By Andrew Curry, Writer 
People drank the stuff (alcohol) for the same reasons primates ate fermented fruit: because it [made them feel good and because] it was good for them. Yeasts produce ethanol as a form of chemical warfare–it’s toxic to other microbes that compete with them for sugar inside a fruit. That anti-microbial effect benefits the drinker. It explains why beer, wine, and other fermented beverages were, at least until the rise of modern sanitation, often healthier than drinking water.
What’s more, in fermenting sugar, yeast make more than ethanol. They produce all kinds of nutrients, including such B vitamins as folic acid, niacin, thiamine, and riboflavin. Those nutrients would have been more present in ancient brews than in our modern filtered and pasteurized varieties. In the ancient Near East at least, beer was a sort of enriched liquid bread, providing calories, hydration, and essential vitamins.
 National Geographic, Feb 2017, p. 45