The gut is essential since it is mainly responsible for digesting food and absorbing nutrients. In recent years, it has been widely established that the digestive system hosts trillions of microbes that keep the gut healthy. The diversity in the gut’s microbiome is associated with better gut health, improved immunity and overall health.
Microbes present in the gut not only help in food digestion but also in harvesting energy from these foods. However, not all guts are equal. Some guts are more efficient in harvesting energy than other guts, as demonstrated in a study conducted in Denmark.
Danish study on the microbiome
The study [1], which was led by a team of researchers from the Netherlands and Denmark, reported that microbes present in the guts of some Danish individuals are better at harvesting energy than other fellow Danes.
The research study findings are crucial since these provide evidence on why certain people gain more weight than others when both groups eat the same amount of food and calories.
It would seem unfair why people are more prone to gain weight after eating chocolate cookies than others who never gain weight after eating the same amount of cookies. Part of why some could munch away all those chocolate goodness cookies without gaining a gram of weight could be the composition of their gut’s microbiome. The study, published in the Microbiome journal and conducted in the University of Copenhagen’s Department of Nutrition, Exercise and Sports, provides evidence of this observation.
A total of 85 adults who were overweight were recruited. The variations in the microbiome diversity and intestinal transit time were examined for six days. Researchers in the study investigated the residual energy present in the faeces of 85 participants to determine and estimate how effective the microbes in the gut are at harvesting energy from food. Simultaneously, they also mapped the gut microbes’ composition for each individual.
Results revealed that individuals whose gut hosts Bacteroides enterotype (B-type) bacteria had significantly shorter transit times, lower stool energy density, and lower alpha diversity. In contrast, participants with guts hosting Runinococcacea enterotype (R-type) bacteria had longer intestinal transit times and higher stool energy density. This implies that individuals with R-type bacteria are less efficient in extracting colonic energy than individuals with B-type bacteria in the gut. Notably, individuals with the R-type energy had lower body weight, while those with more efficient colonic energy extraction had higher weights.
Further, findings showed that approximately 40% of study participants (B-type groups) extract more energy from food than the other 60% in the study (R-type groups). The study’s authors observed that those who extracted energy efficiently tend to weigh more than 10% on average. When translated in kilos, there was an average difference of 10 kilos between the B-type and R-type groups.
The study’s lead author, Joe Boekhorst, cautioned that it would be challenging to correlate body weight with efficiency in harvesting energy from food. However, the findings indicated that individuals with B-type bacteria in the gut tend to harvest energy from food efficiently. This might explain differences in people’s weight with the same diet and amount of food eaten. As one of the lead authors explained: “We may have found a key to understanding why some people gain more weight than others, even when they don’t eat more or any differently. But this needs to be investigated further.”
Gut microbiome and obesity
Results of the study indicate that being obese or overweight may not only be related to how one eats or the amount of physical activity one gets. Instead, findings suggest that being overweight or obese may have something to do with a person’s gut microbes.
As demonstrated in the study, those who belonged to the 40% of the participants who have predominantly Bacteroides bacteria in their guts were more effective in extracting nutrients and energy from the foot that they ate.
After the study, the investigators suspect that some individuals in a population may be disadvantaged if they have gut microbiome or bacteria that are too effective in harvesting energy. This efficiency could result in more calories being available for the same food.
One of the investigators points out that the ability of Bacteroides bacteria to extract energy from food is welcoming news. The ability of this group of bacteria to metabolise food and provide extra energy in the form of glucose or short-chain fatty acids would ensure that the body has a sufficient energy supply. However, if more energy from the food is extracted than what is burned by the person, the extra energy can be stored and increase the risk of being overweight or obese over time.
Researchers on short gut transit time
Food transit time is about 12 to 36 hours, passing from the mouth to the oesophagus, then the stomach. From the stomach, food is digested and formed into a bolus (liquified food) before it is passed on to the duodenum in the small intestine, where most of the nutrients are absorbed. Food waste is then passed to the large intestine, where gut microbiome or bacteria digest insoluble fibre and other materials not digested or absorbed in the small intestine. Hence, food passes through several stations before the body can extract all the nutrients and energy from the food.
The researchers likewise studied each participant’s intestinal transit time or the length of the food journey through the digestive system. Results revealed that all participants share similar dietary patterns. Following this finding, the researchers hypothesised that those with longer food transit times would extract the most energy and nutrients from their food. However, the researchers found the exact opposite.
As observed by one of the authors, the investigators thought that the length of travel time of the food would allow more nutrients to be harvested or extracted. However, the researchers found that participants hosting the B-type bacteria extracted the most energy and had the fastest food transit time.
What are gut bacteria?
Gut microorganisms are collectively called the gut microbiome, while the gut microbiota refers to the bacteria in the gut. At least a trillion bacteria reside at any given time in an adult bacteria. Per gram of stool contains a staggering 100 billion bacteria.
Gut bacteria develop following childbirth when an infant is exposed to microorganisms in the mother’s birth canal or the skin when the birth is through caesarean delivery. Bacteria are also passed from the mother’s milk to the infant. The type of infant food eaten, the weight of the mother when breastfed, and the kind of formula milk given all influence the early development of the infant’s gut.
Later, the gut is exposed to different types of bacteria through one’s diet. The diversity of bacteria is dictated by the types of food eaten. Those who eat more fruits and vegetables tend to have more diverse bacteria than those who consume fewer fruits and vegetables. Apart from genes and diet, the environment and lifestyle also influence the diversity in the gut microbiota.
Gut bacteria in the colon play an essential role since it breaks dietary fibre that cannot be broken down naturally in the gut. The body lacks digestive enzymes that break down dietary fibre. Apart from breaking down food, gut bacteria are responsible for producing vitamins such as vitamin K. Approximately half of the vitamin K needed by the body is made in the gut [2]. Additional vitamins produced by the gut microbiota include folate, riboflavin, thiamine, biotin, and pantothenic acid [3].
Gut bacteria are also responsible for producing specific enzymes needed by the body for the metabolism or breakdown of particular molecules or proteins. The microbiota is also involved in the production of neurotransmitters. One of these neurotransmitters includes serotonin, an important neurochemical that regulates mood and gastrointestinal activity. About 95% of the serotonin in the body is produced by the gut microbiota [3].
Humans are divided into at least three groups based on the abundance and presence of three main groups of bacteria. These include the R-type (Ruminococcaceae), B-type (Bacteroides), and P-type (Prevotella). As demonstrated in the study, the P-type group had characteristics between the B-type and P-type groups. Individuals with P-type bacteria harvest energy less than the B-type but more than the R-type group.
Longevity and gut bacteria
The study is one of the first to demonstrate that gut bacteria may play a role in the development of obesity and why those with the same dietary patterns as lean people tend to be obese or overweight.
One of the leading health challenges that can result in poor health and premature death includes obesity. However, knowledge of gut health and how optimising the gut microbiota could promote a healthier and longer life could prevent long-term conditions and early death.
Improving gut health by eating healthy foods and engaging in a healthy lifespan is one way of improving longevity. While one may not be able to control the dominant population of bacteria in one’s gut, individuals can still improve their gut health by taking probiotic supplementation. Probiotics are recognised to improve gut health and longevity and reduce the risk of obesity.
Finally, you can talk to your doctor about the best probiotic supplements to promote optimal gut health and start your journey to wellness and longevity.
[1] https://microbiomejournal.biomedcentral.com/articles/10.1186/s40168-022-01418-5
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3144392/
[3] https://www.apa.org/monitor/2012/09/gut-feeling
