Glutamine and microplastics: effects on your gut health

Two seemingly opposite topics converge in one conversation about health: glutamine, an amino acid with regenerative properties for the gut and immune system, and microplastics, omnipresent contaminants that accumulate in the body. In this expert discussion, two specialists explore what each does inside the body and what practical steps you can take to protect yourself.

What glutamine is and why it matters

Glutamine is an amino acid the body can synthesize, but under conditions of high physiological stress (intense exercise, inflammation, illness) it becomes conditionally essential. It can be converted into:

• Alpha-ketoglutarate: an energy source for the mitochondria.
• Glutamate: a neurotransmitter.

Glutamine and gut health

The epithelial cells lining the intestine use glutamine as their preferred energy source. When it is in short supply, the integrity of the intestinal barrier is compromised, which can facilitate intestinal permeability and allow bacterial lipopolysaccharides into the bloodstream.

Glutamine restores this barrier rapidly because it provides immediate energy to gut cells for repair. Alongside malate and citrate, which also feed the citric acid cycle, these are among the most effective compounds for maintaining intestinal mucosa integrity.

Glutamine and the immune system

Activated immune cells are heavy consumers of glutamine; they use it as their primary fuel through conversion to alpha-ketoglutarate. In endurance athletes performing high training volumes, glutamine supplementation reduces the incidence of respiratory tract infections.

The typical dose is 5 g per day, which can increase to 10 to 30 g during periods of intense training or illness exposure. People with leaky gut, Crohn's disease, or ulcerative colitis may benefit from higher daily doses under medical supervision.

Does glutamine increase cancer risk?

This is a common concern. Cancer cells also use glutamine as an energy source. However, for this to be a real risk it would require active cancer in the intestine or liver and very high doses. In healthy individuals or those with cancer in other tissues, current evidence does not justify this concern. When in doubt, consult with a physician.

Microplastics: the silent threat

Microplastics are fragments resulting from the degradation of larger plastics by heat and oxidation. They range from 5 micrometers down to nanometer sizes. The smaller they are, the more easily they cross cell membranes and accumulate in tissues.

Microplastics have been found in the heart, brain, blood, and other organs. They are associated with chronic inflammation, cardiovascular disease, and Alzheimer's disease. Exposure is practically unavoidable with current lifestyles.

Plastic-associated chemicals

Beyond the particles themselves, plastics contain chemical additives that leach over time:

• BPA (bisphenol A): when replaced by BPS in "BPA-free" products, it turns out BPS is equally or more harmful. The "BPA-free" label is largely marketing.
• Phthalates: especially problematic during pregnancy; associated with hypospadias, undescended testicles in male children, and increased cancer risk.

Phthalates and BPA are excreted primarily through urine. To accelerate their elimination, the body needs to activate enzymes that convert them into water-soluble metabolites. The most potent natural activator of these enzymes (via the NRF2 pathway) is sulforaphane, found in broccoli and broccoli sprouts.

Human studies show that consuming sulforaphane in the form of its precursor glucoraphanin leads to 60% more benzene (a common air pollutant) being excreted within 24 hours.

Forever chemicals (PFAS)

Per- and polyfluoroalkyl substances have a half-life of years in the body. Their excretion pathway is different: through bile acids. Beta-glucans found in oats and mushrooms may support the excretion of these compounds by facilitating bile acid cycling.

How to protect yourself: fiber as a shield

Fiber is currently the most scientifically supported strategy for reducing microplastic absorption:

• Insoluble fiber (vegetables, whole grains): accelerates intestinal transit, reducing the time available for microplastics to be absorbed. More insoluble fiber means more microplastics excreted in feces.
• Soluble fiber (fruits, artichokes, onions, inulin, oat and mushroom beta-glucans): forms a viscous coating in the gut that traps micro- and nanoplastics, preventing them from crossing the epithelial cells.

Combining both types of fiber creates a double protective effect. Consuming chia seeds or flaxseed with some fat (which facilitates bile acid secretion) is a simple and accessible strategy.

Sulforaphane: activating the detoxification system

Sulforaphane is the most potent natural activator of the NRF2 pathway, which regulates detoxification enzymes. It can be obtained from broccoli, broccoli sprouts, or clinically validated glucoraphanin supplements. Products like Avmacol have been evaluated in 12 clinical studies for their bioavailability and efficacy.

Practical summary

• Take glutamine (5 to 10 g per day) if you train with high intensity or have intestinal issues.
• Increase intake of both soluble and insoluble fiber: vegetables, fruits, oats, mushrooms.
• Include broccoli or broccoli sprouts regularly, or consider a clinically validated sulforaphane supplement.
• Reduce plastic exposure: use glass or stainless steel for water, avoid heating food in plastic.
• BPS is as problematic as BPA. "BPA-free" does not mean safe.