Picture someone who has done everything the wellness pages recommended. They swapped coffee for herbal tea. They buy coconut water after the gym. They start the morning with lemon water and make a green smoothie most days. They are more careful about what they drink than almost anyone they know, and they are still tired, still foggy, still reaching for another bottle by the afternoon. Their fridge looks like an advert. Their energy does not.
The answer to what they should be drinking is not on the shelf with the pretty labels. It was worked out in hospitals, for cholera. A drink of clean water with salt and a little sugar, given by mouth, is estimated to cut the risk of dying from diarrhoea by up to 93%. The salt is what makes the difference: water with salt stays in the body longer than water alone.
Plain water hydrates. It is the yardstick everything else is measured against. But it is not the only good drink, and many of the popular alternatives are worse than they look.
The 13-drink test
Seventy-two men drank a litre of plain water, and on other days a litre of one of 12 other drinks, and then everything they passed over the next four hours was collected and weighed. The question was simple: which drinks stay in the body longer than water?
Only three did. An oral rehydration solution, full-fat milk and skimmed milk all left the men with noticeably more fluid on board than water. Everything else, cola, diet cola, hot tea, iced tea, coffee, lager, orange juice, sparkling water and a sports drink, did no better and no worse than plain water.
Two things follow. The sports drink with the hydration branding is, for fluid, just water with sugar. The branding is the only thing it has over the tap. And the winners have something in common: the rehydration solution carries salt, and milk carries salt and protein. What keeps water in is what comes with it.
Milk does it after exercise too. Eleven people sweated off nearly 2% of their body weight in a warm room, then drank low-fat milk, water or a sports drink. After the milk, they passed about half as much urine over the next five hours and stayed topped up. After water or the sports drink, they were running short again within an hour. It is no use if milk disagrees with you, but if it does not, it is a better recovery drink than the bottle with the lightning bolt on it.
The rehydration solution is the oldest of the three. Hemendra Nath Chatterjee published its use in mild cholera in The Lancet in 1953, and the recipe recommended today is still salts and glucose in clean water. Sodium crosses the gut wall hand in hand with glucose, and water follows.
Its biggest moment came in 1971. War in Bangladesh had driven millions into refugee camps, cholera broke out, and the intravenous fluid ran out. Dilip Mahalanabis had an oral solution mixed and handed to families to give themselves. Of more than 3,000 people with cholera treated that way, 3.6% died, against 30% of those on the drip. The groups were not matched, so it is not a controlled test, but it showed what a drink of salted, sugared water could do when there was nothing else.
What works
Salted bone broth. A mug of hot broth is water with salt in it, plus the gelatine from the bones and no sugar at all. A bowl of salted chicken soup was doing this long before anyone measured it. It is the savoury version of the rehydration idea, and it suits a low-carb or carnivore table perfectly. Make it in a big batch, salt it to taste, and keep it in the fridge. When there is no time to make it, stir into hot water in a minute, and you can salt them to taste.
Water with a little salt. The simplest version of all. It helps most in the first weeks of low-carb eating, when the kidneys let more sodium go and the "keto flu" of headaches and tiredness turns up. Salt it to taste, not to a formula.
One honest limit on the salt. Across 34 controlled tests with 3,230 people, eating less salt brought blood pressure down, and more so in people whose pressure was already high. If that is you, or you have heart or kidney disease, salt the broth and the water carefully, and check first.
Mineral water. Natural mineral water carries calcium, magnesium and bicarbonate from the rock it ran through, and the amount varies hugely from one spring to the next. Natural mineral water usually prints its own analysis on the label. Read it: two waters at the same price can carry very different amounts of magnesium.
Meat, fish and eggs. Food carries water too, and meat, fish and eggs are mostly water by weight. They bring their own sodium and potassium with it. A diet built around them supplies fluid and the minerals that hold it, before you have poured a drink.
Sugar-free electrolytes. For a hot day, a long sweaty session, an illness that has you losing fluid, or the first weeks of keto, a sugar-free electrolyte mix puts back the salts. are one, salt-forward and without sugar. Check the sweetener before you buy. 10 Eye-Opening Benefits of Cutting Out Sugar and Choosing Healthier Sweeteners has the people with the most erythritol in their blood who were about twice as likely to have a heart attack, a stroke or to die over three years, and the same pattern with xylitol. If it is on the label, pick another one.
Coconut water
Coconut water is sold as nature's sports drink on the strength of its potassium. It does carry potassium. It also carries sugar, about 2.6 grams in every 100, about a quarter of what cola has, and much less sodium than a rehydration drink. 7 Fun and Tasty Ways to Stay Hydrated Without the Boredom, linked below, has the figure.
Fresh from a young coconut, it is at least just coconut water, with nothing added. Packaged versions can carry added sugar and flavourings, so read the label. Either way it is an occasional drink, not a hydration plan. Nature's sports drink turns out to be nature's sweet drink.
Juice and smoothies
Juice concentrates the sugar of the fruit and drops most of what made the fruit filling. The Hidden Cost of Your Daily Sugary Drink, linked below, has the 7% higher risk of type 2 diabetes with each daily glass, and why the NHS counts a smoothie the same as juice: blending frees the sugar from the fruit just as juicing does.
The green smoothie, the symbol of the disciplined morning, puts a pile of spinach and kale and a handful of fruit into one glass. That is far more raw leaves than anyone would eat at breakfast, with the fruit sugar on top. It is a lot of plant in a hurry, and none of it is what keeps water in. Breakfast for a rabbit, in a glass.
Kombucha
Kombucha is sold on its live cultures and a long list of benefits. A review that went through 310 articles on it found just one that had tested anything in people and, as of 2018, no human tests registered anywhere. It is brewed from sweetened tea, so it brings some sugar and, unless the label says otherwise, some caffeine. It may taste good. As a health drink, it is still waiting for its evidence.
Herbal tea
Herbal tea has been given a bad name in some corners, and it does not deserve it. Herbal teas made without caffeine, such as peppermint, rooibos, chamomile or hibiscus, count towards the day's fluid like water does, and they bring flavour without sugar. Brew them loose rather than from bags, and drink them hot or iced. No caffeine, no sugar, no catch.
Lemon water is fine too, with one catch of its own: it is acidic, which is why 7 Fun and Tasty Ways to Stay Hydrated, linked below, says the morning lemon water deserves a straw.
One caution stands. In pregnancy, the NHS advises a limit on herbal tea and none made with liquorice root, because so little is known about them. 7 Fun and Tasty Ways to Stay Hydrated, linked below, has the detail.
Aloe vera juice
Aloe juice is sold as a gentle cleanse. Its laxative ingredient tells a less gentle story. Aloin, from the yellow latex under the leaf skin, used to be a common ingredient in over-the-counter laxatives in the United States, until the Food and Drug Administration banned it in 2002 when the makers failed to provide the safety data. Since 2016, whole-leaf aloe extract has been classed as a possible human carcinogen by the World Health Organization's cancer agency.
Swallowed, aloe can cause cramps and diarrhoea, which is the opposite of hydration, and it can interfere with how medicines are absorbed. For a drink, there is nothing here that water does not do better. A cleanse that flushes out your water is not much of a cleanse.
Coffee and alcohol
Coffee matched water in the 13-drink test. A cup of coffee hydrates, and the old line that it dehydrates you does not hold. That is not the problem with coffee. The caffeine is. Why You're Still Exhausted Despite Doing Everything Right has the strong coffee six hours before bed that still cut sleep by more than an hour, and the tiredness that a night without caffeine builds up. Count it as fluid, and as a cost. Your bladder will not complain about coffee. Your sleep will.
Alcohol works against the body's water-keeping hormone, vasopressin, so the kidneys let more water go. Lager at ordinary strength matched water in the test, because it is mostly water. Stronger drinks bring more alcohol and less water, and the morning after is the bill.
The bottle and the tap
Glass beats plastic in the heat. Plastic water bottles are made of PET, which contains no BPA. What has been measured coming out of it is antimony. In nine bottled waters kept at room temperature, it stayed well below the US limit. Heat speeds it up: at 65 °C, a temperature a car or a garage can reach in summer, the limit would be passed in about 38 days. Do not leave the case of water in the boot, and use a glass or steel bottle for every day.
There is more in the plastic than antimony. A 2024 count found about 240,000 plastic particles in a litre of bottled water, nine in ten of them nanoplastics, far smaller than the eye can see and many times more than earlier counts had found. What they do inside the body is not yet known. Glass and steel avoid the question.
The tap. In 2024, a worldwide analysis of 45,000 groundwater samples found harmful levels of PFAS, the "forever chemicals", in 31% of them, including in areas with no obvious source nearby. Reverse osmosis is one of the methods used to take PFAS out of water. A sits on the worktop with no plumbing, and this one puts some minerals back after filtering. It takes the minerals out as well, which is one more reason for the salt, the broth and the mineral water above.
The shorter list
Go back to the person who did everything right. They drank the colourful list: coconut water, lemon water, green smoothies, and herbal tea, the one good choice among them. The list that actually holds water in the body is shorter and much less photogenic: water, salt, broth, milk if it suits you, mineral water, and food that is mostly water already.
None of it needs a label that says "hydration". The best hydration drink has been coming out of the tap all along, with a little help from the salt cellar.
Tomorrow, make your first drink a mug of salted broth or a glass of mineral water, and see how the morning goes.
How much water do you really need? 7 Fun and Tasty Ways to Stay Hydrated Without the Boredom — the pale-yellow check, herbal and sparkling ideas, keto and carnivore, and when too much water becomes the problem.
Swapping out the sweet drinks? The Hidden Cost of Your Daily Sugary Drink — what a daily sugary drink does to your liver, teeth and blood sugar, the "healthy" drinks with nearly as much sugar as cola, and how to stop.
Know someone whose fridge is full of coconut water and green juice? Send them this, and make them a mug of broth.
Disclaimer: This article is general information. For advice about your own health, talk to a qualified health professional. If you have high blood pressure, heart disease or kidney disease, check before adding salt or electrolyte products.
Affiliate Disclosure: This article contains affiliate links. As an Amazon Associate, All For Life earns from qualifying purchases, at no extra cost to you. We only link to products we would recommend without the commission.
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