Understanding digestion

There are four things about digestion that I believe to be essential to understand, remember, and always keep in mind. The first is that although the environment of the stomach can be, and is generally at least mildly acidic, the intestines must be alkaline. The second is that the level of acidity inside the stomach depends on what is in it: it is in response to whatever comes into the stomach that specialised cells of its lining secrete hydrochloric acid in greater or lesser amounts. The third is that only protein requires a highly acidic environment to be properly broken down into the amino acids that make up protein before moving on into the small intestine; fats and carbohydrates neither require nor stimulate the secretion of acid in the stomach because they are broken down in the alkaline environment of the intestine. And the fourth is that water is totally crucial to the proper function of all digestive organs, and to the whole process of digestion from start to finish.

Because proteins are so hard to break down, they must remain in a highly acidic environment in the stomach for about 3 hours before the resulting chyme should be, can be, and is normally transferred to the small intestine. (Obviously, the time depends on the amount.) And the more acidic the environment of the stomach, the better it is for the breakdown of protein, but also to protect the organism by destroying pathogenic bacteria that could have come with the protein, as is presumably often the case in the wild.

In addition to the hydrochloric acid secreted by the stomach, protein-digesting enzymes (proteases) like pepsin are also secreted by the stomach when it contains protein. Moreover, the acid activates the inactive forms of the enzymes prorennin and pepsinogen into their active forms: rennin is necessary for digesting milk protein, and pepsin breaks down the proteins into polypeptides. It is very important to remember that the stomach has cells that sense what nutrients are present, so that it knows what and how much to secrete for their digestion.

Many people suffer simultaneously from amino acid deficiency, and the consequences of putrefaction of undigested protein in the intestine, even though they eat plenty, if not too much protein, because their stomach does not produce the amount of hydrochloric acid that is needed for proper protein breakdown. In fact, this is very common in older people, but it is also a problem in the middle aged and even in young adults. This problem can be partially remedied by taking hydrochloric acid supplements with protein meals, an approach that works very well for the elderly, but addressing the fundamental issues that lead to digestive dysfunction is obviously most important. The digestion of fats and carbohydrates is entirely different.

Simple carbohydrates eaten on an empty stomach will move out of it and into the intestine in a matter of minutes. This is why blood sugar levels go up almost instantly when we eat or drink simple carbs like whole fruit or fruit juice. Starchy carbohydrates begin to be broken down into sugar when they come into contact with those enzymes in the mouth whose purpose it is to do this (primarily amylase), and will be broken down completely over the course of a few hours, not in the stomach, but in the small intestine.

The same goes for fat: fat or oil by itself eaten on an empty stomach will swiftly move to the small intestine as it does not need an acidic environment, and thus simply does not need to stay in the stomach. But unlike carbohydrates, fats need to first be emulsified into droplets that can mix in the watery environment of the small intestine. This is done by the bile produced by the liver, but stored and secreted by the gall bladder into the small intestine. The emulsified triglycerides are then broken apart by pancreatic lipase that separates the glycerol backbone from the three fatty acids. The free fatty acids are absorbed in the small intestine and into the bloodstream by passive diffusion (as is water).

Another important difference between the digestion of carbohydrates and fats is that while it is no problem at all for fat to sit in the stomach for hours, together with the protein being broken down by the acidic chyme, carbohydrates, and especially simple carbs, start to ferment very quickly if they do not move out of the stomach. This is what gives rise to the characteristic bloating that we feel when we eat simple carbs together with other foods, but especially when combined with any kind of protein, the best example of which is having sweet things either with or after a large meal that typically contains plenty of protein, such as the terrible habit of having fruit after the meal, as is done in most western countries, as opposed to the much wiser habit of eating the fruit as a starter, before the meal, as is done in some other cultures. Bloating, burps, gas, stomach aches, etc, as well as really bad digestion followed by really poor absorption all result from the fermentation of the simple carbs that remain in the stomach for longer than a few minutes, as they normally would, before passing to the small intestine, as well as the incompatibility of various digestive enzymes, each with its own specific nutrient to break down, released into the intestine by the pancreas, all trying to do their work, but clashing against one other in the process.

Therefore, to properly digest protein there should be no simple or starchy carbohydrates in the stomach for the entire breakdown process that lasts about 3-4 hours for a normal (smallish) meal. In addition, there should not be any alkalising liquids like alkaline water, sodium bicarbonate water, lemon water, or green juice in the stomach, because they will work to neutralise the acid needed to break down the protein, and thus cause bad digestion and stomach aches. You can try any of the combinations described here if you want evidence through personal experience, but I’m sure you have experienced most of them at various times, although most probably unaware of it. I guarantee that it works in exactly the same way for everyone, even if some are definitely more sensitive than others.

In case you don’t know or don’t remember from other articles, I think no one should consume simple or starchy insulin-stimulating carbohydrates because their consumption in any amount inevitably damages body and health in any one of several very predictable ways. The reason why I am emphasising these points about carbohydrate digestion is not only because the majority of people in the world get most of their calories from insulin-stimulating carbohydrates, but also because these carbohydrates are most disruptive to digestive health in many more ways than we tend to know or consider.

I have written recently in the article Detoxification about the disastrous consequences on the digestive system of a diet consisting mostly of simple or starchy carbohydrates, all of which are caused by chronic acidosis of the intestine. To recover from or avoid these digestive disorders and the diseases that result from them, it is of paramount importance to, on the one hand, eliminate these acid-forming sugars and starches, and on the other, alkalise as much as we can the intestinal tracts on a continual basis, day after day, and year after year.

The natural consequence of these facts and considerations is that the most healing and health-promoting of diets is one that consists primarily of alkalising drinks and foods—alkaline water, green juices, lemon water, and green and leafy vegetables—and in which energy needs are covered by the best fats—coconut oil, raw grass-fed butter, wild fish and meats, and whole, soaked nuts and seeds—with protein consumption kept to the essential minimum based on individual needs.

Water is exceedingly important for digestion, and I have written about this in Why we should drink water before meals. The two most crucial roles of water in the digestive process are: First, to provide the stomach the level of hydration needed to make, maintain and adjust the thickness and consistency of both the layer of mucus that protects the lining of the stomach from the corrosive acidic secretion required for the breakdown of protein, and for of the chyme itself during the initial phases of digestion when it is churned by the stomach. Second, to provide the pancreas the required hydration for it to be able to produce the all-important pancreatic fluid (bicarbonate solution) whose purpose is to neutralise the acidic chyme once it is transferred from the stomach to the small intestine, as well as to carry the enzymes produced by the pancreas to break down those foods that do not themselves carry and provide the enzymes needed for their proper digestion.

As is always the case for everything that relates to health, we can only truly understand by understanding the physiology—how things work. The digestive system is the one around which all other systems are arranged because the health and survival of the organism as a whole depends entirely on it. And the key to optimal digestion and health is the understanding that the stomach only needs to be acidic when there is protein in it, the intestine must always be alkaline, and the digestive system as a whole always requires a good supply of water.

Therefore, we should aim primarily to alkalise and hydrate by drinking lots of alkaline mineral and chlorophyll rich drinks together with liberal but appropriate amounts of unrefined sea salt (see How much salt, how much water, and our amazing kidneys); consume plenty of fat; always consume protein either by itself, with fat or with green vegetables, but never with simple or starchy carbohydrates; if you eat simple carbs such as sweet fruit, make sure you eat it by itself on an empty stomach; and always make sure that when you eat protein, the environment of the stomach is kept acidic, and thus do not have any alkalising liquids for at least 60 minutes before and 3 hours after the protein meal, but also make sure to have at least half a litre of plain water, at least half an hour before eating.

Keeping to these simple principles will ensure optimal digestion, optimal digestive health, and optimal overall health, day and day, and year after year, throughout life, from childhood to old age.

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Why we should drink water before meals

We all need to drink at least about two litres of water every day. Not juice, not sodas, not coffee, not tea: plain water. None of these other liquids have the properties of water, nor do they have the desirable effects of water on the body. Most of us don’t however, and so we are chronically dehydrated. Whether it is 75% or as high as 90%, it is evident that a very large portion of the population is chronically dehydrated.

The digestive system can be viewed as the most fundamental because everything used to sustain life in the body goes through it. In a very real sense, we are a digestive system, supplemented by a central nervous system and refined sense organs to allow us to devise ways to get food (and avoid being eaten), coupled to a refined locomotor system to allow us to gather the food (and run away when it is needed). Since every component of every cell in the body is made from the nutrients in our food, it is obvious that everything in the body depends on the digestive system. And for the digestive system, the single-most important element is the presence of ample amounts of water.

As soon as we even think about eating, the digestive system starts to get ready. The pancreas secretes a little jolt of insulin just in case carbohydrates come in, and the stomach starts to produce the highly acidic digestive gastric juice (pH of 1-2). This gastric juice is composed of only a little bit (0.5%) of hydrochloric acid (HCl) and a lot of salt, both sodium chloride (NaCl) and potassium chloride (KCl). The stomach has sensor cells to know exactly how much protein, fat and carbohydrates are present at any given time, and thus can adjust the production and composition of the gastric juice.

Although present in very small amounts, the hydrochloric acid is the essential compound for activating the enzymes responsible for breaking down protein, which is its main purpose because both fats and carbohydrates are mostly broken down in the intestine. But to make it to the stomach without causing any damage along the way, the two constituents of this highly corrosive acid, the hydrogen (H) and the chlorine ions (Cl), are produced separately and transported to the inside of the stomach where they combine to form the acid.

The delicate lining of the stomach with all its different kinds of highly specialised cells, is protected from the acidic gastric juice by an alkaline layer of mucus. This mucus is between 90 and 98% water, with some binding molecules and a few other components. It can be regarded as a blanket of water whose primary role in the stomach is to protect its lining from the gastric acid. The very thin mucosa that produces and maintains the mucus layer, also secretes sodium bicarbonate that sits in it, and neutralises the acid upon contact when it penetrates the layer, leaving only sodium chloride (salt), water and carbon dioxide. The neutralisation reaction is simple: HCl + NaHCO3 -> NaCl + H2O + CO2.

As we get progressively more dehydrated, not only are the stomach cells incapable of releasing adequate amounts of water into the stomach in order to allow for the proper mixing of the food and acid into chyme with the optimal consistency, but the thickness of the protective mucus layer decreases, thus allowing the acidic contents to damage the fragile lining. This is what eventually leads to stomach ulcers, according to a well known specialist in the matter, Dr Batmanghelidj, author of Your Body’s Many Cries for Water.

The contents of the stomach are churned and blended between one and three hours depending on the amount and composition, until the chyme is liquified and smooth, at which point it is poured into the duodenum, the first part of the small intestine. It is in the small intestine that the real work of the break down and absorption of nutrients into the bloodstream takes place over a period of about 24 hours. The sensor cells in the duodenum will immediately determine the pH and composition of the chyme in order to send the messenger hormones to the pancreas to secrete the right amount of the alkaline, watery sodium bicarbonate solution necessary to neutralize the acid, and to the liver to secrete the right amount of bile needed for the breakdown of fats.

And even though the pancreas is known primarily for its role in producing and secreting insulin needed to clear the bloodstream of sugar, it is arguably its role in secreting this alkaline solution that is the most important. Indeed, as the duodenum does not have a protective layer of mucus as the stomach, it is this sodium bicarbonate solution that protects it and the rest of the small intestine from the devastating effects that the highly acidic chyme can have on it.

However, just as even partial dehydration causes the protective mucus layer in the stomach to dry out and shrink, making it permeable to the gastric acid that eats away at the delicate soft tissues, dehydration also causes the pancreas to be unable to secrete as much of the watery sodium bicarbonate solution as is required to fully neutralise the acidic chyme that, therefore, also damages the intestine. In fact, that there are several times more cases of duodenal as there are stomach ulcers attests to the reality that the lining of the intestine is all that much more fragile as it is unprotected and thus directly exposed to the excessively acidic chyme.

Therefore, water is of the utmost importance in protecting the lining of the stomach and intestine from the acid required for the break down of proteins into amino acids. Water is of the utmost importance for proper digestion and absorption of the nutrients in the food. And hence, water is of the utmost importance in maintaining a healthy digestive system meal after meal, day after day, and year after year throughout our life.

We must make sure that the body and digestive system are properly hydrated before eating. And for this, all we need to do is drink half a litre of plain water 30 minutes before meals, and not drink during nor after the meal for two to four hours.

Drinking during or soon after a meal will only dilute the chyme, making it excessively watery. This will not lower the pH, because water does not neutralise acid. It is best to ensure proper hydration prior to the start of the digestive process, providing the water necessary for the mucosa and pancreas to function optimally, and allow the stomach to adjust the water content of the chyme on its own. I personally usually wait two hours after a snack or small meal, and at least three to four hours after a large meal.

The time needed for the chyme to leave the stomach through the pyloric sphincter and enter the duodenum depends on its amount and composition. For example, fruit or any other food consisting mostly of simple sugars eaten on an empty stomach will make it into the intestine, and the sugar into the blood, in a matter of minutes: Since there is no protein, no acid is required for its breakdown in the stomach; and since there is no fat, no bile is required to break it down in the intestine.

Naturally, the time needed for the stomach to process a small meal will be less than that needed to process a large meal of more or less equal composition. In fact, given that our stomach is a very small pouch with an empty volume of about 50 ml, and a full volume of about 1 litre (up to a max of 2-3 litres when it is really extended),  the time needed for large meals increases substantially and disproportionately compared to smaller meals.