Coffee is an extremely popular beverage, and you may be one that drinks it for the caffeine jolt. In fact, the U.S. Department of Health and Human Services notes that caffeine is the world's most widely consumed psychoactive substance, and eight out of 10 U.S. adult caffeine users are coffee drinkers. There are pros and cons to coffee consumption, but one important negative side effect to be aware of is nutrient depletion.
Coffee Intake and Overall Health
Coffee itself is not necessarily unhealthy, says Dr. Rob Van Dam of the Harvard School of Public Health. That's because coffee is not composed only of caffeine; it also contains numerous other compounds that benefit certain aspects of health. For example, Van Dam notes, coffee protects against Parkinson's disease, type 2 diabetes, liver cancer and liver cirrhosis. But the flip side of coffee and health is the effect of caffeine on nutrients.
Coffee and Calcium Loss
One coffee-related health concern is the loss of calcium. According to Columbia University Health Services, the caffeine in coffee contributes to calcium excretion, which could lead to osteoporosis later in life. Specifically, caffeine is a diuretic, meaning that it causes increased urination. This increased fluid loss results in increased calcium loss, too, as calcium is excreted in urine. For every 150 milligrams of caffeine consumed, about 5 milligrams of calcium are lost, notes Columbia University. While this might not sound like much, over many years this can add up to significant bone thinning. However, it's possible to off-set this calcium depletion by adding milk to your coffee; as little as 2 tablespoons of milk per cup can make up for the loss.
Coffee and Iron Depletion
Coffee also negatively affects your body's absorption of iron. If you consume coffee along with an iron-containing meal, your body's absorption of the iron will be reduced by as much as 50 percent, notes the Colorado State University Extension. This can be especially detrimental to women of child-bearing age, whose iron needs are greater than many other groups due to the blood loss of menstruation. The elderly are another group at risk for low iron and for whom coffee consumption could therefore prove problematic.
Excessive Intake and Magnesium
Coffee also depletes magnesium, notes the Massachusetts Institute of Technology, or MIT. Magnesium is a crucial mineral that works with calcium and vitamin D to facilitate the muscle contraction-relaxation response and aid in energy production; it also plays a key role in more than 300 enzymatic reactions in the body. Therefore, depletion due to coffee intake can be worrisome. MIT notes, however, that depletion results from "high coffee consumption." If you have questions or concerns about whether your coffee intake is excessive and might be depleting your body of magnesium or any other nutrients, speak to your doctor, who can advise you regarding an appropriate and safe level of coffee consumption for you. MedlinePlus.com notes that up to 300 milligrams of caffeine per day -- three 8-ounce cups of coffee -- is considered moderate and usually causes no detrimental consequences. Anything more than that, or roughly 10 cups of coffee per day, is considered excessive.