Benefits of Magnesium-Rich Mineral Waters:
Water Magnesium Retention
and Absorption with meals
(Newsletter, Vol. 2, N°2 - Sept. 2000)
Role of magnesium
Magnesium is an essential mineral for humans, playing a key
role in many biological processes through its function in enzyme
activities. For example, those involved in energy production,
neuromuscular excitability, muscle contraction, blood
coagulation, protein and nucleic acid metabolism. It has been
suggested that aging, stress and various diseases may increase
magnesium requirements. Inadequate intake and impaired absorption
of magnesium are thought to contribute to disorders in humans
such as osteoporosis, hypertension and atherosclerotic vascular
diseases.
Magnesium requirements
It is recognized that changes in lifestyle since the middle of
the 20th century has led to a decrease in dietary magnesium
intake. In the USA, it is reported that the dietary intake of
magnesium decreased from 450-480 mg/day at the beginning of the
20th century to 185-260 mg/day at the end of the 1980s.
Recommended dietary allowances in the USA show 400- 420 mg for
men and 310-320 mg for women aged 19-30 years and above 31 years
respectively. In most industrialized countries, it has been shown
that magnesium intake is below dietary recommendations, due to an
increased consumption of refined, fat-rich and processed
foods.
Magnesium intake was assessed over a one-year period in 5,448
French volunteers participating in an epidemiological study
called SU.VI.MAX. In this cohort, 77% of women and 72% of men had
dietary magnesium intake lower than the French recommended
dietary allowances (RDAs), i.e. 380 mg for men and 350 mg for
women. Furthermore, 23% of women and 18% of men consumed less
than two-thirds of RDAs. In Switzerland, the mean daily dietary
magnesium intake is 290 mg, with a range of 110- 475 mg/day,
while RDAs are 300 and 350 mg/day for men and women
respectively.
Magnesium from water: its contribution to total intake and
its retention (bioavailability)
Magnesium-rich mineral waters provide significant amounts of
calorie-free magnesium. It was shown by the SU.VI.MAX study, in
which the Water Institute was involved, that natural mineral
waters such as Contrex and Vittel Grande Source respectively
provided 17% and 7% of total magnesium intake in subjects
regularly drinking the two brands. It was also demonstrated
earlier from animal experiments that magnesium from Hépar
is well absorbed from the intestine and subsequently retained by
the body, in particular being incorporated into the bones.
However, no data on humans shows the absorption and retention
(bioavailability) of magnesium from Hépar or more
generally from water. It was one of the objectives of the
research program of the Water Institute.
Magnesium bioavailabiity from magnesium-rich mineral water
and the effect of meals
With a content of 110 mg/I of magnesium, Hépar, the
mineral water chosen for the study, has the highest magnesium
content among all mineral waters sold in France. The objectives
of the study, carried out at Nestlé Research Centre (NRC),
were first, to evaluate magnesium absorption and retention from
drinking Hépar and second, to show whether the
simultaneous consumption of a meal with mineral water has an
effect on magnesium bioavailability. Magnesium absorption and
retention by the body were calculated in 10 healthy women aged
25-45 years with stable isotope techniques. These naturally
occurring elements are used as markers to follow the transit of
magnesium through the body.
The results demonstrate the bioavailability of magnesium from
mineral water in humans. In addition, an enhancement of magnesium
absorption was observed when water was consumed with a meal [
from water alone: 45.7 ± 4.6% and with a meal 52.3
± 3.9%; i.e. a mean absolute increase of the absorption of
6.6%, corresponding to a relative increase of 14.4%]. Magnesium
body retention was also significantly higher when water was drunk
with meals [ ± 4.2% and 37.4 ± 4.0% retention with
and without a meal, respectively; i.e. a mean absolute increase
in retention of 4.1%, corresponding to a relative increase of
11.0%].
This increased absorption and retention may be due to a slower
gastrointestinal transit time, which enables a better contact of
digested food with intestinal cells and/or the presence of
products of digestion from meals such as carbohydrates, which may
stimulate specific mechanisms of intestinal absorption. In
conclusion, the regular consumption of a magnesium-rich mineral
water (>50mg/l) would provide a valuable contribution to
magnesium requirements. Thus, drinking magnesium-rich water with
breakfast or other meals enhances the utilization of
magnesium.
The new results were presented at conferences, e.g. that of
the Federation of American Societies of Experimental Biology
(EB99), Washington, D.C., April 17-21, 1999 (see poster). They
have been accepted for publication in the American Journal of
Clinical Nutrition (2001).
New techniques for the determination of magnesium
At the Western Human Nutrition Research Center of the US
Department of Agriculture -- one of the most famous teams for
mineral and micronutrient research into nutrition, new methods
were developed for the determination of magnesium absorption,
retention and metabolism in humans. A mathematical model of
magnesium metabolism is to be established. It may be useful in
detecting chronic magnesium deficiency.
The first part of this study (Preparation and ICP-MS
Measurement of Magnesium Stable Isotopes in Human Samples, by M.
Sabatier, W.R. Keyes, M.J. Arnaud and J.R. Turnlund) was
presented at two congresses (Téma 10, May 2-7, 1999 and
International Conference on Stable Isotopes and Isotopic Effects,
Carry le Rouet, France, June 20-25, 1999).
This page was first uploaded to The Magnesium Web Site on
November 14, 2002
http://www.mgwater.com/
Healthy Water
Association--USA