Should be “under” … sorry.
The RDA for vitamin D is 600 IU, but an 8 oz. glass of milk typically only has around 100 IU of vitamin D, so you’d have to drink six glasses every single day. And many people require a few thousand IUs of vitamin D per day.
Also note that most milk is “fortified” with vitamin D. Seems like it would be easier just take the supplement directly.
My daughter’s doctor discussed this with me more than a decade ago.
He said at the time the recommendations had recently changed and it was due, in part, to skin colour.
If you’re living in a northern latitude (such as NYC) and were olive-skinned or darker there was a risk of vitamin D deficiency, but because those who wrote the recommendations didn’t want to ostracize people, or be seen as being part of a conspiracy, everyone was being recommended supplements.
He then looked at my blonde-haired blue-eyed baby and said “don’t worry about it.”
A couple years later with a new baby in the country one border to the north, and that doctor was concerned about Vitamin D – until Mrs B (then a research PhD, about to become an MD) showed her the underlying research.
If you’re white, you probably get enough Vitamin D by being outside for 15 minutes.
https://www.vitamindcouncil.org/about-vitamin-d/how-do-i-get-the-vitamin-d-my-body-needs/
Here’s the thing surreal … I know that you know how to follow a series of links to find the actual article that is being used to claim something and to actually see if the claim is supported by what the article found.
So let’s follow the links from the one you gave, to their “health matrix” page, to the article that concludes that “daily intake of 1000-2000 IU/day of vitamin D(3) could reduce the incidence of colorectal with minimal risk.” Was it a study that tested supplementation with 1000-200 IU/d of Vitamin D(3) and follow for rates of colorectal cancer?
No.
It was a meta-analysis of studies that looked at serum levels and determined that there was a correlation of colorectal cancer incidence and low serum levels of 25-OH vitamin D.
Yes, clearly established that lowish 25-OH vitamin D is correlated with markers of inflammation and risk for various disease states. Colorectal cancer is associated with gut inflammation and gut inflammation decreases vitamin D absorption. The meta-analysis is also consistent with the conclusion that the low vitamin D results from being in a state of chronic gut inflammation that increases risk of colorectal cancer.
There are biologically plausible mechanisms for the effects that believers believe vitamin D might have. And there are at least as plausible mechanisms for at risk states to result in low 25-OH vitamin D levels.
So no studies have shown positive impacts of vitamin D supplementation on colorectal cancer rates. The studies done have shown no positive impact. Now believers are free to believe that higher dose than studied so far would have positive impact. It “could” be. But there is no convincing evidence there is despite the large numbers who believe, including practicing health professionals.
Maybe someday there will be. Maybe not.
Sorry for multi-posting but another thought comes to mind … some potential harm from the presumption that the vitamin D is causative rather than a marker of something else going on …
Among the people with similar vitamin D intake and similar sun exposure there are some who have normal 25-OH vitamin D levels and some who are low. Those who are low have vitamin D supplements thrown at them, 5000 IU/d or more, and often remain low on retesting, and the response is often to throw more vitamin D at them. Even with large doses of supplements many just barely nudge into the “normal” range
IF the problem is not the vitamin D level, if the vitamin D being low is instead a sign of some other factor that is predisposing to greater risks and to greater ill health, then this mindset is giving a simple knee jerk response, maybe a placebo effect, but facilitates putting off doing something about whatever else might be going on that might be a more significant contributor to the at risk state. Doing something effective about the fundamental problem may cause vitamin D to increase better than vitamin D supplements do.
Also just wondering if there is any data on the this: the active for is 1,25 OH vitamin D - is it perhaps regulated into a narrower range than 25 OH vitamin D is? A person could be low in 25 OH and perfectly normal in 1,25 levels.
I agree, if the only evidence for the vitamin D/colorectal cancer link is based on observational data I would consider this very weak evidence for supplementation.
That said, if I met the clinical guidelines for vitamin D deficiency, I’d take a supplement. It probably won’t do anything to reduce my chances of getting ass cancer but the pills are cheap (a few cents per day), safe (within certain latitude ranges, typical supplement dosages are equivalent to just a few minutes of summer sunlight exposure), and they don’t appear to have any side effects.
I agree, doesn’t seem like the medical establishment knows if vitamin d being low is just another symptom of whatever is actually going on or the actual cause of the issues they associate with it. Guess they are just going with what their best evidence suggests and hoping it works out. Hopefully in 20 years they will have enough data to tell if simply upping vitamin d fixed the issues they are prescribing it for or not. And I get to be a datapoint in that dataset, exciting stuff!
I think the symptoms of low D are better known than they used to be. Certainly my elderly Merck Manual (from 1999) focuses more with infantile and childhood low D pathology than on adult low D. There is no mention of the symptoms of low levels of D in adults beyond those that come with extreme and ongoing low D. There is no mention of the tiredness, depression, muscle aches, feeling of weakness, or skeletal aches that occur as early symptoms of low levels of D.
People are tested more now than they used to be. I’ve been told that doctors here test D3 levels right away if you come with with a complaint of tiredness, weakness, aching, and/or arthritis pain.
ETA: the current version of the Merck manual discusses the symptoms of low D in adults (“Vitamin D deficiency can cause muscle aches, muscle weakness, and bone pain at any age.”) and that people who don’t get enough sunlight are at risk (“Inadequate direct sunlight exposure or sunscreen use and inadequate intake usually occur simultaneously to result in clinical deficiency.”).
Hey, rickets are totes natural!
If that’s the case, then might it be better to just get those few minutes of sunlight exposure? Yes, all else being equal, sun exposure also increases the risk for skin cancer, but all else isn’t equal, and given modern outdoor habits, more sunlight is also likely to mean more exercise, which is definitely something most Americans could use.
Treating clinical “deficiency” is pretty much without dispute and has been for a long time. Defining “deficiency” and the associated label of “insufficiency” is a bit more debatable. “Deficiency” used to less than 10 ng/ml but became 20 sometime over the past decade. And a label of “insufficiency” used to mean 10 to 20 and has become the 20 to 30 range. The two often get conflated and “insufficiency” is usually treated as well.
That under 10 is the level clearly associated with rickets and fracture risk. Remember that 25 OH vitamin D is not active itself. It’s just the raw material that the body activates to keep the active hormone, 1,25 vitamin D, in a very narrow range, and activated locally in certain tissues with uncertain impacts on systemic levels. Under 10 seems to not be enough to reliably allow for that to occur. And it’s pretty accepted that under 20 increases the risk of fractures in the elderly by some slight amount. Treating those under 20 seems advisable.
But note that there really is no “typical” supplement dose used to treat. Some treat with 400 IU added/d, some with 5000 IU/d, some with 50,000 IU/week.
So yes if you find out that you are under 20 being treated is certainly reasonable. Is it reasonable though to test everyone to find those people?
It really is not clear that there are symptoms of “low D” short of rickets. And falsely attributing those problems to low D levels if the low D is actually just an effect of some other issue that is actually casing those problem, rather than addressing those problems … could be an unintended result. But yes people sure are tested lots more now.
It’s not completely clear that a few, even slightly somewhat more than a few, minutes of sunlight exposure per day regularly increases skin cancer risk (no question high dose intermittently does), but your point about what tends to go with it is very valid. Still it was striking to me that those Louisiana runners and triathletes who had inflammation markers also had low vitamin D.
I am quite confident that I do not know. But I am also pretty confident that many who are thinking they do know don’t really know either. My guess remains that inflammation results in low 25 OH vitamin D, possibly merely by more 1,25 OH being used up regulating the inflammation, so more raw material (25 OH) being used to replenish it to its tightly controlled levels, and possibly by impacting the function of the 25 hydroxylase in the liver. We’ll have to revisit in a decade or so …
The Merck Manual disagrees. As stated above, “the current version of the Merck manual discusses the symptoms of low D in adults (“Vitamin D deficiency can cause muscle aches, muscle weakness, and bone pain at any age.”)”
Additionally, muscle aches, weakness, and bone pain are early symptoms of rickets (called osteomalacia or soft bones in adults).
It’s not “additionally” … it is what Merck is likely talking about and why, no, Merck is not disagreeing with that statement.
Yes, rickets, which can manifest with muscle aches, weakness, and bone pain, can be a result of true and severe vitamin D deficiency, and can hit any age. Unlike osteopenia, adult osteomalacia is extremely uncommon in the United States.
That said, yes, there is a clear association of a inflammation in general with lower 25 OH vitamin D levels. The direction of the causality chain is the question.