Vitamin D

Hey everybody, guess what time it is? It’s time for me to tell you that this blog is for entertainment purposes only. Anything I talk about should not be considered personal medial advice, or general medical advice. Please talk with your doctor before doing ANYTHING!

So let’s say it’s the middle of January, and you live in some town in the northeastern US. You’re feeling a little “off”. Nothing serious, just a little tired, so you schedule a visit to see your primary doctor. Your doctor orders a bunch of lab work, and lo and behold, your Vitamin D level is low! What does this mean? What does this mean for your health? What can you do about it?

Unless your doctor suspects some deeper metabolic or endocrine issue, chances are he/she ordered a 25-hydroxyvitamin D level. This is a basic screen and (maybe) a reasonable guide of vitamin D levels in an otherwise healthy person. We take in vitamin D2 or D3 from supplements and dietary sources, and enzymes in the liver convert them into 25-hydroxyvitamin D, which is a storage form of vitamin D floating around in the blood until it is converted by enzymes in the kidneys to 1,25-dihydroxyvitamin D, the active form. There is another more magical (and arguably more important) pathway- photosynthesis! That’s right, it’s not just for plants. Exposing our skin to sunlight allows for the conversion of cholesterol into vitamin D3, which is then liverized and kidney-ized.

“So that’s great and all, but what does this mean for me?!,” you might ask. Turns out Vitamin D is kind of an “everything vitamin”. It facilitates absorption of calcium in the intestine, and helps regulate calcium and phosphorus levels in the blood. This makes it important for maintaining healthy bones. Rickets, shockingly on the rise in the 21st century, is specifically linked to vitamin D deficiency, and vitamin D is also important for preventing osteoporosis. Given it’s role in calcium regulation it is vital to muscle and nervous system functions. For example, that twitchy eyelid thing you get when you’re sleep-deprived might happen more frequently if you have a little vitamin D deficiency.

Vitamin D deficiency seems to be a factor in asthma attacks (PMID: 34462708), development of food allergies in babies (PMID: 33014916), and immune function (PMID: 30400332). A study recently published in the Emergency Medicine Journal (PMID: 35715206) demonstrates an association between vitamin D deficiency and 90 day mortality from sepsis. There are also links to high cholesterol, high blood pressure, and pre-eclampsia.

Now, everyone repeat after me: “Correlation does not equal causation”. But, sometimes it does! Besides, if all it takes is some vitamin D supplementation to ward off assorted badness, sign me up. Unfortunately, it may not be that easy. While supplementation in the form of pills and injections does increase serum 25-hydroxyvitamin D levels, that doesn't always translate to real-world outcomes, like decreased 90 day mortality or reduced severity of asthma attacks. In sepsis, for example, quickly correcting that vitamin D level in the emergency department or ICU does not seem to help. Rather you may need to be tuned up with healthy vitamin D levels before you develop sepsis for it to be of benefit. Dietary sources, as in real food rather than supplements, and sun-synthesized vitamin D are where it’s at.

Regarding sun, there is some bad news for us in northern latitudes. Even if the sun did come out more than once every 10 days, it is not high enough in the sky to deliver the UV rays we need to make vitamin D for several months of the year. The good news is, we can sort of store it. In the summer, we can make hay while the sun shines, so to speak, and build up a surplus to use during the winter. The bonus with making vitamin D is that since it’s made from cholesterol, if your doctor also noted high cholesterol on that panel he ordered, maybe it will go down without the need for drugs and their pesky side effects. The other bonus is that your body knows what it’s doing. It won’t make enough to overdose on vitamin D by standing in the sun. The same goes for vitamin D through food selection. I suppose one could develop vitamin D toxicity from chugging a whole bottle of cod liver oil, but they would probably vomit first. Either way, don’t try it (chugging a whole bottle, that is). Talk to your doctor and read the serving size on the bottle, please. Fatty fish such as salmon and tuna, eggs, beef liver are all great dietary sources of vitamin D.

Taking a vitamin D supplement is a choice you have to make for yourself. This column is not meant to be personal medical advice. It is meant to encourage you to think about the pro’s and con’s of taking a vitamin D supplement, or any supplement for that matter. There is no such thing as a free lunch in Nature. Please talk with your doctor about whether vitamin D supplementation is for you. If they can’t talk to you about it, don’t blame them. They may simply be too bogged down accommodating various mandates (sorry, guidelines) from insurance companies, government agencies, and business administrators to actually have time to talk to their patients. But you may want to find a doctor who can take that time (Hint: this may not be a doctor your insurance will pay for).

In the meantime, spend a little time educating yourself about the medications and supplements you do take, and tests and procedures that your doctor recommends for you. And start taking a daily walk at sunrise!