NEW YORK -- Anheuser-Busch and MillerCoors, two of the world's biggest beer makers, are posting online what's inside bottles of Budweiser and Miller Lite after pressure from a food blogger.

The two companies on Thursday posted the ingredients of some of their most popular brands, and promised to be more transparent in the future. The announcements come a day after blogger Vani Hari posted a petition on FoodBabe.com to get major brewers to list what's in their beverages.

Anheuser-Busch posted the ingredients for its two top-selling brands on its website, tapintoyourbeer.com. It lists the same ingredients for Budweiser and Bud Light: Water, barley malt, rice, yeast and hops. The company, which also makes Beck's, Busch and Michelob beers, said it will list the ingredients for all of its other brands online "in the coming days." It's the first time Anheuser-Busch has detailed the ingredients of its beers.

MillerCoors posted the ingredients of Miller Lite, Coors Light and six other brands on its Facebook page. Most are made from water, barley malt, corn, yeast and hops, the company said.

"We also value transparency and are happy to comply with the request for additional information," MillerCoors said in a statement. The company says that consumers can call to ask what ingredients are in their beer, and it will also put more information online "in the days ahead." Its other brands in the U.S. include Peroni and Redd's Apple Ale.

Both companies said that they are not required to list ingredients, but are doing so voluntarily because customers want it.

The online petition, started Wednesday by Hari, now has more than 44,000 signatures.

Hari has become a powerful voice in the food industry. She is the same blogger who pushed sandwich chain Subway to remove an ingredient in its bread that's also used in yoga mats. Subway has since removed that ingredient.

She chose to petition beer makers because her husband drinks beer and she wants to be able to see what she is buying.

Representatives from Anheuser-Busch invited Hari and her family to visit its brewery in St. Louis and see how its beers are made. Hari said she is working with the company to figure out a time to visit.

Anheuser-Busch is part of the world's largest brewer, Belgium-based Anheuser-Busch InBev. MillerCoors is a joint venture owned by London-based SABMiller PLC and Denver-based Molson Coors Brewing Co.