As coffee is one of the most popular drinks in the world, there has been many studies that look into its health effects. Studies have been conducted on just about everything, from how it impacts our immune system, to the risk of heart disease, and cancer risk. A new study, is looking into coffee's effects on kidney disease.
Studies have shown an association between the consumption of coffee and a possible protective effect on kidney function. In 2008, a study from Korea that involved 2600 women, showed that consumption of coffee was associated with a decreased risk of kidney disease, even in diabetic women. Bear in mind that population-based surveys are not enough to draw hard conclusions.
Consequently, a meta-analysis published in 2016 attempted to answer this question, in which it showed no association between coffee consumption and increased risk of kidney disease in male patients. Actually, it noted the possibility of a reduced risk of kidney disease in women who drink coffee.
Based on the aforementioned data, coffee appears to be harmless on male kidneys and beneficial to women's. Furthermore, the results of the above meta-analysis are similar to another study from the Pacific Coast of Nicaragua, where lower prevalence of chronic kidney disease in coffee growing villages has been recorded.
Speculation on why coffee might play this active role is still being studied, though it is believed that it is due to antioxidants present in coffee.
Coffee's Effect in People With Genetic Kidney Disease
In the past, scientific studies indicated that caffeine could increase the risk of growth of kidney cysts in patients with autosomal dominant polycystic kidney disease (PKD). However, more current clinical studies found that coffee consumption was not noted to be a risk factor for PKD progression.
Risk of Kidney Stones
Nevertheless, special situations where intake of coffee might need to be moderated still apply. Kidney stones are one such scenario. Oxolate stones in particular, one of the more common varieties of kidney stones, occurs due to regular coffee intake - with black tea being the other culprit.
Risk of Kidney Cancer
Evidence regarding coffee risk and cancer is quite mixed. Some studies indicate a reduced risk of renal cell carcinoma with coffee consumption. But this only appears to be true for caffeinated coffee only. Decaffeinated coffee consumption seemingly increases the risk of clear renal cell carcinoma subtype - a particular kind of kidney cancer. Still, more studies need to be conducted to better understand this potential link.
Indirect Effects of Coffee on Kidney Function
One of the biggest causes of kidney disease is high blood pressure (after diabetes). Evidence shows that drinking caffeinated coffee could cause a short-lasting increase in blood pressure, with the effects seemingly exaggerated in older patients and people who are not regular drinkers of coffee. An increase in blood pressure is also seen more frequently in people who already have a history of high blood pressure.
Due to the link between coffee intake and elevated blood pressure, concern about coffee's ability to cause damage to the kidneys is often raised. Still, there is evidence to the contrary. Data shows that as long as daily coffee consumption does not exceed 3 to 4 cups, with each 8 ounce cup containing 100-200mg of caffeine, there is no increase in risk of kidney disease in healthy young subjects.
Decaffeinated Coffee and Hypertension
Coffee has been found to increase the nervous system activity as well as blood pressure, independent of its caffeine content. So, the effect of increase in blood pressure is even seen with decaffeinated coffee, making it seem that there might be something other than caffeine in coffee, which could be contributing to blood pressure elevation.