It feels a little paradoxical to be adding this blog while the temperature is scheduled to hit the mid 80s today, however the weather forecast is calling for a temperature cliff at the end of the week, and my Windows automatic photo update posted a beautiful snowy landscape upon firing my machine this morning. I take that as a sign from the universe that it's time to talk about a topic that will very soon affect us all.
The topic of vitamin D levels in health and disease has waned a little bit in popularity since its peak of research around 2010, although it did enjoy a resurgence during the Covid pandemic. The research has really been all over the map for laypeople, and even at times confusing for healthcare professionals, until you dig a little bit deeper into the details of the study such as the type of biomarker measured, the target population, etc.
I recently polished up on the latest research and recommendation from a couple of pretty good trusted nutritional sources to see what a commonsense consensus would be. Here are my highlighted suggestions:
1st of all, vitamin D metabolism is extremely variable among different people so generic recommendations about intake are only going to go so far. Ideally you should get your vitamin D level tested. It's typically lowest in the spring, and highest at the end of the summer. This is assuming that humans follow an ancestral pattern of having outdoors skin exposure for vitamin D manufacturing for the summer, which is not always true of our modern lifestyle and individual lives. I recommend getting it tested at both of these peaks. Testing can be done through a variety of manners, including traditional testing through primary care, through Labcorp/Quest direct, or through home kits using blood spot finger prick method. (It's beyond this blog to talk about resources, but patients can contact the office and schedule a consult for that separately).
Vitamin D absorption is impacted by digestive issues especially along the biliary tree since vitamin D is a fat-soluble vitamin, as well as medications that impact lipid absorption and metabolism (especially certain cholesterol medications). Vitamin D need is also increased by certain illnesses. So you really need to look at your own individual factors when trying to eyeball your needs.
As far as ideal blood levels, you'll see different schools of thoughts. Some outfits recommending very high levels of vitamin D3 above 50 and sometimes close to 80, and some people making much lower recommendations. Looking at the more recent research I think the average population does best between 30 and 50. This would be in line with what we have historically known of traditional human population with levels never exceeding 46 with whole foods diet and outdoor sun exposure. However there are subpopulation of peoples with special health needs, especially autoimmune, that may do better with a therapeutic goal above 50. However those people should always be working with a healthcare professional to ensure that those high levels of vitamin D are not causing secondary problems.
Vitamin D is part of a group of fat-soluble vitamins that are finally regulated as a whole, and depend on each other for the proper management of calcium deposition in bone and soft tissues. Probably the strongest recommendation update I am pushing forward now would be to not routinely supplement vitamin D alone, but rather look at a minimum combination of vitamin D3/K2/A in the right ratios. This will prevent some unwanted effects of over dominant vitamin D3 among fat-soluble vitamin, which could negatively impact the deposition of calcium into soft tissues rather than bone. This is especially true in patients with cardiovascular disease and osteoporosis, and with patients who have to limits the intake of dairy products (which tends to provide the vitamin K2). Professional brands of nutritional supplements have started reformulating their fat-soluble vitamins along those lines with several good options both in gel caps and liquid forms.
