Two studies have provided troubling news for the millions of Americans who spend money on daily multivitamins, suggesting they do not work as advertised, the Associated Press reported.

The two new studies provided evidence that the vitamins did not help men with aging brains or survivors of heart attacks. Government agencies have previously cautioned against taking vitamin supplements as a substitute for diet nutrients and the studies seem to back that up.

Americans that rely on multivitamins may spend in the billions of dollars on these pills, which are advertised as a pill substitute for various dietary nutrients. While they are meant to make up for certain deficiencies, the studies, published in the journal Annals of Internal Medicine, suggest they may not really do so.

"Evidence is sufficient to advise against routine supplementation," read an editorial piece accompanying the study.

Use of these multivitamins does not seem to be close to going away, said Dr. Howard Sesso of Brigham and Women's Hospital in Boston. About a third of U.S. adults take daily multivitamins and that figure increases in adults over the age of 50.

"For better or for worse, supplementation's not going to go away," he said. "[But] there's no substitute for preaching a healthy diet and good behaviors."

According to the Wall Street Journal, vitamin industry groups were critical of the studies and their accompanying editorial.

"It's no secret that many consumers in this country don't get the recommended nutrients from their diet alone, and multivitamin and mineral supplements are an affordable alternative," John Shaw, executive director of the Natural Products Association, said.

The debate remains very much alive, with the vitamin industry pointing to studies that support their claims and scientists trying to prove them wrong.

"We're not taking care of patients with nutritional deficiency. I've never seen a patient with scurvy or beriberi," Gervasio Lamas, a Columbia University cardiologist who led one of the Annals studies told the WSJ. "If you're a healthy person trying to stay healthy, the money is in stopping smoking, exercising, losing weight."