Could diet help delay progression of Alzheimer’s disease?

Alzheimer’s disease is the most frequent neurodegenerative disease. We still do not know the exact mechanisms at play, but little doubt remains that the gut microbiota is involved in its development. Since the gut microbiota is in turn impacted by what we eat, the idea to prevent this disease with our diet is catching on fast. Mediterranean diet (sidenote: Mediterranean diet Rich in fruit, vegetables, cereals, oilseeds (nuts) and fish, and low in red meat, saturated fats and dairy products. Lăcătușu CM, Grigorescu ED, Floria M, et al. The Mediterranean Diet: From an Environment-Driven Food Culture to an Emerging Medical Prescription. Int J Environ Res Public Health. 2019 Mar 15;16(6):942. ) and ketogenic diet–known for its impact on the gut microbiota and the brain–seem to be especially indicated. But we first need to understand how they act on the disease progression...

Combined diet

American researchers have thus tried to identify microbiome and brain markers of early stages of the disease, in order to assess the impact of diet on its development. To this end, they enrolled 17 subjects–11 patients with moderate cognitive disorder (early stage of the disease), and 6 healthy volunteers–who were alternately given two types of diet: one combining the principles of Mediterranean and ketogenic diet, and the other low-fat and high-carb. They also compared their gut microbiota, before and after these diets.

Bacterial “signatures” associated to cognitive decline

Even though microbial diversity was relatively similar between healthy volunteers and patients before and after adopting one of the two diets, the researchers identified, in the patient group, several markers (including the activity of various gut bacteria) which could be used to recognize a moderate cognitive decline. They also observed that both diets changed the gut microbiota of participants, but with very different effects according to the type of diet and the cognitive state of subjects. The scientists concluded that these results open the way to further studies to define new cognitive decline markers related to the gut microbiota and understand how these interactions with diet could improve the status of high-risk patients.