Some common questions regarding the link between hydration and foods
Some common questions regarding the link between hydration and foods.
In the third of this series of articles we will answer some common questions regarding the link between hydration and certain foods.
There is a great deal of interest in understanding different ways a person can go about hydrating their body. Many people cite particular foods, nutrients or fluid sources as being especially good for this purpose. Below is a list of those commonly suggested as being beneficial and we will offer some perspectives on how much they help or hinder your hydration.
First lets discuss salt.
The idea here is – if we just eat really salty foods, that will make us thirsty and we will drink more water. Interesting idea but a little flawed. The issue there is with the intake of salt or primarily the sodium in the salt. The body seeks to maintain the concentration of sodium in tissues across a very narrow range. If you take too much salt into the body you turn up the thirst response. You should then consume proportionally more fluid and therefore dilute out the sodium that is present in the system, ultimately flushing it through to the kidneys where it can be released, but you don’t do much for increasing the available water because it’s all required for the flushing action.
There may instances where salt is helpful. For example, exercising very hard in high temperatures where there is a lot of salt lost can exacerbate the dehydration effect of that exercise. This may be a situation where some additional salt intake may help hydration homeostasis. In most cases using additional salt to simply promote more drinking will not result overall in an increased hydration state.
What about energy drinks?
With simple energy drinks we have several issues. First, we have the fact that they do contain fluid. That is a good thing. Second, we have the fact that they often contain electrolytes. From what we have just said about sodium that can be appropriate where those electrolytes are necessary but it can also be unhelpful where they are not. Third, many energy drinks contain calories in the form of carbohydrates. In the process of metabolizing those carbohydrates we generate some new water in the body. Carbohydrate is composed of carbon, hydrogen and oxygen. We breathe in additional oxygen. We use that to burn the carbohydrate and we end up with carbon dioxide which we expire and retain some water fraction. So it is possible to carry some extra water into the body by the burning of that carbohydrate.
Fundamentally the problem for most people is that they do not completely burn the carbohydrates. There is some residual of carbohydrate and those extra calories may not in fact be helpful for the individual and may be laid down as fat. The source of fluid in energy drinks probably makes them quite useful. But for most people - except those who really need the extra energy and the electrolytes - something like water or diluted fruit juice is probably a better way to hydrate.
How about coffee and teas?
The issue with coffee and teas - and we should probably include in this part of the story alcoholic beverages too - is that caffeine and many of those xanthine type compounds and of course alcohol all have a diuretic effect. They will in fact turn up the gain on the filtering capacity of the kidneys. The consequence of that is that we wind up losing fluid from the system through these diuretic effects. Very weak black tea, green tea, dilute tea based drinks are probably ok in moderation. The stronger coffees and certainly the stronger alcoholic beverages probably result generally in a net water loss with a consequence of increased dehydration.
Next on the list are soft drinks like colas?
These generally contain carbohydrates. For many people those additional calories are not something they necessarily need. In the case of cola drinks in particular – they also generally contain caffeine. Caffeine is hidden in many soft drinks today. The caffeine has a diuretic effect. I certainly do not have a prohibition on soft drinks but I think there are better choices you can make if you are looking to hydrate than soft drinks.
How about milk?
Milk is a perfectly good hydrating beverage if it is something the individuals can tolerate. There are a lot of people these days who have various food intolerances, of which lactose intolerance is one of the most common, so conventional cow's milk may not be appropriate. But for those who can tolerate milk it can be an adequate source of fluid. Remember though that milk does contain some protein some carbohydrate calories and, depending on the form of the milk, calories from milk fat. So again for those people who are concerned about their calorie intake it may not be the ideal choice when given the alternative of something as simple as water. There is certainly nothing wrong with it for someone who desires some additional calcium in their diet. Perhaps it is useful, though I think there are some questions around our ability to absorb calcium from dairy foods anyway for many of us.
Dr Jaroslav Boublik B.Sc.(Hons), Ph.D. (Med), MRACI, C.Chem. AACNEM
Jaroslav has spent almost 30 years in medical research with 15 years in drug development and then 15 years in nutritional medicine. He consults to the nutrition industry as a formulator, researcher, presenter and educator. His primary research interest is water and hydration and he is the co-developer of The Aqua Formulas.