Mounting research continues to show the links between the health of the gut and that of the brain. Now, a new study from Lund University in Sweden finds that unhealthy intestinal flora can accelerate the development of Alzheimer’s disease.
The report, published Feb. 8 in the journal Scientific Reports, demonstrates that mice with Alzheimer’s have a different gut bacterial profile than those that do not have the disease.
The gut microbiome is highly responsive to dietary and lifestyle factors. This suggests that a gut-healthy diet may play a powerful role in preventing one of the most feared diseases in America.
“Alzheimer’s is a preventable disease and in the near future we will likely be able to give advice on what to eat to prevent it,” study author Dr. Frida Fak Hållenius, associate professor at the university’s Food for Health Science Centre, told The Huffington Post. “Take care of your gut bacteria, by eating lots of whole-grains, fruits and vegetables.”
In the new study, Hållenius and her colleagues revealed a direct causal association between gut bacteria and signs of Alzheimer’s in mice. When a group of bacteria-free mice were colonized with the bacteria of rodents with Alzheimer’s, they developed brain plaques indicative of Alzheimer’s. When the bacteria-free mice were colonized with the bacteria of the healthy rodents, however, they developed significantly fewer brain plaques.
Beta-amyloid plaques between nerve cells in the brain are a central marker of the disease. These sticky protein clumps accumulate between the brain’s neurons, disrupting signals and contributing to the gradual killing off of nerve cells.
“We don’t yet know how bacteria can affect brain pathology, we are currently investigating this,” Hållenius said. “We think that bacteria may affect regulatory T-cells in the gut, which can control inflammatory processes both locally in the gut and systemically ― including the brain.”
The contributions of microbes to multiple aspects of human physiology and neurobiology in health and disease have up until now not been fully appreciated.
The gut microbiome is intimately connected with the immune system, since many of the body’s immune cells are found in this area of the stomach, Hållenius added.
Anything that happens in the digestive tract can affect the immune system, she explained. “By changing the gut microbiota composition, you affect the immune system of the host to a large extent.”
The findings suggest that Alzheimer’s may be more more preventable than health experts previously thought. The composition of bacteria in the gut is determined by a mix of genetics and lifestyle factors. Diet, exercise, stress and toxin exposure all play a huge role in the gut’s bacterial makeup.
Now, the researchers can begin investigating ways to prevent the disease and delay its onset by targeting gut bacteria early on. And in the meantime, anyone can adopt a plant-based, whole foods diet and probiotic supplementation as a way to improve the health of their microbiome.
“The diet shapes the microbial community in the gut to a large extent, so dietary strategies will be important in prevention of Alzheimer’s,” Hållenius said. “We are currently working on food design that will modulate the gut microbiota towards a healthier state.”
The study is far from the first to show a connection between gut bacteria and Alzheimer’s. In a 2014 paper published in the journal Frontiers in Cellular Neuroscience, researchers listed 10 different ways that the microbiome may contribute to the development of Alzheimer’s disease, including fungal and bacterial infections in the intestinal tract and increased permeability of the blood-brain barrier.
“The contributions of microbes to multiple aspects of human physiology and neurobiology in health and disease have up until now not been fully appreciated,” that study’s authors wrote.