Calcium oxalate kidney stones are the most common type of kidney stone. While oxalate is produced by the liver, it can also be obtained through certain foods, such as peanut butter. The risk of kidney stones may be higher for peanut butter lovers who also have low fluid intake, as dehydration is a main contributor to the development of kidney stones. While anyone can be affected, kidney stones are more often seen in men than women. People with obesity, recurrent urinary tract infections, and those with a family medical history of kidney stones may also be at increased risk.
While rare, eating high-oxalate foods like peanut butter in excess may also make a person more susceptible to kidney damage, according to a 2014 case report published in Kidney Research and Clinical Practice. A man in his mid-40s was diagnosed with peanut-induced oxalate nephropathy that resulted in acute kidney failure after arriving at the hospital with chronic diarrhea and vomiting. While the man did have various other health conditions, his kidneys had been in good health up until two months prior. In addition to taking a variety of medications and drinking an excess of alcohol, the patient had eaten only peanuts during the five days before he was hospitalized — specifically, upwards of 130 grams of peanuts daily. The researchers determined that overconsumption of peanuts and alcohol could potentially contribute to kidney failure.