Activated charcoal: how does it relieve intestinal gas?

Recap: what causes intestinal gas?

Production of intestinal gas is a normal process that affects everyone. It is primarily caused by the accumulation of ingested air in the gut (mostly taken in when we eat), as well as by the fermentation by gut bacteria of certain non- or low-digestible carbohydrates (such as FODMAPs) (1-2). The resulting gas is then released in the form of flatulence: healthy males, for example, pass wind around 14 times a day on average, mainly after meals (3).

Some people, however, suffer from excessive flatulence. This is normally the result of over-fermentation, abnormally long retention of air in the intestinal tract, or the presence of certain bacteria in the gut flora. Occasionally, it can be caused by malabsorption or a food intolerance.

Though harmless in itself, flatulence is often synonymous with social embarrassment and digestive discomfort. It is sometimes accompanied by bloating, abdominal distension or pressure, loud gurgling (or borborygmi to use the medical term), and even pain in the navel and lower abdomen areas (5).

What exactly is activated charcoal?

Also known as activated carbon, activated charcoal is made from a carbon-rich raw material. This can be either animal-source (bone) or plant-source (wood, coconut shells …)

Unlike the charcoal we use for barbecues, activated charcoal undergoes various treatments which profoundly change its structure. The aim is to increase its surface area and make it more porous.

With lots of small holes in its sponge-like surface, activated charcoal easily captures and retains a whole host of undesirable compounds: this is known as adsorption. As our ancient forebears guessed, it is this property – exploited by Hippocrates himself – which is responsible for its many therapeutic applications, particularly in the areas of decontamination and detoxification (6-7).

This structural transformation takes place in two stages:

• carbonization: here, the carbon is charred at very high temperatures (600°C-900°C) to eliminate impurities and ensure only the charcoaled matrix remains. The initial ‘dimples’, the pores, become wider;
• activation: whether physical (thermal shock) or chemical (use of acids), activation unblocks the pores by removing tar to further increase its adsorbent capacity.

Activated charcoal and flatulence: how does it work?

It’s now recognised that activated charcoal helps to reduce excessive post-prandial flatulence (8). So by extension, it also has a beneficial effect on associated bloating, by relieving the abdominal area of this ‘weight of air’. But how does it actually do this?

Once ingested, activated charcoal reaches the gut intact: it is neither denatured nor altered by digestion (9).

It’s at this point that its adsorption properties come into play. With a negative electrical charge, its outer surface attracts positively-charged particles – including gases and certain toxins – trapping them in its pores. Like a magnet, but on a microscopic scale!

Though it’s tempting to use the sponge metaphor, it’s not strictly accurate. The substances captured do not get through to the heart of the charcoaled structure (unlike water which seeps into the foam of a sponge). They remain on the surface, settling in the cavities created by the activation – like a key entering a lock.

Though neutralised, the adsorbed compounds are not physically destroyed: they complete their journey anchored to the charcoal, right up to the end of the digestive tract, where they are then excreted via stools.

What is the link between activated charcoal and gut flora?

Although the mechanisms responsible require further clarification, activated charcoal may, by trapping certain waste-products in its net, have a direct effect on gut microbiota composition. Scientists are currently investigating its use as an adjuvant to those antibiotics likely to disrupt the balance of bacterial flora (10).

And it seems that an unstable flora with little diversity may be associated with lower tolerance to intestinal gases (11).

Which activated charcoal supplement should you choose?

Depending on the activation process used, activated charcoal has varying degrees of porosity which determines the type of molecule adsorbed. Trapping gases requires very narrow pores (sometimes less than a nanometre) (12).

And the quality of the raw material used influences the number and size of pores obtained (13).

It’s best, then, to opt for a plant-source activated charcoal with a sufficiently granular micropore network, which will ensure more effective adsorption of intestinal gases (the supplement Charcoal, obtained from a resinous wood, is activated to produce ultra-fine porosity).