Calcium / Vitamin D
March 18, 2023 7:34 AM   Subscribe

Especially for women of a certain age: if you take calcium supplements with added Vitamin D, and a multi-vitamin, do you worry about getting too much vitamin D from the combination?

If so, do you look for a calcium supplement without D? It seems so common to find them made together that I wonder what I'm missing here.
posted by ojocaliente to Health & Fitness (13 answers total) 2 users marked this as a favorite
I looked into this early in the pandemic to see whether I felt I should supplement and if so how much and read a bunch of peer-reviewed articles. Contra internet wisdom, it is very, very difficult to get enough vitamin D to cause problems - we're talking 40,000 IU daily over an extended period, not 10,000 IU instead of 4000. The case studies on vitamin D overuse that caused health problems all had some kind of weird factor - someone was super-supplementing, also drank a very high volume of super-D vitamin drinks every day and got a lot of sun on vacation PLUS had a kidney abnormality - that was one that I remember.

Further, the 4000 IU thing is calculated based on a standard weight - for overweight/obese people 7000-8000 IU is actually a good dose.

It is very, very unlikely that a standard vitamin and a standard supplement are going to cause you any problems - the ones I see have ~2000 IU in the vitamin and ~4000 IU in the supplement, so you're really in a very normal range. I myself don't hesitate to take ~8000 IU daily since I'm fat and honestly wouldn't even worry about anything up to 10,000 IU.
posted by Frowner at 7:48 AM on March 18 [13 favorites]

I did a lot of looking into this also like Frowner and all I read agrees with them. Want to also add that Magnesium is critical in the body's absorbing of Vitamin D (ncbi citation) so you'll probably want to supplement that too with anything but Magnesium Oxide. I use Magnesium Glycinate.

relevant text from what I linked: Magnesium assists in the activation of vitamin D, which helps regulate calcium and phosphate homeostasis to influence the growth and maintenance of bones. All of the enzymes that metabolize vitamin D seem to require magnesium, which acts as a cofactor in the enzymatic reactions in the liver and kidneys.

I take 5,000 IU a day, especially in winter, sometimes I pop a 2nd 5,000 pill.
posted by OnTheLastCastle at 8:13 AM on March 18

You can get a blood test to determine your vitamin D levels. This is a common and simple test. It will give you a better answer to your question than comparing to what other people do.
posted by heatherlogan at 8:42 AM on March 18 [2 favorites]

You can get a blood test to determine your vitamin D levels. This is a common and simple test.

... and the doctor won't think you're asking something weird if you ask about getting tested for your vitamin D levels, even if they turn out to be normal.
posted by aniola at 9:26 AM on March 18

And if the blood test shows you’re low they also have a simple injection to top you up with Vit D.
posted by koahiatamadl at 9:51 AM on March 18

I’ve been prescribed 50,000 units of vitamin D to take once a week, Dr wasn’t worried about taking too much.
posted by lydhre at 10:02 AM on March 18

47 year old cis woman reporting in: I have a severe D deficiency--I take 50K once a week for 6 weeks, then 5K per day for a few months until my levels go back down to 6-10, then back on the 50K train to get them back up to 35. Rinse, repeat. On top of that I drink a bunch of stuff with various levels of D fortification (mostly plant milks and an occasional juice) and my doctor has never been concerned, even when I'm on the 50K weekly dose.

Concur with everyone recommending adding a D test to your regular bloodwork if that's not already being done (check your GP portal if you have one)--it's good to know what your base levels are when supplementing. (On the advice of my doctor I don't take a multi--they recommend I take specific supplements to address specific issues due to QC issues with multi-vitamins, so I take prescription D for a deficiency and B12 because I am vegan.)
posted by MagnificentVacuum at 12:19 PM on March 18 [1 favorite]

The whole topic of how much Vitamin D we could or should get from the sun, is subject to all kinds of debates and “what ifs” - but I do recall (I think from here) that our bodies can produce about 10,000 IU in a 30 minute sunbathe. Setting aside skin cancer risks for a moment - that is quite a lot from a natural source - any maybe something to consider when asking “how much is too much”
posted by rongorongo at 1:36 PM on March 18

Vitamin D testing is an unnecessary medical test. Multi-vitamins and calcium supplements, when combined, are unlikely to give you over 4,000 IU. It’s safe to take.
posted by shock muppet at 3:01 PM on March 18 [2 favorites]

I think the bigger risk is taking a calcium supplement, which has been linked with cardiovascular outcomes.

I, too, am a woman of a certain age and have been aiming to get my calcium from food sources. Takes a bit of tracking at first but it's definitely doable.
posted by lulu68 at 3:46 PM on March 18

I don’t take calcium because I read a study that found it builds up in arteries. Have also read that in addition to needing to take magnesium with vitamin D, K2 is needed to help prevent arteries from getting calcified.
posted by cotton dress sock at 8:10 PM on March 18

I read an interesting article a year or two ago, about a man who made a supplement that was basically vitamin D. It had a ridiculous amount in it, and he outsourced the production to a friend who screwed up and made it a lot stronger.
Being a great believer in his own product he took more than his own recommended dose, and he got sick. Obviously the problem was vitamin D deficiency, so he started taking ten and twenty times the dosage.
The article said that the person who investigated the matter estimated he was taking eight million units a day for weeks, and he was quite sick with a variety of strange symptoms.
Once he stopped taking it he improved and was better in about four days.
Vitamin D is something your body makes and can handle. The latest report I've read came out of Finland and suggested that a good dose would be 11,000 units a day.
I wouldn't worry about getting too much.
posted by AugustusCrunch at 10:59 PM on March 18

Calcium is constipating without magnesium (usually 2:1). And as mentioned already, you need K2 so the calcium doesn’t block your arteries. A new study looked at the impact of Vitamin D on dementia. It showed a 40% reduction in dementia among study participants.
posted by strasbourg at 1:44 PM on March 19

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