Well for one thing... Vitamin D is stored in FAT cells. this has been mentioned in regards to people who are overweight needing higher doses to compensate for that storage.

Taking one big whopping dose once a week seems to me to be
likely to be stored rather than utilized.

Taking lower doses every day, seems more logical to me for tissue utilization. The enzyme systems that use D will become overloaded (saturated) and the excess would be stored.

That is just my take.

How would it show up in serum labs if my large dose ends up stored only in fat? It must be available to be utilized if in the serum, right?

That is a good question. are you consuming D3 in foods?
Getting some sun exposure?

You went from 28 t0 58 and is only 30 points. 1000IU D3 is estimated to raise 10 pts
so your increase is not quite representing your 50,000 IU dose of D2 per week.

I don't consume much in the way of D3 in foods. My understanding is that few foods have good amounts of D. Beef liver, milk, OJ, egg yolks and fatty fish are best sources. I am not a big milk drinker, but do have small amounts of OJ, and egg yolks. I don't do fish or liver. Are there other foods that are D rich?

I work in the garden in spring/summer months, so get good sunlight then...but not in the winter months, like now.

NO...I didn't raise it in comparison with D3 increases. But 30+ points (26-58) isn't bad...being that I didn't expect it to do much of anything. But the question also remains as for how long it will last....since it's not something taken all the time. The 3 month level will be very interesting.

Well is a great Big unknown for you. But others here have come on their posts with levels below 10 and have used the D2 and showed little or no progress for them.

So everyone is different...why look for the answer when D3 works so well anyway? No one is likely to do a study against a better product IMO.

I will test at 3 months to see what happens (just because I want to know how long it lasts). But after that (all depending on the result), maybe it would be best to take small amounts of D3, now that I'm at a healthy level...just to 'maintain' that level. What do you think? If someone is just wanting to 'maintain' their current level, what is the recommended dosage of D3? Or is that necessary? Or should the body 'maintain' on it's own?

I too have used D2 with NO results before...BUT I also had severe absorption issues with SIBO, which Rifaximin fixed. Many here have neuropathy, which includes GI dysfunction, so they may be having the same problem (with absorption)...as for why they didn't have good results with D2.

I didn't go looking for an answer. I was asked to give his theory a try. I did, and it worked. Now I have to wonder if I can maintain a healthy level (if it stored properly, etc). If I don't have to take daily D, that is a win/win...if I can maintain. I don't know if that will be the case. Taking small amounts of D3 at this point may be the best move...to keep my level stable.

I see that discussion has progressed.

From what I've read, including what I linked to in the initial post in this thread, D3 seems to have a longer life/sticks around longer. Secondly, it's more potent, so you need less.

Now, I think there's little doubt that they both work and studies show they both work. There are people who take D3, I've met a few, including family, whose numbers also don't go up. I think it's all quite a bit more complex.

In the end, if you find something that works for you, and it's natural (ideally), then whether it's D2 or 3, really doesn't matter, I think.

But as you both mention, it's important and interesting to see how long it lasts. Honestly, given it's importance, I wouldn't not take any for 3 months in the dead of winter. If you want to see if D2 works without tainting the results with D3, then take some D2 supplements, no? I will say that I'm curious what your numbers will be like in 3 months and don't think your upswing is due to lab error. That doesn't seem very plausible, but that it's not possible.

As for this:

"I have to ask you: If you are afraid of coming off the D3 for just 3 weeks, doesn't that indicate that it would, in fact, be only a short term fix? Certainly, D3 should last longer than that. If it doesn't, then that would confirm exactly what my doctor stated...that it only increases numbers quick and short term...not long term. I know that D2 is Rx and NOT taken every day/week/month, etc...because it's supposed to last in the body (or cells, maybe, as he stated)."

It's worth emphasizing that I'm only taking 1500-2000 IU per day of D3, so nowhere near the numbers I should be taking, because despite using the cream and getting past the GI issues, I'm still getting insomnia, and last night was the worst. The amount of energy and alertness that I get is too intense for me to take higher doses. Clearly I'm sensitive. Once possibility is that I'm not getting enough magnesium, so starting tonight I'm going to up that and see whether the insomnia goes away. If it does, I'll up the dose of the cream by a 1000 IU or so, maybe up to 5000. Let's see. If the insomnia continues, I'll have to switch to D2, since I can't not sleep with my SFN.

D is not something you can take until you get a "good reading" and then stop. The body needs it every day ..this is illustrated by how it is made in the skin from sun exposure and that replenishes what is used up in the tissues.

You started at 28, which is not really that low, compared to others here on NT. Many chronic pain patients come here and find they are below 10. The average is between 10 and 20. Then only a few hover around 30. To have a level like yours, you must be making it for yourself in the skin, and/or getting it in a fortified food or multivitamin. It has to be coming from somewhere.

Taking up to 4000IU of D3 daily is considered safe today, by the IOM.

Keep in mind that you should watch calcium intake by supplements or antacids while on high D treatment. Some cardiologists recommend no more than 600mg a day. D increases calcium absorption in the GI tract so food sources are typically much more successfully absorbed.

I think a level of 58 is pretty good. Many people here had difficulty reaching that from supplements.

I started at 20-22 over 1.5 years ago...I have been working on this for a while with both D3 and D2. Neither worked at first. I gained small amounts at a time...up to 24 and then most recently to 26 (before I did this last course of D2 after Rifaximin). I may not be grossly deficient in terms of others that come here....but I am significantly deficient for someone with an autoimmune disease. I'm not worried that I don't make any D...as obviously, I do. I just need to get a good healthy level and then maintain it.

If the body is functioning properly, then I don't see why we should have to supplement at all...for ANY substance. But of course, we don't all function at peak performance and don't eat all the foods necessary for obtaining all the proper nutrients. We do the best we can and supplement where needed.

Rx version of D2 is not meant to be taken all the time...but of course we need D every day. There is no way to know whether I am able to maintain a healthy level on my own (with foods, sun, etc) unless I see what the level does over the next 3 months or so. It will also tell me whether the D2 stays in the system. If i start to drop, then I will likely take small amounts of D3 to maintain a healthy level for my autoimmune condition. It's just nice to know that D2 will work for me (and maybe for others, if they have proper absorption).