have you developed an idea of how much D3, A, and K2 is reasonable to supplement?

    Thank you for your contribution to the debate.


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