28 votes

Vitamin D: the basics, Shannon’s story, the evidence

27 comments

  1. [7]
    skybrian
    Link
    This is a three-part review by a parathyroid surgeon of what’s known about Vitamin D. From the first blog post: … … … Going on to part 2: She goes on to describe a case where a patent took 5000 IU...

    This is a three-part review by a parathyroid surgeon of what’s known about Vitamin D.

    From the first blog post:

    Most studies follow this pattern: Two sets of people are evaluated. One set has a certain disease (diabetes, for example). The other set does not have the disease. Vitamin D levels are measured in both groups. Vitamin D deficiency is found to be much more common in the group of diseased individuals.

    Using this study method, Vitamin D deficiency is correlated with many diseases. But correlation does not equal causation. The fact that two things are related does not imply that one caused the other.

    But the temptation to equate correlation and causation is strong. Many articles showing a correlation with Vitamin D will add an untested but completely plausible physiological explanation for how low vitamin levels could lead to the disease. Armed with a solid correlation and a reasonable argument for causation, they may feel justified in concluding that the evidence for causation is strong. And once you have made that leap, you are almost obligated in recommending Vitamin D supplementation for anyone affected by or concerned about your disease of interest.

    Vitamin D is a hormone that binds to the Vitamin D Receptor, a protein made by cells throughout your body. The vitamin acts like a key, while the receptor is a lock. A key and lock are pointless individually, but useful together. Vitamin D and its receptor are inactive until they combine, and then they interact with DNA to produce certain actions within the cell. Based on what we already know, it is easy to understand why the intestines, parathyroids, and bones make Vitamin D Receptors – these organs are all involved in regulating calcium levels, and we know Vitamin D regulates calcium metabolism. But those are not the only organs that have the receptors. We find these receptors all over the place, in the kidneys, lungs, pancreas, uterus, and blood cells involved in immune function, just to name a few.(4,5)

    Unfortunately, we do not have a full unified explanation for how Vitamin D deficiency could lead to the list of diseases that are associated with it. We know the correlations are there, and we can show that the Vitamin D molecule has an effect on multiple cells and organs. But this is clearly not as straightforward as the role of Vitamin D in calcium metabolism and bone health.

    Going on to part 2:

    We think of vitamins and supplements differently. A few readers have made comments like this: “I understand that the evidence for Vitamin D in healthy adults doesn’t really show a benefit, but I take Vitamin D because it probably won’t hurt me, and it might help.” This is a common sentiment regarding supplements, but not a statement that most people would make about metoprolol, or any prescribed medication. Medications are generally understood to be substances taken in response to a specific disease or condition, and we hope that research has shown that they work. Supplements are given a pass; we take them if they might help, even though they may not be needed.

    She goes on to describe a case where a patent took 5000 IU of Vitamin D for 5 years on the advice of a doctor, stopped taking it, but it took six months to recover.

    Of course, there is a selection bias in who comes to me. There are people out there doing just fine on 5000 units of Vitamin D daily. I only see the ones who develop high calcium levels. But I see enough of them to know that this is not an exceptionally rare occurrence. I have been to lectures in which physicians have claimed that Vitamin D toxicity almost never occurs. In my experience, this is false. I have seen many cases of Vitamin D toxicity in people who were taking the recommended dose from an over-the-counter bottle.

    Part 3 is a review of the major studies and ends with these recommendations:

    1. Recognize that Vitamin D is not a panacea. It is an essential hormone, definitely, but not a magical pill that will ward off disease. […]

    2. Use a reasoned approach to supplementation. There are benefits to Vitamin D in cases of severe deficiency (not mild deficiency). If you are elderly, frail, and not getting sunlight, there is a chance you are significantly deficient in Vitamin D. If you think you may be deficient, you can check this with a blood test.

    3. Act in moderation. Low to moderate doses of Vitamin D (e.g. 400 to 2000 IUs daily) have proven to be safe in trials. If you think there is a benefit and we just don't have enough data to prove it yet, you may be right. We do know the harms of taking too much, though, so supplement in moderation. And if you are taking Vitamin D, ask your doctor to check your blood levels.

    20 votes
    1. [6]
      C-Cab
      Link Parent
      Intriguing take that many researchers are assuming the low vitamin D is in the causal side of the correlational relationship. Calcium (among the other elements that vitamin D regulates) is super...

      Intriguing take that many researchers are assuming the low vitamin D is in the causal side of the correlational relationship. Calcium (among the other elements that vitamin D regulates) is super important across many different systems in the body, so I can see how one might think that low levels of calcium is influencing some pathology. I'm coming at it from the other side though. I would think that since vitamin D is super important for holding onto calcium that it is comorbid - some third factor is influencing them both.

      I also agree with the general sentiment of the author in the third part. Supplements are nice and all, but you typically don't need them as long as you're eating a healthy diet, getting enough time outside, etc. This certainly isn't the case for everyone, but this need to just supplement, supplement, supplement always rubbed me the wrong way. Talk with your doctor, check your blood work and other things, and make a plan that works best for you.

      10 votes
      1. [3]
        Habituallytired
        Link Parent
        There is also a third case here: those who do eat healthy and go outside, but their body just isn't doing the things it's supposed to and isn't holding on to the vitamin D (or whatever thing...

        There is also a third case here: those who do eat healthy and go outside, but their body just isn't doing the things it's supposed to and isn't holding on to the vitamin D (or whatever thing they're deficient in). But again, talking with your doctor and taking a blood test to determine your baseline levels at the very least, if not finding out that you're deficient and need to take supplements.

        I agree with you that this is definitely a comorbidity issue rather than a causal issue - there are a lot of different diseases that attack multiple bodily functions at once.

        11 votes
        1. [2]
          ThrowdoBaggins
          Link Parent
          I believe vitamin D is synthesised when your skin is exposed to sunlight, to some extent, so I’m wondering if dealing with Disease XYZ causes the patient to go outside less often, which then...

          I believe vitamin D is synthesised when your skin is exposed to sunlight, to some extent, so I’m wondering if dealing with Disease XYZ causes the patient to go outside less often, which then causes the deficiency… and that there’s no causal link other than “feeling sick means you do less stuff that’s good for you”..?

          1 vote
      2. [2]
        FeEnthusiast
        Link Parent
        I agree with you that a healthy diet is mostly what it comes down to. I take 40 micrograms (1600IU) of vitamin D in the winter because I live close to the artic circle so sunlight is kinda... not...

        I agree with you that a healthy diet is mostly what it comes down to. I take 40 micrograms (1600IU) of vitamin D in the winter because I live close to the artic circle so sunlight is kinda... not there for 4 months so it helps to get a bit from pills. It seems to have a positive effect as far as general happiness is concerned so that's enough for me. As far as other supplements it's all very confusing, like I don't know what food you get zinc from but also maybe I should have zinc?

        3 votes
        1. C-Cab
          (edited )
          Link Parent
          Certainly in places or times of year where there isn't much sunlight you should supplement, and if it's low amounts it's not really bad for you and may be needed! Regarding zinc, you find that in...

          Certainly in places or times of year where there isn't much sunlight you should supplement, and if it's low amounts it's not really bad for you and may be needed!

          Regarding zinc, you find that in many foods: meat, nuts, beans, dairy, grains. That's why I mentioned that if you have a healthy diet eating a variety of foods you will be getting all of the vitamins and nutrients you need without having to supplement.

          Also, the same with iron if your name is any indication on your feelings towards it.

          6 votes
  2. patience_limited
    (edited )
    Link
    Additional "I am not a doctor" advice - tell your health providers about every single dietary supplement you take. I supplement Vitamin D under medical advice at the usual over-the-counter 2000 IU...

    Additional "I am not a doctor" advice - tell your health providers about every single dietary supplement you take.

    I supplement Vitamin D under medical advice at the usual over-the-counter 2000 IU dose, with periodic testing, due to medications that cause sun sensitivity. I'm at risk of both Vitamin D deficiency from low sun exposure, and osteoporosis from RA. Spouse followed along and took the same quantity, assuming it was harmless and generally beneficial. He's had a heart valve replacement, and spends much of the warmer months outdoors without sun block.

    When his cardiologist found out he was supplementing Vitamin D, the doctor immediately ordered a calcium level test and put a stop to supplementation. It turns out that even slightly excessive calcium is an active risk for arrhythmias in valve replacement patients, can cause earlier calcification of biological heart valves, and may contribute to atherosclerotic plaque formation. Spouse wound up back on antiarrhythmic drugs for a couple of months until his calcium levels dropped into normal range.

    I'm inclined to agree with the doctor in the article that Vitamin D is a potent enough regulatory hormone that higher doses should be restricted from OTC sales.

    18 votes
  3. [3]
    AlexeyKaramazov
    Link
    Wow this is incredibly interesting and amazing that this is nowhere near common knowledge. My wife's parents take a ridiculous amount of supplements daily and she was taking a lot too. I've...

    Wow this is incredibly interesting and amazing that this is nowhere near common knowledge. My wife's parents take a ridiculous amount of supplements daily and she was taking a lot too. I've convinced her to pare it down but she has me taking a multi and a few other vitamins including a lot of vitamin D.
    Interestingly, her mom complains of the symptoms of Shannon, feeling foggy, tired, muscle soreness and insomnia. I would not be surprised if she had vitamin D toxicity.
    I'm definitely going to only take it if I'm feeling run down in the winter now, and not as much.

    9 votes
    1. [2]
      OBLIVIATER
      Link Parent
      Would issues like that show up on a yearly physical blood test?

      Would issues like that show up on a yearly physical blood test?

      1 vote
      1. AlexeyKaramazov
        Link Parent
        Oh I'm sure it would but she's a conspiracy theorist. She thinks doctors lie because big pharma pays them. I don't have conversations with her about many things anymore. I mentioned that my wife...

        Oh I'm sure it would but she's a conspiracy theorist. She thinks doctors lie because big pharma pays them. I don't have conversations with her about many things anymore. I mentioned that my wife could talk to her or send the article but my in-laws will almost certainly just say that doctors lie and my wife doesn't want to have that conversation again.

        5 votes
  4. V17
    Link
    This is a very interesting article, but some parts of it seemed a tad too contrarian, perhaps as a response to the too uncritical views of the general public. It's been a couple years since I...

    This is a very interesting article, but some parts of it seemed a tad too contrarian, perhaps as a response to the too uncritical views of the general public.

    It's been a couple years since I looked through some of the research, so I don't have the sources on me and I don't have time to look for them, but here some of the issues that I see and that she doesn't mention. Bear in mind that I am not a doctor, but I did actually read the studies at the time.

    There definitely are studies that explored effects of supplementation, not just correlation with high/low levels, and found results. Increased cardiopulmonary output in individuals with chronic fatigue was one.

    Another was better outcomes in certain hospitalized patients, including people with covid, but with one very significant caveat that I'm also a bit disappointed wasn't mentioned: the supplementation was done with high dose iv calcifediol, which is the active form of vitamin D that normally gets created in the liver from cholecalciferol (the form that is in over the counter pills). Supplementation of cholecalciferol did not work, high doses like that bring too many side effects and the increase in calcifediol blood levels is too slow (days to weeks) to be useful, but it was a situation where a correlation was found first and a causation later, it just required a specific type of supplementation.

    In general the metabolism of cholecalciferol is sometimes an issue with chronically ill patients and there is some evidence indicating that this may be the reason why some studies found either weak or no effects from supplementation. The specifics are beyond my understanding.

    I was also surprised that vitamin K2 was not mentioned anywhere, especially in the section (and at least one linked metastudy) regarding bone fractures. Afaik it is now slowly beginning to be common practice to recommend vitamin K2 together with vitamin D supplementation, the reasoning being specifically that vitamin D supplementation on its own can cause deposits of calcium in the arteries because vitamin K2 is needed to transfer calcium where it belongs. Like bones: some physicians consider vitamins D and K2 the best way to treat osteoporosis. Is it possible that the high levels of blood calcium she mentions are only caused by supplementing vitamin D without vitamin K2? I don't know and it's possible that this is not the case at all, unfortunately the article did not mention this relationship either positively or negatively.

    Last but not least, I would have liked to see her issues with studies that found significantly higher daily doses than her mentioned 2000 IU daily to be well tolerated. Not because I don't believe her, but because her findings indicate there is something more going on than just the D3 levels and I'd like to see some hypotheses about what it could be.

    8 votes
  5. [3]
    ButteredToast
    Link
    Reading the comments here I can’t help but think the situation with not only Vitamin D but also other supplements will improve immensely once high accuracy, cheap home blood testing becomes...

    Reading the comments here I can’t help but think the situation with not only Vitamin D but also other supplements will improve immensely once high accuracy, cheap home blood testing becomes available. Having to go in to get blood work done periodically is a huge point of friction which I believe is leading people to make assumptions.

    5 votes
    1. [2]
      skybrian
      Link Parent
      I'm not sure how that would work. People pricking themselves doesn't seem all that safe? Maybe more pharmacies could do it, though, like they do for vaccines.

      I'm not sure how that would work. People pricking themselves doesn't seem all that safe?

      Maybe more pharmacies could do it, though, like they do for vaccines.

      1 vote
      1. ButteredToast
        Link Parent
        I’d assume similarly to how people currently do home blood sugar testing, but education around safety would absolutely be a must.

        I’d assume similarly to how people currently do home blood sugar testing, but education around safety would absolutely be a must.

        4 votes
  6. feanne
    (edited )
    Link
    Thanks for sharing! My last blood test (early Feb) showed I have low vitamin D. I was at 13 ng/ml, and the normal range is supposed to be 30-40 ng/ml. I'm trying sunlight first, and if it doesn't...

    Thanks for sharing!

    My last blood test (early Feb) showed I have low vitamin D. I was at 13 ng/ml, and the normal range is supposed to be 30-40 ng/ml. I'm trying sunlight first, and if it doesn't work, I'll take supplements. I'm using an app, dminder, to help me get enough sunlight for vitamin D while still avoiding sunburns. Its recommended sun exposure time is based on my exact location and skin type. It gives me an estimate of how much vitamin D IUs I get per sun session, and my current vitamin D blood level. After several weeks of consistently getting 2000-3000 IUs from the sun daily, it says I'm now at 27 ng/ml. I'm hoping to get that up to 40-50 ng/ml before my next blood test in a few months, and then I'll know if the app is accurate in its estimation.

    I was surprised that I have low vitamin D. I live in a sunny tropical country and walk to the gym regularly, I just assumed it would be enough. But I was walking at 4-5pm. Turns out you don't really get vitamin D from the sun at that time. I now walk around noontime, I can get about 3000 IUs in 10 mins, which is just about how long it takes to walk to and from the gym.

    Good to be aware re. vitamin D toxicity!

    3 votes
  7. [10]
    Tigress
    Link
    Dang... i guess i better take my vitamin D deficiency more seriously (it was caught last year cause my blood calcium levels were high). And yes I take supplements (the recommended amount by my...

    Dang... i guess i better take my vitamin D deficiency more seriously (it was caught last year cause my blood calcium levels were high). And yes I take supplements (the recommended amount by my internalist) but I am bad about forgetting to take them (in fact I'm on vacation right now and ran out and am waiting til I get home to buy more).

    I think I have the opposite problem than what this article is warning against but the first part is displaying to me that I should be better about keeping up with my supplement.

    2 votes
    1. [3]
      skybrian
      Link Parent
      Maybe I'm misunderstanding something, but high calcium blood levels don't seem to be an indicator of a vitamin D deficiency - rather, the opposite. Not a doctor, but see here:

      Maybe I'm misunderstanding something, but high calcium blood levels don't seem to be an indicator of a vitamin D deficiency - rather, the opposite.

      Not a doctor, but see here:

      Results from a total calcium test that are higher than normal may be a sign of many types of conditions, such as:

      • Taking too much vitamin D over a long period of time
      3 votes
      1. [2]
        Tigress
        Link Parent
        Well, tell my doctor and internalist that. I tested for high calcium so my doctor had my blood tested for D levels and something else and it came back I had low Vitamin D so she sent to me an...

        Well, tell my doctor and internalist that. I tested for high calcium so my doctor had my blood tested for D levels and something else and it came back I had low Vitamin D so she sent to me an internalist (forget the actual name for the specialist). Anyways, has something to do with my parathyroid isn't working right and is causing calcium to be leeched from my bones and is linked to low Vitamin D.

        So, excuse me if I believe my doctors over some one on the internet who just read an article.

        6 votes
        1. skybrian
          Link Parent
          Yeah, I'm sure they're right, I just think something must have gotten lost in the telling. It sounds like a complicated situation.

          Yeah, I'm sure they're right, I just think something must have gotten lost in the telling. It sounds like a complicated situation.

          5 votes
    2. [6]
      C-Cab
      Link Parent
      As skybrian pointed out, high calcium typically results from lots of vitamin D. Vitamin D helps promote calcium absorption in the gut, so if your calcium levels are too high you should not be...

      As skybrian pointed out, high calcium typically results from lots of vitamin D. Vitamin D helps promote calcium absorption in the gut, so if your calcium levels are too high you should not be taking vitamin D!

      1. [5]
        Tigress
        Link Parent
        Uh. my doctor and internalist would disagree with you. My yearly blood test showed high calcium so my dr. tested for low vitamin d (cause yes, that can be linked). And yes, I was low on Vitamin D...

        Uh. my doctor and internalist would disagree with you. My yearly blood test showed high calcium so my dr. tested for low vitamin d (cause yes, that can be linked). And yes, I was low on Vitamin D (this isn't just me pulling this out of my butt, when I said I had a deficiency, this was diagnosed by both a doctor and the internalist she sent me to.

        It has something to do with parathyroid being low on D will do something that will end up with calcium being leeched out of your bones (hence high calcium levels in my blood work). So... high calcium levels don't necessarily mean you are getting too much calcium, it could mean that calcium is being taken from your bones so you are actually losing calcium that you need (Which yes, my internalist also wanted me to take calcium supplements too).

        (and she sent me to an internalist in case this was something I might need surgery for on my parathyroid. For now though just supplementing D and calcium seem to be enough).

        3 votes
        1. [4]
          C-Cab
          (edited )
          Link Parent
          Sorry, I shouldn't have told you what to do with your diagnosis and treatment plans - especially after I said to listen to your doctor in my other comment. That was foolish of me. The parathyroid...

          Sorry, I shouldn't have told you what to do with your diagnosis and treatment plans - especially after I said to listen to your doctor in my other comment. That was foolish of me. The parathyroid gland is the regulator of calcium in the blood. Absolutely right that high calcium, coupled with low vitamin D, means it's being pulled from your bones which is bad! I just saw the high calcium and vitamin D and got worried because too much calcium is bad beyond just your skeletal health, as I'm sure your doctor told you.

          I also apologize I'm gonna go physiologist here - I would guess based off what you're describing that your parathyroid glands aren't secreting enough calcitronin. Alternatively, if your parathyroid has a growth or some other issue with being overactive you could be producing too much parathyroid hormone (handy graphic on calcium homeostasis regarding the skeletal system). Alternatively the fact that you're not making enough vitamin D seems to point towards not getting enough sunlight, or the photosynthetic mechanism in your skin is having an issue.

          Did they give you any formal diagnosis like hyperparathyroidism or are you still working through it? Because disrupted calcium signaling is associated with a lot of things, as the article of this post points out. I totally understand if you don't want to talk about it. I'm asking both out of curiosity and out of concern for your well being because I know people where their doctors missed things.

          2 votes
          1. [3]
            Tigress
            (edited )
            Link Parent
            Well my internalist looked at my bloodwork. Had me try doing vitamin D for a few months. Then rechecked the blood work after I had been on a supplement for a bit. Said I didn't need my parathyroid...

            Well my internalist looked at my bloodwork. Had me try doing vitamin D for a few months. Then rechecked the blood work after I had been on a supplement for a bit. Said I didn't need my parathyroid operated on (for now, it seems like she was of the opinion that could change one day) and increased her recommendation of how much Vitamin D to take as well as calcium. She did mention to me why they might want to recommend operating on the parathyroid if they thought that supplements alone wouldn't help (or that the supplement wasn't fixing the problem) and mentioned it can lead to all sorts of problems like kidney stones and some other stuff (the stones though is what stood out to me most.. .that and osteor - can't spell but the thing where your bones get brittle cause too little calcium).

            My internalist seemed to be of the opinion sunlight has less factor in it than most people think and diet has more factor than most people attribute. Honestly my diet sucks (and I don't take any supplmenets at all other than now the Vitamin D and calcium which a doctor told me to take) and I don't get much sunlight so either way I am not getting enough. I don't actually not take supplements on purpose, I just won't remember to take them so I don't bother. Since a doctor has said I really need these I'm a little better about trying to be disciplined but I still forget many times. Also, vitamin tablets tend to be huge and I have a hard time taking pills if I can feel them at the back of my throat (hard to use the method I've gotten used to so I don't feel them when they go down). I am doing chewables now which my husband gripes has been shown to have way less of the vitamin then they claim but every Vitamin D pill that has enough to satisfy what they told me to take are like horse pills so I figure better the ones I'll take and not as good then the ones I just won't. Besides, they are the ones I took when they retested me and said that was good enough for now.

            Also a bit confusing is my doctor and internalist differed on whether it was just lack of vitamin D (my doctor thought it could just be that but had sent me to an internalist to make sure) where as my internalist gave me the impression that something is wrong with my parathyroid but for now supplements worked well enough. There was something else I got kinda conflicting info from both of them but I don't remember what... i think on whether lack of vitamin d could cause the parathyroid to function wrong (my doctor) where as my internalist seemed to think the problem starts(started) with the parathyroid.

            1 vote
            1. [2]
              C-Cab
              Link Parent
              If you're white, you typically need less than 10 minutes of sunlight per day to make the appropriate amount of vitamin D (I think about 30 minutes if you're black), so I'm inclined to agree with...

              If you're white, you typically need less than 10 minutes of sunlight per day to make the appropriate amount of vitamin D (I think about 30 minutes if you're black), so I'm inclined to agree with your internalist that sunlight is less the factor. But vitamin D is usually readily made by your skin when you're outside, so unless you're completely covered up or out for very short amounts of time you shouldn't have low vitamin D. Also, as far as I'm aware, vitamin D is made independent of any signals from the parathyroid gland. However, the parathyroid gland does tell the kidneys to convert vitamin D into its usable form, calcitriol, for calcium absorption, but that's downstream from the initial steps of vitamin D synthesis.

              Ultimately though, vitamin D is there to help increase absorption of calcium from the food you're eating, so it comes down to your diet no matter how you slice it. If you have low vitamin D, or not eating the right foods, then your calcium intake is going to be low and so it would make sense that your parathyroid gland is going to try and harvest calcium from your bones, which over enough time will lead to osteoporosis (I spelled it wrong the first time, I never can remember if it's osteoperosis or osteoporosis - but I guess it is pores in the bones).

              If the vitamin D supplementation seems to be working and is bringing your blood calcium into the normal range, then from my perspective and the information you provided it seems like your parathyroid is either working as intended or maybe overcompensating - in which case surgery down the line makes sense if it can't be managed. Again - not a doctor, but I teach introductory physiology, including calcium regulation. This means I know the fundamentals and some aspects of diseases that affect your physiology, but I am no expert and there is always a lot more nuance and mystery the deeper you dive.

              I'm with you on the struggle of taking pills/supplements. One thing that I've found works is incorporating them into my morning or evening routine. I was having a hard time remembering to take my hypertension medications, so I started taking them before I brush my teeth at night and now I never miss them.

              1 vote
              1. Tigress
                Link Parent
                That's what I do for my other pills but supplement pills are so big that I go with chewables for my vitamin D (that don't fit in my pill container). I try to make it so they are part of my...

                That's what I do for my other pills but supplement pills are so big that I go with chewables for my vitamin D (that don't fit in my pill container). I try to make it so they are part of my breakfast regime but it doesn't work as well as part of my brush my teeth regime that my other pills are on. But yes, routine for me is key in getting me to remember something.

                1 vote
  8. skybrian
    Link
    The author of the blog has a Hacker News account and posted some followups.

    The author of the blog has a Hacker News account and posted some followups.