An Experimental Ketogenic Diet for Alzheimer Disease Was Nutritionally Dense and Rich in Vegetables and Avocado

Abstract

Background: The ketogenic diet (KD) has gained interest as a potential therapy for numerous conditions; however, studies rarely report the food and micronutrient profile of the diet.

Objective: The aim of this study was to report changes in food selection and nutritional quality from the baseline diet (BD) to a KD therapy in participants with Alzheimer disease (AD).

Methods: Fifteen AD patients participated in a single-arm clinical trial to assess the feasibility of a 3-mo KD intervention. A registered dietitian instructed participant study partners to assist participants with a self-selected, nutritionally dense KD. We collected food and nutrient intake via monthly 3-d food records. Serum β-hydroxybutyrate was measured within 48 h of each 3-d food record to assess ketosis status. Food records before KD initiation characterized the BD. Food records during the intervention coincident with the most robust ketosis characterized the KD. Principal components analysis identified foods affiliated with the BD and KD. Mean food and nutrient intake change was tested by the Kruskal-Wallis test for variance with significance set at P ≤ 0.025.

Results: Ten participants adhered to the KD. Study partners provided complete food records for 6 KD-adherent individuals. The KD was characterized by increased medium-chain triglyceride (MCT) oil, nonstarchy vegetables, butter, eggs, olive oil, avocados, and nuts and seeds with practical elimination of potatoes, grains, red meat, sugar-sweetened beverages, and desserts. Fruit intake, including avocado, was similar between diets. Nonstarchy vegetable intake increased from 1.2 servings/d to 4.3 servings/d (P < 0.01) on the KD. Micronutrient intake was similar between diets, meeting Dietary Reference Intakes for most nutrients. Between diets, the KD was associated with increased intake of choline and vitamin K and decreased intake of manganese and fiber.

Conclusion: As a potential therapy in AD, the KD can be nutritionally dense with high intake of vegetables and substantial variety. This trial was registered at clinicaltrials.gov as NCT03690193.

Keywords: Alzheimer disease; fruits; ketogenic diet; principal components analysis; vegetables.

Figures

FIGURE 1

Food group loadings for the principal components analysis diet pattern (n = 6). Rotated food group loading coefficients are represented as the bars. Foods located toward the positive terminal of the graph are foods that had the largest increase in consumption with adherence to the KD. Conversely, foods located toward the negative terminal are foods that were most associated with the BD and had the largest decrease in consumption with adherence to the KD. BD, baseline diet; KD, ketogenic diet; MCT, medium-chain TG; SS, sugar-sweetened.

FIGURE 2

Individual change in adherence to the PCA diet pattern between the baseline and ketogenic diets. The lines indicate the individual change in PCA diet pattern adherence scores between diets (n = 6). Individual scores are calculated by multiplying the PCA factor loading score for each food group by the standardized intake of that food, then summing the products of all the food groups. Negative scores indicate high consumption of non-ketogenic diet–related foods. Positive scores indicate high consumption of ketogenic diet–related foods. PCA, principal components analysis.

FIGURE 3

Individual change in fruit and vegetable intake between the BD and KD. The lines indicate the individual change in standard USDA food group serving intake between diets (n = 6). (A) Change in nonstarchy vegetable intake from BD to KD. (B) Change in fruit intake (excludes avocado) from BD to KD. This was of interest owing to the message to limit fruit to ½ cup of berries per day. (C) Change in avocado intake from BD to KD. Two participants have overlapping lines as they did not consume avocados at either time point. (D) Change in total fruit (includes avocado) and nonstarchy vegetable intake from BD to KD. BD, baseline diet; KD, ketogenic diet.

FIGURE 4

Comparison of mean nutrient intake with DRI values on the baseline and ketogenic diets. Nutrients are RDAs unless noted as AI. Intake is presented as percentage of the specified DRI. Mean differences were tested by the Kruskal–Wallis test for variance. n = 6. *,**Significant intake change: *P < 0.025, **P < 0.01. AI, Adequate Intake; DRI, Dietary Reference Intake.