Water as a Surprising Source of Magnesium
Magnesium, a vital mineral involved in over 300 enzymatic reactions in the body, is typically obtained through diet, but many people don't meet their daily requirements. While food is the primary source, drinking water can serve as a valuable and bioavailable secondary source. The amount you receive, however, is highly dependent on several factors.
Factors Influencing Water's Magnesium Content
Water source: Tap water can come from various sources, such as surface water (rivers, lakes) or groundwater (wells). Groundwaters, which have percolated through mineral-rich rocks and soil, often have higher magnesium concentrations than surface water.
Geological area: The specific geology of a region dictates the types and amounts of minerals that dissolve into the water supply. In areas with 'hard' water, mineral content is naturally higher, with magnesium and calcium being the key contributors to this hardness.
Water treatment: The process your water undergoes can drastically alter its mineral profile. Standard disinfection typically leaves minerals untouched, but treatments like chemical or ion-exchange softening specifically remove divalent cations such as magnesium and calcium. Conversely, some advanced filtration systems, like reverse osmosis, may remove all minerals, but special re-mineralizing filters can be used to add them back.
The Bioavailability Advantage: Water vs. Food
While magnesium is available in food, the absorption, or bioavailability, from water is often comparable, and sometimes even better, than that from certain dietary sources. The body effectively absorbs magnesium from dissolved mineral salts. Some research even suggests that consuming mineral water with a meal can slightly increase the body's absorption efficiency, likely due to a slower passage through the digestive system. This makes water a particularly effective delivery mechanism for this essential nutrient.
Health Benefits of Magnesium from Drinking Water
Consistent intake of magnesium from drinking water has been linked to several positive health outcomes, particularly for individuals with low dietary magnesium levels. Here's a list of potential benefits:
- Cardiovascular Health: Numerous studies have investigated the link between drinking water magnesium and heart health. Some research suggests an inverse relationship between higher magnesium levels in drinking water and mortality from coronary heart disease (CHD), especially in European populations.
- Blood Pressure Regulation: Adequate magnesium intake is crucial for regulating blood pressure. Mineral water rich in magnesium has been shown in some studies to help lower blood pressure levels in people with borderline hypertension.
- Bone Density: Along with calcium, magnesium plays a key role in bone formation and maintenance. Adequate intake through water and food can help improve bone mineral density, a crucial factor in preventing osteoporosis.
- Digestive Health: Magnesium has a natural laxative effect by drawing water into the intestines. Drinking magnesium-rich water can help promote regular bowel movements and relieve constipation.
- Improved Hydration: Magnesium is an electrolyte that aids in optimal cellular hydration. Some mineral waters boast high electrolyte content, maximizing hydration levels.
Comparison of Magnesium Content in Different Water Types
| Water Type | Typical Mg Content Range | Key Characteristics |
|---|---|---|
| Hard Tap Water | Variable (often higher) | Naturally contains more dissolved minerals, including magnesium and calcium, based on local geology. |
| Soft Tap Water | Lower to negligible | Processed to remove hardness-causing minerals like magnesium. Softeners replace these minerals with sodium or potassium. |
| Natural Mineral Water | Consistent and often higher | Bottled at the source, containing a stable mineral profile. FDA-regulated to contain at least 250 ppm total dissolved solids. |
| Purified Water | Negligible | Treated by reverse osmosis or distillation, which removes almost all dissolved solids, including magnesium. Re-mineralization may be added back by some brands. |
The Bottom Line on Water as a Magnesium Source
For most people with a balanced diet, magnesium from drinking water is a complementary, rather than primary, source. A USDA study found that for average US tap water, the contribution is relatively small (around 5% of the DV). However, for those with insufficient dietary intake or in regions with particularly hard water, the contribution can be significant. It's an effortless way to boost your daily intake, especially when choosing naturally mineral-rich water sources. For a comprehensive overview of magnesium and its functions, refer to this detailed fact sheet from the National Institutes of Health: Magnesium - Health Professional Fact Sheet.
Conclusion
Ultimately, whether or not you get magnesium from water depends entirely on the source you're drinking. Hard tap water and natural mineral water can be valuable contributors, while softened or purified water offers very little. Rather than relying solely on water for this nutrient, consider it a beneficial supplement to a diet rich in leafy greens, nuts, seeds, and whole grains. For those concerned about their intake, checking local water quality reports or opting for bottled mineral water are simple steps to take. This effortless contribution can add up over time, supporting everything from your heart and bones to your digestive health.
