Ketogenic Diets and Their Impact on Cognitive Brain Health

Ketogenic Diets and Their Impact on Cognitive Brain Health

What is the Ketogenic Diet?

The ketogenic diet, a very low-carbohydrate ketogenic (VLCK) diet, aims to make the body use “ketones” as its primary fuel source. In simple terms, this diet involves consuming mostly fats, a moderate amount of proteins, and a few carbohydrates. Fats are commonly found in everyday foods, while protein intake is adjusted based on growth needs, and carbohydrates are limited.

In a ketogenic diet, about 90% of the energy comes from fat, with the remaining portion from proteins and carbohydrates combined. The main goal of the ketogenic diet is to achieve a state called “ketosis.” Normally, your body relies on carbohydrates, converted into glucose, as its primary energy source. However, when you significantly reduce carbohydrate intake and increase fat consumption, your body adapts to using a different energy source.

The Role of Ketones

During ketosis, your body breaks down both the fats from your diet and the fats stored in your body into molecules called ketones. These ketones serve as an alternative fuel source for the body, replacing the usual dependence on carbohydrates and glucose. This process of relying on ketones for energy is what defines the ketogenic diet.

Benefits of Keto Diet

Ketogenic Diets and Brain Benefits

Intriguingly, benefits of ketogenic diets on the brain have been known since at least early 1900s, wherein ketogenic diets had been used to help control epilepsy and prevent seizures before development of effective medications. 1  Recent scientific research has been exploring how these diets can protect the brain, improve cognitive function, and potentially help with neurodegenerative disorders.

Remarkable Benefits for Alzheimer’s Dementia

The ketogenic diet has shown remarkable benefits for conditions like Alzheimer’s dementia. It has also been found to enhance cognition in otherwise healthy individuals, as supported by both animal and clinical studies. Studies have demonstrated correlation between increased serum levels of β-hydroxybutyric acid and improved cognitive function and memory 2. This same molecule might also help compensate for the glucose utilization issues commonly seen in Alzheimer’s dementia, as shown in Positron Emission Tomography studies when patients were given medium chain triglycerides(MCTs). 3.  It has also been demonstrated that ketone bodies improved verbal memory in patients with mild cognitive impairments. 4

One significant trial called The Ketogenic Diet Retention and Feasibility Trial (KDRAFT) revealed that when the body is in a state of ketosis achieved through an MCT-supplemented ketogenic diet, there was a significant improvement in the Alzheimer’s disease Assessment Scale-cognitive subscale score (ADAS-cog). This means that the cognitive abilities of the participants improved while following this diet have significantly improved. 5

Ketones as an Efficient Brain Energy Source

Several different mechanisms have been proposed to explain how ketone bodies can be neuroprotective, and the most widely accepted mechanism is that ketones are an efficient energy source for the brain that can improve mitochondrial function by enhancing nicotinamide adenine dinucleotide (NADH) oxidation in the mitochondrial respiratory chain and by inhibiting mitochondrial permeability transition. 6 

Reducing Oxidative Stress

The ketogenic diet is also associated with a lower production of Reactive Oxygen Species (ROS) and thus, a reduction in oxidative stress, as compared to glycolysis, that can exert a protective mechanism against oxidative stress as well as induce an antioxidant, glutathione in the hippocampus offering possible protection against neurodegeneration. 7,8 Lastly, it is also well known that a ketogenic diet can improve insulin secretion and sensitivity, as insulin resistance is a risk factor for both cognitive impairment and Alzheimer’s disease.

Potential Issues and Concerns

Despite these promising findings, there have also been studies that have failed to show benefits, and the restrictive nature of the diet may cause other issues, particularly in elderly patients. Furthermore, the diet’s long-term impact, particularly on brain health, is unknown, and more research is needed to understand the diet’s neuroprotective mechanisms fully. Therefore, clinicians should offer personalized dietary advice, considering an individual’s genetic, metabolic, and clinical profile.


In conclusion, the ketogenic diet shows promise for enhancing brain health, particularly in the realms of cognitive function, neurodegenerative diseases, epilepsy, and mental health disorders. However, more long-term, well-controlled human studies are needed before firm conclusions can be drawn and before the ketogenic diet can be widely recommended for brain health. As always, it’s advisable to consult with a healthcare professional before making substantial dietary changes. Despite the burgeoning interest in the ketogenic diet for brain health, it’s essential to remember that diet is just one piece of the puzzle, and a holistic approach, encompassing various lifestyle factors, is crucial for optimizing brain health.


1. Barborka CJ. Ketogenic Diet Treatment of Epilepsy in Adults. Journal of the American Medical Association. 1928;91(2)doi:10.1001/jama.1928.02700020007003

2. Augustin K, Khabbush A, Williams S, et al. Mechanisms of action for the medium-chain triglyceride ketogenic diet in neurological and metabolic disorders. The Lancet Neurology. 2018;17(1):84-93. doi:10.1016/s1474-4422(17)30408-8

3. Cunnane SC, Courchesne-Loyer A, Vandenberghe C, et al. Can Ketones Help Rescue Brain Fuel Supply in Later Life? Implications for Cognitive Health during Aging and the Treatment of Alzheimer’s Disease. Frontiers in Molecular Neuroscience. 2016;9doi:10.3389/fnmol.2016.00053

4. Krikorian R, Shidler MD, Dangelo K, Couch SC, Benoit SC, Clegg DJ. Dietary ketosis enhances memory in mild cognitive impairment. Neurobiol Aging. Feb 2012;33(2):425 e19-27. doi:10.1016/j.neurobiolaging.2010.10.006

5. Taylor MK, Sullivan DK, Mahnken JD, Burns JM, Swerdlow RH. Feasibility and efficacy data from a ketogenic diet intervention in Alzheimer’s disease. Alzheimer’s & Dementia: Translational Research & Clinical Interventions. 2017;4(1):28-36. doi:10.1016/j.trci.2017.11.002

6. Veech RL. The therapeutic implications of ketone bodies: the effects of ketone bodies in pathological conditions: ketosis, ketogenic diet, redox states, insulin resistance, and mitochondrial metabolism. Prostaglandins, Leukotrienes and Essential Fatty Acids. 2004;70(3):309-319. doi:10.1016/j.plefa.2003.09.007

7. Achanta LB, Rae CD. β-Hydroxybutyrate in the Brain: One Molecule, Multiple Mechanisms. Neurochemical Research. 2016;42(1):35-49. doi:10.1007/s11064-016-2099-2

8. Ziegler DR, Ribeiro LC, Hagenn M, et al. Neurochemical Research. 2003;28(12):1793-1797. doi:10.1023/a:1026107405399

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