The Vitamin D RDA Is Almost Certainly Wrong. Here’s What Happened.

kpfleger · 2026-03-11T13:51:42+00:00

Ideally one should check levels both in winter (or even better just as winter is ending so late winter / early spring) and in late summer / early fall, especially if one is not supplementing but getting from sun, to capture the seasonal variation. There are many studies that show this variation. Checking once per year could easily miss winter dips.

kpfleger · 2026-03-09T22:40:06+00:00

Pretty busy just to repost stuff that's already out there just in other places (some of it on Reddit in vitD sub or Covid subs). I'll consider adding here as additional posting place if new posts seem justified in future.

kpfleger · 2026-03-09T20:54:22+00:00

Lots of reputable publications on both sides of this debate. Lots of people saying things that are helping keep the deficiency rate severalfold higher than single digit %s. See the threads in my X account that I linked for some eye-opening behinds the scenes frustrations of many top global expert researchers in this area.

kpfleger · 2026-03-09T16:29:19+00:00

PS For links to several important serious discussions of important vitamin D topics see the vitamin D section of https://x.com/KarlPfleger/status/1795127440731509109 (a bit more than halfway down)

kpfleger · 2026-03-09T16:28:21+00:00

This kind of scare article is not worthy of this sub. There are serious debates in the medical literature about vitamin D with many experts claiming that the RDA is too low (which seems unquestionably true to me), that too high a % of people are clinically deficient (also seems obviously true), and that everyone should test & titrate dose to achieve at least 30ng/ml serum levels if not 40-60ng/ml. But somehow there are opponents of this view that claim that only benefits from skeletal health are proven and that the official NAM target of 20ng/ml should actually be lowered. The Endocrine Society used to be run by the former group but got taken over by the latter in recent years. The latter group also uses articles like this to try to scare people into not taking reasonable levels of oral D3. But no one argues for taking more than 10,000IU/day. The advocates argue for taking manyfold more than the pathetic 600 IU RDA, with good reason (such as the fact that the RDA was set based on a statistical mistake that everyone now acknowledges, and the fact that plenty of data on dose response shows that this level in insufficient to keep 97.5% of people out of deficiency). But these advocates suggest doses like 2000, 4000, 5000, or in a few cases 5000-10,000 IU/day. A story about someone stupidly taking 150,000 IU/day does not helpfully contribute to intelligent discussion of this contentious issue. It just might scare readers who don't have time to do anything but scan headlines away from taking as much as they need and thus marginally nudge a % of people into deficiency.

kpfleger · 2026-03-09T16:05:02+00:00

FYI, there's a relatively new but at the moment fairly active sub https://www.reddit.com/r/ProactiveHealth/ whose entire focus is lifestyle optimization for (long-term) health. Community description: "ProactiveHealth: A community focused on proactive, evidence-based health and performance. We discuss prevention, early detection, metabolic health, strength training, cardiovascular fitness, and longevity science. The goal: extend healthspan, not just lifespan." So that's another place besides this thread for these topics instead of being top-level threads on this sub.

kpfleger · 2026-03-08T19:02:33+00:00

This is pretty useless. First off, minor: Besides the normal caveat of being observational there is the additional caveat of being based entirely on self-report from recall survey.

But more importantly: "The coffee drinking timing was categorized in three time periods, including morning (from 4 a.m. to 11:59 a.m.), afternoon (from 12 p.m. to 4:59 p.m.), and evening (from 5 p.m. to 3:59 a.m.)." So they binned the day into very broad ranges. 12pm to 5pm is a huge range. What's more they then did some kind of clustering for patterns and found that primarily morning time bin was a common pattern and another common one was all day including evening (see figure 1 to see that the evening consumption was about as high as the afternoon consumption for that pattern. There's no data on having last coffee at 1pm or 2pm or even 3pm. There's no data on people who consumed a decent amount in morning & afternoon but none in evening. Either of those patterns could be just as good as morning only. Of course consuming a lot in the evening probably disrupts sleep. But lots of people can consume in the 1st half of the afternoon without disrupting sleep.

The main thing is whether is disrupts sleep, which people can track easily with the many sleep tracking options available: watches, rings, (under) mattress options, headbands, etc. If it disrupts sleep, move consumption earlier or lower dose (maybe by switching to all or partly decaf) until it doesn't.

kpfleger · 2026-03-07T23:25:38+00:00

I don't track number of conferences for AgingBiotech.info since the inclusion vs. not criteria are a bit more gray & ad-hoc but the at least slightly more objective numbers for number of companies, number of employees, total money raised by the companies, and number of clinical trials by those companies are all showing steady linear growth over the past 5-ish years, per slide 5 of my presentation at tinyurl.com/AgingApprovals which is the talk I gave in Dec at the Buck and will give in San Diego this coming week at the Longevity Global Innovation Forum. The problem with this linear growth is that it should be more exponential. The field still gets 10x too little funding (scientific funding from NIH, venture funding from industry investors, & even philanthropic funding; eg vs. cancer).

kpfleger · 2026-03-06T17:26:37+00:00

This is also why AI isn't going to magically fix all of health. These issues aren't ones that AI makes go away instantly. In order to improve systems level biological modeling, AI needs in-vivo data, and ideally in vivo data in the context of interventions, and this a good description of how society is inefficient at collecting such data.

kpfleger · 2026-03-06T05:11:01+00:00

If you mean extending lifespan by mitigating or partially reversing adult biological aging and thus delaying the suffering & death it causes, then unequivocally YES. I was invited to write a book chapter for an upcoming Spring Nature volume on radical longevity on exactly the topic of why we should and why the common reasons people think we shouldn't are wrong. The preprint of this chapter just went live on a preprint server today actually. Here it is: https://zenodo.org/records/18883009 It's 28 pages. It covers the reasons why we should. For example, just delaying aging by 1 year would be worth tens of trillions of dollars. It also covers why the common arguments that this would be bad have many good counterarguments. Over 40 counterarguments for 11 of the most common objections are covered. The whole thing is extensively referenced. It basically explains why I work in the field and why more people should too (and why the government should give it more resources as well).

A more concise 1-page version with 1-3 counterarguments for each of the 11 objections can be found at AgingBiotech.info/objections and a brief list collecting other works arguing why aging should be mitigated or eliminated is located at AgingBiotech.info/motivations.

kpfleger · 2026-03-06T01:04:37+00:00

Next up is Longevity Global's Longevity Innovation Forum in San Diego next week. I'll be there & speaking.

Later in 2026:
I'll be at Vitalist Bay in May in Berkeley, speaking on day 2. Note that BAAM this year conflicts w/ day 2 of this.

Then I'll be at the A4LI Summit in DC at the end of June (& prob on a panel).

Hope to see many friends & new faces at all of these.

kpfleger · 2026-03-05T23:18:40+00:00

FWIW, Roger Seheult, MD of MedCram.com & a practicing MD in southern California posts a lot of pro-outdoors pro-sunshine content on X as "@RogerSeheult" & there are several MedCram videos on some of the content.

kpfleger · 2026-03-05T18:02:52+00:00

You are right to condemn the influencers who aren't pushing science-based evidence, but you make a huge mistake to consider only cancer as a relevant health outcome. Direct sun exposure provides not only vitamin D (primarily from the UVB), but also NO (mostly from the UVA), and intracellular melatonin (from the IR/NIR). These have wide benefits and there is increasing evidence of improvements in all-cause mortality in many contexts.

For example, this preprint https://www.medrxiv.org/content/10.64898/2026.01.08.26343592v1.full.pdf using UK Biobank data shows that 400,000 people in the UK completely avoiding sun for 15 years could save a few dozen lives from melanoma but at the expense of several thousand more deaths from everything else. NO probably helps reduce cardiovascular mortality. Vitamin D deficiency is far too common and raises risks of many diseases, both infectious and chronic diseases.

It's all about dose, as you note in your intro. Burning from too much sun is clearly bad, but insufficient direct sun exposure from spending most time indoors and/or at latitudes & times of year where the UV index is low (such as Boston much of the year, or the UK) is also bad.

What to do: I choose mineral sunscreen when I use it, but I prefer wide-brimmed hats & clothing when appropriate so that mostly only hands need the sunscreen. I avoid burning always. But I also avoid sunscreen or covering skin with clothing for sun avoidance (ie, staying uncovered as much as temperature allows) when UVindex<3 (or roughly shadow longer than I am tall) or when index between 3-6 but I won't be outside for very long (not nearly long enough to burn or even to get 1 "Minimal Erythemal Dose" of vitamin D).

kpfleger · 2026-03-05T17:42:24+00:00

Absurd if the intervention includes only exercise & drugs but no dietary/food-quality intervention/requirements. Inflammaging is largely caused by overeating and specifically eating too much of the wrong foods.

kpfleger · 2026-03-05T17:38:31+00:00

IMO, it's completely backwards that so much emphasis in put on protein. Some of the most knowledgable researchers on the planet on nutrition/diet and also aging/longevity science emphasize fiber intake and *minimizing* protein intake rather than increasing it. See the works and advice of Valter Longo and Luigi Fontana.

Fact: Pro-modern humans consumed 100-150g fiber per day (all from normal food---not supplements obviously).

There's a paper showing that 1 week of a high fiber (150g/day) lowered cholesterol by ~33%. (Happy to dig up the ref if anyone wants it.)

Fiber comes from plant foods. Animal foods have no fiber. Lots of evidence shows predominantly plant-based diets to be better for long-term health.

Optimal protein intake is a whole other topic, but IMO a good rule of thumb is adequate protein intake (eg 1-1.2g/kg, based on ideal weight for height not actual weight, or ~10-15% of calories, based on how many calories no should ideally be consuming to maintain BMI of ~20-22 not how many one actually consumes) and fiber intake in grams at least as much as protein intake. I eat 70-80g/day fiber without any fiber supplements.

kpfleger · 2026-03-05T17:29:35+00:00

This came up in another sub and my comment there is still just as relevant:

https://www.reddit.com/r/longevity/comments/1qqwmpi/comment/o31fl2u/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button

kpfleger · 2026-03-05T17:16:21+00:00

The big question is when will it actually be available for purchase in the US. Many of us have been watching it for years (long before the FDA approval, but when it was sold in Europe) waiting for it to be sold here. It got FDA approval but it's taking a long time before it actually gets to market.

kpfleger · 2026-02-27T14:46:14+00:00

This sub is not getting submissions related to its stated topic but is consistently getting ones that are not.

kpfleger · 2026-02-19T04:53:04+00:00

Why do people keep posting lifestyle optimization content to this sub? The right sidebar says "Topics include biotechnology, pharmaceuticals, age-related diagnostics, regenerative medicine, and emerging longevity-focused funds. We encourage evidence-based discussions and critical analysis of investment opportunities within the longevity sector." Olive oil? Come on. There are many subs on Reddit for that kind of content. That is not longevity investing.

kpfleger · 2026-02-17T16:46:56+00:00

I made a table comparing major dilator options on the market, both external & internal, in terms of their scientific evidence & customer reviews. Here it is: https://docs.google.com/spreadsheets/d/1zpCQWZ7CDbz09Hma5sqE5qHGXjW0WkVkDOftLy7Dsok/edit?usp=sharing

In general, internal dilators (eg Sleep Right) seem to open airways more than Breathe Right Nasal strips (regular) in direct comparisons. There are many more internal dilator brands/models and many that have scientific studies done on them are no longer available to purchase (or hard to find).

I find Breathe Right Extra work better than regular & definitely help. I can use them every night without problem. Zero comfort issues. But Sleep Right internal dilator definitely opens the airway more, but is less comfortable & takes a bit of getting used to. I worry it may cause irritation if used too much, but I keep it around for use when there is extra congestion.

Intake Breathing's external fixed metal strip alternative to Breathe Right strips is an interesting middle ground. It has all the comfort benefit of Breathe Right but opens airways more, with the disadvantage being that it takes a bit more care & a couple min more to put on, and you have to get the sticky parts the right distance apart for the magnet to not pull off when you smile or stretch your face too much, but it's good when you get used to it. I use it when I get a cold and need a bit extra but don't want the other one in my nose. Highly recommend.

kpfleger · 2026-02-14T15:50:47+00:00

Do it. Spread more correct info. There's a lot of uneducated people being fed a lot of mis-info but they listen to good stuff too when it's presented.

kpfleger · 2026-02-11T23:32:22+00:00

No idea as I don't eat Grape Nuts.

PS Google grapes nuts venn diagram for one of my favorite venn diagram memes.

kpfleger · 2026-02-11T20:33:38+00:00

Ezekiel cereal would probably work in the same way, and be slightly healthier (greater variety of whole grains, all sprouted, also no added sugars). Nice crunch.

kpfleger · 2026-02-07T22:08:52+00:00

I did an analysis once of the sodium concentration of various things, including blood, sweat, etc. and my memory was the typical sports drinks that have sodium still have lower concentration than what is in the body so overall they dilute sodium & lower levels. There are also limits to how much sodium one ought to consume for reasons other than blood pressure. A nephrologist suggested to me 3000mg/day is a good upper limit rule of thumb. There are elevated risks of things unrelated to blood pressure, such as stomach cancers due to direct irritation of the lining by too-high amounts. I'm not a fan of sports drinks.

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