Porous silica particles made from pure sand could one day play a role in weight loss efforts.
Previous clinical trials have already produced promising results, but the actual weight loss mechanism underlying the potential treatment is not fully understood.
To explore key variables, the researchers tested different sizes and shapes of silica in a simulated human gut after a heavy meal.
The findings support the idea that porous silica can “disrupt digestion,” which is normally catalyzed by enzymes that break down fats, cholesterol, starches, and sugars in the stomach and intestines.
In addition, the size of ingested nanoparticles appears to determine the degree of digestive inhibitory activity.
The researchers admit that their model is too simple to fully mimic the intricacies of the human gut during digestion, but given the ethics involved in human clinical trials, gut modeling and animal models are as close as researchers can get.
Unlike other human gut models, this new model represents both fat digestion and carbohydrate digestion. The researchers also analyzed the degree of absorption of organic substances by the digestive system.
Porous silica has the potential to reduce weight gain in other ways, but the new results provide additional research with a more reliable starting point.
In 2014, researchers found that mice fed a high-fat diet gained significantly less weight when given nanoporous silica particles (MSPs). The percentage of total body fat has also decreased. However, this effect seems to depend on the relative size of the silica particles used. In the end, larger particles proved to be more effective.
Subsequent studies in mice confirmed these findings. It appears that the appropriate size and shape of the porous silica particles determine the ability of mice to digest food in the small intestine.
And in 2020, the first clinical data on 10 healthy obese people showed that MSPs can lower blood glucose and cholesterol levels, which are known risk factors for metabolic and cardiovascular complications.
What’s more, the treatment did not cause any abdominal discomfort or bowel changes, which is not the case with modern weight gain drugs such as orlistat.
The current study explains these promising results by comparing a set of 13 porous silica samples with different widths, sorption potential, shape, size, and surface chemistry.
Each of these samples was exposed to a model of the human gastrointestinal tract, which mimicked the nutritional state after ingestion of a meal rich in carbohydrates and fats. The model was allowed for half an hour of gastric digestion and an hour of intestinal digestion and absorption.
Fat digestibility was monitored by titration of absorbed fatty acids, while starch digestion was monitored by measuring the concentration of absorbed sugars.
The researchers say the ideal silica samples were fine silica particles with pores 6 to 10 nanometers wide. These volumes seem to inhibit the enzymes that are best studied.
And it seems that pores do more than just trap enzymes. Researchers believe that everything is much more complicated. For example, some pores that were optimally sized to prevent starch digestion were too large to optimally trap enzymes involved in fat digestion.
It also appears that the porous sand particles absorb both digested and undigested nutrients from the digestive tract before they enter the system’s bloodstream.
This may be another way molecules resist calorie intake. Those particles that have a large surface but smaller pores, unable to influence digestive enzymes, actually absorb most of the organic matter in the models.
More studies in animal models will be needed to replicate these results. Perhaps then the proposed mechanism will be tested in human clinical trials.
The study was published in a journal. Pharmacies.
Source: Science Alert.