Effect of a Sodium and Calcium DL-β-Hydroxybutyrate Salt in
Tobias Fischer ,
and Thorsten Marquardt
Department of Food, Nutrition, and Facilities, FH M¨
unster-University of Applied Sciences Muenster, Corrensstraße 25,
48149 Muenster, Germany
Department of Pediatrics, University Hospital Muenster, Albert-Schweitzer-Campus 1, 48149 Muenster, Germany
Center of Laboratory Medicine, University Hospital Muenster, Albert-Schweitzer-Campus 1, 48149 Muenster, Germany
Correspondence should be addressed to Tobias Fischer; tobias.ﬁscher@fh-muenster.de
Received 8 December 2017; Revised 1 February 2018; Accepted 12 February 2018; Published 12 April 2018
Academic Editor: Jos´
Copyright ©2018 Tobias Fischer et al. is is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Background. Ketone body therapy and supplementation are of high interest for several medical and nutritional ﬁelds. e intake of
ketone bodies is often discussed in relation to rare metabolic diseases, such as multiple acyl-CoA dehydrogenase deﬁciency
(MADD), that have no alternatives for treatment. Case reports showed positive results of therapy using ketone bodies. e
number of ketone body salts oﬀered on the wellness market is increasing steadily. More information on the kinetics of intake,
safety, and tolerance of these products is needed. Methods. In a one-dose kinetic study, six healthy subjects received an in-
tervention (0.5 g/kg bw) using a commercially available ketone body supplement. e supplement contained a mixture of sodium
and calcium D-/L-β-hydroxybutyrate (βHB) as well as food additives. e blood samples drawn in the study were tested for
concentrations of D-βHB, glucose, and electrolytes, and blood gas analyses were done. Data on sensory evaluation and observed
side eﬀects of the supplement were collected. e product also went through chemical food analysis. Results. e supplement led to
a signiﬁcant increase of D-βHB concentration in blood 2.5 and 3 h after oral intake (p�0.033;p�0.043). e ﬁrst signiﬁcant
eﬀect was measured after 2 h with a mean value of 0.598 ±0.300 mmol/L at the peak, which was recorded at 2.5h. Changes in
serum electrolytes and BGA were largely unremarkable. Taking the supplement was not without side eﬀects. One subject dropped
out due to gastrointestinal symptoms and two others reported similar but milder problems. Conclusions. Intake of a combination
of calcium and sodium D-/L-βHB salt shows a slow resorption with a moderate increase of D-βHB in serum levels. An inﬂuence of
βHB salts on acid-base balance could not be excluded by this one-dose study. Excessive regular consumption without medical
observation is not free of adverse eﬀects. e tested product can therefore not be recommended unconditionally.
Interest in the importance of ketone bodies has risen in the
recent past. Ketone bodies are an alternative fuel produced
in the liver, in a process referred to as ketogenesis, in the
event of reduced availability of glucose . Insulin inhibits
ketogenesis as opposed to glucagon and epinephrine, which
both stimulate this process [2–4]. e base material is acetyl-
CoA which is derived from the β-oxidation of fatty acids.
e basis of all three “ketone” bodies is acetoacetate. Ace-
toacetate can then either be reduced to beta-hydroxybutyrate
(βHB), or acetone is generated by spontaneous de-
carboxylation of acetoacetate. Only acetoacetate and βHB
are relevant for energy expenditure [5, 6]. e maximum
amount of daily ketone body production in adults is 150 g .
Normal postprandial βHB serum levels are less than
0.1 mmol/L . ey increase to approximately 0.1-
0.2 mmol/L after fasting overnight in healthy subjects . e
term ketosis describes an increased concentration of ketone
bodies in blood. In clinical application, ketosis is often deﬁned
as a concentration of ketone bodies in the range of 2–
7 mmol/L and 3–5 mmol/L in therapy [10, 11].
Journal of Nutrition and Metabolism
Volume 2018, Article ID 9812806, 8 pages
e human organism has two nutrition-related ways of
reaching ketosis. e ﬁrst is starvation and the second is
a high fat and at the same time low carbohydrate (HFLC)
diet which is also known as a ketogenic diet [8, 12]. Ketosis
can also be reached by an energy deﬁcit caused by prolonged
exercise . In all cases, the organism reacts by an in-
creasing ketone body production because of the decreased
availability of glucose and therefore making the alternative
fuel, ketone bodies, necessary as brain fuel or as energy
substrate for other tissues, especially muscle [1, 8]. e main
diﬀerence between the two nutrition-related states of ketosis
is that in starvation fat reserves are used for ketone body
synthesis and in HFLC fat from daily nutrition [8, 12]. Aside
from the nutritional trend of low-carb diets with a maximal
βHB serum concentration of 0.4 mmol/L, ketone bodies and
speciﬁc diet forms like the ketogenic diet are of high sci-
entiﬁc interest [14, 15].
ere are diﬀerent types of clinically relevant ketogenic
diets. e milder forms are the low glycaemic index diet
(LGID) and the modiﬁed Atkins diet (MAD) where carbo-
hydrate intake is limited to 15 grams per day. More stringent
are the medium chain triglycerides (MCT) diet as well as the
3 : 1 and the 4 : 1 classical ketogenic diets. e ratio depicts the
fat contents in relation to the sum of carbohydrates and
proteins based on their weight . A well-known problem of
ketogenic diets is limited patient compliance . e daily
intake of high amounts of fat is not tasty and has negative
eﬀects on the quality of life. Carbohydrate restriction is often
even more diﬃcult to adhere to. Adverse eﬀects, especially
soon after starting the diet, are often recorded and lead to
dropouts. Typical undesirable side eﬀects of the traditional
ketogenic diet are gastrointestinal discomfort, weight loss, and
negative changes in lipid proﬁles . e application of
moderate (≤50 g carbohydrates per day) ketogenic diets for
weight loss show partially diﬀerent eﬀects when compared to
clinically applied ketogenic diets. Positive eﬀects on blood
lipids, blood pressure, and weight are reported in obese
subjects . ere are various very low carbohydrate and
ketogenic trend diets that are milder than medical diets be-
cause trend diets have a lower fat content. e palatability of
food in medical or trend diets increases strongly with the
introduction of more carbohydrates and protein to the daily
nutrition [20, 21].
e ketogenic diet has proven to be an eﬀective therapy
for epilepsy, although not only the anticonvulsive eﬀect is
used in medicine. In addition, some inherited metabolic
diseases of glucose uptake or metabolism, for example, the
GLUT1 or pyruvate dehydrogenase deﬁciency, are treated
using ketogenic diets to ensure suﬃcient energy supply .
In special severe metabolic diseases of β-oxidation, like
multiple acyl-CoA dehydrogenase deﬁciency (MADD),
a direct intake of ketone bodies for energy supply is nec-
essary. Inducing ketogenesis using normal food products is
not possible due to the impairment of fatty acid oxidation.
e genetic defect in the electron transport ﬂavoprotein or
the electron transport ﬂavoprotein oxyreductase causes a dys-
function of all acyl-CoA dehydrogenases in β-oxidation by the
impaired oxidation of FADH
to FAD . For this disease,
direct ketone body therapy using D,L-3-hydroxybutyrate
sodium salt can be life-saving. Ketone body therapy in MADD
is documented in some case reports. In treated patients, an
increase of D-βHB in serum was detectable within one hour of
intake and led to dramatic clinical improvements. After 2 and
9 months, MRI investigations showed a progressive decrease
of leukodystrophy, a typical problem in MADD patients .
In cases of hypoglycemia caused by hyperinsulinisim, treat-
ment with βHB as a supplement has been used without any
adverse side eﬀects and increased the serum concentration of
Good eﬃcacy of ketogenic diets is clouded by poor
practicability and the necessity of maintaining a constant
ketosis during the day. erapeutic levels can be achieved
more easily through oral intake of βHB . e direct oral
intake of ketone body salts or acid, as described in some case
reports, may not be totally free of health risks. Possible
adverse side eﬀects are cation overload or acidosis/alkalosis
. Newer publications on ketone body salts concentrate
on their application in sports [27, 28]. However, available
knowledge is still very limited. To manage potential prob-
lems, researchers are concentrating on synthesizing ketone
body esters consisting of the primary ketone βHB and an
alcohol, for example 1,3-butanediol .
Supplements containing ketone bodies have potential
applications in cases of severe metabolic diseases, cancer,
neurodegenerative disease, and many more. Apart from the
medical use, such supplements are also of interest for life-
style applications such as weight loss .
In an Internet search of the worldwide supplement
market, a lot of products with βHB as the main ingredient
are available since 2015. e ﬁrst available product was
a simple mixture of calcium and sodium βHB salt with an
added ﬂavor. ere is currently no scientiﬁc opinion or
direct testing published about products with a calcium and
sodium βHB salt as the main ingredient. e aim of this
study is to provide additional scientiﬁc information for an
easily available ketone body salt mixture and discuss the
potential beneﬁt of such products in clinical application.
2. Materials and Methods
2.1. Subjects. A total of six healthy adult subjects (3 males
and 3 females) aged between 18 and 57 years (40 ±15.9
years) were selected for this study. e participants, 4–
normal, 1–overweight, and 1–obese, had an average BMI of
25.44 ±5.99 kg/m
. e criteria for inclusion were absence of
metabolic diseases (like diabetes), not pregnant, medically
healthy with a normal medical history, and no intake of
drugs (excluding oral contraceptives) or nutritional sup-
plements in the previous 30 days prior to the start of the
study. Subjects were excluded if they suddenly got ill or
consumed a restrictive diet, low carb, or ketogenic diet, in
the 60 days before the day of testing. Recruitment was done
by putting up a notice on a board at the University Hospital
of Muenster. After ﬁlling in a precheck questionnaire,
a short clinical examination was performed by a medical
doctor. On the day of testing, those that had qualiﬁed for
inclusion had to appear with an empty stomach. e intake
of food and caloric beverages was not allowed for 12 hours,
2Journal of Nutrition and Metabolism
24 hours for alcoholic beverages, before testing began. Black
unsweetened coﬀee and water were allowed on the testing
day. All subjects were informed in detail about the study and
signed the consent before they participated in the study. e
study was conducted in accordance with the Declaration of
Helsinki, and the protocol was approved by the Ethics
Committee of the Medical Association of Westfalen-Lippe
and the University of M¨
unster (project identiﬁcation code:
2.2. Procedure. A single-center one-dose kinetic study was
conducted at the Muenster University Hospital, Germany, in
accordance with the guidelines of good clinical practice. e
present design of a one-dose kinetic study does not require
randomisation, placebo-control, and blinding of the medical
staﬀ or subjects. e subjects fasted from 6 pm on the day
before the test until the test began at 8 am. After weighing,
placing a venous access and drawing the ﬁrst blood sample
), the subjects ingested the prepared test solution. e
solution was prepared for each subject by using the formula
0.5 grams of βHB-salt supplement per kilogram body weight
dissolved in 250 milliliters (8.45 ﬂ oz) of water. is
translated to 30–57.5 g of the supplement per subject
depending on their bodyweight. e taste of the beverage
was recorded in a sensory interview after intake. Blood
samples were drawn every 30 minutes over a period of
5.5 hours. roughout testing, subjects were free to drink
mineral water without gas and black unsweetened coﬀee or
tea as well as move within the building. Each subject
recorded observed side eﬀects in a predetermined protocol.
e concentrations of βHB and glucose were determined;
blood gas analyses (BGA) in a two-sample series was per-
formed every 2.5 hours, and the content of the minerals Na
, and Ca
in serum was quantiﬁed. A medical doctor was
available all the time and monitored the course of the study.
2.3. Nutritional Supplement. e supplement, with the trade
name KetoCaNa Orange, is produced by a manufacturer in
the USA (Ketosports) and was purchased from an online
shop in the Netherlands. e main ingredient is a combi-
nation of sodium and calcium βHB-salt (racemic mixture;
D-/L-βHB). Additional ingredients are citric acid, natural
ﬂavor, and stevia as sweetener. e supplement facts are
shown in Table 1. All calories in the product are derived from
the contained ketones. e producer recommends a serving
size of 19 g powder dissolved in 236ml (8 ﬂ oz) of cold water
that can be consumed up to three times a day. e producer
mentions that the product properties praised have not been
approved by the Food and Drug Administration (FDA) and
the product is not intended for use in diseases.
2.4. Sampling and Analysis
2.4.1. Blood Sampling. At the start of study, a venous
catheter was placed and the ﬁrst blood sample was drawn.
For further sampling, the catheter was ﬂushed with physi-
ological saline. To avoid dilution of the sample, ﬁve
milliliters of blood were discarded up front each blood
sample. In case of a blocked venous access, a new catheter
was placed. e samples were immediately cooled at −20°C
for analysis on the same day. Otherwise, storage temperature
2.4.2. βHB, Glucose, and Minerals in Serum. Serum levels of
D-βHB were determined by using an enzymatic assay kit
produced by Sigma-Aldrich (St. Louis, USA). e kit is
designed to produce a compound whose colorimetric in-
tensity, determined at a wavelength of 450 nm, is pro-
portional to the concentration of D-βHB. Glucose and
, and Ca
) content in serum were de-
termined using the analyzer Cobas 8000 manufactured by
Roche Diagnostics (Mannheim, Germany) and carried out
in the clinical laboratory of the university hospital in
2.4.3. Blood Gas Analyses. Blood samples were transported
in a cooling box to the central laboratory immediately after
sampling. e fully automated blood gas analyzer ABL800
Flex manufactured by Radiometer (Krefeld, Germany) was
used to measure pH, electrolytes, and metabolites.
2.4.4. Food Chemistry Analysis. Content of citric acid was
determined using an enzymatic test kit for food, manu-
factured by Boehringer Mannheim (Darmstadt, Germany).
e amount of oxidized NADH is stoichiometric to the
citrate content. Diﬀerence between NADH and NAD
determined photometrically at 340 nm. Determination of
pH was done using a pH meter and an electrode manu-
factured by Mettler Toledo (Giessen, Germany), after per-
forming a three-point calibration. e quantiﬁcation of
minerals was carried out by a certiﬁed food laboratory. For
sodium, potassium, calcium, and magnesium, ICP-MS and
ICP-OES according to DIN EN ISO 11885/DIN EN ISO
17294-2 were used.
2.4.5. Sensory Interview. e taste of the beverage was
recorded in a face-to-face interview. All subjects had to
describe the ﬂavor and mouth-feel of the product in their
own words supported. e questions of the interview were
“Please describe as accurately as possible the taste of the
beverage” followed by “How is the mouth-feel?” and “How
Table 1: Nutritional information and caloric content per serving
size (19 g) and in 100 grams of the supplement.
19 g (serving size) 100 g
Calories 68 358
Macronutrients and minerals Grams Grams
Fat 0 0
Carbohydrate 0 0
Protein 0 0
Sodium 1.30 6.84
Calcium 1.15 6.05
βHB 11.70 61.57
Journal of Nutrition and Metabolism 3
would you describe the aftertaste?.” e last question was
“Did you notice anything else?.” e test person was not to be
interrupted when answering the questions, and the in-
terviewer was prompted to interrupt only when responses
were ambiguous or it was unclear what the test person meant.
Especially positive or negative statements were examined
more closely. e interview was recorded in its entirety.
2.5. Statistical Analysis. Data preparation was performed by
using Microsoft Excel 2016, and for the data analysis, IBM
SPSS Statistics 24 was used. Kolmogorov–Smirnov test,
Shapiro–Wilk test, and graphical analyses were used to
evaluate normal distribution. All data were ﬁrst analyzed
using descriptive statistics such as mean value, median, and
e basis for comparison was the ﬁrst blood sample
drawn from the subjects (t
). To calculate the diﬀerence
between the results, a t-test for paired groups or Wilcoxon
test was used. e level of signiﬁcance was set at p≤0.05. For
relation among diﬀerent sample series, the area under curve
(AUC) was calculated.
In order to detect a clinical relevant change in the main
outcome variable βHB (μ
�0.5; SD �0.2; eﬀect size
dz �1.5) with power of 80% and two-sided alpha of 0.05,
a total of 5 participants were required. For security in case of
dropout, one more subject (20%) was recruited.
One of the subjects (female, obese) dropped out directly after
imbibing the solution due to a severe reaction to the intake.
ese reactions included severe vomiting, nausea, and upper
abdominal pain. All other volunteers (n�5) successfully
3.1. βHB and Glucose Levels. e 0.5 g/kg BW dose corre-
sponded to 0.31 g D-/L-βHB/kg BW (3 mmol D-/L-βHB/kg
BW) was calculated using the information provided by the
manufacturer. e free D-βHB in serum increased after 2.5
hours from 0.232 ±0.177 mmol/L at t
to the maximal mean
value of 0.598 ±0.300 mmol/L at t
. e diﬀerences between
0 min, 150 min (maximum), and 180 min after treatment
were signiﬁcant (p�0.033;p�0.043). e ﬁrst eﬀect of the
βHB salt intake was noted 2 hours later in the form of an
increased concentration of serum D-βHB. Directly after
reaching a maximum, the concentration declined continuously
to near the baseline. ere were large diﬀerences in D-βHB
concentrations between the test persons as depicted in the
rather large standard deviation in AUC (1.917 ±0.811; n�4).
Serum glucose concentrations in the serum of the test subjects
remained constant almost right through the study period with
an increase at the maximum of D-βHB concentration and after
4-5 hours. Both diﬀerences in serum glucose were not sig-
niﬁcant (t5p�0.741;t10p�0.689; Figure 1).
3.2. BGA and Serum Minerals. Blood gas analysis showed no
diﬀerence in pH, pCO
, cations, and lactate concentration.
An increase was detected in base excess (cBase; 2.350 ±1.909 to
5.450 ±0.071 mmol/L) and anion gap (1.450 ±0.778 to 2.350 ±
1.061 mmol/L). e measured electrolytes sodium and calcium
presented no diﬀerence during the study period. Potassium
increased, and the increase was directly proportional to D-βHB
levels in tested subjects. Determination of signiﬁcance was not
possible due to the small number of cases.
3.3. Side Eﬀects. One of the subjects dropped out directly
after solution intake due to severe vomiting, nausea, and
upper abdominal pain. All other volunteers (n�5) ﬁnished
the test successfully. One proband reported feeling of full-
ness directly after beverage intake, which was caused by the
volume of the solution. Two others had nausea and slightly
upset stomach in the ﬁrst 30 minutes of testing. One of the
subjects developed stomach cramps, diarrhea, and severe
nausea after one hour, and a metoclopramide medication
was necessary. In further course, one person felt hyperactive
and three reported not feeling hungry over the complete
3.4. Sensory Tasting. All subjects described the fragrance of
the product as fruity and appetizing. One participant found
the aroma unnatural and was reminded of medicine. e
optical impression was neutral as the beverage had no color
and was clear in appearance. Two test subjects found a color,
corresponding to the fruit aroma, missing. One person
reported a tolerable sour taste and four an extensive sour
taste after solution intake. e ﬂavor was pushed to the
background by the high acidity. One subject additionally
described the beverage as salty and soapy. Overall, the testers
described the product as not being tasty and hard to drink
especially in such a high volume.
3.5. Food Chemistry. Determination of citric acid showed
a content of 0.286 g/g amounting to 5.434g per serving size
(19 g) with a mean pH of 4.32 when prepared according to the
recommendation made by the manufacturer. An intake of
0.5 g/kg of the product corresponds to 0.7 mmol/kg citric acid.
e content of minerals was analogous to the speciﬁcations on
the product package. For magnesium and potassium, possible
contaminations causing slight deviation were detectable
(Table 2). e chosen dose of 0.5 g/kg in this study amounts to
1.3 mmol/kg sodium and 0.8 mmol/kg calcium. A three-times
daily supplement intake of 0.5 g/kg would lead to an intake of
0.44 g/kg (2.2 mmol/kg) citric acid, 0.09 g/kg (3.9 mmol/kg)
sodium, and 0.09 g/kg (2.3 mmol/kg) calcium.
e results show a slow and moderate increase of D-βHB
serum levels with a slow decline in healthy humans. Intake of
a high concentration of D-/L-βHB supplement caused an
average maximum increase of 0.366 mmol/L. Interpersonal
variation of ketone body levels in humans is a well-known
fact, a publication from 1958 determined a diﬀerence of 30
4Journal of Nutrition and Metabolism
percent in healthy young men after fasting overnight . In
a collection of normal weight and overweight subjects, the
standard deviation of βHB concentration was around 50
percent which is similar to our ﬁndings .
A direct comparison with other data is not possible due
to absence of publications on the mixture of sodium and
calcium D-/L-βHB salt. Only some case reports on the usage
of sodium D-/L-βHB in severe metabolic diseases in children
and studies testing diﬀerent sodium and potassium D-/L-
βHB salts are available. Van Hove et al. described a peak
between 0.19mmol/L and 0.36 mmol/L after 30 minutes to 1
hour caused by intake of 0.150g/kg BW D-/L-βHB .
Gautschi et al. found a D-βHB concentration increase of
0.055 mmol/L within 1-2 h (150 mg/kg BW) and a measured
maximum of 0.343 mmol/L after 2 h (200 mg/kg BW) .
Another group did not observe any rise in D-βHB con-
centration after the intake of 0.9 g/kg BW, and only after
increasing the intake to 2.6 g/kg BW was there a measurable
change in D-βHB levels . All presented data originated
from children with MADD and cannot be transfered to
healthy adult subjects. ere was an almost 10-fold increase
in blood D-βHB within 0.5–3 h measured in two children
with hyperinsulinism . Especially, the second case report
from Gautschi et al. shows in part a similar absorption of
βHB salt when compared to our data . In all case reports
with children, no adverse eﬀects were reported after the
intake of sodium βHB [24, 25, 33, 34].
Testing of a ketone body ester consisting of D-1,3-
butanediol and D-βHB (3-hydroxybutyl-3-hydroxybutyrate)
exhibited a concentration peak between 1,5 and 2.5 h into
testing. e recorded c
D-βHB was 1.00 mmol/L achieved
using 357 mg/kg BW of ester; this value corresponds to
2.80 mmol/L achieved using 1 g/kg BW of ester. In the single
intake study, no adverse eﬀects using a maximum dose of
714 mg/kg BW were reported. Only in a repeated dose study
with a concentration of 2142 mg/kg BW per day did gas-
trointestinal side eﬀects like vomiting, nausea, diarrhea, or
abdominal pain occur . A study with male athletes as test
subject showed a rapid rise of D-βHB concentration in 10
minutes after drinking a solution made using 573 mg/kg BW
of the 3-hydroxybutyl l-3-hydroxybutyrate ketone ester.
In diﬀerent experimental setups with young athletes, no
adverse eﬀects of βHB were reported . In healthy sub-
jects, Stubbs et al. showed a maximum increase of D-βHB
concentration after 1.5 h to 1.00 ±0.1 mmol/L after the intake
Table 2: Measured content in grams of selected minerals per
serving size (19g) and in 100 grams of the supplement.
Minerals 19 g (serving size) 100 g
Sodium (g) 1.140 6.000
Potassium (g) 0.003 0.016
Magnesium (g) 0.006 0.031
Calcium (g) 1.178 6.200
0 30 60 90 120 150 180 210 240 270 300 330
Serum D-βHB (mmol/L)
0 30 60 90 120 150 180 210 240 270 300 330
Figure 1: (a) Mean, standard deviation of blood glucose (mg/dL) and (b) mean, standard deviation of D-βHB (mmol/L) level in serum of all
subjects (n�5) within a time period of 5.5 h after intake of βHB salt mixture (0.5 g/kg BW).
Journal of Nutrition and Metabolism 5
of 282 mg/kg BW of a sodium and potassium D-/L-βHB salt.
At the same time, tested βHB-ester leads to higher values at
the same concentration (2.8 ±0.2 mmol/L) . Two further
studies evaluated the adminstration of supplements con-
taining D-/L-βHB salts to athletes during exercise. e levels
of D-βHB concentration were between 0.60 and 1.00 mmol/L
after the intake of the supplements [27, 28]. In all studies, no
direct side eﬀects were reported in healthy adults [27, 28, 37].
One publication reported a potential risk of gastrointestinal
distress for high doses of βHB . e tested product
showed some gastrointestinal side eﬀects directly after or
within 2 h of solution intake. In comparison to these data, the
intake of βHB was not high enough for speciﬁc side eﬀects
caused by ketone bodies. A possible reason is the high content
of cations and citric acid in this product, causing the intense
sour taste. As a whole, use of combination of calcium and
sodium βHB salt is not free from adverse eﬀects and exhibits
a slow resorption kinetic. Just like in other supplements, such
as the ester of 1,3-butandiol and βHB, the combined sodium
and calcium salt exhibits a fast decrease in serum concen-
tration. A direct comparison between the salts and the ester
is not possible due to the structural diﬀerences and the
metabolization of 1,3-butanediol being unclear. ere are
indications that 1,3-butandiol is metabolized to ketone
bodies. is and the hydrolysis to D-βHB, not D-/L-βHB as
in the salts, are possible explanations for the reported high
βHB concentration in subjects after intake of this ester
[35, 38, 39]. e sodium and potassium salt exhibits an
earlier increase of D-βHB concentration in serum and
a higher maximum using nearly the same dose when
compared to our testing . Likewise, the ester compound
predominantly showed a faster increase of serum D-βHB
concentration [35, 37, 40]. It seems that the salt combi-
nation aﬀected the resorption of βHB. e results of ath-
letes during exercise are not comparable to our population
A limitation of the measurements is the usage of an
enzymatic assay speciﬁc for clinically relevant D-βHB.
D-βHB acts as the main energy substrate in fasting humans
and is therefore of high therapeutic relevance . L-βHB,
acetoacetate, and acetone were not analyzed in this study.
Accordingly, an underestimation of total ketone bodies is
possible. e eﬀect of active substrates is considered to be
low because there was an intake of βHB without longer
fasting time period and a resulting short-time increase of
βHB in serum. L-βHB is the nonphysiological enantiomer of
D-βHB. ere is an indication that L-βHB can be converted
to physiological active ketone bodies (acetoacetate and
D-βHB) and lipids in animal models but only in a limited
amount [41, 42]. In humans, L-βHB showed a much lower
metabolic rate and conspicuously higher elimination in
urine than the D-βHB after intake of a D-/L-βHB salt .
More research is necessary to get more information about
the metabolization of L-βHB in humans.
A one dose intake did not result in an increase of calcium
and sodium. e relatively high amounts of both salts had no
direct eﬀect on their serum levels. In an example, a person
weighing 70 kg would take around 2.100 g (91 mmol) sodium
and 2.170g (54 mmol) calcium with one dose (0.5g/kg) of
the supplement. e three-times daily dosage of 19 g product
recommended by the manufacturer would lead to an intake
of 3.420 g (149 mmol) sodium and 3.534 g (88 mmol) calcium.
e calculated loads of both elements are above the tolerable
upper intake level (UL) for adults recommended by the Institute
of Medicine (IOM) (sodium 2.3 g/d (100 mmol/d); calcium
2.5 g/d (62 mmol/d)) [43, 44]. In comparison to the physio-
logical need of sodium for body function, estimated at 500 mg/d
(∼22 mmol/d), an estimated ∼4–7-fold increased ingestion takes
place . e high intake of sodium is combined with nu-
merous adverse eﬀects like thirst, ﬂuid retention, hypertension,
and higher risk for cardiovascular disease. Furthermore, a high
sodium load has an eﬀect on calcium metabolism expressed by
higher calcium loss with a potential risk for urinary tract stones
and bone demineralization [46–48]. An excessive ingestion of
calcium leads to gastrointestinal side eﬀects, renal stones, and
a potential increase in cardiovascular events [49, 50]. e impact
on cardiovascular diseases is still under discussion . In case
of an overload of sodium and calcium, a cumulative eﬀect
cannot be excluded. Long-term intake of high dosage of both
elements could lead to side eﬀects and have to be investigated
e ﬁnding of a similar increase between D-βHB and
potassium levels needs further research. In our testing, we can
exclude the inﬂuence of the test product (16mg K
/100 g) or
a pseudo hyperkalaemia by venous catheter.
e excessive intake of ketone body salt or acid could
have consequences for the acid-base balance. According to
a theory by Stewart, a shift of the strong ion diﬀerence (SID)
can cause alkalosis or acidosis. On one hand, a high SID
generated by intensive resorption of cations (e.g., Na
) is a potential risk factor for alkalosis. On the other
hand, a low SID and at the same time high strong ion gap
(SIG) triggered by ketoacids can cause a metabolic acidosis
[51, 52]. Stubbs et al. detected an increase of pH after intake
of a sodium and potassium D-/L-βHB mixture, but no
similar eﬀect in a corresponding test using βHB-ester. Both
products had a mild inﬂuence to the acid-base balance .
In an earlier study in the 1980s, a rise in pH after ketone
body salt infusion was detected . Surveillance of blood
parameters, like the pH, pCO
, and product speciﬁc cations,
are necessary to avoid adverse metabolic eﬀects.
ere are suggestions in the literature of an impact of
increased βHB on reducing food intake. e mechanisms for
this are not clear . In our study, the majority of par-
ticipants reported a loss of appetite and hunger beyond the
testing time of 5.5 h. us, βHB may have an eﬀect on the
regulation of hunger and satiety. Further research with
a double-blinded test design is needed to eliminate the
inﬂuence of a known product ingredient.
In conclusion, the tested product cannot be recom-
mended for an intake of 0.5 g/kg BW and leads to adverse
gastrointestinal eﬀects. e high acidity and general taste
were not well accepted by the subjects making the product
unsuitable for long-term application. Clinically, the high
content of sodium, calcium, and the release of potassium is
crucial and requires further research to establish short-term
as well as long-term eﬀects on the human organism. An
additional aspect is that a higher intake is necessary to reach
6Journal of Nutrition and Metabolism
a ketosis suﬃcient for therapeutic purposes. us, an intake
of 1 g/kg BW of the product would lead to a maximum of, in
average, around 1.2 mmol/L (0.598 mmol/L at 0.5 g/kg BW).
No interpersonal factors have been included in this simple
calculation of our results. In combination with a higher
intake, the cation load and proportion of additives increases,
therefore increasing the potential risk of side eﬀects. For
treatment with high doses of external ketone bodies, further
clinical trials on healthy adults are needed to gather more
information on metabolic utilization.
Conflicts of Interest
e authors declare no conﬂicts of interest.
e human kinetic study was funded by the Department of
Congenital Metabolic Disorders of the University Hospital,
Muenster. Sensory and food chemistry analyses were funded
by the Department of Food, Nutrition, Facilities of the
University of Applied Sciences, Muenster.
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