Centenarians and microbiota

Centenarians are people older than 100 years (this is what we call longevity). When they are healthy, they are good examples of successful ageing. Living over 100 is more common in some parts of the world than others. The highest density of centenarians is present in Japan and Southern Europe, People aged between 100 and 104 have reduced microbial diversity and compromised stability of microbiota. They also got specific age-related microbes, higher levels of opportunistic pathogens and lower levels of beneficial butyrate producing bacteria. But healthy people with great longevity reaching 104-109 are different than normal centenarians. They have the same bacteria, but the proportion is different. They got more Bifidobacterium, Akkermansia and Christensenellaceae. Longevity is indeed associated with microbiota changes, and further studies of the specific bacteria linked with longevity can help us to find strategies that use diet to promote a healthy microbiota and a healthy ageing.

Dietary habits can play a role on the development and the severity of the chronic diseases such as diabetes type 2, heart disease and certain types of cancer. You probably know that nutrition has a role in preventing diseases and promoting health. Caloric intake and timing of eating food, and well as the nutrients provided by the food consumed, all of these have a role in improving health and even longevity.

For example, reducing food but preventing malnutrition improves ageing (first research on this subject, made in 1935, found that food restriction avoiding malnutrition resulted in higher maximum lifespan in rats). Since then experiments followed on nematode worms, fruit flies, fish, mice up to non-human primates and humans, and all of them underlined that the quality of diet and the caloric intake plays a role in improving health and longevity. Basically a caloric restriction between 10 to 50% improves the lifespan in most of the cases, however there is a small number of cases where a higher percentage of the calorie restriction will not increase the lifespan, an 40-50% is too much for these subjects.

Microbiota-wise, longevity is characterized by a stable core microbiota. The core microbiota shrinks with age, and the subdominant bacteria increase in abundance. For Chinese, Japanese and Italian elderly groups the bacteria that are enriched include Clostridium, Ruminococcaceae, Akkermansia and Christensenellaceae. These bacteria are linked to gut body mass index, immunomodulation and healthy homeostasis. In conclusion, there are several factors of one's diet to influence longevity. Caloric restriction is one of them, having a major potential to increase life expectancy.

General knowledge on the relationship between gut microbiota and longevity can be used to improve the lifespan of the elderly through diet and modulation of their microbiota.

Microbiota, ageing and basic changes

When you age, your microbiota ages with you. Most significant changes in adult microbiota are caused by diet and medicine. After age of 65 hormone regulation changes, impacting energy levels, changing the physical activity, the smell, taste, feeling of fullness and satiety. Sometimes this can lead to a nutritionally imbalanced diet. Elderly people microbiota contains Proteobacteria (a group of bacteria with many potential pathogens) and because of this group, they are at higher risk of infections. Intestinal microbiota of older people is less diverse and has a compromised stability, making them vulnerable to infections and chronic diseases. Taking medicines can disturb the microbiota, but eating healthy and doing exercise helps to age graciously. Microbiota seems to play a role in healthy ageing, keeping immune system in check and protecting against pathogens.

At the moment 13 % of the world population is over 60 years old and this will only increase in the future. There are age-related diseases (cancer, diabetes type 2, atherosclerosis, insulin resistance etc.) and surprisingly many of them are associated with an alteration to the microbiota.

Is the microbiota composition changing with age? Let's first define ageing as a continuous and progressive decrease of physiologic function across all organ systems. All these changes sometimes lead to different diseases. One of the most important effect in our case is the reduction of the gut motility as you get older. The changes in the microbiota follow the changes in the diet, physical activity patterns and other gut related physiological changes. As you get old, there is a decrease in the core gut microbiota (and we already know that the gut microbiota is a very important modulator of the immune system, being involved in ageing related low-grade inflammatory responses). Being an adult, the core microbiota is dominated by Ruminococcaceae, Lachnospiraceae and Bacteriodaceae. The older we get, the smaller the core microbiota becomes. For example semi-super centenarians (105-109 years old) microbiota will have a reduction of the core and an increase of the subdominant fraction (the sub-dominant fraction has many health-associated groups like Bifidobacteria, Akkermansia and Cristensenellaceae).

But overall there are not many researches related to the gut relation with healthy ageing, and the existent ones will consider the elderly age 60, 65 or even 70, so they are not using the same subcategories of people age segments.

Next post will be about centenarians and microbiota.
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G.

Antibiotics and microbiota

Antibiotics are lifesaving in many cases. But for microbiota development antibiotics are a big threat. The transmission of microbiota from mother to infant provides the child with beneficial microbes. If the mother of the child has antibiotic treatment upon birth or right after, this will have devastating effect on the infant microbiome development. Because of this the child can have long lasting shifts in microbiota composition and metabolism, including the depletion of Bifidobacteria. Antibiotics are routinely administered during c-section, and this has a role in the delayed Bifidobacteria colonization. Bifidobacteria has been shown to be transmitted vertically from mother in case of normal birth. We have several long term effects if antibiotics treatment were prescribed early in life, such us the decrease in Bifidobacteria, increase in Firmicutes and Clostridial groups of bacteria, associated with the development and onset of allergic diseases. Perinatal antibiotic exposure and infant antibiotic use are also increasing the risk of allergies.

Antibiotic induced disturbances of the microbial balance early in life can play a role in being overweight and obesity later in life (association between early life antibiotic exposure and childhood obesity has been observed in large cohort studies and is a certainty). Antibiotic usage in early life should be taken very seriously and consciously. The described association between microbiota, antibiotics and later life risks requires further investigation.

Next: Ageing and basic changes in microbiota.

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G.

Nootropics, brain boosters and fake geniuses

All of you need to know this.

According to this post, very soon we will find in here a lot more about how to use our brain 101% (pun intended).

Microbiota - gestational age

A pre-term delivered infant is at greater risk for health complications. The microbiota of a pre-term baby is less stable than that of a baby born at the right term. The health risks that pre-term delivered babies face are related to the differences in the gut microbiota.

When a baby is born earlier than week 37, we talk about premature birth. A pre-term delivered baby is prone to health complications, more susceptible to infections (which are more dangerous as their immune system is not ready to face them yet). We know that the microbiota can play a role in the defense against pathogens. The microbiota development is affected by the birth mode, nutrition, environment and medication. All of these factors are not only associated with the microbiota, but also with the newborn physiology, growth and development. Some infants are at higher risks of different microbiota development because of the c-section delivery, antibiotic use and formula feeding (and/or sometimes enteral feeding also). All of these are common traits for pre-term delivered babies. Every one of these factors can lead to sub-optimal conditions for the microbes living in the intestines, so the microbiota of a pre-term born baby is less stable that that of a baby delivered in term. The immediate risks of a premature baby microbiota composition are the increased risk of sepsis and of necrotizing enterocolitis (NEC). All of these infections are life threatening for the baby. There is a direct correlation between the microbiota colonizing rate and the gestational age (meaning that the infants born at younger gestational age got less colonizing microbes).

Another major issue is related to the colonization with Bifidobacteria, which is delayed in pre-term born infants. The duration of the antibiotic treatment is associated with the delayed colonization too, as treating the premature baby with antibiotic form one to seven days will directly affect the colonization rate of Bifidobacteria. The longer the treatment, the longer it takes for Bifidobacteria to start colonize the intestine. To add to this problem, the respiratory support seems to prevent strictly anaerobes such as Bifidobacteria to colonize the intestinal tract. Instead, facultative anaerobes and aerobic bacteria could be present, many of them being opportunistic pathogens. This can contribute to higher risks of infection. The delay in the colonization with Bifidobacteria can be linked to nutritional status, as the lack of it can reduce the nutritional value because of the lesser degradation of the food. We all know that efficient energy uptake from food will improve the growth and development of the infant. All of these pre-term babies have increased colonization by potential pathogens and a delay/decrease colonization of Bifidobacteria.

Awareness of the possible benefits of the microbiota composition for pre-term born infants will help to develop strategies to improve health status of this vulnerable group of children.

Next post will be about the antibiotics effects on the microbiota.

Microbiota - ways of delivery and later life effects

The way you are born determines how your microbiota develops. A child who is born naturally will have a different microbiota than a child who is born via c-section. A c-section child will have less diverse microbiota, so their guts will contain fewer different microbes. These differences in microbiota related to the mode of birth are present only early in life, but they have potential risks later in life: allergies, asthma, type 1 diabetes and obesity.

Why, would you ask? One hypothesis is that different microbes colonizing the babies' gut have different effects on the immune system development. The window of opportunity to train and develop your immune system health may be different for natural born and c-section born children. Another hypothesis is that mom's gut microbes are already selected and deemed safe, being also beneficial for food digestion, decreasing the risk of exposure to pathogens and increasing the chance of beneficial food degradation in the child's intestine.

The mode of delivery determines which microbes will colonize the gut right after birth, but has no effects of the microbiota existing later in life. All the correlation between mode of delivery and overall health as an adult might be possible because of the differences in the microbiota composition from the newborn's gut.

Next post will be about gestational age of microbiota.

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G.