Response to "Waterlogged?" feature by Margaret McCartney
This rapid response has been co-authored by:
Professor Ivan Tack, MD, PhD, Specialist in renal patho-physiology,
Head of the Department of Medical Physiology, Toulouse Hospital, France
Professor Jean-Francois Duhamel,MD,PhD, Chief of Paediatrics, The
Medical University Hospital of Caen, France
Professor Max Lafontan, PhD,Emeritus Director of Research INSERM UMR
1048, Toulouse University, France
Doctor Lise Bankir, PhD, Director of Research Emeritus, INSERM, Unit
872 - E2, Paris, France
Professor Florian Lang, MD, PhD, Chairman, Department of Physiology
Eberhard-Karls-University of Tuebingen, Germany.
Doctor Michel Daudon, PhD, Laboratoire CRISTAL, Centre de Recherches
et d'Informations Scientifiques et Techniques Appliquees aux Lithiases,
Service de Biochimie A, Groupe Hospitalier Necker-Enfants Malades, Paris,
France
Professor Hardinsyah, MS, PhD, Department of Community Nutrition,
Faculty of Human Ecology, Bogor Agricultural University, Indonesia.
With regard to the article entitled "Waterlogged?" posted by Dr
Margaret McCartney on July 12th 2011, we believe that it is important to
clarify some points.
Your readers should be aware that The European Food Safety Agency
(EFSA) published a scientific opinion on dietary reference values for
water in 2010 (1). The Agency recommended a total water intake of 2.0L for
normal women and 2.5L for normal men. Once the assumed quantity of water
typically present in food is taken into account, this leaves a net liquid
intake of 1.6L and 2.0L respectively.
In fact, EFSA's scientific opinion states that we should drink enough
water to maintain total water balance and enable our kidneys to eliminate
wastes under the best conditions. With this in mind, their advice to drink
1.6L or 2.0L a day is relevant.
The guidance provided by the EFSA makes particular sense in view of
their review of national fluid consumption levels, which revealed under-
consumption of liquids by significant population segments(2).
In this context, we think it is wrong to imply that encouraging
children to drink six to eight glasses a day could be dangerous. This
amount of water is only a small fraction of the urinary maximal excretion
rate of 0.7-1.0 L/hour and is readily excreted by the intact kidney.
Hyponatremia typically only occurs in cases of excessive hydration after
prolonged endurance activity or in clinical settings in which dehydration
is erroneously diagnosed and inappropriately treated as such. Fluid intake
studies in the US indicate that the mean, 95th and 99th percentiles of
liquid intake amounting to 2.5L, 4.9L, 7.4L respectively per day (3), and
all above EFSA recommended levels, have not led to hyponatremia.
Therefore, no single upper tolerable intake level for total water intake
has been identified by EFSA (1).
Water can, of course, come from any beverages, but it would be
preferable to get the bulk of the daily liquid intake from plain water,
because it is free of added ingredients.
Rapid Response:
Response to "Waterlogged?" feature by Margaret McCartney
This rapid response has been co-authored by:
Professor Ivan Tack, MD, PhD, Specialist in renal patho-physiology,
Head of the Department of Medical Physiology, Toulouse Hospital, France
Professor Jean-Francois Duhamel,MD,PhD, Chief of Paediatrics, The
Medical University Hospital of Caen, France
Professor Max Lafontan, PhD,Emeritus Director of Research INSERM UMR
1048, Toulouse University, France
Doctor Lise Bankir, PhD, Director of Research Emeritus, INSERM, Unit
872 - E2, Paris, France
Professor Florian Lang, MD, PhD, Chairman, Department of Physiology
Eberhard-Karls-University of Tuebingen, Germany.
Doctor Michel Daudon, PhD, Laboratoire CRISTAL, Centre de Recherches
et d'Informations Scientifiques et Techniques Appliquees aux Lithiases,
Service de Biochimie A, Groupe Hospitalier Necker-Enfants Malades, Paris,
France
Professor Hardinsyah, MS, PhD, Department of Community Nutrition,
Faculty of Human Ecology, Bogor Agricultural University, Indonesia.
With regard to the article entitled "Waterlogged?" posted by Dr
Margaret McCartney on July 12th 2011, we believe that it is important to
clarify some points.
Your readers should be aware that The European Food Safety Agency
(EFSA) published a scientific opinion on dietary reference values for
water in 2010 (1). The Agency recommended a total water intake of 2.0L for
normal women and 2.5L for normal men. Once the assumed quantity of water
typically present in food is taken into account, this leaves a net liquid
intake of 1.6L and 2.0L respectively.
In fact, EFSA's scientific opinion states that we should drink enough
water to maintain total water balance and enable our kidneys to eliminate
wastes under the best conditions. With this in mind, their advice to drink
1.6L or 2.0L a day is relevant.
The guidance provided by the EFSA makes particular sense in view of
their review of national fluid consumption levels, which revealed under-
consumption of liquids by significant population segments(2).
In this context, we think it is wrong to imply that encouraging
children to drink six to eight glasses a day could be dangerous. This
amount of water is only a small fraction of the urinary maximal excretion
rate of 0.7-1.0 L/hour and is readily excreted by the intact kidney.
Hyponatremia typically only occurs in cases of excessive hydration after
prolonged endurance activity or in clinical settings in which dehydration
is erroneously diagnosed and inappropriately treated as such. Fluid intake
studies in the US indicate that the mean, 95th and 99th percentiles of
liquid intake amounting to 2.5L, 4.9L, 7.4L respectively per day (3), and
all above EFSA recommended levels, have not led to hyponatremia.
Therefore, no single upper tolerable intake level for total water intake
has been identified by EFSA (1).
Water can, of course, come from any beverages, but it would be
preferable to get the bulk of the daily liquid intake from plain water,
because it is free of added ingredients.
References:
(1) http://www.efsa.europa.eu/en/scdocs/scdoc/1459.html and EFSA
Journal 2010; 8(3):1459
(2) http://www.efsa.europa.eu/EFSA/ScientificPanels/DATEX/efsa_locale
-1178620753812_ConciseEuropeanConsumptionDatabase.html
(3)Food and Nutrition Board (FNB). 2004. Dietary reference intakes
for water, potassium, sodium, chloride, and sulfate. Chapter 4: 73 - 185.
Competing interests: No competing interests