In mice fed an unhealthy diet, probiotic supplements are linked to improvements in gut bacteria, lower inflammation in the intestines and brain, and reduced loss of cognitive function.
Mechanism
Synthesis from 1 study
Eating too much fat and sugar changes the gut bacteria, which damages the gut lining and lets toxins into the blood. These toxins stress cells, causing their energy factories to break and leak DNA. The body sees this DNA as an infection and turns on inflammation, which spreads to the brain and...
Most probable mechanism
When mice eat a diet high in fat and sugar, the good bacteria in their gut die off and bad bacteria take over. This damages the gut lining, letting bacterial toxins leak into the bloodstream. These toxins cause stress in cells throughout the body, including in the brain, making mitochondria — the energy factories inside cells — break down. When mitochondria break, they release their own DNA into the cell fluid, which the immune system mistakes for an infection. This triggers two alarm systems that release powerful inflammatory signals. These signals reach the brain, activating immune cells there, which then damage nerve cells in the memory center. Over time, this leads to memory problems.
A high-fat, high-carbohydrate diet alters the composition of gut microbiota, reducing beneficial species and increasing pro-inflammatory microbial strains
Dysbiosis increases intestinal permeability, allowing microbial products such as lipopolysaccharide to translocate into systemic circulation
Systemic microbial toxins induce mitochondrial stress and reduce expression of TFAM, a key regulator of mitochondrial biogenesis
Mitochondrial dysfunction leads to release of mitochondrial DNA into the cytosol, where it acts as a damage-associated molecular pattern
Cytosolic mitochondrial DNA activates the AIM2 inflammasome and cGAS-STING signaling pathways, triggering production of interleukin-1β, interleukin-18, and type I interferons
Pro-inflammatory cytokines and interferons cross the blood-brain barrier or activate resident microglia and astrocytes, initiating neuroinflammation
Chronic neuroinflammation activates intrinsic apoptotic pathways in hippocampal neurons, leading to neuronal loss
Loss of hippocampal neurons impairs synaptic plasticity and memory consolidation, resulting in cognitive decline
Evidence from Studies
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