why is vitamin d so important to your body maybe you've heard it helps with your bone health your immune system even calcium getting involved and yes we'll definitely talk about the sun and your skin getting involved in the story about vitamin d but did you know that your liver and kidneys play a huge role with vitamin d synthesis so we'll take a look at those organs as well as answer some questions like why are many people deficient with this vitamin and how do you get adequate amounts inside of your body it's gonna be a fun one so let's do this now one of the characteristics of vitamin d is that it's a fat soluble vitamin fat-soluble vitamins dissolve in fats and tend to accumulate more in the body as compared to say like the water soluble vitamins like vitamin c now since we love our video quiz questions our video quiz question of the day is can you name the four fat soluble vitamins where we got the first one with vitamin d but if you can list the rest post them in the comments below and we'll pin the correct answer at the top of the comments now there are many compounds that belong to the vitamin d family and they all have similar functions but by far the most important is vitamin d3 also known as cola calciferol now this can be synthesized in the skin but we need uv light to do it so let's use this example down here on this skin dissection we have where i'm tracing with the probe is the top layer of the skin called the epidermis and this cut edge there the majority of that is actually the second layer down called the dermis but in the epidermis we're gonna see this other compound called seven dehydrocholesterol and when the uv light comes down hits the epidermis that seven dehydrocholesterol within the epidermis gets converted to vitamin d3 and so in theory we could get all the vitamin d3 that we needed from uv exposure we can also get it from our diet granted there's not a ton of foods that are just packed with vitamin d but you find it in like fatty fish or fish oils and also in some of our fortified products like we've fortified a lot of dairy products like milks and even fortified things like orange juice and you can even get it through supplementation but what's crazy to think about is that there are still many people who are deficient with vitamin d3 or cholecalciferol and when you think about it from this perspective say you live in the northern hemisphere and you're one of those people that is exposed to those gnarly winters where the days get shorter and you're inside more and you don't get a ton of sun exposure there are many situations with people where cutaneous synthesis or synthesis of vitamin d in the skin ceases in the winter and so in that case you'd have to get it through the diet or supplementation now another thing that i think is really interesting is if the skin pigment is darker or i should say the darker the skin pigment the longer it takes or the more some exposure is needed to have that conversion process to take place and so we're also seeing risk factors in people who are elderly if they're staying inside more you also don't convert things as efficiently when you're getting older in life i know it's a shame but one of the things to think about is how do i know if i'm deficient because you don't really get symptoms until you get really severely deficient people with mild to moderate deficiency won't even know it and the answer to that to knowing this is you pretty much just got to get tested which gives me a nice shameless segue to mention the sponsor of today's video let's get checked let's get checked provides convenient in-home private testing what they do is they ship these cool little testing kits to you you go online order the test you want gets shipped to your house and then you gather the specimen and ship it back with their prepaid label and they even have medical staff to help go over some of the results with you they have multiple different types of tests things like hormone tests routine blood work std testing and yes of course vitamin d3 testing so if you're interested in getting your vitamin d levels checked or using any of their other amazing tests go to trylgc.com iha vitamin and they'll give you 30 off any of their test kits if you use our coupon code iha30 the link is in the description below so we've got this vitamin d3 or cholecalciferol that was either synthesized in the skin or ingested through our diet through food or supplementation but this is still not considered the activated form of vitamin d3 and so we need to actually have it go through a couple conversions conversion processes and that vitamin d3 whether it was ingested or synthesized in the skin is going to be circulating throughout the blood and it will eventually pass through this amazing organ here called the liver and i'm tracing the bottom portions of the liver here and i'm just reflecting this muscle called the diaphragm that's draped over the liver but once that vitamin d3 again known as cholecalciferol makes it into the liver it will start converting it into something called 25 hydroxycholocalciferol and this is a really cool thing too that happens the liver has this feedback mechanism as the levels of that conversion go up as it's making more 25 hydroxycholocalciferol eventually it's going to shut off conversion even if there's more vitamin d3 and this is a really cool way that the liver regulates the blood levels of that new 25-hydroxycholocalciferol and the excess vitamin d that wasn't converted can get stored in the liver so that kind of creates this mechanism that if you ingest a high amount of vitamin d you can store the extra in that liver and so now you might be thinking okay we've converted it totally active right nope we still have one other place and another conversion step that has to happen so now this 25 hydroxycola calciferol that was converted in the liver from the vitamin d3 is gonna go through the bloodstream again and eventually make it to another set of organs called the kidneys if you take a look at this cool dissection here we've got this frontal section through this kidney and that 25 hydroxycholecalciferol is going to go through the bloodstream here and eventually you can see those blood vessels branching and will eventually make it out to the outer portion of the kidney referred to as the renal cortex and within that renal cortex there's these tiny little tubules called proximal convoluted tubules and inside those tubules under the direction of this hormone called parathyroid hormone the kidney will complete the final conversion into something called one 25 dihydroxycola calciferol the name just keeps getting longer but we're finally to this fully active form of vitamin d so it can start to have its main effects but i do want to go back to that parathyroid hormone that i mentioned if i go to this other dissection here this is a trachea or your windpipe and here is your larynx which we nicknamed your adam's apple so me touching right there is the same as me touching here but i want to reference below the larynx or the atom that adam's apple this structure or a little organ called the thyroid gland and within the thyroid gland you can't really see them but they're embedded in here are the parathyroid glands the parathyroid glands surprise surprise secrete parathyroid hormone and parathyroid hormone is all about regulating calcium levels in the blood so in a way we can kind of think of this parathyroid hormone is telling the kidney hey we need the final conversion of this vitamin d3 to its activated version so we can get more calcium into the bloodstream now you may have heard of this link before between vitamin d3 and calcium and here's exactly what's going on here it's super cool that now converted 125 dihydroxycholocalciferol you know it's kind of fun to say will have an effect on the digestive digestive tract specifically the small intestine but let me reflect this fatty apron called the greater momentum and then you can see the small intestine in the abdominal cavity here now again the small intestine is a hollow tube where food is going to pass through and be absorbed but again keep in mind this is a hollow tube and the inside lining of that tube has the cells that are going to be absorbing nutrients and in this case we're going to be talking calcium that 125 dihydroxycola calciferol causes these intestinal cells to make more calcium binding proteins so it'll bind the calcium and bring it into the body from the things that you've ingested it's super amazing and calcium is so important to body functions bone health is so important with calcium also for proper functioning nervous tissue and muscle tissue calcium is important so you can see why this vitamin d3 going through this activation process so it can absorb this calcium is so important and frankly quite amazing and because it is so amazing i want to take the chance to do a whiteboard session to make sure we're clear on all the steps we just talked about so we've got this area this box representing our skin and inside our skin we have the seven dehydro cholesterol and as the beautiful rays of the sun shine upon our skin that 7-dehydrocholesterol gets converted into vitamin d3 now this is one pathway we can also ingest vitamin d3 through our diet put it in our mouth swallow it down and poof both of these pathways will end up in the same place by going to the liver the vitamin d3 once it's in the liver will get converted into the 25 hydroxycholecalciferol now i did mention there's this cool feedback mechanism with the liver that as the levels of 25 hydroxycola calciferol increase eventually the liver's gonna be like okay let's shut this conversion process from here to here down because we've got enough of this and any of the extra vitamin d3 say we're getting lots of sun exposure or we're ingesting a lot in our diet any of that extra vitamin d3 can be stored in the liver for later conversion to start this process again when needed now once this is converted it will eventually make it down into the kidneys and under the direction of parathyroid gland it secretes parathyroid hormone because again the parathyroid gland is all about regulating calcium levels in the bloodstream we'll get this conversion of 25 hydroxycola calciferol into the 125 dihydroxycola calciferol again totally fun to say and the reason there's cute little stars here is because this is when we've got kind of our activated form here this is where we're going to have some of the magic happen because this will then move into the small intestine and that 125 dihydroxycholocalciferol will increase the number of calcium binding proteins in the cells of the intestine those cells that absorb nutrients and if we increase those proteins we increase the amount of calcium absorption and that's one of our main functions of vitamin d it's all about getting more calcium into the bloodstream and like we said earlier it's pretty amazing and if the effects of vitamin d on calcium aren't amazing enough there's some other potential effects that vitamin d can have throughout your body i say potential because there's a need for more research and more information about how these mechanisms work through vitamin d for example many of your immune cells have the receptor for the activated form of vitamin d so it's thought that it may promote your immune system help with infections as well as inflammation there's also some laboratory studies that show that vitamin d may also inhibit the growth of cancer cells so some pretty cool things that we can look into through this amazing vitamin and let me just come back to this discussion about vitamin d deficiency as we mentioned earlier people with mild to moderate deficiencies often don't know because they're asymptomatic again the only way to know in that situation is through proper testing but as the deficiency becomes more prolonged or more severe then things can start to manifest as symptoms and it most often manifests with the bones and because remember when we have vitamin when we don't have vitamin d we're not going to be able to absorb calcium into the bloodstream so what happens is it gets pulled from the storage in the bone and then bones can become weaker you can get bone pain even easier fractures and sometimes people can develop something called osteomalacia which is the softening of bone tissue ricketts is the kids version of osteomalacia and luckily because of our knowledge of this and our ability to supplement we don't see that as much anymore but again kind of this cool thing to think about with vitamin d and i can get it from the sun if i want to and i just have to mention one thing about that because i'm one of those people who burns pretty easily and so i layer up with sunscreen which will inhibit vitamin d formation because that sunscreen blocks out uv rays and so it's kind of a mean trick i feel like it's like this catch 22 where you're supposed to get some sun exposure but if you get too much you're at risk of skin cancer if you have lighter skin but luckily we've got those supplements thanks for watching our video on vitamin d and jeffrey the skeleton as you haven't noticed is extremely concerned about bone health and he thinks you should be too so if you're interested in testing your vitamin d levels be sure to check out that link in the description below with today's sponsor let's get checked and i'll give you guys 30 off the vitamin d test as well as the other tests that they offer liking and subscribing definitely helps the channel so we appreciate any of that and we've got that quiz question that you can answer in the comments below and i think i've covered everything so we'll see in the next video [Music] [Music] you