Sodium butyrate is widely recognized and applied in food and pharmaceutical industries for its significant effects in regulating intestinal flora and repairing intestinal mucosa. However, there has long been a controversial focus in the industry regarding dosage form selection: does uncoated sodium butyrate completely degrade in the stomach, and only coated sodium butyrate can pass through the stomach to function effectively? To answer this key question, this paper provides a comprehensive and in-depth analysis based on scientific research data, combined with the physicochemical properties of sodium butyrate and physiological mechanisms.
I. Uncoated Sodium Butyrate: Can Successfully Pass Through the Stomach and Function Broadly
Sodium butyrate is chemically a short-chain fatty acid salt, with butyric acid as its core functional component. Some hold the view that uncoated sodium butyrate is rapidly absorbed in the stomach and cannot reach the intestine. However, multiple scientific studies have confirmed that this view is inaccurate.
(I) Human Trial: Over 70% of Uncoated Butyric Acid Passes Through the Stomach
A 1991 study by David R. Saunders on the absorption rate of short-chain fatty acids in the human stomach provided direct evidence for the gastric passage ability of uncoated sodium butyrate.
The study used healthy human subjects, who received intragastric infusion of 500 mL simulated meal solution (pH 2.8) containing 40 mM acetic acid, 40 mM propionic acid, and 40 mM butyric acid. Gastric contents were collected 20 minutes later to measure residual levels.
Results showed that the human gastric absorption rate of butyric acid ranged from 19% to 26%, with an average of 23%. This means that at least 77% of butyric acid avoids gastric absorption and successfully passes into the intestine.
Given the similarities in gastric structure and acid secretion between humans and most animals, these findings provide important reference and indirectly prove that uncoated sodium butyrate also has strong gastric passage ability in animals.
(II) Animal Trial: Uncoated Sodium Butyrate Passes Through the Stomach to the Intestine and Systemic Tissues
A 2022 carbon isotope tracing study by Professor Yang Xiaojing’s team at Nanjing Agricultural University further verified the metabolic pathway of uncoated sodium butyrate in animals.
Rats were orally administered isotope-labeled uncoated sodium butyrate. Four hours later, labeled tracer levels were measured in various tissues and excreta.
Results showed significant levels of labeled sodium butyrate not only in the duodenum, colon, and other intestinal segments, but also in the liver, kidney, spleen, brain, leg muscle, abdominal fat, and other systemic tissues. A certain amount was also detected in feces.
This fully demonstrates that uncoated sodium butyrate not only passes through the stomach, but is also absorbed into the bloodstream, distributed to various tissues and organs, and exerts broad biological regulatory effects beyond the digestive tract. The presence in feces further confirms that part of uncoated sodium butyrate remains effective in the intestine after passing the stomach.
Based on the above two studies, it is clear:
Uncoated sodium butyrate can pass through the stomach, reach the intestine and even multiple systemic tissues to exert biological regulatory functions, and is not completely lost in the stomach.
II. Coated Sodium Butyrate: Cannot Achieve 100% Gastric Passage
The core purpose of coating technology is to wrap sodium butyrate with lipophilic materials (e.g., palm stearin, hydrogenated oil) to reduce decomposition and absorption in the stomach, allowing it to reach the intestine.
However, practical studies show that even coated sodium butyrate cannot achieve 100% gastric passage.
A 1993 study by FRÉDERIC CARRIERE on the hydrolysis of fats by gastric and pancreatic lipases revealed the limitations of coated sodium butyrate.
The study found that gastric lipase in the acidic gastric environment hydrolyzes approximately 10% of triglycerides. After entering the duodenum, gastric lipase retains partial activity and further hydrolyzes 7.5% of triglycerides.
Since most coated sodium butyrate uses triglyceride-based coating materials, gastric lipase hydrolyzes part of the coating, causing premature release and absorption of sodium butyrate in the stomach.
This means about 10% of coated sodium butyrate is absorbed in the stomach and fails to reach the intestine.
III. Conclusion and Application Recommendations
– Uncoated sodium butyrate can successfully pass through the stomach, with over 70% of active ingredients reaching the intestine. It can be absorbed and distributed to systemic tissues for broad biological regulation.
– Coated sodium butyrate cannot achieve 100% gastric passage; approximately 10% is hydrolyzed and absorbed in the stomach by gastric lipase.
– Regardless of dosage form, the core functional component is butyric acid, which ultimately exerts physiological effects. Therefore, the effective butyric acid content is the key factor determining product cost-effectiveness.
