A Mediterranean-based ketogenic diet may help lower Alzheimer’s disease risk

Both the Mediterranean and ketogenic — often shortened to “keto” — diets have been around for a while.

Past research shows that the Mediterranean diet may help slow the development of Alzheimer’s disease. And other research has found that the keto diet may offer a new way to treat Alzheimer’s.

The Mediterranean diet is based on foods traditionally eaten in the Mediterranean region, including the countries of Greece and Italy.

This diet focuses on eating fruits, vegetables, whole grains, fish, legumes, olive oil, and limited amounts of red meat. Processed foods, sweets, and sugar-sweetened beverages should be avoided.

The keto diet focuses on eating healthy fats and decreasing carbohydrate intake. Foods focused on in the keto diet include animal proteins, non-starchy vegetables, dairy, oils, and butter.

“The Mediterranean ketogenic diet is a low-carbohydrate, high-fat, normal-protein diet, in which the fat and protein are derived mostly from healthy sources such as olive oil, fish, and poultry,” Dr. Suzanne Craft, professor of gerontology and geriatric medicine at Wake Forest University School of Medicine and co-lead author of this study explained to Medical News Today.

Dr. Craft said past studies have indicated that diet may be a powerful modulator of brain health.

“Diets that include high levels of saturated fats, sugars, and processed foods have been associated with increased risk of Alzheimer’s disease in studies of large populations. Conversely, Mediterranean diets rich in fruits and vegetables and healthy fats are associated with reduced risk of Alzheimer’s disease.”

– Dr. Suzanne Craft

“These studies looked only at associations, however, so we decided to examine [the] effects of a diet intervention which can help determine whether diet can cause changes in brain health,” she continued.

For this study, Dr. Craft and her team conducted a randomized study with 20 adults with prediabetes. Nine had previously received a diagnosis of mild cognitive impairment (MCI) and 11 had normal cognition.

Participants were randomly asked to follow either the Mediterranean-based keto diet or a low-fat, high-carb diet for 6 weeks. They then followed a 6-week “washout” period and switched to the other diet they had not followed yet for another 6 weeks.

Upon analysis, researchers found participants with MCI on the Mediterranean-based keto diet had lower levels of gamma-aminobutyric acid (GABA) and GABA-producing microbes.

“GABA is a chemical that helps brain cells communicate,” Dr. Craft explained. “GABA modulates brain activity so that it achieves appropriate levels. In persons with Alzheimer’s disease, GABA does not function effectively, so balancing GABA may help regulate their brain activity and improve brain function.”

Additionally, the research team discovered participants with MCI who had curcumin — a compound found in turmeric — in their diets experienced lower levels of bacteria containing bile salt hydrolase (BSH).

“We found that adults with MCI who had curcumin in their diet had lower levels of a substance (BSH) related to gut motility — the time it takes food and waste to transit the gut,” Dr. Craft detailed. “Lower gut motility may allow the gut to be exposed to pathological substances for longer periods and magnify their negative effects.”

Dr. Craft said this was a small pilot study intended to demonstrate whether a ketogenic diet might benefit adults with Alzheimer’s disease.

“Based on our successful results, we are in the process of carrying out a larger study that will confirm our findings and determine whether this approach should be considered as a therapeutic strategy for preventing or treating Alzheimer’s disease,” she added. “That larger study will be completed in a year.”

This research also correlates to another recent study published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association that found non-drug interventions for Alzheimer’s disease were both effective and cost-effective.

The four non-drug interventions included at-home care, counseling through an outpatient clinic, individual care plans, and an adult day care service with face-to-face support.

Researchers from Brown University used a computer simulation to model what results may be like if people with Alzheimer’s use one of the four non-drug interventions. Scientists used data from Medicare, clinical trials, and national surveys of families with people with dementia.

At the conclusion of the study, the researchers found the four non-drug interventions saved between $2,800 and $13,000 in societal costs. Additionally, it helped reduce nursing home admissions and improve quality of life.

MNT also spoke with Molly Rapozo, a registered dietician nutritionist and senior nutrition and health educator at Pacific Neuroscience Institute in Santa Monica, CA, about this study and its implications.

“Why this [study] could be beneficial is because there’s a focus on anti-inflammatory fats and foods, which is part of the disease process with Alzheimer’s,” she told us.

“[A] big risk is elevated blood sugar and this study actually looked at people with pre-diabetes — it wasn’t a metabolically healthy population. [A diet] lower in carbohydrates has the benefit of potentially lowering blood sugar and insulin,” Rapozo added.

When it comes to using what a person eats to lower their Alzheimer’s disease risk, Rapozo said that complex carbohydrates are foods that would be supportive.

“Some of those are low in carbs, like non-starchy vegetables, nuts, seeds, berries,” she explained. “And doing less refined carbohydrates, like sugar and highly processed grain foods, snack foods.”

“You want to do a quarter of your plate at lunch and dinner to be starchy food like a sweet potato or a whole grain like quinoa,” Rapozo added. “Half your plate is going to be the non-starchy veggies. And that [last] quarter is something protein-dense — Mediterranean choices might be tempeh, seafood, or poultry.”