Grapevines, too, need their calcium, and they share it with humans through wine. Soil rich in calcium, magnesium, potassium, and sodium makes for healthy vines. A grape can contain 14 mg of calcium. (Compare that with its 4 mg of vitamin C.)
Thus, grape juice contains calcium, and wine contains even more after the wine-making process. A clay-filtration step can add calcium, as can a finishing with calcium bicarbonate to soften an overly acidic cru.
You can find 43 mg (between 1-4% DV) of calcium in a glass of wine. This is about half the amount found in a glass of Gerolsteiner mineral water. Since wine doesn’t contain any protein, however, it’s still not advisable to go pour yourself a bottle for dinner. Alas!
Forkaš, Ján, Technology and Biochemistry of Wine. New York: Gordon and Breach Science Publishers, 1988.
Puckette, Madeline, https//winefolly.com/review/wine-additives-explained/