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What is the KetoFLEX diet and can it prevent Alzheimer's?

Doctor's lifestyle plan attracts both buzz and critics.
Low-carb diet
A low-carb, plant-rich and mildly ketogenic diet is one of the main components of the plan.Shutterstock
/ Source: TODAY

About a third of Alzheimer's disease cases may be preventable if people do “everything right,” experts say.

But what does that actually mean? Many researchers are trying to answer to that question.

One take comes from Dr. Dale Bredesen, a neurologist and author of the new book “The End of Alzheimer's Program: The First Protocol to Enhance Cognition and Reverse Decline at Any Age.” It’s a follow-up to his 2017 bestseller, which explained his research identifying 36 factors he believes contribute to cognitive decline.

There is currently no known cure for Alzheimer’s disease, so the certainty of the book’s title and Bredesen’s message that “hope has finally come to those with dementia or risk for dementia” have attracted vocal critics.

“When carefully examined, multiple red flags appear in the scientific studies supporting the Bredesen protocol,” warned Dr. Joanna Hellmuth, a neurologist at the University of California, San Francisco Memory and Aging Center, in an editorial in Lancet Neurology in May.

She cited concern about everything from the study design to some of Bredesen’s papers being published in “scientific-sounding publications that hijack the open access model for profit.”

Elements of the Bredesen protocol that haven’t been shown to be effective are the “costly regimens of dietary supplements,” Hellmuth wrote, noting that “to date, the evidence does not support its claim to prevent and reverse cognitive decline.”

The Alzheimer’s Association “has seen no rigorous scientific evidence to support the program’s claims and cannot recommend anyone adopt this program to try to improve their or a loved one’s memory and thinking,” it said in a statement to TODAY.

“This area of research — multi-component lifestyle interventions to treat or prevent dementia — is intriguing and hopeful. It may have therapeutic possibilities on its own or in combination with future drug therapies, as we now treat heart disease,” the organization added.

Hellmuth acknowledged some of Bredesen’s recommendations could be beneficial for brain health, including aerobic exercise, a Mediterranean diet and managing cerebrovascular risk factors.

Previous research has shown lifestyle changes may protect against, or delay, memory loss. This could be especially important for women, who make up two-thirds of Alzheimer’s disease cases.

Bredesen himself dismissed the criticism of his approach as typical of any new views in medicine, which doesn’t welcome disruption, he said. But the current focus on a drug that would block the production of amyloid plaques — clumps of protein seen in the brains of Alzheimer’s patients — as the only solution has to change, he added.

“It’s not a single thing. There are multiple contributors to the pathology of what we call Alzheimer’s,” Bredesen told TODAY.

“It does not comport with the classic view that there’s some sort of misfolded protein going on and we’re going to give a drug to get rid of that. The amyloid is not what causes the disease; it’s what your body is doing to respond to these various insults.”

He tells patients: “Imagine you have a roof with 36 holes in it. A drug is an excellent cover for one hole but it doesn’t (stop) the other things.”

Keto/FLEX 12/3:

That’s where Bredesen believes “Keto/FLEX 12/3” — a lifestyle of diet, fasting, exercise and quality sleep — is key. He recommends people implement it in their 30s, 40s and 50s to prevent cognitive decline and enhance their cognition.

Keto stands for ketosis, or burning fat instead of blood sugar for energy. Bredesen writes his mildly ketogenic low-carb diet provides excellent fuel for cognition and increases the production of brain-derived neurotrophic factor, which plays a role in brain development and plasticity.

FLEX refers to the body’s flexibility to metabolize either fat or glucose on this diet, and to the option for people to eat meat or not. “This is not your typical bacon-induced ketosis; this is a plant-rich diet that turns out to have the best benefits for cognition,” Bredesen said.

12/3 is the number of hours spent fasting: at least 12 hours between the last meal of the day and breakfast; and at least three hours between dinner and bedtime. Fasting leads to a decrease in inflammation and activates autophagy, a mechanism that helps to regenerate cells, he noted.

Bredesen illustrated the basic rules of the Keto/FLEX 12/3 in his “brain food pyramid”:

Brain Food Pyramid
Bredesen calls this the brain food pyramid.Courtesy Penguin Random House

Diet basics:

After fasting overnight, non-starchy vegetables and good fats — like extra virgin olive oil, avocados, nuts and seeds — support the best cognition and are the base of the diet, he said.

The brain and the gut are connected, so gut health is important. Bredesen advised consuming plenty of prebiotic fiber like mushrooms, onions and garlic; “resistant starches” that act more like fiber including beans and lentils; and probiotic foods that contain beneficial bacteria such as sauerkraut, pickles and miso.

Fruit and animal protein fall into the “choose wisely category” on the pyramid. “I grew up with the idea that you’re supposed to each as much fruit as possible,” Bredesen said. “The problem is the fruit we’re now exposed to has all been bred to have extremely high sugar levels.” He recommended focusing on berries, which have natural plant chemicals that may protect the brain.

When it comes to the best animal foods for optimal cognition, wild-caught seafood and pastured eggs are the “clear winners,” Bredesen writes.

The top of the pyramid lists foods that should only be enjoyed occasionally and in small amounts, like red wine and dark chocolate. Bredesen advises eliminating all grains and conventional dairy from your diet.


“Being active is the single most important strategy you can employ to prevent and remediate cognitive decline,” Bredesen writes in his book. It improves blood flow to the brain, among other benefits. He recommends alternating aerobic exercise with strength training, and working out at least five days a week, for a minimum of 45 minutes per day.

Inversions, like headstand, can also be beneficial: “You ultimately want to be able to get blood to places that — when you’re just sitting on the couch — you’re not getting a lot of oxygenation and blood flow to the far reaches of the brain,” Bredesen said.


“It’s a badge of courage to not have much sleep and it turns out this is horrible for your cognition,” he noted. Bredesen recommends making seven to eight hours of sleep the goal. He calls it the foundation of the Keto/FLEX 12/3 lifestyle.