When you think of hydration, water is likely the first thing that comes to mind. However, new research suggests that milk—a high-protein, nutrient-dense beverage—might be just as effective, if not better, at keeping you hydrated. With a unique combination of electrolytes, carbohydrates, and water, milk is emerging as a top contender for hydration, especially after intense physical activity.
Why Milk Helps with Hydration
Milk contains three essential components that support hydration:
- Electrolytes like sodium, potassium, calcium, and magnesium.
- A high water content—about 90% of milk is water.
- Carbohydrates that aid in fluid absorption and retention.
A study published in the American Journal of Clinical Nutrition compared 13 different beverages and found that whole milk, skim milk, and even orange juice provided better hydration than water. Similarly, a 2020 study in Nutrients revealed that a milk-based hydration drink kept the body hydrated longer than both water and sports drinks by increasing fluid retention and reducing urine loss.
Electrolytes: The Key to Fluid Balance
Electrolytes play a crucial role in maintaining hydration. These minerals regulate chemical reactions, support muscle function, and help maintain fluid balance in the body. According to Katie Brown, Ed.D., RDN, executive vice president of the National Dairy Council, dairy milk naturally provides a strong electrolyte profile.
Nutritional Breakdown of 8 oz. Reduced-Fat (2%) Milk (Source: USDA)
- Calories: 122
- Carbohydrates: 12g
- Protein: 8g
- Total Fat: 5g
- Sodium: 96mg (4% DV)
- Calcium: 309mg (24% DV)
- Potassium: 390mg (8% DV)
- Magnesium: 29mg (12% DV)
- Phosphorus: 252mg (20% DV)
Matt Pikosky, Ph.D., RD, vice president of nutrition marketing at the National Dairy Council, explains that sodium is particularly important because it helps the body retain fluids and supports hydration. Without the right balance of sodium, potassium, and other electrolytes, the body cannot effectively hold onto the water it consumes.
Water Content in Milk: A Hydration Boost
Like many fruits and vegetables, dairy milk is naturally rich in water. According to Melanie Betz, M.S., RD, CSR, FAND, and founder of The Kidney Dietitian, milk’s high water content contributes to hydration in a similar way to water itself. However, its added electrolytes give it an edge in keeping the body hydrated longer.
Carbohydrates and Hydration
Dairy milk contains lactose, a natural sugar that plays a role in hydration. Carbohydrates aid in fluid absorption by assisting electrolytes in carrying water into the bloodstream. Pikosky points out that the presence of carbohydrates slows digestion, leading to a more gradual release and absorption of water, making hydration more effective over time.
Can Plant-Based Milk Alternatives Offer the Same Hydration Benefits?
With the growing popularity of plant-based milks such as almond, oat, and soy, many wonder whether these alternatives can offer the same hydration benefits as dairy milk. The answer is complicated.
According to Pikosky, most plant-based milks do not match dairy milk’s natural balance of water, electrolytes, and macronutrients. Betz adds that plant-based options tend to have lower potassium and sugar levels, which may make them less effective at maintaining hydration.
For those avoiding dairy, fortified soy milk is the best alternative, as recognized by the Dietary Guidelines for Americans. When choosing plant-based milk, checking the nutrition label for electrolyte content can help determine its hydration potential.
Should You Drink Milk Instead of Water?
While milk is a great hydrating option, experts agree that water should remain the primary source of hydration. The Institute of Medicine recommends that young men (ages 19-30) consume about 3.7 liters (125 ounces) of fluid per day and women about 2.7 liters (91 ounces). If all of this came from 2% milk, it would amount to 1,342 to 1,952 calories—nearly an entire day’s worth of calories for some people.
However, milk can be particularly beneficial in specific situations, such as post-workout recovery. Pikosky recommends milk or chocolate milk as an effective sports drink alternative due to its combination of protein, carbohydrates, and electrolytes. Not only is it a more natural and budget-friendly option, but it also helps refuel muscles and rehydrate the body more effectively than water alone.
Studies suggest that milk may be just as hydrating as water due to its water content, electrolyte balance, and carbohydrate composition. However, water remains the best overall choice for hydration. That said, if you’re feeling extra parched—especially after an intense workout—a glass of milk can be a great alternative.
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