https://www.livestrong.com/article/464884-does-caffeine-affect-the-absorption-of-vitamins-or-minerals/
Caffeine Vs. Vitamin D
In a collaborative study at Creighton University in Nebraska and the University of Miami, Florida, researchers showed that caffeine may interfere with vitamin D absorption. The results, published in the "Journal of Steroid Biochemistry and Molecular Biology," demonstrated that the higher the level of caffeine, the more it interfered with vitamin D absorption. The study suggested that caffeine did this by reducing the expression of vitamin D receptors on osteoblasts in the body -- the cells responsible for producing bone.
Caffeine Vs. Calcium
Caffeine can also interfere with the absorption of calcium. A study published in the journal "Osteoporosis International" showed that just a cup of coffee can slightly reduce calcium absorption in the body and increase its loss in urine due to its diuretic effect. Additionally, bone loss has been shown in people with low milk or low total calcium intake who drink 2 or more cups of coffee per day, according to a study of 205 postmenopausal women published in the "American Journal of Clinical Nutrition." And the results of a study in Norway, in which almost 20,000 women participated, suggested that women who drink 9 or more cups of coffee per day may be at risk of bone fracture. Another study in the "American Journal of Clinical Nutrition" even showed that bone mineral density may be reduced in older women who drink cola every day, compared with those who drink it less than once every month.