Linkage between Gut Microbes and Obesity Lecturer

Gut Microbes and Obesity 4

Linkagebetween Gut Microbes and Obesity


Linkagebetween Gut Microbes and Obesity

Thefood consumed by humansis broken down before it is absorbed into thebody. This function is done by microbes that exist in the gut. Somefood particles may fail to be broken down and they are stored in thebody in the form of fat. The microbes start forming in the gut of achild at the time of birth and new ones are acquired frominteractions with the surroundings. The microbes in the gut ofhumanbeings play a big role in the metabolism and physiology of theirhosts. The cooperation between them and their hosts mutually benefitsboth of them.The microbes have enjoyed being hosted in human beingsthrough out the history of man. In returning the favor, they havehelped people to break down tough plant fiber. Scientists think thatgut microbes perform more than just digestive functions (2). In orderfor maximum results to be achieved, the right mix of the gut microbeshas to be achieved. Having the wrong composition is what has led toobesity and other conditions in many people. After many years ofresearch, scientists are starting to get the difference between theright and poor mix.There has been continued interest in the functionof microbes in humans which mainly focuses on their capacity toferment indigestible nutrients, lower the amount of toxins andproduce micronutrients. In later studies, the relationship betweenthe microbes and their hosts has been found to maintain a balance ofvital functions in humans and uphold their wellbeing. In manydeveloped countries, there has been an increase in obesity cases. Inthe US for example, nearly two-thirds of the population is obese.Obesity is a serious condition which improvesthe risk ofcardiovascular diseases, type 2 diabetesand several types of cancers.In earlier times, the supply of food was not sufficient and peoplesuffered hunger at times. Therefore, thehuman body was designed tobuild and safeguard energy stores (3). Although the food supply hassince increased, human physiology has not changed to allow lessretention of energy in the body. Complex systems have developed overthe years to regulate energy in the bodies of humans. It has beenfound in recent studies thatmicrobes are responsible in determininghow nutrients are taken up by the body, energy regulation andmetabolic conditions. The human gut is like an ecosystem with a widevariety of microbes that play different functions. The environment inthe gut has been ruined by the kind of food people eat. Themedication taken by individuals also affects the composition of gutenvironment, making it hostile for the existence of useful microbes.When some of the microbes are destroyed, food particles will not bebroken down effectively and the end result will be to have themstored in the body. The situation is quite sensitive in the case ofchildren whose environment is just forming. The food or drugs takenby children should be safe for gut microbes. It is very is veryimportant to have the right gut environment to ensure the microbesare not ruined. This essay will show the role played by microbes inthe regulation of energy in the body.

GutMicrobes and Obesity

Studieshave been conducted that confirm the role of microbes in harvestingand storing energy from food eaten by human beings. The studies wereconducted on germ free mice and it was found that body fat increasedby 60% after the microbes was introduced into their bodies. Insulinresistance was also noted within a period of two weeks even thoughthe food rations were slashed by 29% and activity raised by 27%. Themicrobeswere found to harvest more energy from the waste matter (4).Microbes influence the way energy is harvested from diet components,its usage and storage in the body. It can therefore be concluded thatobesity is as a result of a section of the microbes present in thegut. Comparison between lean and obese mice revealed consistentvariations in the two major types of bacterial phyla found in theintestines. The same differences in intestinal microbes are said toexist in obese and lean human beings. Although there have been manyfindings on the impact of microbes and their effect on obesity, thereis still no consensus on how each type functions in the body.

Inhuman beings, development of body weight is determined by the make upof gut microbes in the early years of a person’s life. A sample of25 obese and 24 normal weight children was selected and their fecalsamples taken for analysis. It was found that the presence ofbifidobacterial numbers in the fecal samples was higher in those kidswho maintained normal body weight by the time they were 7 yearsold(6). Those infants who later became obese were found to have ahigh content of Staphylococcusaureus.Another study was conducted in obese and normal-weight pregnantwomen. Similar differences were noted in the pregnant women. Sincethe original inoculum of a child is determined by the mother, it maybe possible that this is the reason why the condition is conferredfrom mother to child. A relationship has been identified between thefecal composition of infants and their mothers’ weight conditionwhile they were carrying the pregnancy.

Thereis a wide range of microbesin the gut which includesArchaeaanddifferenttypes of eukaryotes. These different types of microbes compete andinteract differently which may largely influence obesity in theirhosts. In obese humans and mice, studies have found a higher presenceof Archaeawhichproduces methane than it is the case in those who are lean (7). Formany years, scientists have always known that human bodies containdifferent microorganism. However, they did not know that theseorganisms are 10 times more than the cells in the body. A lot ofthese microbes exist in the intestine and the mouth, although thereare others found on the skin and the genital tract.

FigureSchematic diagram of the main metabolic pathways of dietary poly- andoligosaccharides in the gut ecosystem

Themicrobes start gathering in the system of a human being at birth.Every new born baby inherits microbes from the mother. Newmemberswill be gained through interaction with the environmentthroughout ones life. After many studies, researchers can nowidentifymost of the microbes. However, they have noted that theseorganisms have differences among individuals and between groups ofpeople in various locations (8). The focus of the researchers has nowshifted from just knowing how many the microbes are, to determiningthe role played by each one of them individually regarding the healthof their hosts.

Thefirst indication that obesity may be caused by intestinal microbesemerged when bacteria in the guts of lean and obese people werecompared. The studies showed that the community of gut bacteria inlean people was quite diverse unlike what was found in obese people.This means there were fewer organisms in obese people to help in thebreakdown of food nutrients receivedinto the body. Lean people werefound to have a high presence of Bacteroidetes.This is a huge category of microbes that help to breakdown bulkystarches from plants into shortermolecules that provide the body withenergy (6,9). According to research, the microbes in the gut ofhumans have particular roles to play. The functioning of thesemicrobes is necessary for the proper operation of the body whichensures it is healthy at all times.

Anotherrole linked to obesity inducing bacteria is one that is usuallyplayed by Helicobacterpylori.This bacterium is normally found in the stomach and helps in appetiteregulation (5). It is responsible for controlling ghrelin levels inthe body, which stimulates hunger. Helicobacterpyloriwerehighly common in digestive tracts of many Americans before hygienewas improved in the living conditions and the use of antibiotics wasincreased.

Thecomposition of the gut bacteria is determined by different factorsand diet is one of the main determinants. In modern times, peopleconsume highly processed foods than before. The consumption of suchdiets has been associated with a reduced diversity of gut microbes inpeople as the ruin the environment that supports their existence.Studies have showed that there is a close link between food, microbesand body weight. The experiment involved feeding humanized mice onunhealthy diet comprised of mainly fat and carbohydrates (10). Thisis the kind of diet many people consume today. The mice that fed onthis kind of diet continued to grow fat even when they were livingwith lean mice and therefore exposed to other types of bacteria. Thevirtuous bacteria were rendered ineffective by the unhealthy dietthat the mice were fed on.

Peopleare predisposed to obesity from the day they are born, due to theinteraction of diet and the gut microbes. This can also be as resultof how one is born. Children born through Cesarean section run a highrisk of becoming obese and than their counterparts who are bornnormally. Microbes are sourced from the environment people live in.The first place a child gets contact with new microbes is in thebirth canal (8,9). As the child travels through the birth canal, itswallows bacteria that will be usedin the digestion of milk. Thisprocess is skipped by children who are born differently. Breastfeeding is crucial for the development of gut bacteria in the body ofthe child. Breast milk containssubstances that allowinfants todevelophelpful bacteria. These bacteria from breast milk also helpreduce the growth of harmful microbes. Therefore, feeding infants onformula milk denies the babies a chance to develop bacteria that arecrucial for their future. Formula fed babies have a gut bacteria thatis not evident in children who are breast fed until they start eatingsolid food. This may be the reason why many children are vulnerableto allergies and other health condition from very early stages oftheir lives.

Aspeople appreciate the impact of microbes on body weight, there isconcern about using antibiotics in children. The use of antibioticsis responsible for some of the bacteria in the body that could helpcounter increase in body weight. Studies have been conducted in micethat were given low doses of antibiotics and this resulted in agrowth of weight by about 15%. When the baby is given the antibioticsat an early stage, the result is the extinction of the usefulbacteriathat are just forming (3). The use of antibiotics amongchildren in the US varies from one state to another. The prevalenceof obesity also shows similar variations.

Theresearch that has been conducted is hoped to inspire other approachesand tools that will be used to cure and probably prevent obesity. Theproblem of obesity is relatively new and any solutions to it may notbe very effective. This field of research is new and there is a lotthat needs to be done before the best responses to the problem ofobesity can be found. Although most of the studies have beenconducted on humanized mice, the conditions are a lot morecomplicated in humans (2,4). The variation in individuals is so widethat it is difficult to pick out the role of individual microbes inrelation to a complex health condition like obesity. Even with thecurrent situation, a lot of scientific efforts are being made thatare likely to provide treatment in future. For instance, clinicaltrials are being conducted in Puerto Rico in which children deliveredthrough Caesarian section are swabbed with a piece of cloth lacedwith vaginal fluids from the mother. This helps the child take thebacteria from the birth canal that will be used to digest the breastmilk. The researchers behind this trial will monitor these childrenand compare them with those who did not receive the treatment.

Anotherapproach aimed at seekingpossibletreatment is being conducted by agroup of researchers in Amsterdam. They are considering thepossibility of treating obesity by transferring fecal matter fromlean people to overweight ones. Some researchers especially in the USdo not approve this approach and they view it as being too risky. Thebest approach would be to identify the bacterial strains linked withleanness (6). The functions of these bacteria should then be analyzedand treatment developed. Another approach would be to improve thequalityof diet by enriching them with useful bacteria and thenutrients that they require in order to flourish. The war againstobesity is truly on and it will not be easy to get over it. Whilethere are many approaches that can be used in this regard, it is goodto improve the condition of the bacteria in the gut. This is the onlysafe and natural way to ensure the body does not retain too much fat.The effects of obesity on the society are immense and its results canhave very devastatingconsequences on your well being.

Thegut microbes can be manipulated by using antibiotics together withother clinical methods. Probiotics are alive and non toxic microbes.When consumed correctly they have a therapeutic effect. The use ofantibiotics and probiotics is clinically relevant as its use has beenevidenced by farmers on their animals (10). When they are used onlivestock, the end result is an increase in weight. Surgicalprocedures can also help in combating the condition. The use ofantibiotics should be reduced especially in infants. They affect thedevelopment of microbes in the gut which might affect their healthlater in life.


Thereis no doubt that the microbesin the gut play a key role in theregulation of body weight of animals and human beings as well. Theirpresence influences the occurrence of obesity. Obesity is not treatedcan lead to other metabolic conditions like diabetes type 2. Thereare various methods that have been recommended to combat obesity.People suffering from obesity should not neglect them even when theirguts have been manipulated. Apart from the novel idea of gutmanipulation, various other approaches are being suggested byscientists across the world. There need to be increased research thatwill ensure there is more leverage to the gut manipulation approach.All the approaches being considered currently are relatively youngand more research need to be conducted on them (2). While attemptingto modify the gut environment, vacation needs to be exercised. Theideal composition of gut microbes is not known yet. Therefore, beingcautious will help notdestroy the current situation in differentindividuals. Lifestyle changes can have a very huge impact incombating this kind of disease. People should eat more food thatcontains vegetables and other useful nutrients. Most people turn toprocessed food as they are ready to consume as they are moreconvenient. However, these meals can have very serious effects on thehealth of the people. Any success that is gained in this endeavorwill certainly be a relief to many people who are struggling withobesity.


1. O`HaraAM, Shanahan F. The gut flora as a forgotten organ.EMBORep20067:688–693.&nbsp|&nbspArticle&nbsp|&nbspPubMed&nbsp|&nbspISI&nbsp|&nbspCAS&nbsp|

2. Bocci V. The neglected organ: bacterial flora has a crucialimmunostimulatory role. PerspectBiolMed199235:251–260.&nbsp|&nbspPubMed&nbsp|&nbspCAS&nbsp|

3. Ogden CL, Yanovski SZ, Carroll MD etal.The epidemiology ofobesity.Gastroenterology2007132:2087–2102.&nbsp|&nbspArticle&nbsp|&nbspPubMed&nbsp|&nbspISI&nbsp|

4. Hensrud DD, Klein S. Extreme obesity: a new medical crisis in theUnited States. MayoClinProc200681:S5–10.&nbsp|&nbspPubMed&nbsp|

5. Backhed F, Ding H, Wang T etal.The gut microbiota as an environmental factor that regulates fatstorage.ProcNatlAcadSciUSA2004101:15718–15723.&nbsp|&nbspArticle&nbsp|&nbspPubMed&nbsp|&nbspCAS&nbsp|

6. TurnbaughPJ, Ley RE, Mahowald MA etal.An obesity-associated gut microbiome with increased capacity forenergy harvest.Nature2006444:1027–1031.&nbsp|&nbspArticle&nbsp|&nbspPubMed&nbsp|&nbspISI&nbsp|

7. BackhedF, Manchester JK, Semenkovich CF etal.Mechanisms underlying the resistance to diet-induced obesity ingerm-free mice. ProcNatlAcadSciUSA2007104:979–984.&nbsp|&nbspArticle&nbsp|&nbspPubMed&nbsp|&nbspCAS&nbsp|

8. LeyRE, Backhed F, Turnbaugh P etal.Obesity alters gut microbial ecology. ProcNatlAcadSciUSA2005102:11070–11075.&nbsp|&nbspArticle&nbsp|&nbspPubMed&nbsp|&nbspCAS&nbsp|

9. TurnbaughPJ, Backhed F, Fulton L etal.Diet-induced obesity is linked to marked but reversible alterationsin the mouse distal gut microbiome. CellHost Microbe20083:213–223.&nbsp|&nbspArticle&nbsp|&nbspPubMed&nbsp|&nbspISI&nbsp|&nbspCAS&nbsp|

10. LeyRE, Turnbaugh PJ, Klein S etal.Microbial ecology: human gut microbes associated with obesity. Nature2006444:1022–1023.&nbsp|&nbspArticle&nbsp|&nbspPubMed&nbsp|&nbspISI&nbsp|&nbspCAS&nbsp|