Saturday, December 16, 2017

HEALTH SPECIAL..... What’s your gut feeling?

What’s your gut feeling?

Your gut may hold the secret to your anxiety, heightened stress levels and depression. Here’s how it works

We all have, at some point of time in our lives, encountered symptoms of bloating, loose motions, indigestion, constipation etc. These symptoms are typically attributed to a condition called “gut dysbiosis”, which refers to an imbalance of beneficial and harmful bacteria in the intestine (gut). The human gut harbours multitudinous species of bacteria, which normally remain in a harmonious relationship with the body. This complex community of microorganisms in the gut is collectively called the “gut microbiome”. The flora comprises of both, good and bad bacteria. When the bad bacteria grow in number at the expense of the good bacteria, it results in illness. The balance between the good and the bad bacteria is affected by human lifestyle, diet and environment.

Bacteria and birth history
The foetus in the mother’s womb is protected from all bacteria by the placenta. So, when and where do we acquire these microbes from? How a baby takes birth determines the kind of microbial flora that flourishes in his/her gut.
Natural birth results in the colonisation of the gut with unique beneficial bacteria acquired from the mother’s birth canal, whereas a C-section causes the gut to be colonised by bacteria present on mother’s skin, hospital instruments, etc. Also, whether a baby is breast fed or formula fed largely determines the kind of bacteria that grow in the infant’s gut. Breast milk contains substances that promote the growth of beneficial bacteria in the body. For instance, mother’s milk contains substances called Human Milk Oligosacchrides (HMOs) that are used as sources of energy by good bacteria to grow. These bacteria feed on HMOs and not only aid in its digestion, but also release substances as by-products that play an essential role in both the physical and mental development of the child.

How does it affect your health?
The gut microbes maintain a mutualistic relation with our body, i.e., the microbes use energy from the food we take and in turn improve our physical and mental health. They aid in the digestion of complex substances like cellulose, which normally cannot be digested by the body. Their presence in the gut enhances metabolism by extracting maximal energy from the remnants of digested food in the gut.
Gut microbes have also been shown to secrete substances like Vitamin K2, which can neither be supplemented through diet, nor produced by the body. The microbes strengthen the body’s immune system and keep a check on the levels of pathogens in the body. Hence, maintaining a good number of these beneficial bacteria in the gut is essential for overall well-being.

Mind matters
Another interesting and revealing finding is that these bacteria in the gut have been shown to have an impact on one’s psychological state, especially emotions and mood.
Studies have shown that both increased number of bad bacteria and the absence of good bacteria in the gut can lead to increased anxiety, and depression.
A disturbed gut microbiome has been shown to be associated with increased stress levels, autism, Alzheimer’s Disease etc. On the other hand, an increase in number of good bacteria has been seen to be correlated with a state of relaxation and well-being.

Watch what you eat
The composition of the gut microbiota changes during initial years after birth and stabilises by the time a child is five or six years old. However, diet, environment and lifestyle have an impact on the balance and diversity of microbes in the gut.
Whereas a healthy, well balanced, fibre-rich diet ensures that all the gut bacteria get the fuel necessary for their growth, an unbalanced, high fat and low fibre diet leads to reduced diversity of these microbes by depriving them of specific substances needed for their survival.
Studies have also established that mice fed on high fat diets experienced increased inflammation, reduced immunity, had thinner gut linings (leaky gut), and showed symptoms of obesity, insulin resistance, greater susceptibility to infections, etc. Interestingly, it has also been shown that transplantation of bacteria from gut of a healthy mouse into the gut of a mouse kept on a high fat diet helped restore the diversity of microbes in its gut and resulted in an improvement in insulin resistance and immunity, and reduced obesity. Also, microbes transplanted from gut of an obese mouse into that of a germ free mouse (special experimental mice grown in germ free conditions such that their gut has no bacteria) lead to development of obesity and metabolic disorders in the mouse, thereby indicating that these microbes may have a causative role to play in the development of these disease states. Hence, a healthy lifestyle promotes growth of good bacteria in the gut, and these bacteria, in turn, aid in maintaining good health.

Probiotics trump antibiotics
Many other factors influence the gut microbiome. For example, the overuse of antibiotics has been shown to negatively impact the composition of microorganisms in the gut. Excessive use of antibiotics leads to death of not only the disease causing bacteria but also the good bacteria, culminating in reduced diversity of microbes in the gut. This may result in gut dysbiosis.
Hence, non-prescribed and indiscriminate use of antibiotics should be prevented as it can deprive the gut of the good bacteria and negatively impact health. It is to prevent this situation that doctors prescribe probiotics, that is good bacteria in a capsule, or prebiotics, that is dietary substances that promote the growth of good bacteria in the gut as a part of the antibiotic course regime. Similarly, excessive alcohol intake, smoking, sedentary lifestyle, all, have been shown to negatively impact the gut microbiota.
It follows from this that a healthy lifestyle comprising of balanced diet, regular exercise, meditation and avoidance of alcohol, artificial sweeteners, carbonated drinks, junk food etc. would help in the proliferation of the good bacteria. This would also reduce the bad bacteria in the human gut.
The author is a researcher in the department of biological sciences at the Tata Institute of Fundamental Research.| Harshita Kaul
MM2DEC17

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