By Dr. Asnat Raziel, specialist in obesity treatment, metabolic health and healthy longevity; Director of the Multidisciplinary Center for Obesity Treatment, Assia Medical, Assuta Ramat HaChayal
Gut bacteria and inflammation: what the study found
Gut bacteria and inflammation are closely linked, and now there is strong new evidence for it. A Danish study published in Nature Communications examined about 1,200 adults. The researchers found that the makeup of the gut bacteria explained inflammation levels in the blood far better than age did. In addition, people with one particular bacterial profile later developed disease at a rate about 21% higher.
Background: the silent inflammation of aging
Over the years, many of us develop chronic, low-grade inflammation. It does not hurt and we do not feel it, but it damages tissues over time. The Italian researcher Claudio Franceschi named it “inflammaging.” According to a comprehensive review, this inflammation is linked to heart disease, diabetes, stroke and cognitive decline. The review also names the gut bacteria as a central factor.
Until now, most studies have treated age as the main driver of inflammation. The new study asked a different question: which explains inflammation more accurately, age or the microbiome, the community of bacteria living in the gut?
Gut bacteria and inflammation: how the study was designed
The study drew on DanFunD, a large population cohort from the Copenhagen area. The researchers examined 1,199 participants aged 20 to 72 who gave both a stool sample and a blood sample. In the blood they measured 30 cytokines, the signaling proteins of the immune system. They also checked 19 physical and biochemical measures, such as BMI, blood fats and blood sugar.
The researchers then sorted participants into four “enterotypes,” the main patterns of gut bacteria. One of them is called Bacteroides 2, or Bact2 for short. Earlier studies linked this pattern to obesity and inflammation. The researchers followed the participants for up to nine years through national hospital records.
Gut bacteria and inflammation: the key results
The headline finding: bacterial makeup explained inflammation levels better than age for 29 of the 30 cytokines, or 97% of them. Gut bacteria also “beat” age for 16 of the 19 physical measures. These included BMI, blood fats, blood sugar and HbA1c, a marker of average blood sugar over recent months. In contrast, age won only for blood pressure and aerobic fitness.
People with the Bact2 pattern had higher levels of eight inflammatory substances, including CRP and IL-6. They also had higher BMI and triglycerides, and lower HDL cholesterol and aerobic fitness. Even so, most values stayed within the normal range.
During follow-up, people with Bact2 had a 21% higher risk of being hospitalized with any new disease (hazard ratio 1.21). The risk was higher in seven disease groups, for example heart and blood vessel, respiratory and digestive diseases and infections. In contrast, a rich and diverse bacterial pattern came with a 21% lower risk (hazard ratio 0.79).
A note of caution: association, not necessarily cause
This is an observational study, so it shows an association, not cause and effect. It is possible, for example, that diet or medications affect both the bacteria and health. In addition, inflammation itself explained only about 4% of the link between Bact2 and disease risk. In other words, the bacteria probably act in other ways beyond inflammation. One more point: the figure that inflammation “arrives 37 years earlier” is a statistical estimate from the model, not a measure of biological age.
What can you do to improve your microbiome?
The link between gut bacteria and inflammation gives us a point of action, because the makeup of the bacteria can change. A diet rich in fiber, vegetables, legumes and whole grains feeds helpful bacteria. Fermented foods, exercise and good sleep also support bacterial diversity. On the other hand, unnecessary antibiotics and highly processed food harm it.
Obesity also plays an important role. In a 2020 study, among people not taking statins, the Bact2 pattern appeared in about 18% of people with obesity, compared with only about 4% of those who were lean or overweight. So treating obesity is also a way of treating the gut environment. On this topic, see my articles on semaglutide and aging and on zombie cells and inflammation. For more on daily habits, read about sleep, metabolic health and longevity.
The bottom line
The Danish study shows that the makeup of the gut bacteria reflects the body’s state of inflammation far better than a birth certificate. One bacterial pattern, Bact2, came with inflammation and a higher risk of disease. The good news: the microbiome is not destiny. Lifestyle and diet can change it, and perhaps slow inflammatory aging as a result.
The information in this article is general only and is not a substitute for personal medical advice. For questions about your own health, please consult your doctor.
Sources
Statin therapy is associated with lower prevalence of gut microbiota dysbiosis
Inflammaging: a new immune-metabolic viewpoint for age-related diseases
Gut microbiome may reveal inflammation and future disease risk better than age
The Hebrew version of this article is available here.
