Nutrition expert Dr. Edwina Raj confirmed that coffee rarely leads to dehydration, despite the common belief that it has a diuretic effect.
She explained that studies have shown caffeine to be the primary agent responsible for the diuretic effect, as it increases blood flow to the kidneys, thus enhancing glomerular filtration, the process by which fluids are filtered from the blood into the renal tubules to form urine. Caffeine also reduces water reabsorption within these tubules.
She added that coffee may indeed slightly increase fluid excretion, but this does not usually lead to dehydration, because the water in coffee often compensates for the amount of fluid lost with urine.
She pointed out that the real risk of dehydration arises when several factors combine, such as near-total reliance on coffee as a source of fluids throughout the day, exposure to high temperatures, and regular physical activity. Additionally, some people are more sensitive to caffeine, which can cause dehydration symptoms to appear more quickly.
According to the expert, the most prominent signs of dehydration include feeling thirsty, dry mouth, headache, dizziness, fatigue, in addition to a decrease in the amount of urine and an increase in its dark color.
Dr. Edwina Raj advised drinking coffee in moderation and making sure to drink enough water, noting that drinking a small glass of water after a cup of coffee is a healthy habit that helps maintain fluid balance in the body.
