What is safe to drink?

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What is a healthy and safe drink? Over the course of history, the answer to this question illustrates the fact that no wisdom is eternal. This is not only due to more and better information, but it also depends on changes in conditions.

In the developing countries, water is still today one of the most important health risks, because it is often contaminated by infectious micro-organisms. Therefore one has to boil it, or chlorinate to such an extent that it will smell and taste unpleasant. This used to be the case also in the industrialized countries. Infant death rates were about the same as today in developing countries, with one of the most important reasons being diarrhoeal diseases caused by poor drinking water. This is still one of the most important reasons to favour breast feeding in developing countries, and to campaign against infant formulas, especially those requiring addition of water to make the final product. There are many other reasons to recommend breast feeding.

Heating and acidification

In different conditions, hygienic drinks have evolved after trial and error. In China, tea has been consumed for thousands of years, and many food items such as vegetables are also boiled or heated. This is a very efficient way to protect from microbial diseases. In many areas, where dairy products have been important, milk has been soured to yoghurt or sour milk. Both the acidity and the competition by safe microbes and their antimicrobial products prevent the growth of both pathogenic and saprogenic microbes in the product. Thus they are a way of preserving it, stopping it going rancid.

Alcohol is a disinfectant

A similar story can be found behind wine and beer. While hygiene was not very good, it was best to let a knowingly harmless yeast to grow under relatively controlled conditions. The yeast produced alcohol, and this kept other microbes under control due to its toxicity. In this way it was possible to avoid also the growth of pathogenic microbes. Therefore wine and beer were safer than water for many centuries even though they contained a toxic compound – ethanol. The risk of ethanol was less than the risk of the contaminating microbes. This is exactly the same logic that we have seen in water disinfection with chlorine. Chlorine may produce compounds with adverse health effects, but the risk is much less than the risk of cholera or other infections. Of course people then acquired a taste for alcoholic drinks for completely different reasons.

Today human beings are spoiled for choice. Usually good quality ground water or thoroughly purified and disinfected surface water is available. It is also possible to drink traditional liquids like tea, sour milk, or alcoholic wine or beer; although nowadays this is not so much for hygienic reasons but according to individual preferences and customs. Each one of these dinks has its own advantages and disadvantages, but in essence the microbial risk can be well controlled under normal conditions. Occasionally there are water-borne epidemics, but this usually can be traced to breaking the rules of established practices. Even non-pasteurized organic milk is usually safe, even though milk is a good growth medium for many microbes, and pasteurisation was introduced because of the risk of tuberculosis. The safety of dairy products is now mainly guaranteed through the continuous chain of refrigeration from the farm to the fridge of the customer. Without proper refrigeration, milk goes bad in a day or two. Before the advent of refrigerators, dairy shops were open every day, even on Sundays, or in some countries milk was delivered to the houses of customers every morning.

How about bottled drinks?

In most western European countries, tap water is microbiologically cleaner than bottled water. As any traveller will know, this is not the case everywhere. So this is a typical optimisation of safety. At home there is no need to buy bottled water; you never know how long it has been standing on the shelf in the shop. Moreover the production of unnecessary plastic waste is environmentally unfriendly. However, when travelling, it is wise to consider the local hygienic conditions, and it may make sense to buy bottled water.

With other bottled drinks, the most common problem is excessive sugar. In addition cola-drinks are so acidic that they can damage tooth enamel. Sugar is problematic for several reasons, it causes caries of teeth, and it promotes weight increase by introducing deceptively high amounts of useless energy (calories). Therefore it is wise to educate children to avoid soft drinks. One of the most reprehensible policies is the decision to allow the sales of soft drinks and snack vending machines in schools, since they are at odds with all sensible rules of good nutrition. Home-made juice with a minimum added sugar is a much better choice than the sugar-saturated commercial drinks. An alternative is a commercial juice with no or little added sugar.

There are no absolute or eternal truths when it comes to drinks and beverages. In most countries, tap water is good and safe both for health and the environment, usually better than bottled water. With respect to other drinks, the safety depends on the amount consumed, alcohol has its own risks, and in many drinks the energy content is deceptively high.

One level up: Is man defiled by what goes to his mouth?

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