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Osmolality and pH of sport and other drinks available in Switzerland

Authors:
  • Consulting Colombani GmbH

Abstract

Sports drinks are widely used during exercise to avoid or delay the depletion of the body's carbohydrate stores and the onset of dehydration. Both the osmolality and the pH of a sports drink can infl uence its effectiveness and its impact on mouth health. Unfor- tunately, data about osmolality and pH are usually missing on the labels of commercially available sports drinks and are unknown in the case of homemade sports drinks. Therefore, we analyzed the osmolality and pH of 35 sports and recovery drinks, as well as that of 53 other beverages usually consumed in Switzerland. The osmolality of the analyzed sports and recovery drinks varied over a relatively wide range (157-690 mmol/kg) with the homemade sports drinks being at the lower end and some commercial recov- ery drinks at the higher end. The osmolality of some commercial sports drinks, which are designed to be consumed during exercise, tended to be in the hypertonic range, although such drinks should rather be slightly hypotonic. The pH of nearly all analyzed sports drinks was in the range of about 3 to 4, which is of some concern because of the potential of low pH solutions to erode teeth. Al- though some of the tested sports drinks did not have an optimal osmolality, issues like individual tolerance and fl avor preference of the drinks must also be considered before generally discourag- ing their consumption. Future generations of sports drinks should, however, also address the pH of the drinks to minimize their im- pact on dental erosion.
Mettler S. et al.92
Originalartikel
Samuel Mettler1, Carmen Rusch2, Paolo C. Colombani1
1 Department of Agricultural and Food Sciences, ETH Zurich
2 Institute for Human Movement Sciences and Sport, ETH Zurich
Osmolality and pH of sport and other drinks
available in Switzerland
Zusammenfassung
Sportgetränke werden von Sportlern genutzt, um die Entleerung
der körpereigenen Kohlenhydratreserven zu verhindern oder zu
verzögern, und um einer Dehydratation entgegenzuwirken. Die
Osmolalität und der pH von Sportgetränken können sowohl die
Wirksamkeit wie auch die Zahngesundheit beein ussen. Leider
werden von den Herstellern meistens keine Angaben über Osmola-
lität und pH gemacht und im Falle von selbst hergestellten Sportge-
tränken sind die Daten ebenfalls unbekannt. Wir machten deshalb
eine Marktübersicht über die Osmolalität und den pH von 35
kommerziell erhältlichen oder selbst hergestellten Sportgetränken
sowie von 53 weiteren Getränken, die in der Schweiz konsumiert
werden. Die Osmolalität der analysierten Sportgetränke variierte
über einen relativ grossen Bereich von 157–690 mmol/kg, wobei
die selbst gemachten Sportgetränke eher am unteren Ende und
einige kommerzielle Regenerationsgetränke am oberen Ende der
Skala zu nden waren. Die Osmolalität einiger Sportgetränke, die
für den Konsum während der sportlichen Aktivität konzipiert sind,
lag tendenziell im hypertonen Bereich, obwohl diese Getränke
idealerweise eher leicht hypoton sein sollten. Der pH fast aller
Sportgetränke war im Bereich von 3–4. Dies ist nicht ideal, da
Getränke mit tiefen pH-Werten das Potenzial haben, den Zahn-
schmelz aufzuweichen. Obwohl einige Sportgetränke eine nicht
ideale Osmolalität aufwiesen, sollten weitere Faktoren wie die in-
dividuelle Toleranz oder geschmackliche Präferenzen berücksich-
tigt werden, bevor man von einem Sportgetränk abrät. Zukünftige
Generationen von Sportgetränken sollten jedoch die Problematik
der tiefen pH-Werte angehen, um das zahnerodierende Potenzial
zu reduzieren.
Abstract
Sports drinks are widely used during exercise to avoid or delay
the depletion of the body’s carbohydrate stores and the onset of
dehydration. Both the osmolality and the pH of a sports drink can
in uence its effectiveness and its impact on mouth health. Unfor-
tunately, data about osmolality and pH are usually missing on the
labels of commercially available sports drinks and are unknown
in the case of homemade sports drinks. Therefore, we analyzed
the osmolality and pH of 35 sports and recovery drinks, as well as
that of 53 other beverages usually consumed in Switzerland. The
osmolality of the analyzed sports and recovery drinks varied over
a relatively wide range (157–690 mmol/kg) with the homemade
sports drinks being at the lower end and some commercial recov-
ery drinks at the higher end. The osmolality of some commercial
sports drinks, which are designed to be consumed during exercise,
tended to be in the hypertonic range, although such drinks should
rather be slightly hypotonic. The pH of nearly all analyzed sports
drinks was in the range of about 3 to 4, which is of some concern
because of the potential of low pH solutions to erode teeth. Al-
though some of the tested sports drinks did not have an optimal
osmolality, issues like individual tolerance and avor preference
of the drinks must also be considered before generally discourag-
ing their consumption. Future generations of sports drinks should,
however, also address the pH of the drinks to minimize their im-
pact on dental erosion.
Introduction
Sports performance can be impaired by many causes; two domi-
nant factors leading to premature fatigue are the depletion of the
body’s carbohydrate stores and the onset of dehydration result-
ing from the loss of water and electrolytes in sweat [12]. Fatigue
caused by energy depletion and/or dehydration can be postponed
by the ingestion of sports drinks whose main purposes are to
prevent dehydration, to supply energy, and to replace electrolytes
[12]. Today, sports drinks are some of the best researched food
items and there is a consensus about the optimal composition of
such drinks: sports drinks should contain water, carbohydrates as
an energy source, sodium for particular situations, and a de ned
osmolality [2, 4].
The osmolality of a beverage can in uence the rate of gastric
emptying and intestinal water ux [12, 20]. Hypotonic solutions
promote gastric emptying and water absorption from the proximal
small intestine [10, 12, 13], whereas hypertonic solutions slow
gastric emptying and uid absorption, and probably also promote
the occurrence of exercise-related abdominal pain (also called a
stitch; [10, 15]). It is also reported that the perceived pleasantness
of uids increases with decreasing osmolality [1], a circumstance
that may promote voluntary drinking.
Athletes consume sports drinks on a daily basis and the ingested
amount can easily reach more than 1 L per day. Since sports drinks
are usually ingested a sip at a time, the drinks’ residue remains in
the oral cavity for quite some time. This can in uence tooth health
because beverages such as sports drinks may have a low pH value,
which in turn is related to dental erosion [14]. Indeed, different
studies have revealed the potential of commercial sports drinks to
erode teeth [3, 8, 14, 19].
While information on the carbohydrate type and content are
normally displayed on the food package label of sports drinks,
data on osmolality and pH are usually missing. As an alternative
Schweizerische Zeitschrift für «Sportmedizin und Sporttraumatologie» 54 (3), 92–95, 2006
93
Osmolality and pH of sport and other drinks available in Switzerland
to commercially available sports drinks, recommendations about
th e pro duc tio n of homem ade s por ts drinks a re in c ircu lat ion and, a t
least in Switzerland, many athletes mix their own sports drinks us-
ing a selection of basic ingredients including water, sugar, fructose,
glucose, maltodextrin, and syrup or fruit juices. Theoretically, the
osmolality of such homemade drinks could be calculated as long
as the exact amount of all ingredients is known. However, as soon
as natural products like syrup, fruit juices or carbohydrates of un-
de ned chain length like maltodextrin are used, the calculation of
the osmolality becomes dif cult.
To close the knowledge gap on the osmolality and pH data of
sports drinks, we conducted a study to analyze both the osmolal-
ity and pH of many commercially available and homemade sports
drinks. For comparison, we also analyzed a selection of other
beverages commonly consumed in Switzerland.
Methods
Thirty- ve commercially available and homemade sports drinks,
8 mineral waters, 19 soft drinks, 17 fruit juices or fruit drinks, and
9 alcoholic beverages were purchased in local shops in the Zurich
area or obtained from local distributors in November 2005. The
carbohydrate content of a beverage was taken from the food label;
osmolality and pH were analyzed in our laboratory. The ingredi-
ents used to prepare the homemade sports drinks are given in the
results section of this paper.
All beverages were analyzed a couple of days after purchase and
always before the expiry date. Before analysis, sparkling beverages
were shaken until no gas bubbles were seen in the beverages, and
beverages sold as powder were prepared according to the manufac-
turer instructions using a precision laboratory scale (Mettler PM
3000, Nänikon-Uster, ZH, Switzerland) and deionized water as a
solvent (the difference from tap water is about 3 mmol/kg).
Osmolality was measured by freezing point depression (Os-
mometer 2020, Advanced Instruments, Norwood, MA, USA) and
pH with a pH meter (Model 632, Metrohm, Herisau, AI, Switzer-
land). Both analyzers were calibrated according to the manufac-
turer’s instructions before measurements were taken. Measure-
ments of osmolality were done in duplicate and only the mean
values are presented. The mean coef cient of variation for the
duplicate measurements was 0.009.
Results
The carbohydrate content, the osmolality and the pH of the differ-
ent sports drinks are presented in Ta ble 1 and data of other bever-
ages are given in Ta b le 2 in alphabetic order.
Discussion
The osmolality of the analyzed sports drinks varied over a rela-
tively wide range with the homemade drinks being at the lower
end (Table 1). In general, osmolality increases with increasing
total carbohydrate content, but it is also strongly in uenced by the
proportion of monosaccharides, disaccharides or polysaccharides.
The refor e, o smo lal ity d oes not direc tly dep end o n th e ca rb ohyd rate
content. Ethanol is another substance that strongly increases os-
molality (see alcoholic beverages in Table 2 ). Actually, the assess-
ment of sports drinks is multifaceted. The parameters of gastric
emptying and intestinal absorption, for example, are in uenced by
different factors like the volume of uid, energy density, exercise
intensity, mental stress or osmolality [2, 12, 13]. However, in the
following we will focus on osmolality.
The idea behind using the term isotonic in the context of bever-
ages is to communicate that a beverage contains the same number
of osmotic active substances per unit of mass as blood, whose
osmolality is normally regulated around 280–290 mmol/kg [17].
According to the Swiss government decree on specialty food [5]
Physical
state at Carbohydrate Osmolality
purchase [g/10 0 g] [mmol/kg] pH
Commercially available sports drinks
Gatorade Mandarine Liquid 6.0 348 3.3
Gatorade Green Apple Liquid 6.0 362 3.2
Gatorade Red Orange Liquid 6.0 350 3.2
Gatorade Arctic Snow Liquid 6.0 353 3.4
Gatorade Orange Powder 6.0 297 3.0
Gatorade Citron Powder 6.0 297 3.1
Isostar Fast Hydration Liquid 6.7 301 3.9
Isostar Hydrate+
Perform Citron Liquid 6.7 322 3.8
Isostar Hydrate+Perform Powder 7.0 271 3.8
Isostar Long Energy Powder 15.1 260 3.4
M-Isodrink Powder 8.2 289 3.0
PowerBar PowerGel
(diluted 1:4) Gel 12.8 340 3.7
PowerBar Performance
Sports Drink Orange Liquid 4.9 302 3.7
PowerBar Performance
Sports Drink Orange Powder 6.6 295 3.8
Powerade Mountain Blast Liquid 8.2 391 3.5
Powerade Orange Liquid 8.2 346 3.5
Rivi Marathon Powder 5.0 210 3.2
Sponser Hypotonic Powder 5.0 238 3.5
Sponser Isotonic
Red orange Powder 7.0 312 3.1
Sponser Liquid Energy
(diluted 1:4) Gel 15.0 533 6.2
Sportvital Energy
Formula Powder 4.1 214 4.4
Sportvital Quick
Energy Gel (diluted 1:4) Gel 12.0 291 3.9
Ver o t Isotonic Tropical Powder 5.2 263 3.4
Vittel Action Liquid 5.5 294 4.0
Home-made sports drinks
Drink 1: Peppermint tea 1 L
Sucrose 30 g, Maltodextrin* 50 g,
NaCl 1.5 g 7.8 184 6.9
Drink 2: Peppermint tea 1 L
Fructose 30 g, Maltodextrin* 50 g,
NaCl 1.5 g 7.8 264 7.1
Drink 3: Tap water 1 L
Syrup raspberry 30 g,
Maltodextrin* 50 g, NaCl 1.5 g 7.3 157 3.4
Drink 4: Tap water 1 L
Syrup raspberry 30 g,
Maltodextrin* 90 g, NaCl 1.5 g 11.1 186 3.4
Drink 5: Tap water 1 L
Sucrose 15 g, Fructose 15 g,
Maltodextrin* 50 g, NaCl 1.5 g 7.8 215 6.3
Commercially available recovery drinks
Isostar Recovery Powder 13.9 508 6.5
PowerBar Proteinplus
Recovery Drink
Chocolate Powder 18.0 657 6.4
Sponser Recovery Drink Powder 15.7 690 4.2
Sponser Regeneration
Competition Liquid 15.0 427 3.8
Sportvital Regeneration
Quadra Pro Powder 9.1 373 6.1
Ver o t Recovery
Chocolate Powder 16.0 600 6.6
* For all home-made drinks Maltodextrin 100 (Sponser Sport Food,
Wollerau, Switzerland) was used.
Tab l e 1: Carbohydrate content, osmolality and pH of sports drinks avail-
able in Switzerland in alphabetical order. All data refer to the ready-to-
drink beverage.
Mettler S. et al.94
a beverage for persons with increased energy and nutrient needs
can be declared as «isotonic» when its osmolarity is in the range
of 250–340 mmol/L1. This leads to two problems. First, this legal
use of the term «isotonic» for sports drinks with an osmolarity
of up to 340 mmol/L is misleading, because osmolalities above
290 mmol/kg already promote initial water secretion into the intes-
tinal lumen [11]. Second and contrary to widespread belief, even
the really isotonic beverages (around 280 and 290 mmol/kg) are
not the ones that are absorbed the fastest. This fact should already
become evident when considering that per de nition there is a
water ux from hypotonic solutions in direction to the hypertonic
counterpart and along the osmotic gradient. In the case of bever-
ages, this means that water from hypotonic beverages is pulled
into the circulation, which represents the hypertonic compartment.
This pulling force is, by de nition, not present when two solutions
are isotonic to each other. Indeed, it is suggested that intestinal
water absorption rates are higher with hypotonic solutions com-
pared with isotonic solutions [10, 13]. The optimal osmolality for
a sports drink has, therefore, been de ned to be in the slightly
hypotonic range between 200 and 250 mmol/L [13].
As there is evidence that not only uid absorption, but also pal-
atability and intestinal tolerance tend to be better with hypotonic
beverages [1, 12, 13, 15], it is surprising that some commercial
sports drinks were rather high in the hypertonic range. Some
sports drinks had osmolalities of more than 350 mmol/kg. If a
sports drink is to be consumed during exercise, when the risk of
gastrointestinal discomfort is higher than at rest, an osmolality in
the range of 200–250 mmol/kg would be more suitable. On the
other hand, a hypertonic drink usually does not cause discomfort
when ingested at rest, such as during the recovery phase of an
exercise bout. The high osmolality of sports recovery drinks is,
therefore, not an issue of concern – as long as fast rehydration is
not the primary goal. Otherwise the problem may easily be solved
by increasing the dilution of the beverage.
Since we found not only hypertonic sports drinks, but also some
sports drinks with a rather low osmolality (in particular among
the homemade sports drinks), the question might arise if an os-
molality lower than the one suggested for optimal sports drinks
(200 –250 mmol/kg) is of concern. According to a study by Gisol
et al. [6] the observed water absorption rates of sports drinks with
an osmolality of 169 mmol/kg and 245 mmol/kg were not different
and the amount of glucose required to stimulate water absorption
is supposed to be relatively small [10].
A more practical question arises with sports drinks that are sold as
powders. Depending on how precisely the amount of the powder can
be weighed, the concentration and thus the osmolality of the bever-
ages can vary. Most manufacturers solve this issue with a dosage
spoon or by using portion bags. In most cases, it was suf cient to
follow the manufacturer’s instruction to achieve an osmolality that
varied only a little, irrespective of whether the dosage spoon was
lled very carefully or in a hasty real-life shoveling way (data not
shown). However, a relevant problem was detected with one manu-
facturer (Gatorade) where the powder had to be measured by lling
a pretty wide cap with a dosage line that was not easily visible. This
system was not practical and it was easy to substantially overdose
the beverage and consequently produce a hypertonic sports drink.
We would suggest reconsidering the use of this dosage system.
An unexpected result of this study was the consistently low pH
of nearly all commercially available sports drinks as well as of the
homemade drinks based on syrup. The only sports drinks with a
neutral pH were the homemade drinks based on water or tea and
with added carbohydrates as an energy source. Different studies
detected the potential of commercial sports drinks to erode teeth
[3, 8, 14, 19]. Although ways to signi cantly in uence the pH and
erosive po tent ial of s ports drin ks ex ist [3, 7, 9] , this aspec t does not
Carbohydrate Osmolality
[g/100 g] [mmol/kg] pH
Mineral waters
Adelbodner 0 32 5.7
Contrex (mineralization: 2174 mg/L) 0 27 7.1
Eptinger (2630 mg/L) 0 33 5.8
Henniez (581 mg/L)) 0 18 5.9
Rhäzünser (1643 mg/L) 0 39 6.3
Tap water (Zürich) 0 3 7.4
Valser (1918 mg/L) 0 27 6.1
Valser Viva Limette 0 39 5.7
Fruit drinks
Apple juice clear Ju ice Migros 11 736 3.3
Apple juice clear Ju ice Migros (diluted 1:1) 5.5 343 3.3
Apple juice clear Ju ice Migros (diluted 1:3) 2.8 171 3.4
Apple juice clear Ju ice Migros (diluted 1:7) 1.4 82 3.5
Apple juice un ltered Jui ce Migros 11 727 3.3
Bodyguard Michel 11 675 3.4
Carrot juice Biotta 9 561 4.2
Fruit coctail Hawaii Gold Migros 12 717 3.7
Grape juice Gold Migros 16 1193 3.3
Grapefruit juice Juice Migros 11 610 3.2
Multivitamin Gold Migros 12 779 3.5
Orange juice Juice Migros 12 614 3.6
Orange juice with pulp Granini 9 621 3.6
Orange juice with pulp Michel 11 594 3.8
Orange juice with pulp Michel (diluted 1:1) 5.5 282 4.0
Orange juice with pulp Michel (diluted 1:3) 2.8 139 4.0
Orange juice with pulp Michel (diluted 1:7) 1.4 71 4.0
Pear juice Ju ice Migros 11 733 3.7
Pineapple juice Gold Migros 13 692 3.8
Pineapple juice Gold Migros (diluted 1:1) 6.5 309 3.9
Pineapple juice Gold Migros (diluted 1:3) 3.3 158 3.9
Pineapple juice Gold Migros (diluted 1:7) 1.6 77 3.9
Shorley (60% Apple juice) Möhl 6 410 3.7
Tomato juice Naturaplan Bio Coop 3 475 4.1
Vita t Coop 14 777 3.4
Soft drinks
Coca Cola 10.6 493 2.4
Coca Cola light 0 27 2.5
Fanta 10.1 415 2.6
Lipton Ice Tea Lemon* 8.0 268 3.1
Lipton Ice Tea Light 0 29 3.4
Nestea Lemon 7.6 278 3.6
Nestea Light 0 46 3.5
Pepsi light 0.5 25 2.7
Pepsi max 0.5 27 2.8
Red Bull 11.3 601 3.3
Red Bull Sugarfree 0 140 3.2
Rivella blau 1.5 120 3.2
Rivella rot 9 425 3.4
Schweppes Bitter Lemon 12 627 2.7
Schweppes Ginger Ale NA 497 2.7
Schweppes Tonic 8.9 501 2.5
Syrup raspberry Coop (diluted 1:4) 17 756 3.2
Sprite 10.1 479 2.7
Alcoholic beverages
Bacardi Breezer Orange NA 1050 2.6
Cider Ramsauer 3 1159 3.5
Clausthaler beer non alcoholic NA 275 4.3
Clausthaler Panaché non alcoholic NA 452 3.0
Desperados Tequila NA 1379 3.2
Dr. Pepper 10 646 2.6
Eichhof beer alcoholic 3.5 1047 4.1
Red wine NA 2573 3.4
Smirnoff Ice New Taste NA 1192 3.2
NA = Data not available from the food label
* Product has changed in the meantime to lower carbohydrate content.
Tab l e 2 : Carbohydrate content, osmolality and pH of mineral waters, fruit
drinks, soft drinks, and alcoholic beverages in alphabetical order.
1 To calculate osmolality (m mol/kg) from osmola rity (mmol/L), th e density
of a uid must be known. Provided that carbohydrates are the predominant
osmotic substance like i n sports drin ks but not in blood, setti ng osmolarity
equa l to o smolal ity w ould lead to an under esti mation of osmola lity by only
about 1% per 30 g carbohydrates per liter.
95
Osmolality and pH of sport and other drinks available in Switzerland
seem to be of relevance for the manufacturers at this time. How-
ever, the pH value of a sports drink could easily become a market-
ing issue with potentially bene cial or detrimental consequences
for the manufacturers. Besides the pH, other factors like the titrat-
able acid (not measured in this study) are also determinants of the
erosive potential [3].
The attentive reader recognizes that dilutions of some fruit
juices do not show an absolute linear behavior with the osmolal-
ity. This can be seen especially between the pure juice and the 1:1
dilution with water, while the further dilutions come along with a
very similar linear reduction of the osmolality. This is an artifact of
the freezing point depression method [18] as the fruit juices do not
behave like an ideal solution over the whole concentration range.
However, the discrepancy is not very large and the measuring error
is practically not relevant.
Closing Remarks
Sports drinks are an indispensable tool to achieve a suf cient
daily carbohydrate intake and to postpone fatigue during exercise
and competition in many elite sports. Although some of the tested
sports drinks did not have an optimal osmolality, this is not yet a
suf cient reason to generally discourage their consumption, if one
likes such sports drinks. An important issue not discussed so far,
is the individual tolerance and avor preference of a drink as this
in uences voluntary uid intake and gastrointestinal comfort [12,
13, 16]. In contrast, a matter of real concern is the potential for den-
tal erosion related to the low pH value of many tested sports drinks.
Future generations of sports drinks should address this issue.
Address for correspondence:
Samuel Mettler, Department of Agricultural and Food Sciences,
ETH Zurich, ETH Zentrum - LFH A2, CH-8092 Zurich, Switzer-
land, phone +41 (44) 632 73 84, samuel.mettler@inw.agrl.ethz.ch
References
1 Appleton K.M.: Changes in the perceived pleasantness of uids before
and after uid loss through exercise: a demonstration of the association
between perceived pleasantness and physiological usefulness in every-
day life. Physiol. Behav. 83: 813–819, 2005.
2 Brouns F., Kovacs E.: Functional drinks for athletes. Trends Food Sci.
Tech. 8: 414– 421, 1997.
3 Coombes J.S.: Sports drinks and dental erosion. Am. J. Dent. 18:
101–104, 200 5.
4 Coyle E.F.: Fluid and fuel intake during exercise. J. Sports Sci. 22:
39–55, 2004.
5 Eidgenössisches Departement des Inneren: Art. 20: Nahrungsmittel
für Personen mit erhöhtem Energie- oder Nährstoff bedarf (Ergän-
zungsnahrung). Verordnung des EDI über Speziallebensmittel, 2005.
6 Gisol C.V., Lambert G. P., Summers R.W.: Intestinal uid absorption
during exercise: role of sport drink osmolality and [Na+]. Med. Sci.
Sports Exerc. 33: 907–915, 2001.
7 Hooper S., West N.X., Sharif N., Smith S., North M., De’Ath J., Parker
D.M., Roedig-Penman A., Addy M.: A c omp ari son of en ame l ero sion by
a new sports drink compared to two proprietary products: a controlled,
crossover study in situ. J. Dent. 32: 541–545, 2004.
8 Hooper S. M., Hughes J.A., Newcombe R.G., Addy M., West N.X.: A
methodology for testing the erosive potential of sports drinks. J. Dent.
33: 343–348, 2005.
9 Hughes J.A., West N.X., Parker D.M., van den Braak M.H., Addy M.:
Effects of pH and concentration of citric, malic and lactic acids on
enamel, in vitro. J. Dent. 28: 147–152, 2000.
10 Leiper J.B.: Intestinal water absorption – implications for the for-
mulation of rehydration solutions. Int. J. Sports Med. 19 (Suppl. 2):
S129 –S132 , 1998.
11 Leiper J.B.: Gastric emptying and intestinal absorption of uids, car-
bohydrates, and electrolytes. In: Sports drinks, basic science and prac-
tical aspects, Maughan R.J., Murray R. (eds.), CRC Press, Boca Raton,
89–128, 2001.
12 Maughan R. J.: The sports drink as a functional food: formulations for
successful performance. Proc. Nutr. Soc. 57: 15–23, 1998.
13 Maughan R. J., Leiper J.B.: Limitations to uid replacement during
exercise. Can. J. Appl. Physiol. 24: 173–187, 1999.
14 Meurman J.H., Harkonen M., Naveri H., Koskinen J., Torkko H.,
Rytomaa I., Jarvinen V., Turunen R.: Experimental sports drinks
with minimal dental erosion effect. Scand. J. Dent. Res. 98: 120–128,
1990.
15 Morton D.P., Aragon-Vargas L.F., Callister R.: Effect of ingested uid
composition on exercise-related transient abdominal pain. Int. J. Sport
Nutr. Exerc. Metab. 14: 197–208, 2004.
16 Passe D.H., Horn M., Stofan J., Murray R.: Palatability and voluntary
intake of sports beverages, dilut ed orange juice, and water during exer-
cise. Int. J. Sport Nutr. Exerc. Metab. 14: 266–278, 2004.
17 Sherriffs S. M., Maughan R. J.: Water turnover and regulation of
uid balance. In: Sports drinks, basic science and practical aspects,
Maughan R.J., Murray R. (eds.), CRC Press, Boca Raton, 29– 43,
2001.
18 Sweeney T.E., Beuchat C.A.: Limitations of methods of osmometry:
measuring the osmolality of biological uids. Am. J. Physiol. Regul.
Integr. Comp. Physiol. 264: R469–R480, 1993.
19 Venables M.C., Sha w L., Jeukendrup A. E., Roedig-Penman A., Finke
M., Newcombe R.G., Parry J., Smith A. J.: Erosive effect of a new sports
drink on dental enamel during exercise. Med. Sci. Sports Exerc. 37:
39–44, 2005.
20 Vist G.E., Maughan R.J.: The effect of osmolality and carbohydrate
content on the rate of gastric emptying of liquids in man. J. Physiol.
486 : 523–531, 1995.
... Their pH probably does not differ much from the commercially available [3]. The most popular commercially available drinks are low carbohydrate concentrations drinks (<10%) and marketed for general consumption before and during training [1]. ...
... The idea behind using the term "isotonic" in case of sports drinks is to communicate that a beverage contains the same quantity of active osmotic substances per unit of mass as blood, whose osmolality is generally around 280-290 mOsmol/kg. According to different regulations, a sports drink can be declared as isotonic when its osmolality is in the range of 250-340 mOsmol/kg [3]. This variance causes problems. ...
... The optimal osmolality for a sports drink has therefore been defined to in the slightly hypotonic range between 200 and 250 mOsmol/kg [5]. Beverages with higher osmolality can easily cause gastrointestinal discomfort when consuming during exercise [3]. In the recovery phase of the training, this should not be an issue of concern. ...
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Introduction: Modern amateur sportsmen often spend several hours daily on exercise. Especially those doing cycling, long-distance running or triathlon. Sports drinks are widely used by them on every training routine. Some studies have reported a close relationship between sports drinks and dental erosion. Are there any brands or formulations which can be advantageous and recommended by dental professionals? Methods: 5 “isotonic” sports drinks, an energy drink, orange juice, vitamin water and 2 extempore drinks were chosen for the study. Their pH and osmolality were analyzed. Results: The osmolality of the evaluated drinks varied over a relatively broad range (60-648 mmol/kg). In general, it was increasing with total carbohydrate content. The pH value was in the range of 2.76 to 3.90; what may have an impact on dental erosion. Conclusions: It is always advisable for a sport person to choose a drink with a desired osmolality. This is not an easy issue, because the “isotonic” sports drinks and one of the ex tempore (home-made) drink did not have the optimal osmolality in our opinion. The value of big concern for every dental professional is however and undoubtedly the acidity of all the evaluated beverages. Taking into consideration both parameters, there was no drink in the tested group to be recommended by a sports-oriented dentist.
... The two predominant factors that lead to premature fatigue are depletion of the body's carbohydrate reserves and losses of water and electrolytes via sweating. Being appropriately hydrated is, therefore, necessary to ensure that the body functions efficiently when engaged in sporting activities through consuming beverages of suitable osmolalities intended for sportspersons; the main purpose being to replenish any electrolytes lost during exercise, supplying carbohydrates, preventing dehydration, and sustaining endurance capacity [3][4][5][6]11]. Isotonic drinks have osmolalities ranging from 275 to 295 mOsm/kg water and are of similar osmotic pressure to body fluids. ...
... The literature reflects the possible risks of compounds, including sugars, caffeine, glycerol, and vitamin B2 found in sports drinks and energy drinks ingested by athletes and synergistic or antagonistic interactions of components of sports drinks [22]. Regarding dental health and sport dietary drinks, this study related the dental decay to the consumption of sports drinks with low pH [11]. Some of these beverages have cariogenic properties due to their sugar content. ...
... The most active ingredient present in energy drinks is caffeine, which is able to produce synergistic and reinforced stimulant effects in combination with guarana, ginseng, and taurine. Mixtures of different monosaccharides and disaccharides (glucose, fructose, and sucrose) interact, increasing carbohydrate absorption and oxidation during exercise more than themselves alone [11,22]. ...
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Measuring the osmolality of electrolytes, carbohydrates, and other components that contain them, can be very helpful in the design of functional recovery drinks. This study aimed to develop functional recovery drinks based on natural fruit components with the addition of electrolytes and carbohydrates to improve water and electrolyte balance and provide energy after intense physical exertion, as well as ensuring a high content of bioactive ingredients and being of a good sensory quality. The study material consisted of blackcurrant fruit powders obtained by freeze-drying and spray-drying, along with other components such as electrolytes and carbohydrates. The osmolality of the fruit components was measured in aqueous solutions with concentrations from 2.5 to 10%, as well as electrolytes at 0.1 to 4.0% and carbohydrates from 1 to 30%. The sensory quality of drinks was assessed using a scaling method. The content of polyphenols and antioxidant properties were measured spectrophotometrically and the vitamin C content by high-pressure liquid chromatography. Based on the obtained results, five versions of recovery drinks were prepared of defined compositions. These drinks contained fruit powders ranging from 3 to 7%, glucose at 1 to 5%, sucrose 5%, and added electrolytes ranged 0.1 to 0.2% for NaCl and KCl at 0.025%. Their osmolalities ranged from 401 to 564 mOsm/kg H2O, the total polyphenol content was 43 to 62 mg GAE/100 mL, and vitamin C 26 to 35 mg/100 mL. All drinks possessed satisfactory sensory quality. It was established that it is possible to obtain fruit recovery drinks containing defined amounts of electrolytes, carbohydrates, and osmolality values recommended for this type of drink.
... Hypertonic drinks with high osmolality pressure are not recommended for athletes because water absorption rates become decreased, which in turn leads to a risk of gastrointestinal discomfort. Despite this, these drinks may be consumed in restricted amounts for the renewal of glycogen stores [20,21]. Evans et al. (2009) [7] found that a hypertonic 10% glucose-electrolyte solution of around 667 mOsm/kg proved more effective at maintaining rehydration following exercise-induced dehydration for a body mass around 1.9% than a 2% glucose solution of an osmolality that was approximately 193 mOsm/kg, or a 0% glucose solution with an osmolality of around 79 mOsm/kg. ...
... The drinks were high in soluble solids containing mainly carbohydrates, acids, protein and soluble fiber inulin, but varied depending on the recipe (11.2-20.5 • Bx), with the sugar content ranging from 7% to 11%. Indeed, this is consistent with quantities reported for commercially available recovery drinks [20,24]. Research results presented in the literature [10,[16][17][18][19] have recommended that carbohydrate levels of 60-80 g/L are needed in rehydrating sports drinks if they are to provide optimal support for performance and fatigue in both isotonic and slightly hypotonic drinks. ...
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High levels of osmolalities have been found in manufactured carbohydrate-based functional drinks that occasionally include added protein; however, fruit components rich in bioactive ingredients have been absent. It has proved difficult to obtain recovery drinks based on natural fruit components that deliver calories and nutrients to the body whilst simultaneously ensuring that the body is adequately hydrated after physical exertion; the problem being that it is difficult to ensure the drinks’ stability at low pH levels and maintain an appropriate sensory quality. This study aims to develop drinks based on natural fruit components that contain added electrolytes, carbohydrates, prebiotic fiber and protein; an improved water and electrolyte balance; the calories needed after intense physical exertion; a high content of nutrients; and a favorable sensory quality. Furthermore, the relationships between regressive osmolalities of beverage components are herein investigated. The study materials were raspberry powders (prepared via fluidized-bed jet milling, drying, freeze-drying and spray-drying) as well as citrated sodium, potassium, magnesium salts, isomaltulose, hydrolyzed collagen, whey protein isolate and prebiotic fiber. The drinks’ polyphenols and antioxidant properties were measured spectrophotometrically, whilst vitamin C content was determined using high-pressure liquid chromatography. The sensory qualities of each drink were assessed according to a scaling method. Six test versions of recovery drinks were prepared in which osmolalities ranged from 388 to 607 mOsm/kg water, total polyphenol content was 27–49 mg GAE/100 mL and vitamin C level was 8.1–20.6 mg/100 mL, following compositions defined by the study results. It is thus possible to obtain fruit-based recovery drinks of the recommended osmolality that contain added protein, prebiotics and fiber, as well as defined amounts of electrolytes and carbohydrates. All drinks were found to have a satisfactorily sensory quality. The design of appropriate recovery drink compositions was also greatly helped by investigating the relationships among the regressive osmolalities of beverage components (i.e., electrolytes, carbohydrates, fruit powders and protein).
... The osmolality of the different milk subtypes tested ranged from 200.3 to 318.7 mOsm/kg, which is in accordance with values reported in the literature and likely due to the presence of osmotically active ingredients such as lactose and calcium ions (37). The juices and Coca-Cola were hypertonic with osmolality values higher than 300.0 mOsm/kg (38). Significant differences were observed between vehicles of the same subtype, namely between the different squashes and between the applesauces (p < 0.05). ...
... These differences can probably be attributed to the higher sugar content of the blackcurrant squashes in comparison to the orange squash (39). Overall, these results are in accordance with previous studies which have shown that osmolality increases with increasing total carbohydrate content, which is strongly influenced by the proportion of monosaccharides, disaccharides or polysaccharides, as well as the levels of organic acids, vitamins and minerals (38). The sugar content, calorific value and osmotic activity of drink vehicles affect the rates of gastric emptying and intestinal absorption (37,40,41). ...
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Food and drinks are commonly used to facilitate administration of paediatric medicines to improve palatability and enhance patient compliance. However, the impact of this practice on drug solubility and on oral drug bioavailability is not usually studied. Based on recommended strategies for oral administration of paediatric medicines with food and drink vehicles, the aims of this study were (i) to measure the physicochemical properties of (soft) food and drink vehicles, commonly mixed with paediatric medicines prior to administration, and (ii) to assess the impact of the co-administered vehicles on the solubility of two poorly soluble paediatric drugs. Montelukast (sodium) and mesalazine were selected as the model compounds. Distinct differences were observed between the physicochemical properties (i.e. pH, surface tension, osmolality, viscosity and buffer capacity) and macronutrient composition (i.e. fat, sugar and protein content) of the different soft foods and drinks, not only among vehicle type but also within vehicles of the same subtype. Solubility studies of the two model compounds in selected drinks and soft foods resulted in considerably different drug solubility values in each vehicle. The solubility of the drugs was significantly affected by the vehicle physicochemical properties and macronutrient composition, with the solubility of montelukast being driven by the pH, fat and protein content of the vehicles and the solubility of mesalazine by vehicle osmolality, viscosity and sugar content. This vehicle-dependent impact on drug solubility could compromise its bioavailability, and ultimately affect the safety and/or efficacy of the drug and should be taken into consideration during paediatric product development.
... Uncited references. Mettler, Rusch, & Colombani, 2006;Rocha-Mendoza et al., 2021. ...
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The objective of this study was to apply for the first time sugary kefir to produce a new isotonic with low sodium. Additionally, the microbial community profile of grains and fermented kefir was evaluated through metataxonomics. The kefir grains were inoculated into filtered water containing 40 g L-1 sugar at 25 °C for 48h. Grains and beverage samples were collected at 0, 24, and 48h for DNA extraction. The grains were separated, and the beverage was used to prepare the isotonic. The isotonic consisted of kefir (85% v/v), pasteurized juice (15% v/v), sodium citrate (0.2 g L-1), sodium chloride (0.427 g L-1), maltodextrin (22 g L-1) and citric acid (0.7 g L-1). The physicochemical and microbiological parameters were performed on days 0, 7, 15, and 30. All isotonic obtained presented sodium content below the commercial control. The presence of lactic acid bacteria and yeasts in all periods evaluated demonstrated the viability of isotonic kefir. Through metataxonomy, the genus Ethanoligenens was described as dominant for the first time in sugary kefir. Furthermore, the microbial diversity in the beverage was higher than that observed in the grains. This study provided a new low sodium isotonic based on sugary kefir for the first time.
... Considering the free water load and timing and assuming a baseline plasma sodium of 140 mmol/L, we estimated a decrease in serum sodium of ∼17-18 mmol/L in 80 min after drinking 6 L of beer, for a final plasma sodium of ∼122 mmol/L (Supplementary data, Tables S1 and S2 and online Appendix) [1,5,[7][8][9][10][11][12][13][14][15][16][17][18]. This is a conservative estimate since 6 L were used for calculations. ...
Article
Hyponatremia is acute when present for < 48 hours. Most cases of acute hyponatremia involve both excess free water intake and an, at least partial, urinary free water excretion defect. By contrast, hyperacute water intoxication may result from a large excess electrolyte-free water intake in such a short time that properly working urinary free water excretion mechanisms cannot cope. A hyperacute decrease in serum sodium may lead to death before medical intervention takes place. Well-documented cases have been published in the Military Medicine literature. In addition, news reports suggest the existence of cases of voluntary ingestion of excess free water by non-psychiatric individuals usually during ‘dare’ activities. Education of the public is required to prevent harm from these high-risk activities. Adequate training of emergency medical units may prevent lethal outcomes. Spanish media echoed the case of a male that died following his triumph in a 20-minute beer drinking contest. ‘From a heart attack. Man dies after drinking six liters of beer in a contest’ ran the news. We now review the physiology underlying hyperacute water intoxication and discuss the potential contribution of hyperacute water loading and acute hyponatremia (HAWLAH) to the demise of this patient.
... Studies had to compare the effect of ingestion of solutions formulated to different osmolality by altering either the CHO concentration and type and/or the electrolyte concentration or type. Dosing regimens had to be specified and were classified as: hypertonic (> 300 mOsmol kg −1 ), hypotonic (< 275 mOsmol kg −1 ), isotonic (275-300 mOsmol kg −1 ) or water from tap, mineral or beverage containing noncaloric flavouring, minerals or vitamins but without CHO at < 40 mOsmol kg −1 [43]. All drink osmolality values were measured or in some waters were unreported (Table 4; an analysis value of zero was assigned to all water treatments, see Sect. ...
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Background Body-fluid loss during prolonged continuous exercise can impair cardiovascular function, harming performance. Delta percent plasma volume ( d PV) represents the change in central and circulatory body-water volume and therefore hydration during exercise; however, the effect of carbohydrate–electrolyte drinks and water on the d PV response is unclear. Objective To determine by meta-analysis the effects of ingested hypertonic (> 300 mOsmol kg ⁻¹ ), isotonic (275–300 mOsmol kg ⁻¹ ) and hypotonic (< 275 mOsmol kg ⁻¹ ) drinks containing carbohydrate and electrolyte ([Na ⁺ ] < 50 mmol L ⁻¹ ), and non-carbohydrate drinks/water (< 40 mOsmol kg ⁻¹ ) on d PV during continuous exercise. Methods A systematic review produced 28 qualifying studies and 68 drink treatment effects. Random-effects meta-analyses with repeated measures provided estimates of effects and probability of superiority ( p + ) during 0–180 min of exercise, adjusted for drink osmolality, ingestion rate, metabolic rate and a weakly informative Bayesian prior. Results Mean drink effects on d PV were: hypertonic − 7.4% [90% compatibility limits (CL) − 8.5, − 6.3], isotonic − 8.7% (90% CL − 10.1, − 7.4), hypotonic − 6.3% (90% CL − 7.4, − 5.3) and water − 7.5% (90% CL − 8.5, − 6.4). Posterior contrast estimates relative to the smallest important effect ( d PV = 0.75%) were: hypertonic-isotonic 1.2% (90% CL − 0.1, 2.6; p + = 0.74), hypotonic-isotonic 2.3% (90% CL 1.1, 3.5; p + = 0.984), water-isotonic 1.3% (90% CL 0.0, 2.5; p + = 0.76), hypotonic-hypertonic 1.1% (90% CL 0.1, 2.1; p + = 0.71), hypertonic-water 0.1% (90% CL − 0.8, 1.0; p + = 0.12) and hypotonic-water 1.1% (90% CL 0.1, 2.0; p + = 0.72). Thus, hypotonic drinks were very likely superior to isotonic and likely superior to hypertonic and water. Metabolic rate, ingestion rate, carbohydrate characteristics and electrolyte concentration were generally substantial modifiers of d PV. Conclusion Hypotonic carbohydrate–electrolyte drinks ingested continuously during exercise provide the greatest benefit to hydration. Graphical abstract
... Some energy and sports drinks have a very low pH, i.e., Isostar with a pH of 2.4-3.8, Red bull with 3.4 and Gatorade with 3.3 [10] and M-Isodrink with a pH of 3.0, PowerBar Performance Sports Drink with 3.7 and Sponser Hypotonic with 3.5 [15], respectively, which can predispose athletes at risk of suffering from dental erosion emerging from the beverage acidity. Due to the lack of studies evaluating the consumption of sports and energy drinks in athletes [2], this study aimed to identify potential risk indicators between dietary habits and dental erosion, including the consumption of energy drinks among athletes (swimmers and non-swimmers). ...
Article
Objectives This cross-sectional study aimed to investigate if the consumption of acidic food and beverages, including energy drinks is associated with dental erosion in athletes. Methods A questionnaire was applied in 110 athletes (swimmers, bodybuilders, football players, boxers, volleyball players and runners) to collect training and sport practice data, medical history and oral hygiene habits. A semi-quantitative food frequency questionnaire was used for acidic beverages and food consumption. The Basic erosive wear examination index was used to evaluate the presence of dental erosion lesions. Participants were organized into 4 groups: swimmers who consumed or did not consume energy drinks, and athletes (except swimmers) who consumed or did not consume energy drinks. Results The prevalence of dental erosion was 83.6%. Of the 110 participants, 49.1% had low risk of erosion, 6.4% had an average risk of erosion, and 0.9% presented high risk of erosion. According to the multivariate logistic analysis, red wine (OR = 1.6; P = 0.038), citrus fruit (OR = 1.3; P = 0.037), frequency of tooth brushing (OR = 2.3; P = 0.018), energy drinks consumption in swimmers (OR = 15.2; P < 0.001), and energy drinks consumption in athletes (OR = 6.3; P = 0.003) were significant risk factors of dental erosion, whereas spicy food was a protective factor (OR = 0.64; P = 0.024). Conclusions The consumption of energy drinks by swimmers more than doubles the chance of dental erosion (BEWE score of “at least low risk”) when compared with non-swimmer athletes consuming the same energy drinks. Athletes consuming energy drinks should be clinical and regularly supervised, especially for dental erosion.
... A recent pH assessment of sports drinks commercially available in the US found all products to be highly acidic (i.e., pH < 4) (22). This is in line with a previous investigation of sports products in Europe (23). That drinks with a pH below 4.0 have been described as potentially damaging to the dentition (24) raises concerns about the long-and short-term effects of repeated sports drink consumption (25). ...
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Osmometry is an important tool in the investigation of biological phenomena, and commercially available instruments for freezing point and vapor pressure osmometry can determine the osmolality of solutions quickly and inexpensively. However, accurate measurements of osmolality using these techniques require that the solutions have specific characteristics, and that measurements do not exceed the limitations inherent to each method or instrument. The thermodynamic principles underlying osmometry constrain the range and accuracy of each measurement method, and these must be considered in establishing the usefulness of each technique. This paper addresses the principles and limitations of routine osmometry techniques. We begin by discussing definitions of osmolality and the thermodynamic concepts of solute-solvent systems that are central to understanding osmometry of biological (i.e., aqueous) solutions. We then explore the application of various methods of measuring osmolality, the nature of errors introduced by overextension or misapplication of osmometry techniques, and the interpretation of data in the literature acquired by various methods and protocols.
Chapter
Water is the largest component of the human body and the total body water content varies from approximately 45-70% of the total body mass, ¹ corresponding to about 33 to 53 l for a 75-kg man. Although body water content varies greatly among individuals, the water content of the various tissues is maintained relatively constant. For example, adipose tissue has a low water content and lean tissue such as muscle and bone has a high water content (Table 2.1), so the total fraction of water in the body is determined largely by the total fat content. In other words, a high fat content is related to a lower total water content as a percentage of body mass.
Chapter
Ingestion of carbohydrate electrolyte drinks before and during exercise has been shown to help delay the fatigue process. Before the body can utilize the constituents of drink they must be absorbed by the small intestine and transported to the appropriate body pools. The role of the gastrointestinal tract in regulating the absorption of a drink and delivering the nutrients to the circulation is therefore crucial in determining the benefits that can be derived from fluid ingestion.
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Dental erosion associated with soft drink consumption probably results from the contained dietary acids in the formulations. The pH value of any formulation is an important variable in acid erosion but not necessarily the only important factor. The aim of this study was to measure enamel erosion by citric, malic and lactic acids at pH values and acid concentrations representative of a range found in soft drink formulations and to determine the effect of adding calcium to citric acid. Flat ground enamel samples were prepared from unerupted human third molar teeth. Groups of five specimens were placed in citric, malic and lactic acid solutions of different pH and acid concentration for three by 10 min exposures at 35 degrees C. Enamel loss was measured by profilometry. Enamel specimens were also exposed to citric acid solutions containing calcium at different pH values and at the same pH with different concentrations of calcium. Numerical data and contour plots for each acid showed a similar pattern for increasing erosion with decreasing pH and increasing acid concentration and vice versa for decreasing erosion. Increasing the concentration of calcium in a fixed pH citric acid solution resulted in decreased erosion. This effect was most marked at higher pH. This study has shown that under highly controlled conditions the erosion of enamel by solutions of dietary acids is influenced by the interplay of pH, acid concentration and presence of calcium. These variables and in particular the concentration of calcium could be manipulated to produce soft drinks with reduced erosivity to enamel.
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Over the past few decades, numerous studies have been carried out to establish the optimal composition of drinks that are designed to rehydrate the body rapidly. These studies have led to the insight that drinks should contain carbohydrate (CHO) and sodium to stimulate fluid absorption and fluid retention. However, the CHO content as well as the osmolality of the drink should be relatively low. According to these findings, the composition criteria for rehydration drinks have quite a narrow range. Drinks that are designed to supply energy or substances that stimulate energy metabolism differ considerably in their composition. This review highlights the most relevant aspects.
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The effects of new experimental sports drinks on dental enamel were studied in vitro using bovine tooth specimens. Profilometric analysis was used to measure the loss of tooth material after immersion of the specimens in the drinks. Thereafter the specimens' surface hardness was measured and scanning electron microphotographs were taken. In addition, 13 commercial sports drinks and experimental drinks containing either citric acid or malic acid were tested for their capacity to dissolve hydroxyapatite in vitro. The erosive effect increased markedly with decreasing pH. The citric acid containing drinks were more erosive than malic acid containing drinks. No erosion was observed with the malic acid containing drink (pH 5.90) but the drink of similar composition containing citric acid caused an erosion 1.3 +/- 1.1 microns deep and a commercial citric acid containing drink caused a lesion 12.3 +/- 4.5 microns deep after 120 min immersion. Softening of enamel was greater in specimens immersed in citric acid than in those immersed in malic acid containing drink. The in vitro hydroxyapatite dissolving effect of the commercial sports drink samples studied (all having a pH under 4.22) was markedly greater (0.48-4.38 mmol/l) than that of the malic acid containing experimental drink (pH 5.50, Ca++ concentration in the supernatant 0.19 mmol/l) and of the similar citric acid containing drink (0.35 mmol/l). The hydroxyapatite dissolving effect of both drinks started to be marked at a pH level of about 5.0 but increased thereafter exponentially with decreasing pH. At pH levels above 4.0 the hydroxyapatite dissolving effect of citric acid containing drinks was greater than that of malic acid containing drinks.
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1. The effect of osmolality and carbohydrate content on the rate of gastric emptying was assessed by using the double sampling gastric aspiration technique to measure the rate of gastric emptying of isoenergetic and isosmotic solutions of glucose and glucose polymer. Six healthy male subjects were each studied on four separate occasions using a test drink volume of 600 ml. 2. The half-emptying time (t1/2, mean +/- S.E.M.) for a dilute (40 g l-1) solution of glucose (LG, 230 mosmol kg-1) was 17 +/- 1 min. This was greater than that (14 +/- 1 min) for a glucose polymer solution with the same energy content (LP, 42 mosmol kg-1). A concentrated (188 g l-1) glucose polymer solution (HP, 237 mosmol kg-1) emptied faster (t1/2 = 64 +/- 8 min) than the corresponding isoenergetic glucose solution (HG, 1300 mosmol kg-1, t1/2 = 130 +/- 18 min). 3. The dilute (40 g l-1) glucose solution emptied faster than the concentrated (188 g l-1) glucose polymer solution with the same osmolality (LG, 230 mosmol kg-1; HP, 237 mosmol kg-1). 4. The two dilute solutions (40 g l-1) delivered a similar amount of carbohydrate to the small intestine, whereas the concentrated (188 g l-1) glucose polymer solution delivered a greater amount of carbohydrate at 20, 40 and 50 min than the isoenergetic glucose solution. 5. These results indicate that both osmolality and carbohydrate content influence gastric emptying of liquids in man, but the carbohydrate content appears to have greater influence than osmolality.(ABSTRACT TRUNCATED AT 250 WORDS)
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Absorption of ingested water and most solutes occurs in the proximal small intestine, therefore the rate at which beverages are emptied from the stomach is an important factor in determining the rate of water absorption. In the small intestine, water absorption is brought about by the creation of suitable osmotic gradients that promote net uptake of water from the intestinal lumen. The absorption of solute, especially that brought about by active carriers, are highly effective in creating the osmotic gradients that promote net water uptake. The activation of these transporters also increases the permeability of the mucosa which helps absorption. Moderate hypotonicity of the luminal contents potentiates solute-induced water absorption while hypertonicity slows fluid absorption. Dilute hypotonic glucose-sodium solutions are highly effective oral rehydration solutions, and the type of carbohydrate used does not appear to be important. The addition of other actively absorbed solutes gives little benefit in potentiating water uptake. The inclusion of sodium in rehydration solutions may not be required to stimulate water absorption but probably assists the overall rehydration process. The amount of glucose required to stimulate water absorption is relatively small and for rehydration purposes ingestion of an adequate amount of a dilute solution is more beneficial than drinking a smaller volume of a more concentrated beverage.
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Fluid replacement during exercise is essential for endurance exercise performance and reducing the risk of heat illness. Fluids supply water, which ameliorates dehydration, and also substrate for the working muscles. Absorption of water and nutrients occurs in the upper part of the small intestine, and replacement may be limited by the rate at which fluid is emptied from the stomach or absorbed in the intestine. Gastric emptying of liquids is influenced primarily by the volume of fluid in the stomach and by its energy density. Increasing the volume will speed emptying, but increasing the nutrient content will slow emptying. Osmolality, temperature, and pH of drinks, as well as exercise intensity, are of minor importance. Intestinal water absorption is a passive process: water follows osmotic gradients but will also follow the active absorption of nutrients, especially glucose, which is actively co-transported with sodium. Water transport is maximised by the presence in the intestine of hypotonic solutions of glucose and sodium. Hypertonic solutions promote net water secretion into the intestinal lumen, resulting in a temporary net loss of water from the body. The amount of fluid ingested by athletes is normally much less than can be tolerated, therefore issues such as palatability and practising drinking during training are important.