Do You Really Just Pee Out Nutrients From A Multivitamin?
Are you flushing your money down the toilet (literally) when you take a multivitamin? A common criticism of multivitamins is that the body doesn't absorb the nutrients and immediately passes them from your system via neon-colored urine. Yes, certain vitamins in higher doses change the color of your pee, but that's just chemistry. It's not a sign of poor (or no) absorption.
With a high-quality, bioavailable multivitamin, your body can extract, utilize, and reap the benefits of all the nutrients it provides. So let's take a step back and see how a multivitamin actually works in the body.
A quick reminder of what a multivitamin is
A multivitamin is a dietary supplement formulated to help you meet the daily recommended amounts of vitamins (like C, D, and the B vitamins) and minerals (like magnesium, iron, and calcium). mbg's vice president of scientific affairs Ashley Jordan Ferira, Ph.D., RDN, asserts that all multis should contain a minimum of 20 essential nutrients in bioavailable forms.
"The term multivitamin is used loosely in the industry, from gummies and certain capsule brands with less than 12 nutrients (I consider that a complex, not a multi), to truly complete multivitamin offerings with impressive formulas," explains Ferira.
In addition to serving up a comprehensive array of nutrients, a forward-thinking multi also delivers key plant-derived phytonutrients (like mindbodygreen's ultimate multivitamin+).
These ingredients are packaged together in capsules, tablets, liquids, gummies (though we don't usually recommend these), and powders, making for a convenient solution to help fill any gaps in your diet. And there are gaps. It's estimated that about 40% of Americans fall short of1 the daily recommended needs for eight out of 14 nutrients (including vitamins A, C, D, E, folate, and thiamin).
If multis contain more than what your particular body needs, some nutrients can be peed out.
Many factors influence whether you'll pee out nutrients
While input of nutrients (i.e., from food, beverages, and supplements) versus output of nutrients (e.g., in one's urine) seems like a straightforward equation, it's simply not. As Ferira points out, "This is a nuanced phenomenon. It assumes normal (healthy) GI, liver, and kidney function. Because if you're peeing out electrolyte minerals like calcium and sodium, you'll need to see a doctor."
So what does this equation hang on? The body's ability to maintain balance. "You see, our bodies are all about striking a beautiful homeostasis [balance]. For example, this includes reabsorbing precious electrolyte minerals in the kidneys for use throughout the body every day and excreting metabolites, toxins, and even extra amounts of water-soluble vitamins through waste (urine and feces)," Ferira notes.
And there's a lot of individualization that goes into the equation as well. "The degree to which someone 'pees out' nutrients is dependent on their personalized health status, baseline dietary pattern and nutrient status, gut dynamics, liver health, kidney function, daily supplement routine, and more," concludes Ferira.
What nutrients does the body pee out?
Water-soluble vitamins—including all eight B vitamins (thiamin, riboflavin, niacin, pantothenic acid, B6, biotin, folate, and B12) and vitamin C—are the nutrients most likely to be peed out when taking a multi.
"Water-soluble vitamins must be dissolved in water, and they are readily used by the body. Whatever the body doesn't need during that time is then eliminated via urine," says registered dietitian Maeson Temple, RDN, L.D., CNSC.
And as Ferira shared, a healthy body has a very logical regulation system (aka homeostasis) to keep levels of these vitamins in check. It's able to take what it needs of these water-soluble vitamins and filter out extra left in the blood with urine. For example, extra riboflavin (or vitamin B2) is the culprit of the fluorescent highlighter hue of the urine. "It does not mean the body did not absorb the vitamin," Temple assures.
It's important to get enough water-soluble vitamins daily, as the body doesn't have internal stores to rely on if your intake is down one day.
Fat-soluble vitamins, on the other hand, can be stored in the body for later use. This includes vitamins A, D, E, and K, which are not excreted in urine. In fact, "fat-soluble vitamins are wonderfully preserved through a fancy homeostatic system in the body known as enterohepatic recirculation," Ferira adds.
A note on minerals
A multi contains more than just vitamins. Minerals can both be used right away by the body or stored for later (e.g., calcium and magnesium in bones). And then if there's still excess in the bloodstream, they can also be excreted.
How do you know if you're absorbing nutrients from a multivitamin?
So now that we established that urine is not an indicator of what nutrients are absorbed or retained from a multi, how can you tell yours is actually working?
"Consistency and quality of supplements are key for reaping the full benefits of these products," says Temple. "Rarely do people feel instantly better after one day or even after a couple of weeks of taking vitamins."
But over time, you may notice changes in energy, brain power, and even in your hair, nails, and skin. "These changes could be very subtle or drastic depending on the individual and the state the body was in initially," notes Temple.
The most objective way to see the impact of supplementation is with a blood test. Temple recommends having your labs checked before you start and then several months later to see how key biomarkers change (this is especially helpful for vitamin D, vitamin C, and B12).
"It can take nine to 12 weeks for many of these nutrients to achieve their new steady state, assuming you're taking your multivitamin daily. Knowing where you started from baseline testing is helpful, but be patient and give your multi enough time to work for you," says Ferira.
Are multivitamins worth it?
Multivitamins aren't a replacement for a nutrient-dense, healthful diet. But they are very complementary.
"In addition to helping promote sufficiency for a comprehensive array of essential vitamins and minerals (micronutrients) in the body, a high-quality multi will support a wide range of health functional areas (bones, immunity, vision, beauty, cellular energy, etc.)—from the cells to the tissues and organs of these systems—and key botanicals and bioactives can synergize those health benefits further for overall vitality,"* Ferira shares.
What's more, multivitamins "do a great job at providing a safety net and filling in the gaps for individuals with picky eating preferences, conditions limiting their intake or increasing their nutrient needs, or those following a restrictive diet where certain food groups are cut out entirely (like a vegan or vegetarian diet)," says Temple.
Just make sure you're choosing a high-quality supplement that provides a comprehensive array of vitamins and minerals (and bonus points if phytochemical compounds are also included!).
"Equally important is what a quality multivitamin does not contain: gluten, soy, dairy, major food allergens, sugar, cheap additives, synthetic dyes or flavors," says Ferira. "In other words, is their 'Other ingredient' list as minimal and thoughtfully clean as possible? Or did they cut some corners? Vegan multi formulas, albeit rare, are also possible to achieve," she adds.
Odds are, you will pee out some excess water-soluble vitamins after taking a multi. That's homeostasis. But you're likely not peeing out a lot if there are gaps in your nutritional intake and if the supplement provides an efficacious (and not outrageous) amount of each nutrient. ultimate multivitamin+ offers useful, efficacious doses of all the essential vitamins and minerals, in readily absorbable and gentle forms.*
And if you are new to taking a multi (especially with a built-in B complex) don't be alarmed if your urine is neon a few hours later.
Molly Knudsen, M.S., RDN is a Registered Dietician Nutritionist and mindbodygreen's supplements editor. She holds a bachelor’s degree in nutrition from Texas Christian University and a master’s in nutrition interventions, communication, and behavior change from Tufts University. She lives in Boston, Massachusetts and enjoys connecting people to the food they eat and how it influences health and wellbeing.