What Happens in the Gut … Goes All the Way to the Lungs

Next time you eat, be sure to load up on lots of colourful plant-based fibre-rich items—and then imagine the trajectory of that good food through your body. Here’s a hint: insoluble fibre in that food helps move things along, while gut bacteria digest the soluble fibre to produce beneficial metabolites known as short chain fatty acids (SCFAs).
SCFAs and gut bacteria boost health by acting on tissues and organs, including those in the lungs. It’s true: our diet influences our respiratory health.

What is the gut-lung axis?

Bacteria get into the lungs from your mouth, from the air you breathe, and from the gut, hence both environmental factors and your gut microbiota will affect respiratory health. Metabolites such as the SCFAs reach the lungs through the lymphatic system and blood circulation. They help reduce inflammation, repair the gut lining, and protect against lung infections.

Though lungs have fewer bacteria than the gut, they are still a dynamic environment with ability to impact immunity.

The gut-lung dialogue

A healthy gut microbiome means better respiratory health and intact mucous layers in the gut and respiratory system. Gut dysbiosis, on the other hand, increases the risk of asthma and allergies. Also, chronic respiratory illnesses occur more often in people with irritable bowel syndrome or inflammatory bowel disease.

Antibiotic treatments, anti-ulcer, and anti-reflux medications affect the gut microbiota and can increase the risk of asthma, allergies, and upper respiratory infections.

From the lung end, influenza and pneumonia can cause gut dysbiosis and can impact the renewal of intestinal cells.

Microbiome 101

Bacteria start colonizing the gut from birth, thriving as they feed on breastmilk prebiotic sugars. Then come solid foods, which further build the gut microbiome.

Fibre and exposure to dirt help increase the diversity of bugs in our body microbiome, boosting overall health. Because the gut is not an isolated organ, any gut imbalance, or dysbiosis, will affect various parts of the body.

Dysbiosis can occur at any age and for many reasons: environmental, unhealthy lifestyle, diet, and/or medication. The microbiome tends to become less robust as we age—yet another reason to maintain a fibre-rich diet.

Fibre for lung health

Fibre-derived SCFAs protect the mucous layer in the gut, which protects against pathogens and reduces inflammation. In the lungs, too, SCFAs reduce inflammation associated with allergic reactions.

Since pollution is often unavoidable, a diet rich in fibre helps reduce the risk of respiratory disease by reducing inflammation caused by particulate matter and other pollutants.

Supplements for digestive health

Probiotics

Oral probiotics can reduce the severity of asthma attacks and allergy symptoms in children. They can also improve the gut barrier and reduce inflammation. However, given the multitude of options, consult with a health professional for best suited probiotic supplement.

Meanwhile, munch on naturally fermented foods such as sauerkraut and kimchi regularly. They contain probiotic bacteria and prebiotics, plus vitamins and minerals formed during fermentation.

L-glutamine

This amino acid can help improve digestive health by decreasing intestinal permeability and reducing inflammation.

Vitamin D

Essential to maintaining the integrity of the gut lining, vitamin D needs to be converted to its active form by diverse and beneficial gut bacteria.

Vitamin C

A powerful antioxidant, vitamin C can reduce inflammation and oxidative damage in the gut.

Eating for trillions

Did you know?

• Almost half the people with IBD and a third of people with IBS have chronic lung inflammation.
• Exposure to dirt and pets in early childhood reduces the risk of allergy and asthma.

This article was originally published in the January 2022 issue of alive with the title the Essential Gut-Lung Axis.