YOU DON'T DRINK ENOUGH WATER

Stay hydrated they say. "You're probably just dehydrated." We toss these words around left and right, but how does one hydration? What is Hydration? A question that I am willing to bet many would be left unable to answer with any sort of cellular mechanisms to back the explanation. 

I had somebody submit this topic to me to write on. I have been thinking about it since I read that submission, and then finally when in CVS I stumbled across DripDrop which is an electrolyte drink that supposedly provides dehydration relief faster and more effectively than water. And of course it got me asking questions... There's many supplements that claim drinking one glass of water with one packet of the supplement is like drinking 4 glasses of water. Is there some sort of hydration exchange rate? Is it like when I travel to Canada and all of the sudden the same US dollar gives me more purchasing power? Got me thinking...

What is optimal hydration? How do we know? What does the literature say is the optimal amount of water to consume on a tangible, measurable level specific to each individual and their lifestyle? Of course, once the questions start, so does the investigating. I dug deep. Here's what I found.

Let's start simple: what is water? Water is a transparent fluid which forms the world's streams, lakes, oceans and rain, and is the major constituent of the fluids of organisms. As a chemical compound, a water molecule contains one oxygen and two hydrogen atoms (chemical formula: H2O) that are connected by covalent bonds (6). The bonds between two water molecules are hydrogen bonds. Since electrons are not equally distributed in a water, it is considered a polar molecule, despite it having the same number of protons and electrons. Lastly, it has a molecular weight of 18.015 g/mol. And,Contrary to what one might think, the properties of water are very bizarre in the world of organic chemistry. Water is the only naturally occurring compound that exists in three physical states of matter: solid, liquid, and gas (1, 3,4). 

Alright, now you know what it's like to take Gen Chem 1 freshman year of college. Covered all the basics. Moving on.

What is hydration: 

Simply put: hydration is the process of causing something to absorb water. Interestingly, when discussing hydration in literature they refer to all sources of water that are: non-caffeinated, non-alcoholic beverages, soups, and foods i.e. you can't count your Celsius or your glass of wine. So we'll be sure we keep that in mind when discussing how much to drink and where you can get it from.

Recommendation: 

So I found something that was very interesting. The most specific recommendation we have is: 1-1.5mL/kcal of energy expenditure, referred to as total daily energy expenditure (TDEE). Now, many people don't know their TDEE or how to figure that out. Luckily, I have that in the practical nutrition calculator because that's actually a relevant metric for many applications—evidently including water intake. Sadly, people don't take much time to figure these sorts of things out, so we just went with what gets most people to hit an adequate mark using measurements one can easily understand: 8 cups/day. Though better than nothing, t's a bit oversimplified, and definitely low for many people. 8 cups (8oz) would be a total of 64oz. I personally don't think that'll I'll be calculating my water intake requirements on a daily basis based on activity level, but it's good to get a baseline and know roughly where I should be, so let's do that.

My TDEE is 3,791. So I would multiply by 1.25 (just to use the average between) 1 and 1.5 to give me: 3,791 * 1.25 = 4,739

The conversion from mL to oz is *.03, so 4,739 * .03 = 142oz of water/day

Now, many of you are thinking that's a lot of water... But remember, other beverages count towards this, and even food. I drink probably around 90-100oz of water (I have a 1 Liter cup (33oz)) and fill it up around 3 times a day. Maybe more. So between that and drinking milk (lots of it) and the foods that I eat—I'm probably pretty close to that mark.

How do we know we're hydrated:

There are many good Indicators of hydration including plasma osmolality, urine specific gravity, deuterium oxide dilution (2). But nobody is going to take the time to learn what these are let alone apply them to their life. The best thing we got right now is to assess the color of your urine. Yes, that works. It's a good way to gauge wether or not you have had enough water. Darker, less hydrated. Lighter and more clear, hydrated.

What am I doing by drinking water?

So we need to drink water because we need to be provide water for our body to distribute and hydrate cells, we should be consuming 1-1.5mL/kcal expended, and we can use the color of our pee to measure hydration level. Seems simple enough. But there's more to it, so let's carry on. 

It's important that you understand where the water exists in your body. You have the intracellular fluid (ICF) and extracellular fluid (ECF). The ECF is comprised of two parts: the interstitial fluid (IF), the plasma. This is all giving me flashbacks to anatomy & physiology...

Why are these important? Well these are the different compartments of water in the body that house anions (-) and cations (+) such as sodium (+), magnesium (+), potassium (+), calcium (+), chloride (-) etc. You guessed it: the electrolytes.

I'm going to try my best to not get too deep into this because it gets REALLY boring, REALLY fast. What does all of this have to do with Hydration? The ions are responsible for regulating water concentration. When we strike an imbalance in these ions, the flow of water from one compartment to another can be thrown off. How do we strike that imbalance? Sweating, not consuming enough water, blood loss, etc. So for those who are curious like me, that's what makes these electrolyte drinks more beneficial when it comes to hydration—they help your body balance the water content between the ICF and ECF more efficiently and therefore help to regulate cellular hydration since drinking water alone does not replace those ions. However, we still need to be drinking enough water overall so that our body has water to move where needed.

It takes both.

The Take Away

Water is very important for us to drink. You can use the nutrition calculator I built to determine your TDEE (total daily energy expenditure) which you can then take to determine how much to drink in a day: TDEE * 1-1.5. Try to get as much water in as you can, but be cognizant of the fact that there's a balance and that this is total water intake so food counts, other liquids count. You can likely shoot to have 80% of your intake come from drinking water.

There are a couple of concepts that were brand new to me in reading about water, and that's what I love about this. I will have to explore these things at future date but will leave them incase you're curious:

Concept 1: Turnover rates of the hydrogen and oxygen of body water

Questions I have that I need to read up on:

• Does this explain how to determine what specifically is happening to our water?
• At what rate of exchange do we need to replace this water?
• Increases with activity and to what extent?

Concept 2: A unique measure of doubly labeled water (DLW): 

• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5486561/
• https://www.ehleringer.net/uploads/3/1/8/3/31835701/384.pdf

~ Bonde

References

1. Ball P. Water is an active matrix of life for cell and molecular biology. Proc Natl Acad Sci U S A. 2017 Dec 19;114(51):13327-13335. doi: 10.1073/pnas.1703781114. Epub 2017 Jun 7. PMID: 28592654; PMCID: PMC5754758.
2. Dietary water and sodium requirements for active adults. (n.d.). Gatorade Sports Science Institute. https://www.gssiweb.org/sports-science-exchange/article/sse-92-dietary-water-and-sodium-requirements-for-active-adults
3. Libretexts. (2020, November 6). 4.1: Unique properties of water. Geosciences LibreTexts. https://geo.libretexts.org/Bookshelves/Oceanography/Oceanography_(Hill)/04%3A_Properties_of_Water/4.1%3A_Unique_properties_of_water#:~:text=Water%20is%20the%20only%20naturally,in%20a%20glass%20of%20water
4. New mechanism found that maintains water balance within cells. (2023, October 19). Imperial News. https://www.imperial.ac.uk/news/248634/new-mechanism-found-that-maintains-water/
5. National Research Council (US) Subcommittee on the Tenth Edition of the Recommended Dietary Allowances. Recommended Dietary Allowances: 10th Edition. Washington (DC): National Academies Press (US); 1989. 11, Water and Electrolytes. Available from: https://www.ncbi.nlm.nih.gov/books/NBK234935/
6. https://pubchem.ncbi.nlm.nih.gov/compound/Water