I've been doing 5000-10.000 iu for about a year now. No testing done, but I don't get sick at all...
CRP is not a marker for just cardiovascular disease or the risk of cardiovascular disease; it's a marker for inflammation in any other part of the body. A person strains their muscle or has asymptomatic allergies, their CRP levels will elevate. Currently, there is no test that can directly relate CRP to cardiovascular disease. Also, the study was based on a comparison of the results of the CDC's National Health and Nutrition Examination Survey. A multivariate analysis of a survey is not a good way to study the cause and effect of two particular variables. In my opinion, an experimental study should have been done after elimination of or controlling for other factors that may cause CRP levels to elevate such as an infection, smoking, insulin resistance, obesity, etc... The article notes that other studies that have been done with vitamin D and CRP status have had mixed results. Obviously more research is needed before anyone can actually state that high levels of vitamin D lead to CRP elevation.
Took a look at the notes for that research. Looks like they surveyd 15,000 people (good size) over the time period. But I see nothing on comparisons for the same person. It looked like they compared overall. So we don't know that a person with a low D in one year and a high D in another year had a high CRP (no cause and effect). We just know that this mass of people that had high D had high CRP. They tried to check 9 factors to see if they had an affect, but we don't know if it is something else causing it.
i.e. Interesting, but I don't see any reason to stop what I am doing.
"Have your blood drawn and your levels checked"
Sounds like fine advice except it doesn't really work in America. The test is very cheap but tests like these seem to be a pet peeve of doctors. You might get your PCP to order one but periodically? They've already got too sick people to see.
Perfect Health Diet has a section near the end on over consumption of Vitamin D btw. Initially, cells start breaking it down or storing it in fat but eventually it gets overwhelmed and causes problems. Worse yet, when the fat is consumed the vitamin D is released which can cause problems later on too.
I don't know if taking a vitamin D test is a good investment.
I had my vitamin D tested after changing my ivory skin to medium beige. It came back at 36. Not overly high considering the amount of sun exposure I'd had. As a result, I still don't know if I need to supplement vitamin D in the winter. After my sun exposure, I went to my dermatologist with a spot on my face that appeared pre-cancerous. Much to her surprise, the sample she took did not test positive for cancer. She advised me that because I freckle easily and don't burn that my risk of skin cancer is much higher than someone who has ivory skin full-time. My mother has had NON-melanoma skin cancer 3 times. NON-melanoma is not related to vitamin D status; melonoma based skin cancer is.
I've observed that studies on vitamin D and certain types of cancer only show a correlation. It doesn't mean that because you increase your vitamin D status, that you won't get a certain type of cancer. That has never been proven.
As a result, I spent $60 on a test and I still have no idea how to proceed.
This doesn't pass the smell test for me.
Note the incremental difference in CRP levels measured - 0.06 mg/dL, or 0.6 mg/L CRP per 10 ng/mL 25(OH)D above 21 ng/mL.
I have had a CRP test done at least twice while taking vitamin D, and on the first test, my 25(OH)D was 66 ng/mL. Guess what my CRP level was? Undetectable low (below 0.2 mg/L).
A more recent test at a different lab showed it at 0.1 mg/L, and that was after the level had dropped to 21 ng/mL and I started correcting by supplementing 5000 IU vitamin D3 a day. I don't know what the resolution for the CRP test was, but I would be willing to bet that 0.1 is within the margin of error for the test. I had miserable skeletal pain at 21 ng/mL of 25(OH)D, and I wasn't making it up. We ordered the test because of the pain.
Of course, everybody is different, but my point here is this: everybody is different! If I don't take 5000 IU a day, my levels don't go above 30 ng/mL, and I will have symptoms.
I have to second the other posters. What else were these people doing? Were they nutritionally replete? Getting enough calcium, magnesium, vitamin K, vitamin A? All unlikely.
I would still be more comfortable somewhere between 40 and 60 ng/mL. The author of the study is right about one thing, though: knowing is better than guessing. Get tested.
EDIT: I just realized that I got my units mixed up, and I have fixed them.