Strictly speaking Ranitidine isn't an antacid. It is a RH inhibitor inhibiting production of stomach acid. Even more powerful are Proton Pump Imhibitors such as omeprazole which can turn off the supply of acid to the stomach.
An antacid just neutralises the acid. eg. Calcium Carbonate producing calcium chloride (harmless salt) and carbon dioxide that'll come up as a belch.
St5omach acid is required to absorb minerals. Insufficient acid in the stomach creates a condition known as hypochlorhydria and, because iron, calcium, zinc, selenium etc, are insufficiently absorbed can lead to problems of anaemia, osteoporosis etc.