WHY CARBS ARE VERY IMPORTANT FOR THE BRAIN
It’s said the best way to a man’s heart is through his stomach. To his brains, too, say new studies! People have long identified the presence of a gut brain which gives you “gut feelings”. They have also known that our guts are filled with a lot of friendly bacteria, comprising nearly 100 trillion organisms belonging to 1,000-plus species of microbes.
This assemblage of microbes, commonly called the “microbiome”, has a role in a variety of bodily functions such as nutrition, digestion, immunity and growth. Some scientists have revealed that the presence of this microbiome is essential for even the normal development of the gut nervous system as shown in studies in germ-free mice. Scientists go on to say that homo sapiens maintain a complex physical form with just 26,600 genes (rice genome has 46,000 genes), thanks to the genetic material from the bacteria (It is postulated that 1,000 species of bacteria contribute around four million genetic transcripts).
Through such a significant role, it can be rightly said that the microbiome may exert both positive and negative effects on our feelings and thinking alike.
They could interact with our nerve cells by secreting various neurochemicals like neurotransmitters and neuropeptides and in doing so, modulate the functioning of our nervous system.
One of the major causes for a person developing psychological disorders is the deficiency/imbalance of neurotransmitters (chemical messages used by nerve cells to talk to each other) like serotonin, dopamine, GABA (gamma amino butyric acid), glutamate, etc., in the body. This is applicable especially in the case of anxiety disorders, depression, eating disorders and schizophrenia.
Recently researchers have been able to identify the chemical reactions occurring within these bacteria and the results are stunning!
Two bacterial species — lactobacillus (which helps turn milk into curd) and bifidobacterium — have been found to be capable of metabolising glutamate to GABA, which is a key mediator in anxiety disorders. This observation was tested in humans by some researchers and they found that humans with anxiety disorders, when given large quantities of probiotics (friendly bacteria in desired quantities) L. helvetics and B. longum, had an improvement in their anxiety levels.
Emeran Mayer, a gastroenterologist at the University of California, Los Angeles, undertook a study by recruiting 25 healthy women.
He gave half of them a cup of commercially available yogurt, twice a day for four weeks, while the other half were not given any yogurt. Yogurt is a probiotic which contains live bacteria, in this case strains of four species — bifidobacterium, streptococcus, lactococcus, and lactobacillus. The women were given brain scans before and after the yogurt to gauge their response to a series of images of facial expressions — happiness, sadness, anger, and so on.
To Mayer’s surprise, he observed significant differences between the two groups. The yogurt-eaters reacted more calmly to the images than the control group. He came to the conclusion that the bacteria in the yogurt changed the make up of the subjects' gut microbes, and that this led to the production of compounds that modified brain chemistry.
There will come a day very soon when we use gastrointestinal microbiomes to promote positive health and cognitive effects as an adjunct to psychotropic and neurological medications.
Dr Aswin Krishnan Ajit is a Kochi-based consultant psychiatrist
The human race is distinguished from other animals because it has the highest development of cognitive functions thanks to an evolved brain. This brain is about 1,400 grams in weight i.e., only about 2 per cent of the body weight. But this has the highest consumption of energy and oxygen. An adult brain consumes about 20% of the oxygen supply to the body and almost 20% to 30% of the energy consumption of the body. A developing brain of an infant can use almost 50% of the energy used by the body. The primary source of energy in the brain is glucose. Rarely, in glucose depleted situations, like fasting etc. it can use ketones to some extent for a limited period. Brain has a very high rate of metabolism, using ~5.6 milligramme glucose per 100 gram of brain tissue per minute. Dr Ashish Shrivastav, senior consultant neurosurgeon at Apollo Hospitals explained, “Carbohydrates are the only nutrients which can match this rate of energy requirement. However, the brain prefers to get its carbohydrates from carbohydrate rich whole foods rather than simple sugars. The cognitive functions or the thinking capabilities of the brain deteriorate if the glucose levels fall in the brain. A rapid relief can be obtained from carbohydrate rich whole foods. At the same time, glucose from simple sugars causes detrimental effect to the brain. Hence, glucose from whole food carbohydrates is essential in diet but excess simple carbohydrates are harmful.”
Fruits, vegetables and cereals or more scientifically, foods with low glycaemic index (a measure of the relative ease of sugar release from any food) is desirable. Food with high glycaemic index, for instance, white sugar or juices, are not the correct sources of carbohydrates.
In type two diabetes mellitus, there is a situation of “deprivation in the presence of excess”. The glucose level remains high outside the cell but low inside it. Thus, the cells, esp. neurones / brain cells cannot function properly. There is a unique metabolism in different types of bodily organs. Contrary to brain, the muscles require more proteins. The fat in our diet has been criticized a lot in recent times as being “The Villain”. But fat is essential for many functions of our body. The membrane covering the nerves is made from fatty material. So, as always, there are no absolute positives or negatives. Carbohydrates are essential for our body, esp. for our brain, but in right quantity and of the right quality ( i.e. from whole foods and of low glycaemic index).
Clinical nutritionist Tanu Arora explained, “Carbohydrates are one of the most important nutrients needed for healthy brains functioning. They are the main source of energy for brain. When carbs are eaten they are eventually digested and broken down into smaller sugars molecules called glucose. Carbohydrates significantly affect the mood and behaviour, they are equally important for mental health also. People who are on high fat, low carbohydrate diet for a year had more anxiety, depression, and anger than people on a low fat, high carbohydrate diet. Without sufficient glucose, the central nervous system suffers, which may cause dizziness or mental and physical weakness. If the body has insufficient carbohydrates, body consume protein for its energy source, which ultimately leads to burden on kidney also. People who don’t consume enough carbohydrate may also suffer from insufficient fibre, which may cause digestive problems and constipation”.