T Nation

Can Lots of a Nutrient Interfere With Another?

We all know that there’s a limit to how much of a given nutrient the body can absorb at once. We also know that some nutrients interfere with the efficacy of other nutrients (e.g. magnesium/calcium).

But is there a combined limit to how much of ALL nutrients the body can absorb at once? For example, if I were to take 10 multivitamins (which I won’t) at the same time as 5mg creatine, would the multivitamins “monopolize” (for lack of a better word) my uptake processes and inhibit uptake of the creatine?

To be honest, I don’t see myself creating any conditions in which this would be a concern, but the question popped into my mind and I got curious…

Of course there is, and it’s a pretty bad idea to do this. Check this out:


Basically, megadoses of vitamins can cause vitamin toxicity and the harmful effects depend on what vitamin you had too much of. I don’t think the vitamins would necessarily inhibit the body from metabolizing creatine or food or anything else though, but I am not a doctor.

Edit: To better answer the question, I found a couple more links.


"Combining supplements will not normally interfere with the way they work and in some cases may be beneficial. However, certain supplements may interact with each other, for example, there is competition within the gut for the absorption of different minerals and a large dose of one might decrease the absorption of another or cause excessive absorption of another. Generally speaking though, this is not a problem. Take vitamin D and calcium for instance. No matter how much calcium you take, it will not be anywhere as beneficial as if you took a moderate amount of both vitamin D and calcium together. "

And then from:

“Because of the demand that large doses of creatine monohydrate powder, with its limited solubility, place on the need for hydrochloric acid in the stomach, there is a risk of producing an HCL deficiency state or the presentation of Achloryhdria. In addition to being involved in protein digestion, hydrochloric acid serves as a potent bactericidal agent and plays a key role in the absorption of vitamins and minerals, and in particular, vitamin B12 and the prevention of anemia. A deficiency of HCL resulting from excessive creatine monohydrate powder supplementation may also cause such symptoms as heartburn (burning sensation in the epigastrum), flatulence and diarrhea.”

So, yes, they could definitely interfere with each other, but we may need a biochemist to explain what exactly will happen :wink:

Thanks for the links, Carnak. I’m not so worried about toxicity, since as I noted, I don’t have any intention of actually creating these conditions. However, those two links you provided do suggest the possibility of uptake interference when “large doses” of certain nutrients are taken.

Unfortunately, neither of them gives any indication of what the contraindicated doses might be. I expect normal doses (e.g. 1 multivitamin, 5g creatine, and 1g/lb bodyweight of protein daily) don’t come anywhere close, but I don’t have any scientific basis for this statement.

Your question is similar to one I’ve had for quite a while regarding how supplemental vitamins effect or work in addition to what we get with our normal food intake. Is it bad to take a multivitamin if I eat a very well balanced diet that gets me most or all of my nutrients? Like could I poison myself by eating too much broccoli or something? I would think most likely not.

I think you’re probably right that a single dose of say a multivitamin isn’t going to overload the system. I know that they stay well under the daily thresholds for all the vitamins.

It doesn’t hurt to think about this stuff though since a lot of the other supplements we take have added vitamins/minerals. My fish oil for example has vitamin E added. I had to check to make sure the 6g I wanted to take weren’t going to poison me.