Do you know the feeling? You have eaten a protein-rich meal — after training, perhaps, or in the evening — and you feel bloated and heavy, with an uncomfortable tightness across the stomach. Bloating isn't only an aesthetic annoyance; it's uncomfortable too. It's also worth looking at the form the protein comes in. Hydrolysed collagen has already been broken down into short peptides.
The digestive dilemma — why ordinary protein often causes bloating
Many digestive complaints start with the laborious, complex process of breaking protein down. For that, it helps to look at the steps in protein digestion where gas can form.
The challenge of digesting protein in the small intestine
The work of breaking down complex, intact proteins
Ordinary, intact proteins — from meat, milk, nuts or plants — consist of long, complex amino acid chains held together by strong peptide bonds. To break these proteins into bioavailable parts, your stomach first has to produce a high concentration of stomach acid (hydrochloric acid at low pH) to denature the protein structure. The protein is then broken down further by pepsin in the stomach and, in the small intestine, by pancreatic enzymes such as trypsin and chymotrypsin. This breakdown is a demanding step in digestion.
Enzyme shortfall, stress and creeping intolerance
How well this breakdown works can depend on several factors:
- Age: the production of stomach acid and digestive enzymes naturally slows.
- Chronic stress: activating the sympathetic nervous system (fight or flight) suppresses the parasympathetic rest-and-digest function, which sharply reduces enzyme secretion.
- Illness: conditions such as chronic gastritis, pancreatic insufficiency or a shortage of the micronutrients needed for enzyme synthesis all worsen the breakdown.
The immediate consequence: complex proteins are incompletely digested and remain as large, unusable fragments.
What actually causes bloating, in the large intestine
Undigested protein as a feast for putrefactive bacteria
The engine of bloating only starts up in the large intestine. When incompletely broken-down protein fragments pass through the small intestine, they meet putrefactive bacteria in the colon. These bacteria break down the protein instead of useful fibre. When bacteria ferment protein in this way, they produce substances that can be harmful, including ammonia, phenols and hydrogen sulphide.[1]
The extra burden with small intestinal bacterial overgrowth (SIBO)
The situation is particularly difficult with small intestinal bacterial overgrowth (SIBO). Here bacteria sit in the upper small intestine, where they do not belong.
Our hydrolysed collagen has already been broken down into short peptides.
Collagen peptides: protein that arrives pre-digested
Hydrolysed collagen powder has already been broken into small pieces with the help of enzymes. It's a protein source that comes already pre-digested.
The definition: hydrolysed collagen as a pre-digested protein
The biotechnological advantage of hydrolysis and molecular weight
The difference lies in hydrolysis. In this controlled enzymatic process, native collagen (300,000 daltons) is broken into tiny fragments before it ever enters the body. The result is collagen peptides: very small pieces of collagen [2]. So the peptides are already in short chains.
Uptake via a transport system in the gut (PepT1)
These short peptide chains often consist of only two or three amino acids — di- and tripeptides. They do not need to be broken down any further in the small intestine. Instead, the gut takes them up as tiny pieces made of two or three amino acids, via a transport protein called PepT1 that is especially common there [3]. This transport route is a dedicated uptake path for short peptides.
Collagen peptides in the digestive tract
Absorption in the small intestine
How much protein reaches the colon is one of the factors researchers look at when they study gas formation. A review that looked at eleven studies with 805 participants in total reported no side effects for the collagen products used [4]. However, none of these studies was designed specifically to look at digestive complaints.
Free of lactose, fructose and gluten
It contains no lactose — which often causes digestive problems with whey concentrate — no fructose and no gluten. In people with the corresponding intolerance, these substances can trigger symptoms such as bloating. So collagen is a protein source free of these substances.
Glycine and the gut
Collagen supplies amino acids the body uses as building blocks.
Glycine: a building block of the intestinal lining
Glycine as a precursor to the body's own antioxidant glutathione
Glycine makes up around 30% of the amino acids in collagen. Glycine is the simplest amino acid [5]. Crucially, glycine together with cysteine and glutamic acid forms the precursor to glutathione, the body's most important antioxidant. Glycine is one of the three amino acids the body uses to build glutathione. Collagen peptides supply glycine as raw material; no effect on the intestinal lining follows from that.
Glycine and the stomach lining: animal studies
Glycine has been studied in rats in connection with the stomach lining. Researchers measured how much gastric juice was produced, how severe artificially induced damage to the lining was, and how much mucus covered the stomach wall [6]. This mucus forms a protective layer over the stomach lining. Findings from animal models do not transfer to people, and none of this describes an effect of collagen peptides in humans.
Amino acids and stomach acid
In a study of 13 men, of the amino acids tested only phenylalanine and tryptophan raised blood levels of the digestive hormone gastrin; glycine did not [7]. Gastrin prompts the stomach to produce acid. The study tested single amino acids, not collagen. Gastrin is part of the normal regulation of stomach acid; no effect of collagen peptides on digestion can be derived from this.
Putting it into practice
Here's how to fit collagen into your day.
Optimal dosing and when to take it
The daily amount
The amounts used in studies vary with the question being asked. Other studies use higher amounts.
Regularity and timing
Timing (morning, evening or after training) is secondary, as long as you reach your daily dose.
If you have a sensitive stomach, the ingredient list of the Kollagen Institut collagen is worth a look. It is free of lactose, gluten and fructose.
Combining collagen
Probiotics and vitamin C
Some people combine collagen with probiotics and vitamin C.
- Probiotics supply the gardeners — the beneficial bacteria.
- Collagen supplies the amino acid glycine, which makes up around a third of its amino acids.
- Vitamin C contributes to normal collagen formation for the normal function of skin, bones and cartilage.
Collagen and drinking enough
A common cause of bloating is constipation. When taking collagen, make sure you drink enough. Fluid generally makes passage through the gut easier.
Conclusion
The summary
Collagen and digestion
Collagen peptides come in an already pre-digested form. Glycine, meanwhile, makes up around 30% of the amino acids in collagen.
Our collagen peptides are hydrolysed, meaning they have already been broken down into short pieces.
To finish
When you choose, look at quality and origin.