How Do We Go About Testing for Vitamin D?
15 Dec 2025 · 5 min
JJ Virgin explains the 25-hydroxy vitamin D blood test and why you need it twice a year. Aim for 50-80 ng/mL, not the lower ranges labs often report. Start with 2,000 IU daily, bump to 5,000-10,000 if deficient, and take it with vitamins K1 and K2.
Questions this episode answers
25-hydroxy vitamin D (25(OH)D) blood test.
Approximately 50–80 ng/mL.
At least twice a year; re-test 2–3 months after starting or changing supplementation.
At least 2,000 IU per day.
Typically between 5,000 and 10,000 IU per day, with faster repletion possible (e.g., 10,000 IU/day) and follow-up testing after 2–3 months.
Chapters
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How do we go about Testing for Vitamin D? This is JJ Virgin, four time New York Times bestselling author, celebrity nutrition expert, and Fitness hall of Fame famer. I've been on a lifelong quest for answers to the toughest health questions and now I'm sharing what I found with you. Welcome to Ask the Health Expert. DW emailed and asked how do we go about testing for vitamin D? I'm excited to share that answer with you and actually do a deep dive into vitamin D. I'll be right back.
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Alright, let's talk vitamin D and how to test for it. The levels you should be looking for and why the heck it matters anyway and why you really do want to be testing for vitamin D. So vitamin D is a fat soluble vitamin. It's actually more of a pro hormone and it does a lot of very important things. It's in the news a lot lately because it's a powerful immune modulator. In fact there was a, a, I don't know if it was so much a study. A paper came out that was looking at people going through the current pandemic and those that were getting sicker had lower levels of vitamin D. So that's just one, one piece of review that I've seen lately on vitamin D. But vitamin D is important for your immune system. It's important for your bones, it's important for your gut, it's important for insulin sensitivity. It does a lot of big deal things. So you want to make sure that you're getting optimal amounts. And I say optimal amounts because the challenge with the lab tests is they're not giving you the optimal amounts. They're giving you just kind of what I would call the break even amounts. And we don't want to be break even, we want to be optimal, especially now more than ever. So the type of test you're going to ask FOR is a 25 hydroxy vitamin D test. And you will want to look, and this is if you're in the U.S. you want to, will want to look for your numbers to be somewhere in the neighborhood of 50 to 80 ngs per milliliter. Now what you'll find is that the range, the lab ranges are lower than that, but those are not the optimal ranges. So I really want to be clear on that piece of it. Why do we need to test for vitamin D? And what you really want to do is you want to test for vitamin D at least twice a year. Because if you live in an area where you're, it's seasonal. All right, let's, well, let's back up and talk about how do you make vitamin D? Well, we get vitamin D from the sunshine. It's called the sunshine vitamin. You go outside without sunscreen, 20, 30 minutes a day. Your body Makes, makes vitamin D from that exposure. If everything's working well, however, some people genetically aren't good at it. Some people may not be going out in the sun at all, or you live in an area where the sun isn't out for a good part of the year or you're wearing sunscreen. Any of those things can get in the way of you producing the vitamin D that you need. Now you can get some from food, but there are not a lot of great food sources out there that are going to give you the levels that you need. It's interesting if you are plant based, there are portobellos and some different mushrooms that are UV exposed that will have some vitamin D, but you're not going to get the levels that you really need there. And in fact I look at a lot of people's vitamin D tests. It is rare without supplementation that I see someone where they need to be. And I think a lot of that is probably because they are avoiding the sun or using sunscreen and that can have a big impact. So you're taking that test and then you're going to want to supplement with vitamin D3 and you want to take that vitamin D3 with vitamins K1 and K2. Only exception would be if you're on a blood thinner. Then you want to talk to your doctor about that. So that's what you'll do. And how do you dose that? I see a minimal dose of vitamin D3 of 2000ius. If you've got any type of a deficiency there, it will be between 5 and 10,000 IU's a day. Now you can dose vitamin D just once a week because it's a fat soluble vitamin but, but I just find it easier to take every day. So if you're low and you're looking to lift your levels up more quickly, you can do 10,000 IUs and then test after two to three months. If you are just slightly low, you could hit 5,000 IUs and test in two to three months. But the important thing here is to consider where you live because you're going to need, if you live in a sunny half the year, it's sunny area as opposed to where I live, which is Florida. You need, you are going to need to test your vitamin D in the winter, see where things are and then dose accordingly. And then you'll probably be able to back off some in the summer if you're outside in the sunshine without sunscreen. So again, it's a 25 hydroxy vitamin D test that you'll want to do. But in the absence of that, if it were me, I'd be taking at least 2000ius of vitamin D3 a day with some vitamin K1 and K2 foreign this is JJ with Ask the Health Expert. I do this five times a week, so make sure you never miss a show by going to subscribetojay.com.
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