Coffee, the second-most widely traded commodity worldwide after oil, is derived from two main species: the arabica tree, which grows at 4,000- to 6,000-foot altitudes and produces superior beans; and the robusta tree, which grows at lower altitudes and produces poor-quality beans. Regardless of the bean's flavor, coffee exerts numerous physiological effects, some of which may include nutrient depletion.
B-complex vitamins may be depleted by coffee consumption, according to a study published in the September 2008 issue of the journal "Clinical Chemistry." In the study of more than 10,000 healthy, middle-aged men and women, higher levels of coffee consumption were associated with lower blood levels of the B-complex vitamins B-6, B-2 and folic acid. Those who drank four or more cups per day showed 14 percent, 5.5 percent and 11.7 percent lower levels of the vitamins, respectively. Additionally, lower B-vitamin levels correlated with 6.8 percent higher levels of homocysteine, an inflammatory molecule associated with increased risk for heart disease. Researchers concluded that coffee consumption depleted surplus B-vitamins at a greater rate than other vitamins present at lower levels.
Coffee's laxative effects may deplete vitamins and minerals, according to the University of Florida Institute of Food and Agricultural Sciences Extension. It does this by promoting fluid loss, which draws minerals out along with fluids to maintain proper concentrations in the body. Laxatives also speed the transit time of food in the intestinal tract, allowing less time for vitamins and minerals to be absorbed.
Coffee acts as a diuretic, promoting production of urine, which depletes the body of water, vitamins and minerals. Caffeine elevates urine volume by as much as 30 percent for a few hours after you consume it, according to Joyce H. Lowinson, coeditor of "Substance Abuse: A Comprehensive Textbook." In particular, calcium loss is increased with coffee consumption, which may result in a calcium imbalance leading to increased risk for low bone density and osteoporosis. Increased calcium filtration by the kidneys in combination with naturally occurring oxalate compounds in coffee can also promote calcium oxalate kidney stone formation, according to a study published in the 2007 issue of the journal "Roczniki Panstwowego Zakladu Higieny." In the study of kidney stone patients, researchers noted that 80 to 85 percent of the oxalate in their diets was from coffee and tea.
Acids in coffee lead to calcium depletion and bone loss, according to Dr. Susan E. Brown, author of the book "Better Bones, Better Body." Coffee is among the more acid-forming foods and causes calcium to be drawn from your bones and teeth to neutralize the acidic effects. This occurs so that chemical processes, which require specific -- usually alkaline -- pH conditions, can function.
Phytonutrient research has shown coffee to provide some potential health benefits that may help balance its nutrient-depleting effects and improve its reputation among health experts, notes the Harvard Medical School Family Health Guide. Phenolic antioxidants in coffee are preserved by up to 90 percent through the roasting process, according to a study published in the September 2011 issue of the "Journal of Dietary Supplements." Also, coffee drinkers experience less risk for developing liver cancer, diabetes and gallstones compared to nondrinkers.
- Clinical Chemistry: Coffee Consumption and Circulating B-vitamins in Healthy Middle-Aged Men and Women
- Substance Abuse: A Comprehensive Textbook; Joyce H. Lowinson, Pedro Ruiz, Robert B. Millman and John G. Langrod
- Roczniki Panstwowego Zakladu Higieny: Tea and Coffee as the Main Sources of Oxalate in Diets of Patients With Kidney Oxalate Stones
- Better Bones, Better Body; Susan E. Brown
- Harvard Medical School Family Health Guide: Coffee's Health Benefits
- Journal of Dietary Supplements: Investigation of Optimum Roasting Conditions to Obtain Possible Health Benefit Supplement, Antioxidants from Coffee Beans
Tracey Roizman, DC is a writer and speaker on natural and preventive health care and a practicing chiropractor. She also holds a B.S. in nutritional biochemistry.