MiO isn’t toxic, but it’s not harmless either. Most of its ingredients are FDA-approved and considered safe in small amounts, yet several components raise legitimate questions when you’re using them daily. The answer depends on which MiO line you’re drinking, how much you use, and what you’re comparing it to.
What’s Actually in MiO
MiO comes in four product lines: Original, Energy, Electrolytes, and Vitamins. They share a common base of water, citric acid, artificial sweeteners, preservatives, and food dyes. Three of the four lines (Energy, Electrolytes, and Vitamins) also provide 10% of your daily needs for vitamins B3, B6, and B12.
Most flavors are sweetened with sucralose and acesulfame potassium, two zero-calorie artificial sweeteners. Only two flavors in the Vitamins line use stevia leaf extract instead. The preservatives across most products include potassium sorbate and sodium benzoate, and many flavors contain synthetic dyes like Red 40 and Yellow 6. MiO Energy is the only line with caffeine, delivering 60 mg per squeeze along with taurine, guarana, and ginseng.
The Artificial Sweetener Question
Sucralose and acesulfame potassium are the ingredients that generate the most debate. Both are approved by the FDA, and in isolation they don’t appear dangerous at typical intake levels. But a 2023 guideline from the World Health Organization recommended against using non-sugar sweeteners for weight control or reducing the risk of chronic disease. The WHO’s reasoning: a systematic review found that non-sugar sweeteners don’t produce long-term reductions in body fat in adults or children. More concerning, the review suggested potential links between long-term use and an increased risk of type 2 diabetes, cardiovascular disease, and mortality in adults.
That doesn’t mean a squeeze of MiO will cause diabetes. These are population-level associations, not proof of direct harm, and the amounts in a single serving are small. But if you’re adding MiO to every glass of water throughout the day, you’re getting a steady stream of artificial sweeteners, and the long-term picture for that habit isn’t reassuring.
What Citric Acid Does to Your Teeth
This is one of the clearest, most measurable risks. Researchers tested the pH of water mixed with liquid water enhancers and found the solutions measured between 2.9 and 3.0, which is highly acidic. For reference, plain water sits around 7.0 (neutral), and tooth enamel starts dissolving below about 5.5. The high citric acid content in these products is the main culprit.
In that same study, teeth immersed in water enhancer solutions for one month lost an average of 4% of their structure, with surface changes consistent with erosive damage. You’re obviously not soaking your teeth for a month straight, but sipping acidic drinks throughout the day keeps your mouth in an acidic state for hours. This matters more than drinking the same amount quickly, because your saliva needs time to neutralize the acid between exposures. If you drink MiO-flavored water all day, your enamel is under near-constant attack.
Preservatives and Food Dyes
Sodium benzoate, one of MiO’s preservatives, has a well-documented interaction with vitamin C (ascorbic acid): the two can react to form benzene, a known carcinogen. The amounts produced in beverages are typically very small, but it’s worth noting since some MiO lines contain added vitamins. A small fraction of the population may also be more sensitive to sodium benzoate due to genetic factors or existing health conditions, and in rare cases children can develop allergic reactions to it.
The synthetic food dyes in MiO, including Red 40 and Yellow 6, are FDA-approved but not without controversy. The FDA acknowledges that while most children show no adverse effects from consuming food dyes, some evidence suggests certain children may be sensitive to them. Yellow 5, another dye used in some flavors, can cause itching and hives in rare cases. The FDA reviewed the evidence in 2011 and concluded that a definitive link between food dyes and behavioral effects in children hadn’t been established, though sensitivity in individual children remains possible.
MiO Energy and Caffeine
At 60 mg of caffeine per serving, MiO Energy sits roughly between a cup of tea and a standard cup of coffee. That’s well within the FDA’s general guidance of 400 mg per day for healthy adults. The risk isn’t in a single serving. It’s in how easy it is to squeeze extra into your water throughout the day without tracking your total caffeine intake, especially if you’re also drinking coffee. The Energy line also contains guarana (which is itself a source of additional caffeine), taurine, and ginseng, a combination similar to what you’d find in energy drinks.
Does MiO Help You Drink More Water?
The most common argument in MiO’s favor is that it makes water taste better, so you’ll drink more of it. This sounds logical, but research doesn’t strongly support it. A study on basketball players exercising in heat found that flavored water received significantly higher taste ratings than plain water, yet the players didn’t actually drink more of it. In fact, the analysis suggested fluid consumption was likely higher with plain water. Without added carbohydrates or electrolytes, flavor alone doesn’t appear to meaningfully increase how much people drink.
That said, individual habits vary. If you genuinely won’t touch plain water and MiO is the difference between drinking enough fluids and being chronically dehydrated, the trade-off may be worth it for you.
MiO vs. Soda and Sugary Drinks
If MiO is replacing regular soda, juice, or sweetened sports drinks, you’re cutting a significant amount of sugar and calories. A meta-analysis of 56 studies found that while artificial sweeteners didn’t produce dramatic weight changes overall, a subgroup analysis showed they were associated with greater weight loss compared to caloric sweeteners. Swapping a daily soda habit for MiO-flavored water is almost certainly a net positive for your metabolic health in the short term, even accounting for the artificial sweetener concerns.
The issue is when MiO replaces plain water rather than sugary drinks. In that case, you’re adding acid, artificial sweeteners, preservatives, and dyes to something that was already perfectly healthy. There’s no upside to that swap beyond taste preference.
The Bottom Line on Daily Use
Occasional use of MiO is unlikely to cause meaningful harm. The ingredients are present in small quantities, and your body can handle low-level exposure to any of them. The concerns stack up with heavy, daily use: repeated acid exposure wearing down your enamel, a steady intake of artificial sweeteners whose long-term safety profile keeps getting less reassuring, and low-level preservative exposure that a small percentage of people are sensitive to.
If you use MiO, a few practical adjustments lower your risk. Drink it with meals rather than sipping it over hours, which limits the time your teeth sit in acid. Use a straw to reduce contact with enamel. Stick to one or two servings rather than flavoring every glass. And if you’re choosing between product lines, the stevia-sweetened Vitamins flavors avoid the artificial sweetener question entirely, though they still contain citric acid and preservatives.