While plain water is the gold standard for meeting hydration goals, warm beverages can also make significant contributions to your daily fluid intake. When consumed in moderate amounts, many warm drinks can provide hydration comparable to that of water.
1. Black or Green Tea
Caffeinated teas, such as black, green, white, and oolong, are produced from the flowering evergreen plant Camellia sinensis (L.). Kuntze. Due to their high water content, these teas can help you meet your daily hydration goals.
The diuretic effect of caffeine is often thought to cause dehydration. However, research indicates that moderate consumption of caffeinated tea does not lead to greater fluid loss than water when consumed in typical amounts, meaning warm tea can support hydration.
Results of a randomized controlled trial comparing black tea to water found no significant differences in hydration markers or fluid balance, indicating that standard tea intake provides hydration comparable to plain water.
2. Herbal Teas
Herbal teas, like peppermint, ginger, and chamomile, are inherently caffeine-free. Since herbal teas are produced from the leaves, flowers, and roots of many plants, rather than the Camellia sinensis plant, they are technically considered infusions, or tisanes.
While most research on hydration has focused on tea broadly, not just herbal teas, low-caffeine or caffeine-free teas, like herbal teas, have been shown to behave similarly to water after mild dehydration.
In a study on fluid balance, tea with low caffeine did not worsen hydration status compared to water, and fluid retention after drinking tea was not significantly different from that after drinking water, as measured 2 hours after ingestion.
3. Coffee
Like tea, black coffee is primarily composed of water and includes enough caffeine to increase urine output in some people. However, research suggests it has a minimal effect on overall hydration among people who consume it regularly in moderate amounts.
A controlled study on the effects of different caffeine doses from coffee on fluid balance concluded that higher caffeine levels (at least 537 milligrams of caffeine; about 4 to 5 strong cups) increased urine output and fluid loss, whereas lower to moderate levels (about 269 milligrams of caffeine; about 2 to 3 cups) did not disturb fluid balance relative to water.
Research comparing the effects of coffee consumption with water ingestion found no significant differences across a wide range of hydration markers in urine and blood samples, suggesting that moderate coffee consumption (about 7 ounces, or four 200-milliliter mugs) daily provides hydration similar to that of water in people who already regularly drink coffee.
4. Warm Milk
Since milk is primarily water, its volume can contribute to fluid intake and hydration, with limited evidence that it may help your body retain fluid better than plain water.
In a study using the Beverage Hydration Index (a measure of the relative hydration properties of beverages, with water as the standard), full-fat milk and skim milk showed higher index values than water, indicating that milk was retained in the body longer than plain water, based on urine output and fluid retention over several hours.
Research indicates that milk helps maintain hydration due to its sodium and potassium content, which are electrolytes known to aid in fluid retention, and its carbohydrates, which help slow gastric emptying and extend the hydration period.
Tips for Using Warm Beverages for Hydration
If you’re seeking the comfort of a warm beverage without concerns about caffeine or extra calories, consider drinking hot water with lemon, which can help keep your body hydrated while supporting a range of bodily processes.While warm beverages such as coffee and tea can contribute to your daily fluid intake, research suggests that alternating them with plain water throughout the day can help you stay properly hydrated and may even contribute to a longer lifespan.Avoid warm beverages that contain added sugars, syrups, or creams, which can offset their hydration benefits by contributing to health problems such as weight gain, type 2 diabetes, and heart disease.While caffeinated warm beverages can support hydration, limiting your total daily caffeine intake to 400 milligrams (about two to three 12-ounce cups of coffee) can help avoid adverse effects.
