Daily calcium needs must be covered to constitute and maintain bone capital.
To do so, a daily intake of 3 dairy products is usually recommended, but sometimes this is not achieved. In this case, a regular intake of calcium-rich mineral water is a good complement that could, if the calcium content of the water is high enough, help to meet the daily calcium needs estimated to be 800mg in Europe.
But the question is: Is this calcium absorbed as well as the calcium in dairy products? And the answer is: Absolutely!
The absorption of the calcium contained in calcium-rich mineral waters is as good as the absorption of calcium in dairy products.
Several studies demonstrated that the calcium contained in water is absorbed as well as the calcium in dairy products (milk and cheese) and even in medicines: the absorption coefficient of calcium in dairy products is around 25% to 35% (1), when that of the calcium in mineral waters is from 23% to 47.5% (2).
As calcium intake decreases, the efficiency of calcium absorption increases (and vice versa) (3). However, the amount of calcium really absorbed will be increasing with the highest calcium intake. Thus, for example, after consuming 100mg of calcium, the absorption rate reaches 47.5% (i.e. 47.5mg of calcium is absorbed), when for 500mg of calcium taken, 23.8% is absorbed (i. e. 119mg of calcium is absorbed) (2).
Note that calcium absorption doesn’t depend only on the size of dose; it’s also influenced by the form of calcium and the presence or absence of some food components such as oxalic acid or phytic acid (3). However, in mineral waters, calcium absorption is similar in healthy people whatever the type of salt is: calcium sulphate or calcium bicarbonate (2).
Beneficial effects on bone mineralization
A number of studies showed that drinking a calcium-rich mineral water leads to a decrease of the bone resorption indicators (4-6).
One litre of calcium-rich mineral water can contribute to meet 50% of the daily calcium needs of an adult!
The average recommended calcium intakes for adults are 900mg/d in France and 1000mg/d in USA. For adolescents, these needs are increased by 300mg/d in both countries making them at 1200mg/d in France and 1300mg/d in USA. Seniors and elderly persons have also increased calcium needs: 1200mg/d (1,3).
The daily consumption of one litre of calcium-rich mineral water, containing 500mg of calcium per liter covers:
- 50% of the Dietary Reference Intakes (DRIs) for calcium in USA for adults
- 60% of the DRIs for calcium in France for adults
- 42% of the DRIs for calcium in France for adolescents
- 38% of the DRIs for calcium in USA for adolescents
- 42% of the DRIs for calcium of an elder person.
Drinking a calcium-rich mineral water is therefore a good way to contribute meeting the daily calcium needs as part of a balanced diet.
Choose water carefully, depending on your preference and specific needs.
References:
1) Apports Nutritionnels Conseillés pour la Population Française. « Calcium » L. Guéguen. p.131-140 - Ed Tec et Doc Lavoisier 2001.
2) Constant F et al. Les eaux embouteillées. Cah. Nutr.Diet, 2011, 46, 40-50
3) Dietary Reference Intakes. The essential guide to nutrient requirements. Washington DC: Institute of medicine of the national academies; 2006. p. 1—543.
4) Roux S et al. Biological effects of drinking-water mineral composition on calcium balance and bone remodeling markers. J Nutr Health Aging 2003 ; 7 (6) : 1-5
5) Meunier PJ et al. Consumption of a high calcium mineral water lowers biochemical indices of bone remodelling in postmenopausal women with low calcium intake. Osteoporos Int 2005 ; 16 : 1203-9
6) Wynn E et al. Alkaline mineral water lowers bone resorption even in calcium sufficiency : alkaline mineral water and bone metabolism. Bone 2009 ; 44 : 120-4