Can a low carb diet help slow down Alzheimer’s disease?

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It is estimated that Alzheimer’s disease (AD) affects about 50 million of people worldwide, and dementia is currently the fourth cause of death. This global estimate is even more disconcerting when considering the early stages of Alzheimer’s disease, which leads to an estimate of 416 million of people affected worldwide, across the AD continuum, or 22% of all persons aged 50 and above (1).

Understanding how to prevent or slow down the development of Alzheimer’s disease is a critical step in taking care of our aging population. As researchers are looking for treatments and causes of AD, diet is appearing to have a significant impact on the disease. In particular, the ketogenic diet has revealed very promising effects on the cognitive abilities of patients with AD.

The ketogenic diet (KD) is a diet that severely limits carbohydrates, which in turns forces the body (and the brain) to rely on fats to produce energy. Sub-products of this metabolism are ketones, which can be measured in the blood or urine and indicate whether ketosis was actually achieved.

It is suspected that glucose transporters are altered in Alzheimer’s disease, leading to poorer brain metabolism and decreased cognitive abilities. The ketogenic diet, by providing an alternative source of energy, could provide a compensatory pathway by which the brain of AD patients could regain more functionality (2).

Several studies looked at the effects and potential benefits of the ketogenic diet on AD populations, and even though not all studies are reporting improvement, several did measure an increase in cognitive function in mild and moderate Alzheimer’s disease (2). However, the ketogenic diet can prove difficult to achieve and sustain, due to the severe restriction required in carbohydrates and the necessary increase in fats. It can even be dangerous for specific populations with abnormal fat metabolism, kidney dysfunction, osteoporosis or atherosclerosis (3). A specific type of ketogenic diet modified from Mediterranean diets supplemented with Medium Chain Triglycerides (MCT) can alleviate some of the difficulties encountered with KD (3).

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Further studies are required to confirm those encouraging results and to delineate more precisely which elements of the ketogenic diet need to be present for the effects to be observed and maximized.

1: Gustavsson, A, Norton, N, Fast, T, et al. Global estimates on the number of persons across the Alzheimer’s disease continuum. Alzheimer’s Dement. 2023; 19: 658– 670. https://doi.org/10.1002/alz.12694

2: Tabaie EA, Reddy AJ, Brahmbhatt H. A narrative review on the effects of a ketogenic diet on patients with Alzheimer’s disease. AIMS Public Health. 2021 Dec 22;9(1):185-193. doi: 10.3934/publichealth.2022014. PMID: 35071677; PMCID: PMC8755961.

3: Devranis P, Vassilopoulou Ε, Tsironis V, Sotiriadis PM, Chourdakis M, Aivaliotis M, Tsolaki M. Mediterranean Diet, Ketogenic Diet or MIND Diet for Aging Populations with Cognitive Decline: A Systematic Review. Life (Basel). 2023 Jan 6;13(1):173. doi: 10.3390/life13010173. PMID: 36676122; PMCID: PMC9866105.