I remember reading somewhere that drinking before/after (10 minutes or so) and during the meal dilutes gastric juice PH level in the stomach and therefore contributes to lesser digestion quality.
Does anyone have any more details (time, amount, different effects with different liquids ..) on this matter ?
asked byWorder_1 (60)
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on July 15, 2010
at 08:50 AM
I've been wondering about this myself recently (if I should hold the water until between meals for rehydration or feel free to drink with meals). Here's the conundrum. Water clearly lowers the pH of the gastric juice by its addition. However, the sensing mechanisms in your stomach turn on the parietal cells when the pH gets too high to once again restore the proper acidity to your stomach (oversimplification, there are actually a couple fascinating mechanisms which contribute to this effect). Also increasing the volume of the gastric juice + food (chyme) increases the time it takes for your stomach to empty thereby increasing the amount of digestion. I found an interesting article here on the avg pH/ volume of gastric juice. It appears that the obese people have significantly higher volumes and pHs to their gastric juice suggesting a transcriptional upregulation of parietal cell activity when the stomach is exposed to high amounts/ volumes of calorically dense food. However, this isn't really the useful information here. It tells us that nonobese people have around 15ml (at avg pH of what looks like about 3.5, roughly just eyeballing it). of gastric juice and obese around 42 ml (at avg pH of 1.3). An avg glass of water is 240 ml, which would raise the pH quite a bit (pH is logarithmic, so less than you would think).
Ultimately, my 'expert' opinion (which is more of a mildly informed opinion than expert) is that the increased volume which makes gastric emptying slower and then the further acidification of your stomach also makes up for the dilution effect. Also water is an essential nutrient needed to hydrolyze bonds in macronutrients. Taking water with your meal keeps you hydrated (obviously).
If you want to minimize these effects you could drink water between meals, but I believe water also facilitates digestion and probably allows for slower eating (or maybe not, maybe it ends up making people half eat their food and then use the added water to swallow down the slurry). If you're worried about proper digestion, the best thing you can make sure you do is chew long and thoroughly and eat slowly.
As per type of beverage, I believe the paleo lifestyle prescribes only water and perhaps coconut milk. Stuff like orange juice and milk (to many people's surprise) is acidic. Acidity can leach calcium from teeth as well as bones via increased osteoclast activity. I'd stick with water or tea both of which are comparable in this scenario.
After doing this bit of research, I'm gonna stick with my drinking during meals. But hey, thats just me. However, in the paleo spirit, I think our ancestors probably drank before/ after meals when they visited the stream. They probably cooked/ ate near their camp site. Who knows? Anyway, the 'do things exactly like our ancestors to emulate their nutrient/ digestive' patterns for the sake of emulating them is pretty stupid in todays contexts.
on July 15, 2010
at 01:58 PM
Do what feels natural, and fits with what your gut feelings IS natural. A few sips or small glass of water likely is not going to wreak havoc on digestion. But consider how our ancestors would travel, likely transport water (or not), and take cues from that.
Obviously we can all agree 2-3 re-fills of a 40oz Mt Dew with your meal is not so good for any human!
on July 16, 2010
at 03:14 AM
Good question! Got me all into research mode! First, I checked the wiki and saw how complex the gastric acid secretion process. SOme of it starts before you even eat. Just by looking at the food, the stomach jumps into preparation. More is secreted according to how much you eat and what is in the food. Food that has been liquified is regularly pushed out as well as liquids while pieces that are not liquified are kept inside until they are more digested. The system is incredibly complex. I would be surprised if it were so easily foiled by a bit of liquid intake. And from a paleo perspective, if it were harmful to drink during this time, I think we would have developed a natural aversion to doing so. The natural body is not so stupid! Another point I noticed is that water is used in the actual digestion process: http://en.wikipedia.org/wiki/Gastric_acid
Then I found this link: http://whfoods.org/genpage.php?tname=dailytip&dbid=120&utm that mentions actual scientific research to the contrary. In fact, somewhere in my recent travels, I recall a comment on this subject from a chemist who explained that it would take a giant super ton of liquid to make any significant change in stomach acidity. The amount of any dilution from regular intake of liquid would be so small as to not make a difference.
Finally, this link explains it well: http://jz-nutrition.livejournal.com/42728.html Acid is not the only important thing in digestion. PLus, digested foods must be turned to a liquid to exit the stomach in a healthy way. If you do not drink liquid, the body will provide it from water stores. Liquid is needed for digestion. The only suggestion is that liquid intake might stuff the stomach more and increase the chances of gastric pressure and gastric reflux for those who suffer from it. Luckily, paleo eating itself seems a great way to help cure GERD.
From what I am reading, I find it likely that the dilution of acid story is probably just another thing that sounds kind of logical to those who don't know much about how the stomach works, and so the story gets passed around without much criticism. From my experience, very few people really check into things before they pass them on to others. Sadly, even most 'experts' seem to do this. Unless I hear some kind of good evidence to the contrary, I plan to continue drinking liquid as I please when I please. -Eva
on July 15, 2010
at 06:15 PM
Our digestive system has a pretty strong buffering system, if I recall correctly from reading about the chemistry some time ago. Drinking water is unlikely to significantly alter the digestive efficacy of the acids in your stomach. In fact, those acids probably count on a certain moisture content in your food.
Hence, if you are thirsty, drink. If not, don't. Don't apply rules as to when you can and can not drink. Let your body be your guide.
I also think any of our ancestors lucky enough to live around coconut trees would have thought of them as sources of food, not drink. Just as our "conventional" (i.e carb-addicted) counterparts can really bomb their systems with sugar by drinking their calories in the form of cokes and juices, I would caution Paleos about drinking fat in the form of coconut milk. Think of it as food and not drink. Liquid calories in any form can be consumed faster than our feedback systems tell us we are sated. And I think a key part of the Paleo lifestyle is we feed our bodies what they were designed to consume, and we listen to them when they say they are hungry, thirsty, tired, etc. By doing so, we stay lean and healthy.
on July 15, 2010
at 04:09 PM
I only drink water after a meal. If I need to drink water during the meal, often it means I have eaten enough and that I should stop.
Water before or during a meal bloats me. that's why I don't drink it during that time. However, as it was pointed out, do what feels natural to you.
on July 15, 2010
at 08:57 AM
Wouldn't we have evolved a mechanism to turn off thirst while we were eating if it was really that big a deal? Having water available while eating hardly seems evolutionarily novel so there would have been plenty of time for such a mechanism to evolve if it was important.
on July 17, 2010
at 01:18 AM
Eva,thanks for doing the research. I had read a really interesting book last year called "The Second Brain" but could not recall the details of the digestive process. In any case, the main theme of the book is about how our GI tract actually has a nervous system that is independent from our central nervous system. And that a lot of important brain chemicals, such as seratonin, get produced primarly in the gut, not in the brain. And it shows why so many neurological diseases, such as migraine, have nausea as symptoms as well.
Paleos may find this book interesting.
on May 16, 2012
at 04:34 PM
Thanks. I'm here at a restaurant wondering if I can have a glass of water. I will.
on July 16, 2010
at 08:24 PM
at pH = 2, you have 0.00015 mol H+ ion in 15ml, diluting 15ml to 255 ml (thats the gastric juice of one nonobese + 1 glass of water) we have .000588 mol H+--> pH3.23. a pH change of 1 can allosterically regulate an enzyme from active to inactive
that is, if the numbers in the paper that I cited above are correct (they seem low, but I'm going to assume they are)
buffer system in the stomach? not as far as I can tell. A buffer system can't protect against the raw effects of dilution in such quantities anyway
also the food you eat dilutes the gastric juice quite a bit (adds volume)
so conclusion: this argument is an unreasonable one to make. Clearly you are still able to digest with a glass of water in you (there is probably a glass of water content in most paleo meals with the amount of veggies we're eating). It has something to do with upregulation of partietal cell activity.
on July 16, 2010
at 12:53 AM
Im not sure about this either. i used to always have a big glass of water with every meal. full 16 ounces. This felt natural but i also did it just to try and slow the whole process/control myself a bit. Then i read on a few sites (Dr. Ben Kim i believe, and maybe Mercola, not sure though) that water dilutes the PH in the stomach (like the OP started with) and since then, and still now, i do not drink with the meal itself. I dont drink for an hour before the meal, too. I usually eat at 9pm, so from 8pm on i dont drink anything. After dinner i have one cup of tea and then sleep. Not sure if its any better than what i used to do. Great question.