Are there any concerns or considerations?

Equivocal scientific support

• The evidence for benefits of acute or chronic supplementation on health and performance is unclear. There is a wide range in the protocols of use, and in the scenarios of exercise, in which it has been investigated. It is difficult to integrate the various findings of these studies.
• The effects of high blood ketone levels on metabolism and other physiological outcomes is extremely complex. Different protocols of use may achieve variable effects on the timing and increase in blood ßHB concentrations with differential effects on substrate metabolism and physiological effects. It may be difficult to pinpoint beneficial uses and the window of benefit may be small. In addition, some of the effects may impair sports performance.
  • Ketone supplementation creates major effects on substrate use (reduces glycolysis, lipolysis, glycogen use and increases use of intramuscular triglycerides. Some of these effects may be counter-productive to some sports scenarios.
  • Causes increase in blood acidity which may be counter-productive to some sports scenarios.
• Some recent studies suggest that the ßHB provides a minor substrate for the muscle (~5% of fuel use) and the claimed benefits to exercise economy (reduced oxygen use) are equivocal.
• The current investigations on ketone ester supplementation fail to cover most of the anecdotal uses/testimonials and the claims around longterm/chronic use.

Nuances of specific supplements

• Ketone ester supplements
  • These are expensive and often hard to obtain due to limited capacity for commercial manufacture (~$50 per 25 g bottle for HVMN supplement).
• Ketone salts
  • These produce a high salt load and gastrointestinal side effects.
  • These appear extremely unlikely to sufficiently increase blood ßHB (> 1 mmol/L).

Perceptions around their use

• Ketone ester supplements are not included on the WADA Prohibited List and it would seem impractical as well as illogical for them to meet the criteria for such a ban.
• Nevertheless, the initial use of “DeltaG” supplement by UK sporting teams and professional cycling teams has received much media/public criticism as being “frankenscience”.