Is Drinking Water with Meals a Healthy Practice?

 

I received a request from Professor Dr Ling Siew Ching in a WhatsApp chat group asking me if it is advisable to drink a lot of water together with a meal?

The reasons she gave were the fear the water may dilute the digestive juices for optimal digestion. She believes  these juices are of the correct dilution,  and we should not dilute them by drinking a lot of water together with a meal?

The other question she asked me was,  even if it okay to drink a lot of water during a meal, or an hour before or several hours after a meal, is it advisable to drink very cold water during a meal because she believes the lowered temperature will constrict the blood vessels in the stomach and also inhibit the gastric and other digestive juices from flowing?

She believes it would be much better to drink warm water during a meal than drinking cold water for this reason. She then  solicited my answers to this dilemma?

I was writing to reply to Prof Ling personally halfway through, then I thought the length and details of my answers may also be useful to a lot of people who may have also asked the same as this is a common question.  I then decided to divert my answers for Prof Dr Ling into my blog here so that it can be shared among a larger common audience.

Below is my take on this very  pertinent question.

Thank you very much Professor Dr Ling for your two excellent questions pertaining to  hydration during meals and its impact on digestion. Let me try my best to answer.

Your first question was on the effects of drinking water during  meals and its impact  on digestion? I think this is commonly asked by people who are concerned  that drinking water during meals might dilute digestive juices, such as gastric acid and enzymes, making digestion less effective. I too have thought of this years ago during my undergraduate in physiology.

As far as I have observed almost none has been affected by this practice. I suppose the body is quite adaptable and produces digestive juices in amounts necessary for digestion, regardless of whether you're drinking water during the meal. It looks to me that water does not significantly dilute digestive juices. In fact, drinking a moderate amount of water (around a cup or so) helps in the breakdown of food and facilitates nutrient absorption. Excessive amounts of water (such as several glasses during a meal) could potentially make you feel overly full or bloated, but from what I observe this has not  significantly hindered digestion.

Small amounts of water can actually aid the digestive process by helping food pass more easily through the digestive tract and allowing the stomach lining to stay lubricated.

My observing in digestive physiology and in nutrition seems to show that  drinking a reasonable amount of water during meals is generally safe and even beneficial for digestion. It's about finding the right balance for your body’s needs.

Pertaining to your second question on cold water and digestion, this becomes a problem.  It is true that cold water may temporarily inhibit digestion. When you drink very cold water, it could potentially constrict blood vessels in the stomach, which might slightly slow down the digestive process. However, the effect is temporary and usually not significant enough to disrupt the overall digestive process, unless it’s in excess.

I should argue that moderate temperature water (room temperature or warm) is less likely to cause this constriction. However,  people who are sensitive to cold drinks, or have conditions like gastritis or irritable bowel syndrome (IBS), warm or room temperature water might be a more comfortable option.

Gastric juice has already being secreted while the food is chewed in the psychic or cephalic phase before any food or water has entered the stomach as shown by Russian physiologist Ivan Pavlov (1849 - 1936) in his "sham feeding" experiment on dogs. The psychic secretion of gastric juice has also been demonstrated in humans during hypnosis. On he other hand, psychic influences such as worry, fear, anger, and pain are powerfully inhibitory to the gastric glands, as are bad odours, an unsavoury character  of the meal, or even an unattractive appearance of general appointments. Pleasant surroundings, contentment, delights for the eyes and ears, such as flowers on the table, cleanliness, and pleasant music - tend towards ab opposite effect, These have no bearing whether  or not water was drunk before or after a meal. The importance of appetite in aiding digestion has been pithily stated by Pavlov in the words "Appetite spells gastric juice:. Macbeth at the banquet expresses a similar thought when he says "Let good digestion waits on appetite and health on both" 

There are substances present in the aqueous extracts of meat and vegetables, such as  soup and beef extracts that stimulate gastric secretion irrespective of the amount of water drunk in a meal. On account of their stimulant action on secretion they are  known from the physiological point of view as 'gastric secretogogues' The products of protein digestion - proteoses and peptones and other  substances act in a similar fashion. Extracts of the pyloric mucosa, obtained from an animal after a meal of meat extract or of other substances rich in extractives, containing a hormone, i.e.  gastrin when injected into the vein of an animal, a profuse secretion of gastric juice  resulted whether  or not water  is drunk during a meal.  

Among the chemicals that stimulate gastric secretion, the most powerful are histamine and alcohol. Atropine by its paralysing action upon the vagus endings temporary suppresses secretion. Alkalies such as sodium bicarbonates in repeated small doses excites the gastric glands, but a single large dose has, an inhibitory effect.

There are  abnormalities in gastric secretion too such as gastric anacidity or achlorhydria, and achylia gastrica. Gastric anacidity is also seen in a number of diseased states, e.g. cancer of the stomach (other than Helicobacter pylori infection of the stomach),  pernicious anaemia, chronic inflammation of the stomach, chronic arthritis, gall bladder disease etc  Chronic  disorders of the stomach are very lengthy to describe, and we shall not go into them.

 The best answer I  can offer is warm water or warm soup during a meal is a great choice. It can be soothing and gentle on your stomach, aiding digestion by promoting better blood flow and enzyme activity. It also doesn’t have the same constricting effect that cold water might. But the best  nutrition and dietary practices is to drink a bowl of warm soup before a meal. Here are the reasons:

Drinking soup before a meal can stimulate the appetite in a few ways.

First, soups contain different types of gastric secretagogues as already described above.

Second, warming the stomach by warm liquids help increase blood flow to the digestive system, priming the stomach for digestion. Warm soup has a sensory stimulation.

Third, the aroma and umami taste from meat-based soup activate the salivary glands and gastric secretions, making the body more prepared for food intake.

Fourthly, soup also causes ghrelin release, the hunger hormone influenced by stomach distension. A light soup can regulate ghrelin levels and enhance appetite in a controlled manner.

Fifthly, drinking soup before a meal can both increase or decrease food intake, depending on its composition and the individual’s dietary habits. If the soup is light and brothy, it may increase appetite by warming up the digestive tract without causing satiety. 

Sixthly, if the soup is thick and fibre-rich (e.g., vegetable or lentil-based) it can reduce overall calorie intake by making a person feel fuller, leading to lower food consumption in the main course.

Studies suggest that a low-energy-density soup (like a clear broth) before a meal can led to a 15-20% reduction in total caloric intake, which may aid in weight control.

Seventhly, brothy warm soup enhances nutrient absorption through intrinsic factors. First, vitamin B12 absorption is facilitated. Meat-based soups, especially those made from bone broth, organ meats, or long-simmered cuts of meat, are rich in protein, gelatine, and micronutrients. The intrinsic factor (IF) is a glycoprotein produced in the stomach, essential for vitamin B12 absorption. 

Drinking meat-based soup before a meal can stimulate gastric secretions, including intrinsic factor, helping with better absorption of vitamin B12. Bone broths and meat extracts may also contain small amounts of B12, contributing to the body's stores.

There are also other nutrient absorption benefits such as gelatine and collagen found in bone broth.  These compounds support gut lining health and may improve digestion and absorption of amino acids, even though nutritionists know the protein quality (biological value) of gelatine is very low – in fact zero where its  nitrogen cannot be retained by the body.

Eighthly, there is also mineral bioavailability. Meat-based soups provide mineral bioavailability such as iron, zinc, calcium, and magnesium, which are more easily absorbed due to the presence of amino acids like glycine and proline. The soup also provides hydration & electrolyte balance.  The sodium and potassium in broth maintain stomach acidity, essential for protein digestion and mineral absorption.

Soup before a meal also has digestive benefits. It prepares the stomach for digestion.  The warm temperature and liquid consistency help the stomach start producing acid and enzymes, ensuring smooth digestion of the upcoming meal. The gelatine and glutamine in broth support the gut lining, potentially aiding in conditions like leaky gut or gastric ulcers.

Ninthly, soup before a meal may reduce bloating.  The fluid content of soup promotes gastric motility and prevents indigestion. Thus, drinking meat-based soup instead of water, beverages before a meal can provide digestive benefits, stimulate appetite, and enhance nutrient absorption. It also helps control food intake depending on its consistency. The presence of intrinsic factor stimulation, gelatine, and essential minerals makes soup a great primer for optimal digestion and absorption of nutrients like vitamin B12. 

Thus, most cultures traditionally start off a meal with a bowl of soup, or together with the meal mid way. This cultural food practices make tremendous amount of scientific sense. 

Having explained all these, however, if you still  prefer cold drinks, just keep in mind that they might cause temporary discomfort, especially with larger meals. But for most people, it’s not a major issue.
 

My conclusion is that drinking moderate amounts of water with meals does not significantly dilute digestive juices or impair digestion. Cold water may slightly slow digestion in some people, but it’s typically not a big issue unless consumed in large quantities. If you’re concerned about this, opting for room temperature or warm drinks might be a better choice. I feel it's generally fine to drink a reasonable amount of water during meals, but if you're sensitive to cold drinks, or if you want to maximize digestion, consider warm soups which is much better.  Our digestive system is quite efficient and can handle varying conditions as long as we are listening to our body's signals and keeping things balanced.

I write my opinion based on sound physiological-scientific reasoning on what I understand in digestive physiology,

When I was an undergraduate student, I remember having to read a massive book called “Physiological Basis of Medical Practice by Best and Taylor.

Charles Herbert Best CBE, MA, MD, DSc (Lond), FRS, FRCP  and Norman Burke Taylor VD, MD, FRS, FRCS, FRCP, MRCS, LRCP  held  highly impressive academic and professional credentials who wrote that classic book on Physiology.  

I think, if I still remember well, Best and Taylor described the reasons why drinking soup before a meal is a healthy practice that is being practised by most cultures.  

Best & Taylor’s Physiological Basis of Medical Practice is indeed a classic textbook used by most medical students and undergraduate students in medical physiology throughout the Commonwealth nations, and I can see why it might have touched on this topic, considering its comprehensive approach to human physiology. Older editions of medical and physiological texts often emphasized practical, observation-based knowledge, and the cultural practice of drinking soup before meals likely had physiological justification even before modern research confirmed it.

Classical medical texts often contain gems of wisdom that modern literature sometimes overlooks and my  memory in recalling such details is still clearly retained even at my age.

It is always my pleasure to assist Professor Dr Ling,  or anyone  in understanding such fascinating topics.

However, having  explained all that, there is a question I need to ask.

Suppose now, someone places a plate of hot appetizing meal on your table for you to eat. 

 Then someone came along and poured icy cold water into your plate of hot and delicious food. What would be your  reactions? First, I supposed you will be stunned. But I am sure you would not mind if he had added some hot soup or hot gravy onto your food - but not cold water.  What then would you do to him next? 

I supposed  you would instantly punch him for doing that. You would call him a mad chap – a mental (psychiatric) case.

If you are sure, you would punch him for doing that, then why are you doing the same thing to your own stomach by drinking cold water on the hot meal you have just swallowed instead of some warm soup?  

Is it  because the stomach is dumb, and cannot fight with you, and you treat it like some kind of a garbage bin where you can dump anything inside without it protesting and calling you a mad chap? 

Don’t you think you too are as insane and a mad chap as that person who poured cold water onto your plate of hot food as much as you did to your own stomach? 

Professor Ling, I leave this soul-searching question for you to answer - drinking icy water with your hot meals.  

 

- Nutritionist jb lim MD MSc PhD (Med) FRSPH FRSM