A bit of an odd topic this week, but one I often hear about from fellow climbers. While the question of magnesium and poop quality isn’t directly relevant to climbing, one of the bigger purposes of this site is to dispel the misinformation flooding the internet and provide a credible source for accurate information.
So does magnesium help you poop, or improve your poop quality or frequency in any way? As the article title states outright, the answer is no! But, there is a rational reason for why it’s such a common belief, which is because high-dose magnesium is a potent laxative.
Basically, when magnesium (usually in the form of magnesium citrate or hydroxide) is supplied in extremely large doses—about 2-5 grams, or 5x-12x the RDA—our body has a tough time absorbing all of it (magnesium is not well absorbed even in small amounts; megadoses are extremely poorly absorbed). All that extra magnesium stays in our intestines and subsequently pulls water from our blood to the intestines, increasing the fluidity our stool as well as triggering intestinal motility, both of which cause you to poop (urgently).
This is only an effect of high-dose magnesium, as the amount of magnesium you’d typically get from your diet or even a supplement is far too low to trigger significant osmosis of water to the intestines. And aside from this osmotic laxative effect, magnesium has no known role in defecation, so trying to boost dietary magnesium isn’t going to do anything for your bowel movements.
If You’re Suffering from Poor Bowel Function, What Should You Do Instead?
There are a few possibilities, though a lot depends on the specifics of your situation. Regardless, the following interventions have the greatest overall amount of support:
Fiber: Fiber comes in both soluble (water-absorbing) and insoluble forms. Soluble fibers absorb fluids, increase intestinal transit time, and are often fermentable by our intestinal bacteria—which improves our gut microbiota and could improve poop quality and frequency. Soluble fiber is often called “prebiotic fiber” for this reason: because it’s food for those healthy gut bugs. Insoluble fiber is not fermentable (and also doesn’t absorb water) but adds bulk to your stool, which triggers intestinal motility and thereby decreases transit time.
Though it might seem like these two types of fiber combat each other for effect, they actually work together, and a diet rich in both improves bowel movement frequency and subjective poop quality and could relieve chronic constipation (particularly soluble fiber, in the latter case).
Probiotics: Our gut is home to many species of bacteria (our body actually contains more bacterial cells than human cells), and these gut bacteria perform numerous important roles in the health of our gut. While most people are likely to have adequate gut bacteria, some situations (such as antibiotic use) routinely lead to compromised gut microbiomes that can be remedied by probiotics and some individuals may even benefit from probiotics outside of these situations. Thus, for some people renewing the gut microbiome is key to solving poor bowel function.
Aside from fiber and probiotics, there are no widely supported interventions. If prebiotics and probiotics don’t work, then something more serious may be going on and it’s best to check with a doctor.
What Does This Mean Practically?
Practically speaking, this means your diet should be rich in fibrous foods such as fruits (often a good source of soluble fiber), vegetables (a universally good source of insoluble fiber, and some such as alliums [garlic, onions, etc.] are a great source of soluble), legumes (a great source of both types), and grains (mostly insoluble, but some such as oatmeal are rich in soluble). In fact, vegetarians and vegans have been noted to have greater bowel movement frequency. This isn’t to imply that meat is bad for gut function (it’s not, at least not when consumed in moderate amounts), but rather that populations that consume greater amounts of fibrous foods have better bowel function.
Of course, if you do increase the presence of these foods in your diet, you’ll also happen to get more magnesium—though I can assure you that your diet is almost certainly magnesium-adequate as it is! Win-win.
Hi Brian, funny to run across this because I was thinking of asking you about magnesium, and if there is any evidence that it has any effect on joint function or repair. I broke my shoulder many years ago and that shoulder (and also the elbow of that arm) used to periodically flare up and cause me a ton of pain, to the point where I’d be taking 800 mg or more of ibuprofen just to be able to fall asleep at night. I had visited the doctor very early on when this began and they basically told me it was some form of tendonitis (or bursitis) and all that could be done was take NSAIDs. So anyway, it basically just got worse and worse over the years (it would flare up for a couple weeks at a time and then die down for a few months) and after looking online, I thought I might give Mg a try. It really seemed to help me out a lot. So I’m curious, is there any evidence that actually supports Mg for arthritis or any other kind of joint pain? Or is it one of those anecdotal things where it may help specific people but doesn’t apply to the general population. I also have psoriasis and have always wondered if I have psoriatic arthritis, but that seems to mostly just affect your distal joints. Anyway, thanks for anything else you want to say about Mg!
I’m not aware of any evidence supporting a link between magnesium and our joints, at least not until an individual is so deficient in magnesium that their overall health would be suffering. Magnesium is just one of those nutrients that, for whatever reason, the natural health community has latched onto (I mean, you don’t see them going crazy over manganese or copper)—in general, I take anything I hear about magnesium with a grain of salt!
After reading this and other writings of your, its obvious you have no idea about some things you write about. You are not taking individuals gene make up into account, methalation ect. This is why some supplements work for people and some don’t. Not everyone is the same, yet you seem to think this. Magnesium citrate, malate, and glycinate do wonders for sore muscles and mag oxide does indeed help one “poop”. Milk of magnesia sound familiar, your grandma prob used it for a reason. Just because something is not scientifically documented does not mean lack of proof. If that were the case, new science research would stop.
I clearly mentioned the one way magnesium—often in the form of Milk of Magnesia—helps you poop, which is by acting as an osmotic laxative: When an extremely large amount of magnesium (or any other molecule) enters our digestive tract, our body pushes water into our intestines causing a laxative effective. Very little of this magnesium will be absorbed, and overall body magnesium status has nothing to do with one’s ability to defecate.
As for the rest of the comment, it has little to do with the article, but I’ll address it nonetheless: genetics play very little role (as in there probably is a role, but it’s indiscernible at present) in how well we absorb different types of magnesium supplements, and while genetics will play a role in an individual’s total need for magnesium, it’s accounted for within the RDA, which is set so as to meet the needs of 97.5% of the population. We don’t have any hard data on the magnesium status of any group worldwide, but we do know that the symptoms of magnesium deficiency—that is, a diagnosed case of too-low-for-health magnesium intake—are extremely rare in healthy individuals (because our body tightly controls excretion) and so magnesium deficiency is not considered something the average person should worry about.
SORRY, But you are totally wrong. Magnesium DEFINITELY makes me poop . Same for every woman I know. I have been trying to find a calcium with LOW magnesium precisely for that reason. Most laxatives that I’ve seen have magnesium in them. So where did you get that idea??
Many laxatives have magnesium because it’s an ion that will cause osmotic diarrhea when consumed in large amounts—if you look at the label, they typically contain around 1,200 milligrams of magnesium per serving, which is around 300% of the RDA. Our body can’t absorb that much magnesium, but it will draw water from the intestinal wall via the blood into the intestinal lumen, giving you the urge to poop. Aside from acting in this way, magnesium doesn’t have any effects on our bowels; if your supplement is causing you to need to poop, it’s fully possible it’s because of this effect, but that’s a very different narrative than the idea that low-dose magnesium will somehow improve bowel function.
Magnesium actually helps constipation by relaxing muscles. Depending what causes your constipation it may or may not help but this is what’s in milk of magnesia.
For milk of magnesia, the motile action is osmotic—it pulls water from the blood and the increased liquidity of the stool causes motility. Magnesium has other roles to play in the body, of course, but for the laxative effect it’s not really a physiological action but rather a purely chemical/physical one.
If your body isn’t functioning right you need Magnesium. As n IBS sufferer, I can tell you that “it does help you to get your stool moving”. You must drink alot is alll!!!
I beg to differ. I started taking Magnesium Oxide on January 1. On the 2nd, I had an almost debilitating bowel movement which surprised me because I’d had a constipation bout with my IBS. Five days later I’m still suffering stomach cramps and having to use the bathroom at different times of day. I have severe gas too. I’m still taking the Magnesium and hope this clears up. Otherwise, it will not be tolerable for me.