Article - Role of Ketogenic Diets in Neurodegenerative Diseases (Alzheimer's Disease and Parkinson's Disease).

Plain Language Summary

The ketogenic diet (KD) is characterised by a low-carbohydrate, high-fat content that induces a fasting-like state in the body. The KD has been used clinically for children with epilepsy and recent studies have shed light on potential neuro-protective effects. The aim of this systematic review was to evaluate the role of the KD in prevention of Parkinson's disease (PD) and Alzheimer's disease (AD). Among the existing literature, there is very limited data on long-term application of the KD in patients with neurodegenerative disease. The research using animal models or in-vitro models look very promising however the use of KD in elderly adults with neurodegenerative disease is very complex. Based on these results, the authors conclude there is a need for further research to evaluate the suitability of KD for patients with AD or PD.

Expert Review

Reviewer: Miguel Toribio-Mateas

6th Apr 2022

Conflict of interest

None

Take home message

The studies into the effectiveness of ketogenic diets in neurodegenerative diseases tend to be too small and heterogeneous to draw firm conclusions.
Specific elements of ketogenic diets may be useful for individual cases, however healthcare practitioners are encouraged to take an individualised approach to the clinical management of neurodegenerative conditions, drawing from different approaches that suit the individual living with the disease.

Evidence category

C: Non-randomized trials, observational studies, narrative reviews

Summary review

The role of ketogenic diets for the management of a number of conditions has become a discussion subject, not only for scientists and clinicians, but also for the general public, however the evidence of their effectiveness in neurodegenerative diseases is patchy. Studies are either too small to be good enough to draw conclusions from, or the interventions are too mixed / heterogeneous to be able to attribute any potential benefit to the ketogenic dietary component alone. This highlights the need to take an individualised approach to the clinical management of neurodegenerative conditions, drawing from different approaches that suit the individual living with the disease.

Clinical practice applications

Specific elements of ketogenic diets might be useful for individual cases. However clinicians should be encouraged to draw from a wide array of approaches and not be limited to one single method when it comes to dealing with complex conditions such as Alzheimer's and Parkinson's Disease. Patient-centred care where dietary recommendations revolve around the individual's needs - based on biochemical markers but also on subjective experience of their own quality of life / wellbeing - should be the basis upon which to tailor nutrition programmes that support those living with neurodegenerative conditions.

Considerations for future research

Good methodological quality studies with placebo / control groups and clear outcomes are needed in order to contribute to the evidence base of the potential role of ketogenic diets in the support of patients living with neurodegenerative conditions.

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Abstract

The goal of this review was to assess the effectiveness of ketogenic diets on the therapy of neurodegenerative diseases. The ketogenic diet is a low-carbohydrate and fat-rich diet. Its implementation has a fasting-like effect, which brings the body into a state of ketosis. The ketogenic diet has, for almost 100 years, been used in the therapy of drug-resistant epilepsy, but current studies indicate possible neuroprotective effects. Thus far, only a few studies have evaluated the role of the ketogenic diet in the prevention of Parkinson's disease (PD) and Alzheimer's disease (AD). Single studies with human participants have demonstrated a reduction of disease symptoms after application. The application of the ketogenic diet to elderly people, however, raises certain concerns. Persons with neurodegenerative diseases are at risk of malnutrition, while food intake reduction is associated with disease symptoms. In turn, the ketogenic diet leads to a reduced appetite; it is not attractive from an organoleptic point of view, and may be accompanied by side effects of the gastrointestinal system. All this may lead to further lowering of consumed food portions by elderly persons with neurodegenerative diseases and, in consequence, to further reduction in the supply of nutrients provided by the diet. Neither data on the long-term application of the ketogenic diet in patients with neurodegenerative disease or data on its effects on disease symptoms are available. Further research is needed to evaluate the suitability of the ketogenic diet in the therapy of AD- or PD-affected persons.