The ketogenic diet (KD) is a high-fat, low-carbohydrate eating pattern that may offer benefits for people at risk of Alzheimer’s disease (AD).
Researchers believe this is partly because the diet can help protect the brain from seizures and improve metabolic function—both of which are linked to cognitive health.
An important player in this process is the gut microbiota, the community of bacteria living in the digestive system.
Gut bacteria influence how the ketogenic diet affects the brain and also play a role in cholesterol metabolism, which has been linked to Alzheimer’s risk.
To explore these effects, researchers examined gut bacteria and brain-related metabolic markers in adults with mild cognitive impairment (MCI) and in those with normal cognitive function.
Participants followed either a low-fat American Heart Association diet or a high-fat modified Mediterranean ketogenic diet (MMKD) for six weeks.
After a six-week washout period, participants switched to the other diet. Stool samples were collected at five time points throughout the study to track changes in gut microbiota and related metabolic substances.
The researchers found that participants with MCI who followed the MMKD showed reduced levels of certain gut bacteria that produce gamma-aminobutyric acid (GABA). GABA is a neurotransmitter that helps calm brain activity and protect against seizures.
At the same time, these participants had higher levels of other bacteria involved in regulating GABA balance. This shift may be beneficial, as it could help prevent excessive brain activity and support more stable neural function.
The study also found that participants with MCI who consumed curcumin—a compound found in turmeric—showed distinct changes in their gut microbiota, along with slower intestinal transit times.
Slower digestion may help prevent disruptions in gut health by allowing more time for nutrient absorption and microbial balance.
Overall, the findings suggest that the modified Mediterranean ketogenic diet may benefit people with mild cognitive impairment by altering gut bacteria and metabolic pathways linked to brain function. These changes could potentially support cognitive health and reduce factors associated with Alzheimer’s risk.
While there is no guaranteed way to prevent Alzheimer’s disease, growing evidence suggests that diet and lifestyle choices may help reduce risk. Several foods have been consistently associated with better cognitive health:
- Leafy green vegetables, such as spinach, kale, and collard greens, have been linked to slower cognitive decline.
- Berries, including blueberries and strawberries, are rich in antioxidants that may help protect brain cells.
- Nuts, such as almonds and walnuts, provide healthy fats and vitamin E, which have been associated with improved cognitive outcomes.
- Whole grains, including brown rice and oatmeal, supply fiber and nutrients that support overall brain and vascular health.
- Fatty fish, such as salmon and sardines, are high in omega-3 fatty acids linked to reduced cognitive decline.
In addition to diet, maintaining a healthy weight, staying physically active, and limiting alcohol and tobacco use are important steps in supporting long-term brain health.
The study was conducted by Amanda Hazel Dilmore and colleagues and published in Alzheimer’s & Dementia.
