You have a second brain - in the guts!

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A look at the Second Brain: The Brain in the Gut

By Amb. Dr. Sir Romesh Jayasinghe

Your body actually has a second brain that controls you much more than you

might realise - and most people have no idea it exists. A few thousand years ago

in ancient India in the Vedas they echoed the hypothesis that you are what you

eat. I suppose that in a literal sense, it is true that you are what you eat since

science is now beginning to confirm this explanation. The gut has a mind of its

own, called the "enteric nervous system". Just like the larger brain in the head,

researchers say, this system sends and receives impulses, records experiences and

respond to emotions. Its nerve cells are bathed and influenced by the same

neurotransmitters. The gut can upset the brain just as the brain can upset the gut.

The gut's brain or the "enteric nervous system" is located in the sheaths of tissue

lining the esophagus, stomach, small intestine and colon. Considered a single

entity, it is a network of neurons, neurotransmitters and proteins that zap

messages between neurons, support cells like those found in the brain proper and

a complex circuitry that enables it to act independently, learn, remember and, as

the saying goes, produce gut feelings.

The gut's brain is reported to play a major role in human happiness and misery.

Many gastrointestinal disorders like colitis and irritable bowel syndrome originate

from problems within the gut's brain.

One of the main ways our brain communicates with the rest of our body is via the

vagus nerve, which passes messages to the vocal chords, heart, lungs, and the

digestive tract.

But researchers have also discovered that within the enteric nervous system - the

extensive mesh-like network of neurons that controls your digestive tract - the

messages are going the other way, too.

In fact, 80 to 90 percent of the nerve fibres in the enteric nervous system are

going from the gut to the brain. And when the vagus nerve is cut, the enteric

system doesn't need the brain at all.

In other words, your digestive system is your second brain, and it controls you far

more than you realise.

Details of how the enteric nervous system mirrors the central nervous system

have been emerging in recent years, according to Dr. Michael Gershon, Professor

of anatomy and cell biology at Columbia-Presbyterian Medical Center in New

York. He is one of the co-founders of a new field of medicine called

"neurogastroenterology." Research indicates how our Second Brain affects

cravings and emotional well-being.

The gut contains 100 million neurons - more than the spinal cord. Major

neurotransmitters like serotonin, dopamine, glutamate, norephinephrine and

nitric oxide are in the gut. Also two dozen small brain proteins, called

neuropeptides are there along with the major cells of the immune system.

Not only has research shown that our gut bacteria can manipulate our food

cravings and behavior in order to ensure their own survival (you can blame them

on your junk food obsession), but the colonies in our digestive system also affect

our mood.

Studies suggest that people with healthy and diverse gut microbiomes are less

likely to be depressed or anxious.

And, in mice, researchers have shown that those that grow up in sterile

environments - where no bacteria colonise their guts - display social traits similar

to those in humans on the autism spectrum. When these mice were fed

probiotics, their symptoms were alleviated.

This kind of effect has been seen in early studies in humans too, leading many

scientists to believe that one of the primary functions of gut bacteria is actually to

promote social behaviours and ensure the survival of the species through

reproduction.

Research has shown that the body is actually composed of more bacteria than

cells. We are more bug than human! Collectively, these trillions of bacteria are

called the microbiome. Most of those bacteria reside in our gut, sometimes

referred to as the gut microbiota, and they play multiple roles in our overall

health.

The gut is no longer seen as an entity with the sole purpose of helping with all

aspects of digestion. It's also being considered as a key player in regulating

inflammation and immunity.

A healthy gut consists of different iterations of bacteria for different people, and

this diversity maintains wellness. A shift away from "normal" gut microbiota

diversity is called dysbiosis, and dysbiosis may contribute to disease. In light of

this, the microbiome has become the focus of much research attention as a new

way of understanding autoimmune, gastrointestinal, and even brain disorders.

The benefit of a healthy gut is illustrated most effectively during early

development. Research has indicated just how sensitive a fetus is to any changes

in a mother's microbiotic makeup, so much so that it can alter the way a baby's

brain develops. If a baby is born via cesarean section, it misses an opportunity to

ingest the mother's bacteria as it travels down the vaginal canal. Studies show

that those born via c-section have to work to regain the same diversity in their

microbiome as those born vaginally. Throughout our lives, our microbiome

continues to be a vulnerable entity, and as we are exposed to stress, toxins,

chemicals, certain diets, and even exercise, our microbiome fluctuates for better

or worse.

In some ways, it seems like our second brain and its gut feeling is even more

influential than our logical thought.

In conclusion, the human gut has long been seen as a repository of good and bad

feelings. Perhaps emotional states from the head's brain are mirrored in the gut's

brain, where they are felt by those who pay attention to them.

Hipokrat'in "Tüm hastaliklar bağirsakta baslar." yaklasimindan sonra günümüzde de bağirsaklar "ikinci beyin" olarak adlandirilmakta ve bağirsaktaki mikrobiyal denge-sağlik ilişkisi yogun araştirmalarin konusu olmaktadir. Bagirsaklarda çeşitli nedenlerle bozulan mikrobiyal dengenin yeniden olusturulmaşinda ise probiyotiklerden yararlanilmaktadir. özellikle son 20 yilda probiyotiklerin sağlik üzerine etkilerine yönelik pek çok bilimsel bulgu elde edilmitir. Bunlar arasinda modern çagin vebasi olarak da kabul edilen kanser üzerine probiyotiklerin etkisini incelemeye yönelik çalişmalar son derece ilginçtir ve bu konu aydinlatilmasi gereken pek çok bilinmeyeni içermektedir. Probiyotiklerin kanseri önleme ve tedavi etmesinde çeşitli mekanizmalar geçerlidir. örnegin kanser öncül maddelerini üreten patojenleri inhibe ederek bağirsak mikroflorasinin düzenlenmesinde ve böylece bu zararli bileşiklerin olusumunun önlenmesinde etkili olmaktadir. Probiyotiklerin, antimikrobiyal ürünlerin üretimi yoluyla patojen bakterileri engelleyici ve immunomodülatör hücreleri uyarici özellikleri gibi kanser olusumunu önleyici olumlu etkilerine ait de birçok bulgu elde edilmitir. Kanseri tetikleyen etkenler oldukça karmasik olmakla birlikte, beslenme yoluyla alindiginda probiyotiklerin mutasyona ve tümör olusumuna yol açan bileşiklerin neden oldugu DNA hasarini önledigi gözlenmitir. Ayrica probiyotikler kisa zincirli yağ asitleri gibi kanserden korunmada yararli olan metabolitleri üretmektedir. Probiyotiklerin kanseri önleyici etkilerini, tümör olusumunu engelleme, tekrar etme olasiligini azaltma ve olusmus kanser hücrelerini ve dokularini yikima ugratma seklinde gerçeklȩtirebildiklerini gösteren çalişmalar bulunmaktadir. Probiyotiklerin yerlesim alani olan kalin bağirsak disinda, mesane, meme ve karaciger gibi yerlesim alani olmayan organ ve dokularda da tümör olusumu ve gelisimini engelleyici etkisi oldugu gösterilmiştir. Probiyotiklerin sağlik üzerine etkilerinin toplum tarafindan anlasilmasi ticari preparatlarin kullanimini dünyada ve ülkemizde yayginlatirmitir. Ancak probiyotiklerin kanserin önlenmesi ve tedavisinde kullanilabilmesi için etki mekanizmalarini somut sekilde açiklayan ve olumlu sonuçlari klinik denemelerle ispatlanmis birçok çalişmanin yapilmasi gerekmektedir. Bu derlemede, probiyotiklerin farkli kanser tiplerine etkilerini ispatlamak amaciyla in vitro ve in vivo kosullarda yapilmis öncü niteliginde çeşitli çalişmalar bu alana ilgi duyan araştiricilar için irdelenmis ve tartişilmitir.

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