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.jpg): Failed to open stream: No such file or directory in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 117 Front+Physiol
2017 ; 8
(ä): 848
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On the Metabolism of Exogenous Ketones in Humans
#MMPMID29163194
Stubbs BJ
; Cox PJ
; Evans RD
; Santer P
; Miller JJ
; Faull OK
; Magor-Elliott S
; Hiyama S
; Stirling M
; Clarke K
Front Physiol
2017[]; 8
(ä): 848
PMID29163194
show ga
Background and aims: Currently there is considerable interest in ketone
metabolism owing to recently reported benefits of ketosis for human health.
Traditionally, ketosis has been achieved by following a high-fat,
low-carbohydrate "ketogenic" diet, but adherence to such diets can be difficult.
An alternative way to increase blood D-?-hydroxybutyrate (D-?HB) concentrations
is ketone drinks, but the metabolic effects of exogenous ketones are relatively
unknown. Here, healthy human volunteers took part in three randomized metabolic
studies of drinks containing a ketone ester (KE); (R)-3-hydroxybutyl
(R)-3-hydroxybutyrate, or ketone salts (KS); sodium plus potassium ?HB. Methods
and Results: In the first study, 15 participants consumed KE or KS drinks that
delivered ~12 or ~24 g of ?HB. Both drinks elevated blood D-?HB concentrations
(D-?HB C(max): KE 2.8 mM, KS 1.0 mM, P < 0.001), which returned to baseline
within 3-4 h. KS drinks were found to contain 50% of the L-?HB isoform, which
remained elevated in blood for over 8 h, but was not detectable after 24 h.
Urinary excretion of both D-?HB and L-?HB was <1.5% of the total ?HB ingested and
was in proportion to the blood AUC. D-?HB, but not L-?HB, was slowly converted to
breath acetone. The KE drink decreased blood pH by 0.10 and the KS drink
increased urinary pH from 5.7 to 8.5. In the second study, the effect of a meal
before a KE drink on blood D-?HB concentrations was determined in 16
participants. Food lowered blood D-?HB C(max) by 33% (Fed 2.2 mM, Fasted 3.3 mM,
P < 0.001), but did not alter acetoacetate or breath acetone concentrations. All
ketone drinks lowered blood glucose, free fatty acid and triglyceride
concentrations, and had similar effects on blood electrolytes, which remained
normal. In the final study, participants were given KE over 9 h as three drinks
(n = 12) or a continuous nasogastric infusion (n = 4) to maintain blood D-?HB
concentrations greater than 1 mM. Both drinks and infusions gave identical D-?HB
AUC of 1.3-1.4 moles.min. Conclusion: We conclude that exogenous ketone drinks
are a practical, efficacious way to achieve ketosis.
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