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Sugars and Proteins in Gastric Digestion

by luciano

 

A high intake of refined sugars, especially when highly concentrated or in liquid form, sometimes consumed together with protein-rich meals, may under certain conditions contribute to rapid gastric emptying. This condition often leads to diarrhea, nausea, and abdominal cramps. In addition, a high intake of sugars can alter the gut microbiota (dysbiosis) and, over time, compromise the intestinal barrier.

Rapid gastric emptying (Dumping):

Sugars and high–glycemic index foods can trigger a rapid emptying of gastric contents into the small intestine.

Impaired digestion:

Rapid transit prevents proper breakdown of food, allowing incompletely digested food and nutrients to reach the small intestine, with possible subsequent bacterial fermentation.

Alterations of the gut microbiota:

Excess sugar can modify the intestinal microbiome and damage the intestinal barrier.

Increase in inflammation:

The combination of undigested food, fermentation, and a compromised intestinal barrier can promote local and systemic inflammation.

Symptoms:
This process often manifests with diarrhea, discomfort, and bloating.

Properly managing nutrition by avoiding excessive gastric overload with high-sugar foods is essential for maintaining good digestive health.

Both proteins and sugars (especially at high concentrations) significantly slow gastric emptying, i.e., the process by which food leaves the stomach and enters the small intestine. Proteins are particularly effective in slowing this process, contributing to glycemic control and increased satiety.

Key Details on Gastric Emptying

Impact of proteins:

Proteins are known to slow gastric emptying, often by stimulating intestinal hormones such as CCK and GLP-1, which inhibit gastric motility.

Impact of sugars/carbohydrates:

High concentrations of sugar (glucose) are powerful in slowing gastric emptying, helping prevent rapid influxes of large volumes of content into the small intestine.

Meal combination:

Combining proteins and carbohydrates (as in the case of dessert) results in more stable and slower digestion compared to consuming sugar alone.

Mechanism:
The presence of nutrients (proteins, fats, and sugars) in the duodenum activates feedback mechanisms that signal the stomach to empty more slowly.

Therefore, the consumption of proteins or sugars (such as in dessert) induces the stomach to retain food longer, resulting in a more gradual release of glucose into the bloodstream.

The “Dessert Stomach” Phenomenon

The “dessert stomach” phenomenon—the feeling of being full but still having room for dessert—is determined by sensory-specific satiety (feeling full only for one type of food) and by a physiological relaxation reflex that creates space in the stomach. When the palate is tired of savory flavors, the brain seeks sugar to feel satisfied, allowing a small indulgent portion to appear as the perfect conclusion to the meal.

Main reasons for this sensation include:

Sensory-specific satiety:

One feels “full” of savory foods, but the sensory desire for sweet/fatty or energy-dense foods persists, allowing further eating.

Physical relaxation reflex:

Upon tasting sweet or pleasant foods, the brain signals stomach muscles to relax, literally creating space for dessert.

Brain reward circuits:

Sugar stimulates dopamine release, pushing the brain to override satiety signals in order to obtain gratification.

Delay in satiety signals:

Satiety hormones take 20–40 minutes to fully exert their effects. Dessert often arrives before the brain has completely registered that the main meal was sufficient.

Faster digestion:

Sugary foods often pass through the stomach faster than proteins or fats, making a small portion feel less “heavy” and more like a simple “filler.”

How to Interpret These Apparently Contradictory Statements

✅ 1. Under normal conditions: proteins and carbohydrates slow gastric emptying

This part is correct:

  • Proteins → stimulate intestinal hormones (CCK, GLP-1, PYY)

  • Carbohydrates → especially if complex or in moderate amounts

Result → the stomach slows emptying.

This is a physiological protective mechanism:

The stomach tries to avoid large amounts of nutrients arriving all at once in the small intestine.

Therefore:

  • Mixed meal (proteins + carbohydrates)

  • More gradual digestion

  • More stable blood glucose

  • Greater satiety

This is standard behavior in healthy individuals.

⚠️ 2. Under particular conditions: high-osmolarity sugars may favor rapid emptying

This part is correct.

Proteins stimulate intestinal hormones such as CCK, GLP-1, and PYY.
Carbohydrates—especially when complex and consumed in moderate amounts—also activate regulatory mechanisms that slow gastric emptying.

The result is a physiological protective response:
the stomach limits the speed at which nutrients are delivered to the small intestine in order to optimize digestion and absorption.

Therefore, a mixed meal containing proteins and carbohydrates typically leads to:

  • More gradual digestion

  • More stable blood glucose levels

  • Greater and longer-lasting satiety

This represents standard physiological behavior in healthy individuals.

gh-osmolarity sugars may favor dumping

The first statement refers to a pathological or para-physiological phenomenon, typical especially when:

  • Sugars are very concentrated

  • In liquid or semi-liquid form

  • In large quantities

  • Sometimes after gastric surgery

  • Or in individuals with intestinal sensitivity

Here the problem is not “sugar slows or accelerates,” but rather:

Highly concentrated sugar solutions create a strong osmotic gradient.

This can:

  • Partly override normal slowing mechanisms

  • Favor rapid passage of hyperosmolar contents into the intestine

The term “dumping” in this context is often used broadly, not always as the classic clinical dumping syndrome.

Fundamental Difference

Situation

Predominant Effect

Solid mixed meal, moderate quantities

Slowed emptying

Concentrated sugary beverage, large quantities

Possible rapid emptying

Sugar + fiber + fats + proteins

Slowing

Sugar alone in solution

Faster

Why Can Both Occur?

The stomach regulates emptying through two opposing forces:

  1. Hormonal signals → slow emptying

  2. Osmotic pressure and volume → can accelerate emptying

If osmotic load is extremely high, regulatory control can be partially bypassed.

Microbiota and Inflammation

There is no contradiction here:

Chronic high intake of simple sugars →

  • Favors dysbiosis

  • Increases fermentation

  • May alter the intestinal barrier

This can occur even if gastric emptying is slow.

They are independent processes.

Final Synthesis

✔️ It is true that proteins and carbohydrates normally slow gastric emptying
✔️ It is also true that highly concentrated sugars, especially liquids, may promote rapid passage
✔️ They are not mutually exclusive: they depend on context and food form

Short version: In a normal meal, proteins and carbohydrates slow emptying.
With large amounts of concentrated sugars (especially liquid), osmotic effects may favor rapid passage.
Both statements are therefore correct, but refer to different physiological scenarios.

Why Smaller, More Frequent Meals Work Better

by luciano

When you eat a very large meal, several things happen:

  • The stomach stretches significantly

  • Blood flow to the digestive system increases

  • A strong hormonal response is triggered (insulin, incretins, etc.)

This can lead to:

  • Sleepiness or drowsiness

  • Mental “fog”

  • A feeling of heaviness

Dividing total calorie intake into several moderate meals:

  • Reduces the digestive load of each single meal

  • Helps keep blood glucose more stable

  • Promotes more consistent energy throughout the day

Better several balanced meals than one very large one.

✅ “Finish eating and not feel your stomach”

This phrase describes an ideal state very well:

  • Not full

  • Not empty

  • No tension or weight

In practice: light satiety, not “fullness.”

A good indicator is stopping when you feel satisfied but could still eat a little more.

This approach:

  • Improves digestion

  • Reduces reflux and bloating

  • Supports mental focus

What causes post-meal “mental fog”

It often results from:

  • Excess calories

  • Too many simple sugars

  • Very high-fat meals

  • Heavy combinations

It’s not only about quantity, but also quality.

How to make a meal easier on the stomach

  • Moderate portions

  • Lean proteins

  • Complex carbohydrates

  • Cooked or raw vegetables in a tolerable amount

  • Chew slowly

  • Avoid large late-evening meals

⚠️ An important clarification

Eating more often does not mean eating continuously.

It’s better to think in terms of:

  • 3 main meals

  • 1–2 snacks (if needed)

The key point is: a manageable digestive load at each meal.

Difference Between Ancient and Modern Grains

by luciano

 

Science indicates that the real difference between ancient and modern wheat does not lie primarily in the total amount of protein, but rather in its quality and structural organization.

A – Scientific Evidence (CREA, University of Bologna, MDPI): Summary of Main Findings

1. Gluten Strength (W Value)

The most marked difference concerns rheological properties, meaning how dough behaves.

  • Modern Wheat:

  • Selected for strong gluten (high W, often between 200 and 400). This creates a tenacious and elastic gluten network, ideal for industrial baking and pasta-making.

  • Ancient Wheat:

  • Characterized by weak gluten (low W, often between 20 and 90). The gluten network is more fragile and less elastic, making mechanical processing more difficult but, according to some studies, making proteins more easily accessible to digestive enzymes.

2. Gliadin/Glutenin Ratio

Gluten consists mainly of two protein fractions:

  • Gliadins – responsible for extensibility and for celiac toxicity

  • Glutenins – responsible for elasticity and dough strength

MDPI research shows that ancient wheats (such as einkorn and spelt) often have a much higher gliadin/glutenin ratio than modern common wheat.

Consequence:
This explains why ancient-grain doughs are stickier and less capable of retaining fermentation gases, producing breads with lower volume.

3. Gluten Quantity and Toxicity

Contrary to popular belief, ancient grains do not necessarily contain less gluten.

  • Protein content:

  • Many ancient varieties contain higher protein levels (14–18%) than modern wheat (11–14%).

  • Celiac disease:

  • Studies from CREA and Fondazione Veronesi confirm that ancient grains contain the same toxic epitopes (and sometimes in greater quantity) as modern wheat. Therefore, they are not safe for people with celiac disease.

  • Non-Celiac Gluten Sensitivity (NCGS):

  • Some research (e.g., Prof. Spisni, University of Bologna) suggests that the different gluten structure and the presence of other compounds (such as polyphenols) in ancient grains may reduce intestinal inflammation markers in non-celiac sensitive individuals.

Synthetic Comparison Table

Feature

Ancient Grains (e.g., Senatore Cappelli, Verna)

Modern Grains (e.g., Manitoba, Creso)

Gluten strength (W)

Low (20–90)

High (200–450)

Elasticity

Very low

Very high

Digestibility (non-celiac)

Potentially higher

Standard

Yield per hectare

Low

High

Plant height

Tall (>150 cm)

Short (60–80 cm)

B – Comparative Study on Gluten Protein Composition of Ancient and Modern Wheat Species

(Geisslitz et al., 2019 – Foods, MDPI)

Study Design

  • 300 cereal samples

  • 15 cultivars per species (einkorn, emmer, spelt, durum wheat, common wheat)

  • Grown in four locations to eliminate environmental variability

Key Findings

Quantity vs Quality

Ancient species show higher total protein and gluten content than modern common wheat.

Gliadin/Glutenin Ratio

Modern wheat contains much higher glutenin levels, responsible for dough strength.
Ancient species exhibit extremely high gliadin/glutenin ratios (up to 12:1 in einkorn vs <3.8:1 in modern wheat).

Technological Weakness

This produces weak gluten incapable of forming a strong network, resulting in lower bread volume but a simpler protein structure.

Conclusion
Modern breeding did not increase gluten quantity but profoundly changed its polymeric quality to enhance industrial performance.

C – Differential Physiological Responses to Ancient vs Modern Wheat (Spisni et al., 2019)

1. The Nutritional Paradox

From a biochemical standpoint, ancient and modern wheat are very similar in macro- and micronutrients.
However, human clinical responses differ markedly.

2. Inflammatory Response and Gluten Strength

  • Modern Gluten:

  • Highly polymerized, strong, and resistant to human digestive enzymes.

  • Ancient Gluten:

  • Structurally weaker and less polymerized, therefore more easily fragmented during digestion, reducing exposure to pro-inflammatory peptides.

3. Anti-Inflammatory and Antioxidant Effects

Clinical trials show that replacing modern wheat with ancient wheat leads to:

  • Reduced pro-inflammatory cytokines (IL-6, TNF-α)

  • Improved metabolic parameters (cholesterol, blood glucose)

4. Role of the Gut Microbiota

Ancient grains promote growth of beneficial bacteria producing short-chain fatty acids (SCFAs) such as butyrate, which:

  • Strengthen the intestinal barrier

  • Reduce intestinal permeability (“leaky gut”)

5. Study Conclusions

Ancient grains are not suitable for celiac disease, but represent a superior choice for:

  • Non-celiac gluten sensitivity

  • Irritable bowel syndrome

  • Healthy individuals seeking to reduce baseline inflammation

Final Synthesis

The industrially desirable technological strength of modern wheat gluten appears to be the main factor placing stress on the digestive and immune systems.

Ancient grains do not contain less gluten—but their gluten is structurally simpler, less polymerized, and potentially more digestible, which may explain their better tolerance in many individuals.

Integrated Approach to Reducing Low-Grade Chronic Inflammation

by luciano

(Low-grade chronic inflammation is not a disease in the strict sense, but a persistent biological state that promotes the development of numerous chronic conditions. This document proposes an integrated approach aimed at modulating it through lifestyle.)

Furthermore:
In the absence of unique and definitive solutions, the most rational strategy for reducing low-grade chronic inflammation consists of adopting a lifestyle model that minimizes exposure to potentially pro-inflammatory factors* and promotes protective ones.

The importance of low-grade chronic inflammation

Although intermittent increases in inflammation are essential for survival during physical injury and infections, recent research has revealed that certain social, environmental, and lifestyle-related factors can promote chronic systemic inflammation, particularly low-grade chronic inflammation (LGCI), which in turn may lead to several diseases that, taken together, represent the leading causes of disability and mortality worldwide, such as cardiovascular diseases, cancer, diabetes mellitus, chronic kidney disease, non-alcoholic fatty liver disease, and autoimmune and neurodegenerative diseases.
(see article: https://glutenlight.eu/2025/08/21/infiammazione-cronica-basso-grado/)

This type of inflammation has multiple triggers:

Gut dysbiosis:

Alteration of the intestinal bacterial flora, which may be caused by an unbalanced diet, excessive use of antibiotics, or other toxic substances.

Unhealthy diet:

Excessive consumption of processed foods rich in refined sugars and saturated fats, which can promote inflammation.

Stress:
Chronic stress can negatively affect the immune system and increase susceptibility to inflammation.

Environmental pollution and toxins:

Exposure to chemicals present in the environment or in foods can contribute to oxidative stress and inflammation.

Smoking and alcohol:

These factors can aggravate oxidative stress and damage cells, promoting inflammation.
(see article: Oxidative stress)

Among the triggers, drug use is not mentioned because drugs are always and in any case considered to be avoided.

The integrated approach must necessarily involve the individual in all aspects of life. This is the central point: a lifestyle model must be “built.” And this model must be personalized.

Another consideration concerns the individual’s general health status, which should primarily remain “healthy,” that is, free from diseases, trauma, wounds, etc., which activate acute inflammation.

It is important to emphasize that, in the presence of acute inflammation, the biological markers used to assess low-grade chronic inflammation appear elevated, making it difficult to distinguish between the two phenomena and potentially masking improvements in LGCI.

With these clarifications, we can begin the integrated approach.

1 – Stress management

This is a very important factor, considering emerging scientific evidence regarding the gut–brain axis, a bidirectional communication system through which psychological stress, emotions, and mental states influence intestinal motility, barrier permeability, and microbiota composition, and vice versa. Alterations of this axis can promote inflammation, digestive disorders, and metabolic imbalances.
Stress should be managed either independently using available techniques or, if not possible, with the help of a psychologist.

2 – Environmental pollution (air, water, etc.)

It goes without saying that the more we can avoid it, the better. This factor is relevant to oxidative stress.

3 – Nutrition: here we can do a lot

Important point:

Diet must be strictly correlated with age, type of activity, eating habits, and general health status.

Foods to avoid

  1. Industrial foods: contain additives that, if taken occasionally and individually, do not cause problems, but if combined together may exert a more or less marked pro-inflammatory action depending on the subject’s health status [A].

  2. Industrial beverages: generally contain many sugars/sweeteners/additives.

  3. Many gluten-free products (especially industrial ones) are highly processed and contain additives (often many) that, if taken occasionally and individually, do not cause problems, but if combined together may have a pro-inflammatory action depending on the subject’s health status.

Foods to consume in moderation

  1. Wine/beer: in moderation.

  2. Alcoholic beverages: on rare occasions (spirits: NO).

  3. Coffee: in moderation.

  4. Processed meats: with great moderation.

  5. Sweets: in moderation. If there are issues with sugars (weight or glycemia), they must be consumed in appropriate amounts to avoid problems.

  6. Cheeses: with great moderation and in amounts compatible with the individual (if lactose/casein intolerant).

  7. Spices: in moderation.

  8. Gluten: in moderation. If possible, whole-grain/partially whole-grain pasta; bread: if possible, whole durum wheat/spelt. Soft wheat contains a gluten component that is very difficult to digest (33-mer). Considering the relationship between gluten strength and digestibility, products made with grains that have less tenacious gluten should be preferred. Among “ancient grains,” many with this characteristic can be found (in reality, even among modern grains there are cultivars with less tenacious gluten, often used for pastries rather than bread). These should be preferred.

  9. Those who are gluten intolerant but not celiac, considering that this intolerance is “dose-dependent,” can, with the help of a physician, try to identify the threshold (quantity) that does not cause problems. Grains with less tenacious gluten facilitate the possibility of consuming products made from them. Further reading: Difference between ancient and modern grains (published separately)

Foods to consume in abundance

  1. Fiber (compatible with any intestinal issues): 3–4 times per day.

Separately, the essential contribution of water in maintaining adequate hydration must be remembered.

4 – Eating behaviors

Nutrition rests on two main pillars: quantity and quality.

The quantity of food consumed should be what is necessary for physiological functions plus what is required for activities performed. This simple principle would greatly help maintain a correct and healthy weight. Not easy for two simple reasons: the first is “gluttony,” the second is that the “full/satiated” mechanism is delayed compared to actual fullness; the sensation of satiety does not coincide with real stomach filling but arrives later. Already 50 years ago, family doctors suggested leaving the table with a slight desire for more food.

Quality: it goes without saying that the more genuine and “clean” (i.e., free of toxic substances) foods are, the better.

The following should also be considered a general framework because, as stated, it must be “designed around the individual.”

A – Avoid consuming too much food in a single meal

The stomach should be allowed to work (digest) optimally. It is often preferable to eat more frequently rather than having a single very large meal. Ideally, one should finish eating and “not feel the stomach,” with the result of no postprandial “fog.”
Further reading: Why smaller, distributed meals work better (published separately)

Food that is not completely digested, in healthy individuals*, is subsequently processed in the intestine and then expelled. However, if the gastrointestinal system is compromised or altered, the passage of inadequately digested substrates into the intestine may promote bacterial fermentation and be pro-inflammatory. (https://glutenlight.eu/2025/06/12/cibo-non-digerito-e-infiammazione-intestinale/)

Not only the stomach, but also and especially the intestine must be able to function optimally and continue digesting food in order to make it absorbable. [B] [C]
*The critical point here is: does a truly healthy individual still exist?

B – Avoid mixing very different foods

The stomach works in an acidic environment, where pepsin digests proteins (further digested in the intestine by trypsin and other enzymes). Sugars begin digestion in the mouth (ptyalin) and are then mainly digested in the intestine (pancreatic amylase). Some clarifications are necessary:

Carbohydrates and proteins in the stomach generally do not cause problems.
A pasta course followed by fish, meat, cheese, and perhaps vegetables, in amounts appropriate to one’s digestive capacity, does not cause problems.

If the second course is very fatty, gastric digestion slows and, depending on quantity, gastric emptying may be delayed, with possible passage of incompletely digested food into the intestine.

The situation is different if a dessert is included.

Here we face a significant amount of simple sugars, not complex carbohydrates (pasta, for example, is mainly starch, and only part of it is transformed into sugars already in the mouth; therefore, mainly starch reaches the stomach).

Sugars are not digested in the stomach except to a negligible extent:

“The stomach has a highly acidic environment that prevents fermentation there; the undigested sugars travel to the small intestine and large intestine, where they are fermented by the gut bacteria.”

Dessert at the end of a meal (intended as a moderate portion) does not cause problems in a healthy person (who today is relatively rare), but it makes digestion more difficult for many people, not only because of possible subsequent intestinal effects, but also due to the sensation of heaviness that may appear.

It should be clarified that this is not a dogma: there are people who digest practically everything without difficulty—we are all different.

Age also plays a fundamental role. Elderly individuals tend to feel better when meals are simpler.
Further reading: Sugars and proteins in gastric digestion (published separately)

Important point

In the presence of diet-related pathologies, the intervention of a specialist (dietitian or nutritionist) is strictly necessary.

5 – Specific behaviors

  1. Engage in physical activity, even moderately.

  2. If working, avoid work that leads to stress. Stress must be managed, otherwise it becomes a cause of low-grade chronic inflammation.

  3. If overweight, weight must be reduced.

  4. After work, engage in activities that require concentration and, if possible, creativity. Developing projects is highly useful for keeping brain functions active.

6 – Medical evaluations

With one’s physician, define the routine general tests necessary for good monitoring of one’s health, as well as specific tests for any conditions.

Final Summary

We must build a personalized lifestyle model for reducing low-grade chronic inflammation.
In a healthy person, a meal containing proteins and sugars in moderate amounts does not create problems. The association becomes potentially problematic when sugars are highly concentrated, especially in liquid form and in large quantities. In individuals with a sensitive or altered gastrointestinal system, even moderate portions (such as dessert at the end of a meal) may cause digestive discomfort.

The integrated approach to reducing low-grade chronic inflammation is based on the available scientific evidence reported in the bibliography section.

Since many studies show significant associations without demonstrating an absolute causal relationship, a precautionary principle is adopted: reduce or eliminate, where possible, potentially harmful factors, favoring choices with low biological risk.