By Sebastian Rushworth, M.D. | May 29, 2021

A sea change is underway. Ten years ago, it was heresy to propose that a ketogenic (a.k.a low carb high fat) diet was in any way healthier than the low fat high carb diet supported by public health authorities. It was branded a “gimmick” diet. In some places, doctors who prescribed it to their patients risked having their medical licenses revoked.

The German physicist Max Planck is often misquoted as having said that “science advances one funeral at a time”. Well, the man who gave birth to the low fat high carb dogma, Ancel Keys, died in 2004. His first generation of acolytes have now joined him in oblivion. The men (they were with very few exceptions all men) who created the current dietary guidelines back in the late 70’s and early 80’s are also gone, after having presided over a massive explosion in the number of people suffering from obesity and type 2 diabetes.

The newer generations of nutrition researchers do not appear to be as wedded to the old dogma. This is visible in the increasing number of studies being published on a ketogenic diet. Some of these are even appearing in the most prestigious and conservative nutrition journals.

One such study was recently published in Advances in Nutrition, a journal owned by the American Society for Nutrition. It was a systematic review looking at randomized trials of a ketogenic diet as a treatment for Alzheimer’s disease, which is the most common cause of dementia. We’re going to get to that study in a minute, but first, a little detour.

There is some evidence to support the notion that dementia can in part be caused by a high carbohydrate diet. An observational study was published back in 2012 in The Journal of Alzheimer’s Disease in which 937 elderly people were followed for four years. The median age at the start of the study was 80 years, and at the beginning, all the participants were asked to fill in a diet questionnaire and were also evaluated for cognitive function. Four years later, 200 of the 937 participants had developed some level of cognitive impairment.

When the researchers correlated this with dietary carbohydrate intake, they found that the quartile with the highest intake had an 89% increased relative risk of developing cognitive impairment during the four years of follow-up, as compared to the group with the lowest intake. And that’s after adjusting for known confounders like gender, BMI, co-morbidities, and APOE4 status (APOE4 is a gene variant that is strongly associated with increased risk of Alzheimer disease). The difference was statistically significant (p-value 0.004).

The quartile with the highest fat intake, on the other hand, had a 56% decreased relative risk of cognitive impairment as compared to the quartile with the lowest fat intake (p-value 0.03).

Interestingly, the differences between the quartiles in terms of carbohydrate and fat consumption weren’t actually that big. The highest quartile in terms of carbohydrate consumption was getting more than 58% of calories from carbohydrates, while the lowest quartile was getting less than 47%. Not a huge difference. The same was true for fat intake. The quartile with the highest fat intake was getting more than 35% of calories from fat, while the quartile with the lowest fat intake was getting les than 27%. This would seem to suggest that even relatively modest differences in consumption of carbohydrates and fats can have big effects on cognitive function over time, and that an even bigger reduction in relative carbohydrate intake might have achieved an even bigger reduction in risk of cognitive impairment.

[…]

https://alethonews.com/2021/05/30/is-a-ketogenic-diet-effective-against-dementia/