Novel ketone diet enhances physical and cognitive performance

Abstract

Ketone bodies are the most energy-efficient fuel and yield more ATP per mole of substrate than pyruvate and increase the free energy released from ATP hydrolysis. Elevation of circulating ketones via high-fat, low-carbohydrate diets has been used for the treatment of drug-refractory epilepsy and for neurodegenerative diseases, such as Parkinson's disease. Ketones may also be beneficial for muscle and brain in times of stress, such as endurance exercise. The challenge has been to raise circulating ketone levels by using a palatable diet without altering lipid levels. We found that blood ketone levels can be increased and cholesterol and triglycerides decreased by feeding rats a novel ketone ester diet: chow that is supplemented with (R)-3-hydroxybutyl (R)-3-hydroxybutyrate as 30% of calories. For 5 d, rats on the ketone diet ran 32% further on a treadmill than did control rats that ate an isocaloric diet that was supplemented with either corn starch or palm oil (P < 0.05). Ketone-fed rats completed an 8-arm radial maze test 38% faster than did those on the other diets, making more correct decisions before making a mistake (P < 0.05). Isolated, perfused hearts from rats that were fed the ketone diet had greater free energy available from ATP hydrolysis during increased work than did hearts from rats on the other diets as shown by using [³¹P]-NMR spectroscopy. The novel ketone diet, therefore, improved physical performance and cognitive function in rats, and its energy-sparing properties suggest that it may help to treat a range of human conditions with metabolic abnormalities.-Murray, A. J., Knight, N. S., Cole, M. A., Cochlin, L. E., Carter, E., Tchabanenko, K., Pichulik, T., Gulston, M. K., Atherton, H. J., Schroeder, M. A., Deacon, R. M. J., Kashiwaya, Y., King, M. T., Pawlosky, R., Rawlins, J. N. P., Tyler, D. J., Griffin, J. L., Robertson, J., Veech, R. L., Clarke, K. Novel ketone diet enhances physical and cognitive performance.

Keywords: energetics; exercise; heart; metabolism; muscle.

Figure 1.

(R)-3-Hydroxybutyl (R)-3-hydroxybutyrate metabolism, experimental protocol and diets. A) (R)-3-Hydroxybutyl (R)-3-hydroxybutyrate, synthesized via a transesterification reaction, is hydrolyzed by gut esterases to yield absorbable d-β-hydroxybutyrate and (R)-1,3-butanediol. In the liver, (R)-1,3-butanediol is converted to acetoacetate and d-β-hydroxybutyrate, and, thus, ingestion of the novel ketone ester yields only ketone bodies, elevating circulating levels. Oxidative tissues, including muscle, take up ketones via monocarboxylate transporters, which leads to their subsequent oxidation in the mitochondria. B) Experimental protocol for treadmill and maze testing. Rats were habituated to the 8-arm radial maze for 28 d and the motorized treadmill for 14 d before baseline testing on 3 consecutive days. After baseline tests, rats were allocated to a diet group, rested for 4 d, and pair fed such that rats received the same calories each day irrespective of group. Rats were then rehabituated to the maze and treadmill over 2 d before 5 consecutive days of performance testing. C) Macronutrient composition (% kcal) of the Western, carbohydrate, and ketone diets, all of which contained 1.76 kcal/g. CoA, coenzyme A; FFA, free fatty acid; LDH, lactate dehydrogenase.

Figure 2.

Effect of feeding the ketone diet for 9 d on physical performance, cognitive function, and cardiac PDH flux. A) Effect of diet on distance run by rats on a motorized treadmill on 5 consecutive days. B) Rats that were fed the ketone diet were faster at completing the 8-arm radial maze than were rats that were fed the Western or carbohydrate diets. C) Rats that were fed the ketone diet made more correct decisions than at baseline. D) Male Wistar rats (n = 5/diet) were fed one of the 3 diets for 9 d and in vivo PDH flux—determined by using hyperpolarized [¹³C] MR—was found to be higher only in the carbohydrate-fed rat hearts. *P < 0.05, **P < 0.01 vs. rats fed the Western diet; ^†P < 0.05, ^††P < 0.01, ^†††P < 0.001 vs. rats fed the carbohydrate diet.

Figure 3.

Effect of feeding the ketone diet for 66 d on myocardial contractile function and high-energy phosphate levels, epididymal fat pad weights, and plasma metabolite concentrations. A) RPP, a measure of workload, was increased by 34% using an infusion of 10 nM isoproterenol (Iso) for 5 min in each rat heart. *P < 0.05 vs. –Iso. B) PCr remained higher in ketone-fed rat hearts during the increased workload compared with hearts from rats that were fed either of the other 2 diets. *P < 0.05 vs. rats fed the Western and carbohydrate diets. C) Free ADP concentration was lower in ketone-fed rat hearts during the increased workload compared with hearts from rats that were fed either of the other 2 diets. ***P < 0.001 vs. rats fed the Western and carbohydrate diets. D) Free energy of ATP hydrolysis was higher in hearts from ketone-fed rats during the high workload. *P < 0.05 vs. rats fed the Western and carbohydrate diets. E) Epididymal fat pad weights were lower in rats that were fed the ketone and carbohydrate diets. *P < 0.05. F) Ketone diet increased plasma concentrations of d-β-hydroxybutyrate and lowered plasma cholesterol and triglycerides. *P < 0.05, ***P < 0.001 vs. rats fed the Western diet. G) Ketone diet lowered plasma glucose concentrations. **P < 0.01, vs. rats fed the Western diet.

Figure 4.

Metabolite analysis of liver and heart after 66 d feeding the ketone diet. A) Expanded region of the [¹H] NMR spectra from liver tissue from animals that were fed the 3 diets to demonstrate the increase in β-hydroxybutyrate. B) Pattern recognition model [orthogonal partial least squares discriminate analysis (OPLS-DA)] of the total fatty acid complement of liver tissue as measured by GC free induction decay, demonstrating the differences between animals that were fed either Western, carbohydrate, or ketone diets (R², 40%; Q², 33%). C) Pattern recognition model of the aqueous metabolites detected by high-resolution [¹H] NMR spectroscopy of liver tissue extracts from rats that were fed the 3 diets using OPLS-DA (R², 83%; Q², 59%). D) Pattern recognition model (OPLS-DA) distinguishing the total fatty acid complement of heart tissue from rats that were fed the 3 diets (R², 64%; Q², 68%). PB, phenobarbital.