Q Does coffee drain calcium from your body and contribute to osteoporosis?
A Drinking a lot of coffee has been linked to an increased risk of fractures in some observational studies. However, other studies have found no such link.
"I wouldn't worry about it," said Dr Robert R. Recker, the director of the Osteoporosis Research Centre at Creighton University in Omaha, Nebraska.
Huge, national studies in different countries have found "no evidence of an increase of fractures due to coffee", said Dr Recker, an endocrinologist.
For instance, a population-based Swedish study, which included more than 61,000 women followed for roughly 20 years, found in 2013 that drinking four cups of coffee or more daily was associated with a tiny reduction of bone density, but it was not linked to an increased risk of fracture.
This year, a systematic review published in the journal Food And Chemical Toxicology concluded that even up to eight cups of coffee daily "is not associated with significant concern regarding the risk of fracture and fall", especially in healthy adults who get enough calcium.
The United States National Institutes of Health recommends that women aged 51 to 70 get 1,200mg a day of calcium, and men of the same age get 1,000mg.
Can drinking coffee lead to calcium loss?
It's true that as people increase their caffeine consumption, calcium in their urine increases too, said Professor Connie M. Weaver of Purdue University's department of nutrition science and an author of the previously mentioned systematic review of coffee.
However, the more calcium lost to urination, the more people will absorb from whatever sources of calcium they consume, said Prof Weaver, who is a paid scientific adviser to Pharmative, a supplement maker.
So the only coffee drinkers who need to worry about calcium they lose when they visit the restroom are those who don't get enough calcium in the first place.