Gut Knows Best: The Guide to the Gut
I’m sure we’re all aware of the basic organs: the heart, the lungs, the brain, and etc. The gut is one such organ, and chances are, you’ve heard of it. Our gut affects everything from the way we look to the way we act. But what happens when our ever-so-important organ starts getting neglected?
To understand that, let’s first take a look at the gut itself. Now, the gut isn’t just an organ itself like the lungs or brain or heart, rather it comprises 39 trillion tiny - or microscopic as the name suggests – microorganisms. These microorganisms consist of bacteria, fungi, viruses and many more. Known as the microbes, together they are the gut microbiome. Combined, they can weigh up to 1-2 kg, almost the same as your brain!
The gut microbiome is crucial for your survival, in fact, it starts affecting you the moment you’re born. The gut-brain axis is one connection that makes up a vast majority of you. The gut-brain axis is a bidirectional connection of nerves from the gut to the brain and vice versa. It allows the two organs to communicate with each other via a series of signals. The gut-brain axis has proven to be vital due to its connections to the cognitive and emotional centres of the brain. Nearly 90% of the body’s serotonin, also known as the biochemical that uplifts your mood and makes you happier, is produced in the gut microbiome. Research has shown that severe fluctuation or disruption in the gut microbiome can cause drastic impact on your communication. Several mood disorders like depression, anxiety and autism spectrum disorders have been linked to (poor) changes in your gut microbiome. Studies have shown that the gut microbiome can also affect fetal and neonatal neurologic development.
The gut microbiome not only affects your mental health, but physical health too. It affects your appetite, energy absorption, fat storage, the body’s cycle of behavioural, physical and mental changes (known as the circadian rhythm), and chronic inflammation in the body, which can lead to obesity. Approximately 40% of obesity is caused by an imbalance of the gut microbiome. Not only this, but it can also lead to diseases like Type-2 diabetes and Alzheimer’s disease.
Spanning over our longitudinal lives, our gut microbiome evolves with us. When we are growing, parts of our gut microbiome can affect the development of others such as the brain, immune system, lungs and more. Other factors in the early-life like a caesarean delivery of the child, or formula feeding too can have various changes on the gut microbiome. Caesarean delivered babies are exposed to a microbiome species of the skin of the parents, and potentially colonized by the hospital or delivery environments. They are also 64% more likely to develop a childhood onset allergy. During the child’s first six months, the effect of the gut microbiome is much more evident, decreasing with time. A diverse microbial population is found in human milk, depending from mother to mother, but overall thereby lacking in terms of formula. Children who have been breastfed tend to have better cognitive development than those fed with formula.
Many desire their lost health as they’re older, but did you know our gut can do it for us? Aging is one of the leading causes for cardiovascular diseases, systemic low-grade inflammation, altered gut microbiota composition, and increased gut permeability are important features of aging. A study showed that adults aged over 65 with a diverse gut microbiome were 26% less likely to develop cognitive decline. Sadly though, an imbalanced gut microbiome can also cause disease like the aforementioned Alzheimer’s, Parkinson’s or Dementia.
Do you have oily or acne-prone skin? It’s all due to your gut microbiome. Habits like stress or poor eating (such as a lot of red meat or sugary foods) is known to cause an imbalance of your gut microbiome which can often occur in turmoil when it comes to your skin. The gut is also a key component to your hormonal cycle and an imbalance of your gut microbiome can lead to PCOS, body and facial acne, as well as greasy skin. Along with that, it can cause skin diseases like psoriasis, eczema, and rosacea.
The gut microbiome and its metabolites can also promote or inhibit cancer. The gut microbiome can increase or decrease suppressed inflammation, which is a major aspect of cancer development. Additionally, specific microbiome imbalance can cause cancer, for example fusobacterium nucleatum is associated with tumour progression in colorectal cancer and Helicobacter pylori is a major risk factor for gastric cancer. For those with cancer, a healthy gut microbiome can also help improve the efficiency and reduce the harmfulness of chemotherapy. Eubacterium limosum deactivates cyclophosphamide (which damages the DNA structure and prevents cell division, hence eliminating cancer from spreading, but also has side effects like nausea, vomiting and haemorrhagic cystitis).
Cow milk and egg allergies are commonly identified as the top food allergens for young children, with egg allergy showing higher prevalence in Asia and Australia, while milk allergy is more frequently reported in the US and Middle East. An investigation proved that the children as infants (3 to 6 months old) had a large amount of Clostridia and Firmicutes, with a milk allergy that later improved as they grew. The susceptibility to eggs was also linked to a greater gut microbiome diversity, with Lachnospiraceae and Ruminococcaceae genera being present in major quantities. However, non-allergy children proved to have a lot more of Leuconostocaceae, something present in lesser amounts in the other children.
Moreover, the presence of bacteria during the first three years of childhood has proven to make the host more susceptible to illness, have long-term effects on their health and cause asthma and dermatitis. An experiment conducted on mice proved that a healthy gut is reliant on the intestinal bacteria, whereas the mice raised in a germ-free environment were prone to a weaker gut. This has thus been associated with conditions like asthma, dermatitis and more. In dermatitis, reduction of the environmental biodiversity causes an increased severity of the condition. Around 300 million people worldwide suffer from asthma, with childhood gut dysbiosis being a major factor. In asthma, the gut microbiome proves to be incredibly important, as children with a family of a history with asthma are at severe risk. The gut-lung axis shows that any respiratory diseases depend on the state of the gut microbiome. Children with a poor and imbalanced gut microbiome and genetic predisposition are likely to develop respiratory diseases like asthma.
To improve your gut microbiome, there are several measures you can take like eating probiotic foods (like yogurt, kombucha and kimchi), adding prebiotic foods to feed the gut microbiome (like flax seeds, legumes and whole grains), practicing stress-management and staying active to keep the body fit and in shape. If you fear that your gut microbiome might not be in its desired state, referring to a Gastroenterologist or dietician for tips on rebuilding your gut microbiome would be advised. After all, like Hippocrates once said “All diseases begin with the gut”