Ergogenic aids are substances or techniques for enhancing athletic performance, muscle recovery, and mental focus. Researchers continually evaluate various substances to benefit those participating in endurance exercises like ultra running. Hoping to find something to boost mental alertness, researchers have turned to ketone esters (KE) as a possible aid. While additional research is necessary and ongoing, KE may hold promise.
Ketone bodies are naturally produced in the body in response to low-carbohydrate states such as pregnancy (delivery), fasting, low-carb diets, and exercise.
Ketone esters are external sources of these ketone bodies, which may boost mental alertness in low-energy states.
Oral ketone ester (KE) supplementation may have health benefits, including cardiac health, antiseizure effects, improved recovery times after high-endurance exercise, and boosting memory and cognition during high-intensity activity, like ultra running.
KE may boost dopamine levels, the "feel good" hormone, improving mood, memory, thinking, and alertness in high-endurance exercise.
While the body of research on using KE is growing, more studies with larger sample sizes and similar study designs are needed to determine if one truly benefits from taking KE during high-intensity activities.
What are ketone esters?
In response to decreased glucose availability, the liver produces three small water-soluble compounds known as ketone bodies. The most abundant ketone body is β-hydroxybutyrate (BHB). In states such as fasting, pregnancy/delivery, exercise, and low carbohydrate diets, levels of this specific ketone are generally high. During those times, the brain can use this as an energy source when there isn’t enough sugar (glucose). Thus, ketones help play various roles in metabolism in states of low carbohydrates that can occur in high-endurance training, like ultra running.
Ketone esters (KE) are compounds taken orally that effectively raise these BHB levels without restricting one’s carbohydrate consumption. Some speculation and early research suggest that taking these esters and eating sufficient carbohydrates right before or during exercise benefits the athlete by increasing fuel to the brain and body, thus, enhancing performance. Though, there are other possible mechanisms by which exercise benefits may derive from oral esters. Additional research is needed.
Ketone esters have been evaluated for various medical uses, from seizure disorders to heart failure to possible benefits in memory and cognition in patients with Alzheimer’s. Recent research has looked at the potential benefits of KE in ultra-endurance type exercise.
Early studies with oral ketone supplements and their possible usefulness in aiding muscle energy production were not definitive. They suggested that various factors played a role in the benefits or changes seen in muscle and endurance, including aspects related to the type of exercise and duration, and that carbohydrates and their role in metabolism overrode that of KE under various circumstances.
Early research also assessed the well-known mental weariness phenomenon brought on by doing ultra-endurance exercises. This weariness affects one’s cognitive awareness, which, in turn, affects their capacity for decision-making. Some studies suggest that this mental fatigue may be due to a suppression of dopamine, a key neurotransmitter in the brain. Some research suggests other similar chemicals, serotonin, and noradrenaline, play a role.
Do ketone esters benefit endurance athletes?
Ergogenic aids, substances, techniques, or related measures to enhance athletic performance, are constantly being evaluated, used, explored, and developed. Endurance athletes are curious whether supplements or food additives may help improve performance and aid recovery.
KE may increase dopamine levels
In a Belgian study, researchers evaluated if supplementation with KE would stimulate muscle recovery and decrease mental decline with ultra-endurance exercise. The research claims that taking oral KE increases dopamine levels during high-intensity exercise. Dopamine, the "feel good" neurotransmitter, plays a key role in the brain's reward centers.
By aiding in memory and motivation, and improving mood and attention, even supporting many bodily functions, increasing dopamine levels may help improve mental alertness in athletes. However, this is just one study of many. By aiding in memory and motivation, and improving mood and attention, increasing dopamine levels may help improve mental alertness in athletes.
KE may decrease muscle inflammation
Ketone esters show some potential for decreasing muscle inflammation during exercise, which helps improve muscle recovery. The Belgian study suggests that KE inhibits a specific white blood cell, the macrophage, from being able to access muscle (a cell that can normally lead to inflammation), thereby decreasing overall muscle inflammation postexercise. Less inflammation in the muscle leads to quicker recovery and less soreness, so athletes can return to exercise sooner.
The Belgian study
The Belgian study is just one of many and has a very small sample size. The paper should be reviewed with a fine-tooth comb. There are spelling errors and only one listed limitation in their study. Does this invalidate the data? Not necessarily. However, no conclusions can be drawn from this small study. It is not generalizable to a larger population, and therefore, more research is necessary. Furthermore, there are no other comparable studies from which to draw conclusions.
Are there any benefits of ketone esters?
In looking at additional evidence on possible KE benefits, a 2020 systematic review looked at 161 articles, of which ten were selected for full consideration. Only three of the studies evaluated showed positive outcomes. Ten showed no benefits, while three reported negative effects of supplementation with ketones in overall physical performance.
However, the studies were hard to compare because they have different study protocols, populations, and ways of evaluating health outcomes. Thus, to date, no consensus has been reached on the overall benefits of using KE supplementation. It is still unclear if taking KE helps metabolism and overall performance, has insignificant effects, or causes harm.
Taking KE supplement
So, what does that mean to the general public? Don’t rush out and buy KE supplements just yet. More information and research are needed before clear-cut medical recommendations can be made. As with all supplements, these products are not well-regulated, with minimal oversight on quality control or scientific research to support use. Further, never start taking a supplement without consulting a healthcare provider, as supplements can interfere with medications or be contraindicated with certain health conditions.
Early research shows a glimpse of the possible benefits of taking KE in ultra-endurance athletes. Improving muscle recovery by lessening inflammation and damage from exercise while improving mental alertness, focus, and clarity of reasoning would be greatly beneficial. Hopefully, more robust studies with larger sample sizes and a more diverse study population will provide insight into this possible supplement for future use.
- Journal of Applied Physiology. Exogenous ketosis increases circulating dopamine concentration and maintains mental alertness in ultra-endurance exercise.
- Advances in Nutrition. Utility of Ketone Supplementation to Enhance Physical Performance: A Systematic Review.
- The Journal of Physiology. Ketone ester supplementation blunts overreaching symptoms during endurance training overload.
- The Journal of Nutrition. Ketone Esters and Their Effects on Carbohydrate Metabolism During Exercise.