Why shouldn't we drink seawater (even if it's recommended on social media)

Swimming in the sea is one of the blessings of summer. The act of slowing down, being outdoors, and cooling off is an anti-stress balm that alleviates the headaches accumulated throughout the year. Although the sea offers us multiple virtues, not all those attributed to it can be taken for granted. Regarding seawater specifically, messages are spread, especially through social networks, such as that drinking it "remineralizes," "balances electrolytes," "alkalizes the body," or even "hydrates better," but the fact is that scientific evidence does not support claims like these and, on the other hand, the risks of drinking it are well identified.The idea that drinking seawater is beneficial spread over a century ago with the French biologist René Quinton, who maintained that seawater resembles blood plasma because life originated in the sea and that it contains the chemical elements the body needs. Based on this hypothesis, Quinton developed the so-called "marine therapy." In recent times, with the popularization of social networks, the attribution of benefits to the intake of seawater – even untreated – has spread even further, but one must carefully consider who is saying it and what exactly they are saying to avoid falling into pseudoscientific practices.

The Department of Health of the Generalitat is clear regarding the consumption of seawater and advises against drinking it. "There is no solid evidence of benefits from drinking seawater, and there is a lot of evidence of significant risks," remarks Health, and warns: "Drinking seawater, especially untreated, is harmful to health and is not recommended by any scientific society." According to also warns the doctor in food science and technology and scientific communicator, Miguel Ángel Lurueña, drinking seawater "is not a good idea," because the possible benefits it may have do not compensate for the risks to which those who drink it are exposed."}Lurueña emphasizes that seawater has a "very high" salt concentration, about 35 grams per liter (3.5%), while food is considered to have a lot of salt when it exceeds 1.25% salt. "We are talking about much higher quantities," he assures, and given this, it should be kept in mind that drinking seawater can increase blood pressure – and, in the long run, cause cardiovascular diseases – due to the extra work the body has to do to eliminate excess salt, as well as cause dehydration, because the kidneys need more water to eliminate it. Furthermore, if drunk directly from the sea, there can be a food safety problem, because "you can find anything in it," such as pathogens, bacteria, or contaminants.It is spread by influencers and false experts

The proliferation of messages encouraging the consumption of seawater has not gone unnoticed by the College of Dietitians-Nutritionists of Catalonia (CoDiNuCat), according to Júlia Roig, one of the members of CoDiNuCat, who elaborates on the warnings outlined by Lurueña. The dietitian-nutritionist notes that there are influencers, even individuals linked to the health field without being accredited experts, who "recommend consuming seawater because it will be very good for detoxifying, rebalancing the body, alkalizing the body, and because it provides essential minerals to improve overall health, but there is no solid scientific evidence or clinical benefit with these claims," she warns.That seawater contains multiple minerals – such as sodium, iodine, magnesium or calcium – is a fact, but "that it contains them does not mean it is good for obtaining them". Roig exemplifies that magnesium is sourced from nuts – especially almonds, hazelnuts or cashews –, pumpkin and sunflower seeds or legumes, while iodine can be obtained from fish, seafood, dairy products, eggs and salt, which is recommended to be consumed iodized. Furthermore, one of the main minerals that seawater contains, sodium, is precisely one of the reasons why it is not recommended to drink it, because "excessive sodium consumption is one of the most frequent nutritional problems we find in society", where hypertension is very prevalent.The World Health Organization (WHO) recommends consuming no more than two grams of sodium per day, which is equivalent to about five grams of salt, or in other words, a level teaspoon, counting both what we add and what the food already contains. In this regard, it should be borne in mind that between 70% and 80% of the salt we ingest does not come from table salt, but is hidden, especially in processed and ultra-processed products, such as cold cuts, preserves, sauces, industrial bread, and pastries. "A lot of salt is already being consumed, and if we still recommend consuming seawater, it is feared that there will be a higher sodium intake," states Roig, who works as a dietitian-nutritionist in three primary care centers (CAP).In case of hypertension, remember to "eliminate salt from cooking". Even if you take the pill to lower blood pressure and the parameters appear within the range, it is advisable not to add salt to preparations, use spices as an alternative, read labels carefully, reduce preserves, prioritize fresh foods and reduce processed foods as much as possible. The high concentration of sodium in seawater can also cause "an overload on the kidneys", continues the spokesperson for CoDiNuCat. "Our kidneys are not adapted to eliminate this excess sodium and, in very high quantities, it can promote dehydration and alter the body's water and electrolyte balance", she points out.The food use that experts save: for cooking seafood

Treated seawater is commercialized – with various presentations, such as microfiltered, which is more concentrated, or mixed with mineral water – and is even sold in supermarkets. This "is indeed safe from a microbiological point of view," because there is no presence of toxic substances, specifies Lurueña, but she insists that "this does not mean it is a good idea to consume it" because it also does not allow one to get rid of possible risks such as dehydration or cardiovascular effects.The only use of treated seawater linked to food that can be practiced at home and that Lurueña would admit is for cooking seafood, a practice adopted by trained palates because they can notice a flavor difference, if the water is removed once cooked. Other uses that seawater can have, according to Roig, is in the elaboration of cheeses as a natural preservative, instead of adding fresh water directly, as well as for nasal rinses, in dermatological applications – such as washing, without rubbing, the reaction to a jellyfish sting– or in therapies for athletes to take baths, which, for example, does have scientific backing, highlights the dietitian-nutritionist.So, when it comes to drinking water, the recommendation is to drink it from the tap or from bottled mineral water – not from the sea –, recalls Roig, and points out that drinking tap water is safe because it is always strictly controlled: "In some areas the taste may be less pleasant, but that does not mean it is less healthy". Lurueña also takes the opportunity to debunk the myth that is sometimes associated with hard tap water, very common in Catalonia, and which contains a high concentration of minerals, something that some people link to the formation of kidney stones: he guarantees that "there is no direct relationship" between the two and, as Roig points out, it is another matter if people do not like the taste.