Is it harmful to drink coffee on an empty stomach?

There is a growing body of evidence suggesting the potential health benefits associated with coffee consumption including protection against type 2 diabetes, liver cancer and reduction in heart diseases. This is good news for those of us who like to start our day with a cup of coffee. However, the question of whether drinking coffee on an empty stomach is harmful often arises; even more so in light of intermittent fasting.

The effects of drinking coffee on an empty stomach can vary from person to person. Some may experience discomfort or digestive issues, while others may not notice any adverse effects. Factors such as sensitivity to caffeine, overall health, and metabolism play a role in determining the impact.

One concern is that coffee increases the production of stomach acid leading to symptoms like acid reflux, heartburn or gastritis. While most data are not in favour of a direct effect of coffee on acid reflux (which is rather a combined effect to other risk factors such as obesity and a poor diet), those who already have gastrointestinal issues or a sensitive stomach may be more prone to experiencing these symptoms. Therefore, it is advisable to have breakfast or a light snack before having that cup of coffee especially for those who are already experiencing gastrointestinal symptoms.

Coffee consumption may also interfere with certain nutrient absorption such as iron. Polyphenol compounds in coffee such as tannins, inhibit the absorption of iron making it less bioavailable; reducing the amount absorbed by our body. In other words, for those who are anaemic or have an iron deficiency, it is best to avoid coffee at mealtimes and save that cup of coffee for at least an hour after meal.

Besides keeping us awake, caffeine in coffee is also known for its diuretic effect, increasing urine production. Some may be concerned if caffeine consumption can lead to dehydration. It is unlikely, as most research suggest that the fluid in coffee and other caffeinated beverages can balance the diuretic effect of typical caffeine levels. Nevertheless, if it still concerns you, hydrate with a glass of water before reaching for your cup of coffee.