# Multivitamin absorption **URL:** \ **Category:** In My Humble Opinion\ **Created:** [November 12, 2015, 9:34am UTC](https://boards.straightdope.com/t/multivitamin-absorption/737366 "2015-11-12T09:34:19Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![sara20](https://avatars.discourse-cdn.com/v4/letter/s/e79b87/32.png) [@sara20](https://boards.straightdope.com/u/sara20)\ **Post date:** [November 12, 2015, 9:34am UTC](https://boards.straightdope.com/t/multivitamin-absorption/737366/1 "2015-11-12T09:34:19Z")
I take a centrum multivitamin every day with food, and I was wondering how much of the vitamins are getting absorbed by me? ---
**Author:** ![Shodan](https://avatars.discourse-cdn.com/v4/letter/s/9f8e36/32.png) [@Shodan](https://boards.straightdope.com/u/Shodan)\ **Post date:** [November 12, 2015, 2:23pm UTC](https://boards.straightdope.com/t/multivitamin-absorption/737366/2 "2015-11-12T14:23:27Z")
That’s a pretty broad question. Eating a healthy diet is better than supplements, but supplements don’t hurt and might help in some cases. Taking supplements with food is generally a good idea, although milk somewhat interferes with the absorbtion of iron. Taking more than you need of water-soluble vitamins like B and C doesn’t usually hurt anything - it just gets excreted in your urine. Fat-soluble vitamins like A and D can build up in your fatty tissues, but you have to really overdose on the vitamin (or [eat polar bear li](http://www.google.com/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=4&cad=rja&uact=8&sqi=2&ved=0CCwQFjADahUKEwjegs3diIvJAhXC8CYKHfP2C1A&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC1257872%2Fpdf%2Fbiochemj00974-0009.pdf&usg=AFQjCNH4zBOTqxn8BlGNCwh2iRkv83ARSg&sig2=94M-9kU-G4dI4B02SRPIBg&bvm=bv.107406026,d.eWE)ver) before vitamin toxicity is an issue. The short answer to “how much of the vitamins are being absorbed” is “it doesn’t really matter”. A balanced diet is better than an unbalanced diet with supplements, but an unbalanced diet with supplements is better than an unbalanced diet without supplements. But a balanced diet with supplements is not much better than a balanced diet without supplements. Worrying about what time of day you take your pill or what you take it with is usually not worth the trouble. Personally, I take a generic multi-vitamin with breakfast, and a calcium supplement with vitamin D, because I do a lot of weight-bearing exercise, and live in a northern climate and work indoors, so I don’t get a lot of sunshine, which is needed to produce vitamin D in the body. I am currently taking an iron supplement, because I donated blood a few days ago and want to rebuild my hemoglobin. But I take the vitamins the way many do - it’s just insurance. I am quite aware that I am probably doing no more than vitamin-fortifying my urine. Regards, Shodan ---
**Author:** ![Jackknifed\_Juggernaut](https://avatars.discourse-cdn.com/v4/letter/j/9de053/32.png) [@Jackknifed\_Juggernaut](https://boards.straightdope.com/u/Jackknifed_Juggernaut)\ **Post date:** [November 12, 2015, 3:28pm UTC](https://boards.straightdope.com/t/multivitamin-absorption/737366/3 "2015-11-12T15:28:57Z")
> [@Shodan](#): > > …Eating a healthy diet is better than supplements, but supplements don’t hurt… I know most doctors seem to agree with you, but I’ve read some articles that contradict this. Here’s one: > **[Multivitamins are, at best, a waste of money, Johns Hopkins doctors say](https://hub.jhu.edu/2013/12/17/vitamins-might-be-harmful/)** > > Multivitamins are, at best, a waste of money, JHU doctors say in 'Annals of Internal Medicine' editorial I read a few items on the toxicity of multivitamins a few years ago. I was taking one of those GNC Vitapaks almost daily at the time. I immediately stopped and so far with no ill effects. It’s been about 2 years since I stopped. ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [November 12, 2015, 4:32pm UTC](https://boards.straightdope.com/t/multivitamin-absorption/737366/4 "2015-11-12T16:32:37Z")
Searching “septic tank vitamin” results in hundreds of claims that vitamins end up whole in septic tanks, however I can’t seem to find a primary source for that claim. ---
**Author:** ![GaryM](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garym/32/241_2.png) [@GaryM](https://boards.straightdope.com/u/GaryM)\ **Post date:** [November 12, 2015, 5:10pm UTC](https://boards.straightdope.com/t/multivitamin-absorption/737366/5 "2015-11-12T17:10:27Z")
I have a septic tank and my wife and I take vitamins and calcium. Stand by while I go check the tank! Sorry, not going to look. ---
**Author:** ![Shodan](https://avatars.discourse-cdn.com/v4/letter/s/9f8e36/32.png) [@Shodan](https://boards.straightdope.com/u/Shodan)\ **Post date:** [November 12, 2015, 5:20pm UTC](https://boards.straightdope.com/t/multivitamin-absorption/737366/6 "2015-11-12T17:20:40Z")
> [@Jackknifed\_Juggernaut](#): > > I know most doctors seem to agree with you, but I’ve read some articles that contradict this. Here’s one: > > [Multivitamins are, at best, a waste of money, Johns Hopkins doctors say | Hub](http://hub.jhu.edu/2013/12/17/vitamins-might-be-harmful) > > I read a few items on the toxicity of multivitamins a few years ago. I was taking one of those GNC Vitapaks almost daily at the time. I immediately stopped and so far with no ill effects. It’s been about 2 years since I stopped. To be fair, according to the [label](http://www.gnc.com/graphics/product_images/pGNC1-10516069_gnclabel_pdf.pdf) of one of the Vitapaks it contained massive overdoses of some of the water-soluble vitamins, like C and B-1. As mentioned, this is not likely to do much harm even in high doses (although B-3 in large doses can cause “[niacin flush](http://www.google.com/url?url=http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2779993/&rct=j&frm=1&q=&esrc=s&sa=U&ved=0CE8QFjANahUKEwiOupa7sIvJAhUE2SYKHVMuALQ&usg=AFQjCNEl43hM4anmi7M_U1kjod4Wztwh7Q)”) but it is not quite the same as a daily multivitamin that hits 100% of the RDA. If a little is good, more is not necessarily better, and too much is no better than not enough. And someone is always selling something. Regards, Shodan ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [November 12, 2015, 6:02pm UTC](https://boards.straightdope.com/t/multivitamin-absorption/737366/7 "2015-11-12T18:02:39Z")
[A past thread](http://boards.straightdope.com/sdmb/showthread.php?t=710706) that provided links to studies showing that daily multis are indeed capable of harm and for the typical Western individual more likely to cause harms than goods. My [post#45](http://boards.straightdope.com/sdmb/showpost.php?p=17237749&postcount=45) is most relevant here. That however was not the question. Doubt there is a straightforward answer to it though. Depends on if with food or not, your individual system, the exact preparation, what your state is. Closest to the straightforward answer might be: more above and beyond diet than you very likely need in any case, and not a substitute for real foods at any dose. ---
**Author:** ![Shodan](https://avatars.discourse-cdn.com/v4/letter/s/9f8e36/32.png) [@Shodan](https://boards.straightdope.com/u/Shodan)\ **Post date:** [November 12, 2015, 6:44pm UTC](https://boards.straightdope.com/t/multivitamin-absorption/737366/8 "2015-11-12T18:44:09Z")
> [@DSeid](#): > > [A past thread](http://boards.straightdope.com/sdmb/showthread.php?t=710706) that provided links to studies showing that daily multis are indeed capable of harm and for the typical Western individual more likely to cause harms than goods. My [post#45](http://boards.straightdope.com/sdmb/showpost.php?p=17237749&postcount=45) is most relevant here. I am bound to say that based largely on the post you mention, I switched to a multi-vitamin that did not have iron. I only take the iron supplement after I donate blood, which I do regularly. Mineral absorbtion and their benefits/drawbacks are a separate although related topic to vitamin absorbtion. Regards, Shodan ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [November 12, 2015, 7:16pm UTC](https://boards.straightdope.com/t/multivitamin-absorption/737366/9 "2015-11-12T19:16:27Z")
Yes, one should not heedlessly gobble supplements and vitamins. After a blood test showed I had elevated potassium levels my doc told me to avoid all supplements and salt substitutes containing potassium - good luck finding a multivitamin without potassium. So I take Vitamin D in the winter due to the low sunlight. I eat a lot of fruit, so C is taken care of. Otherwise, I show no signs of needing supplements and would much rather spend my money on actual food. YMMV, of course. ---
**Author:** ![TruCelt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/trucelt/32/523_2.png) [@TruCelt](https://boards.straightdope.com/u/TruCelt)\ **Post date:** [November 12, 2015, 9:37pm UTC](https://boards.straightdope.com/t/multivitamin-absorption/737366/10 "2015-11-12T21:37:50Z")
A good way to get a handle on your dietary vitamin intake is to use the free tracker at [www.cronometer.com](http://www.cronometer.com) . Originally for those who are trying to develop a CRON lifestyle (Calorie Restricted Optimal Nutrition) it is useful to anyone who wants a detailed picture of their dietary intake. I eat fairly well, but have an abnormally slow metabolism. As such, it’s very hard to ingest enough food to keep optimal levels without taking in too many calories. I find the Centrum chewable vitamins very helpful. Four of them equal 100% of most vitamins, so I can tailor the supplement to my food intake for the day. Generally I only need two. But really, my stress level is such that I do anything I can to help my body cope. Maintaining optimal nutrition is just one aspect of that, but it’s easy, cheap and I see no reason not to do it. ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [November 13, 2015, 8:29am UTC](https://boards.straightdope.com/t/multivitamin-absorption/737366/11 "2015-11-13T08:29:21Z")
My strategy: I have a bottle of some generic store-brand multi-vitamin-mineral supplement – the kind with 100% of just about everything, not megadoses of stuff. I break them in half and take one half tablet a day. My theory: I assume I’m getting more-or-less everything I need in my more-or-less reasonable diet. I take that extra half-tablet just to fill in anything I might happen to be missing. ---
**Author:** ![That\_Don\_Guy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/that_don_guy/32/538_2.png) [@That\_Don\_Guy](https://boards.straightdope.com/u/That_Don_Guy)\ **Post date:** [November 13, 2015, 9:39pm UTC](https://boards.straightdope.com/t/multivitamin-absorption/737366/12 "2015-11-13T21:39:52Z")
> [@Jackknifed\_Juggernaut](#): > > I read a few items on the toxicity of multivitamins a few years ago. I was taking one of those GNC Vitapaks almost daily at the time. I immediately stopped and so far with no ill effects. It’s been about 2 years since I stopped. About 20 years ago, I started taking “megavitamins” I got from GNC. About a week into them, I had a pain in one of my kidneys every time I sneezed, and there were bruise marks on my skin where the pains were happening. The pains stopped (and the bruises went away) when I stopped, but even today, if I take something like a Centrum, the pain comes back, albeit not nearly as bad and without the visible bruises.