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Comment by krastanov | Hacker News Reader

I have noticed the significant uptick in vitamin D articles. It is probably related to the current pandemic, but can someone with the necessary background explain (and direct to explanations) how important vitamin D is in the grand scheme of things. Does its common deficiency compare with the effect of the typical over consumption of sugars or with the effects of a typical sedentary live?

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I would have to look it up but there were studies finding that a vitamin D deficiency correlated with a higher risk of developing severe cases of Covid-19.

If there is a causal relationship (i.e. better vitamin D levels will reduce the risk) or if this is because of a confounding factor is not known, as far as I know. A confounding factor could e.g. be a more healthy lifestyle in general. Running outdoors will expose people to more sunlight which leads to more vitamin D production - while couch potatoes with an unhealthy lifestyle would get less sunlight and lower vitamin D levels. In this case, supplementing vitamin D might have little to no effect - because all it would do is raising the vitamin D levels while the person still would have bad health because of their lifestyle.

Here's a simple search for these keywords: https://www.bing.com/search?q=covid+19+severity+vitamin+d

As background, because healthy people tend to get out more there's always going to be a correlation between health and vitamin D levels. That means that most media articles gushing about a new vitamin D to health link are almost always worth ignoring. However, in the case of the Covid-19/vitamin D negative correlation it was much bigger than you'd expect by that route. Then someone actually did a randomized controlled trial and found a protective effect.

I think in that case it was still a beneficial affect due to the marginal person in the study having a vitamin d deficiency and thus diminished immune response. Give them a proper dose of vitamin d and their immune system rebounds and pretty rapidly.

We can deal with this issue by running a randomized trial. Here's a link to a randomized trial [1] that establishes a clear causational relationship between Vitamin D and reduced admittance into the ICU.

[1] https://www.sciencedirect.com/science/article/pii/S096007602...

It's funny how we're only getting this Vitamin D info just now.

Do you know when FearDept first mentioned it on their Twitter account?

2020-04-09.

https://threader.app/thread/1248430652409569287

https://twitter.com/@FearDept/status/1248430652409569287

Here's a link to the study [1]. It is a randomized trial so there's clear evidence that there is a causational link. Specifically, Vitamin D reduces the risk of needing ICU treatment.

[1] https://www.sciencedirect.com/science/article/pii/S096007602...

I'm going to go with an unconventional response. Probably important enough that humans mutated relatively quickly [1] towards low pigmentation/melanin when they migrated towards northern latitudes. This lighter pigmentation must have had provided a significant advantage in the northern latitudes.

[1] https://www.smithsonianmag.com/smart-news/heres-how-european...

> I have noticed the significant uptick in vitamin D articles.

Over here in Canada, this happens every October and every February. In other words, when the sun starts to fade from our days and when the winter is the coldest. This probably happen in most nordic countries.

You are however right, it seems like the spike started earlier this year. Probably because of Covid.

https://trends.google.com/trends/explore?date=all&geo=CA&q=v...

I’ve heard it’s more like no one gets enough from the sun as that would take practically being naked in the sun all day everyday. Much more exposure than the typical “just be outside for 20 minutes.”

It is also supplemented in many “functional foods” - but they tend to be dairy products and nondairy products haven’t followed the trend.

I’ve internalized it as a good reason to have blood work done no less than every 1-2 years for blood levels across the board.

> that would take practically being naked in the sun all day everyday.

We are savanna animals after all.

https://news.uchicago.edu/story/vitamin-d-deficiency-may-rai...

Here's a good review that helps explain what Vitamin D does and why it's much more important than previously thought for the immune system:

Hewison, Martin. “An Update on Vitamin D and Human Immunity.” Clinical Endocrinology 76, no. 3 (March 2012): 315–25. https://doi.org/10.1111/j.1365-2265.2011.04261.x.

Vitamin D supplementation has previously been shown (via RCT) to improve outcomes for acute respiratory tract infections:

Martineau, Adrian R., David A. Jolliffe, Richard L. Hooper, Lauren Greenberg, John F. Aloia, Peter Bergman, Gal Dubnov-Raz, et al. “Vitamin D Supplementation to Prevent Acute Respiratory Tract Infections: Systematic Review and Meta-Analysis of Individual Participant Data.” BMJ 356 (February 15, 2017). https://doi.org/10.1136/bmj.i6583.

So of course it's no surprise that there's been interest/emerging evidence of it's role w/ COVID-19:

Daneshkhah, Ali, Adam Eshein, Hariharan Subramanian, Hemant Kumar Roy, and Vadim Backman. “The Role of Vitamin D in Suppressing Cytokine Storm in COVID-19 Patients and Associated Mortality.” Preprint. Infectious Diseases (except HIV/AIDS), April 10, 2020. https://doi.org/10.1101/2020.04.08.20058578.

Grant, William B., Henry Lahore, Sharon L. McDonnell, Carole A. Baggerly, Christine B. French, Jennifer L. Aliano, and Harjit P. Bhattoa. “Evidence That Vitamin D Supplementation Could Reduce Risk of Influenza and COVID-19 Infections and Deaths.” Nutrients 12, no. 4 (April 2020): 988. https://doi.org/10.3390/nu12040988.

Meltzer, David O., Thomas J. Best, Hui Zhang, Tamara Vokes, Vineet Arora, and Julian Solway. “Association of Vitamin D Status and Other Clinical Characteristics With COVID-19 Test Results.” JAMA Network Open 3, no. 9 (September 1, 2020): e2019722–e2019722. https://doi.org/10.1001/jamanetworkopen.2020.19722.

As for Vitamin D deficiency, it's pretty common. About 40%: "The National Health and Nutrition Examination Survey 2005 to 2006 data were analyzed for vitamin D levels in adult participants (N = 4495). Vitamin D deficiency was defined as a serum 25-hydroxyvitamin D concentrations ≤20 ng/mL (50 nmol/L). The overall prevalence rate of vitamin D deficiency was 41.6%, with the highest rate seen in blacks (82.1%), followed by Hispanics (69.2%)."

Forrest, Kimberly Y. Z., and Wendy L. Stuhldreher. “Prevalence and Correlates of Vitamin D Deficiency in US Adults.” Nutrition Research (New York, N.Y.) 31, no. 1 (January 2011): 48–54. https://doi.org/10.1016/j.nutres.2010.12.001.

That's about the same in the US as the current adult obesity rate (BMI >30) and estimated amount of NAFLD. Of course there's a fair bit of overlap between poor metabolic health and low Vitamin D levels, but the exact relationship is still not completely understood. Here's a recent discussion that's pretty readable:

Vranić, Luka, Ivana Mikolašević, and Sandra Milić. “Vitamin D Deficiency: Consequence or Cause of Obesity?” Medicina 55, no. 9 (August 28, 2019). https://doi.org/10.3390/medicina55090541.

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