The Physicians Committee for Responsible Medicine claims milk does little to prevent osteoporosis.

WASHINGTON (CNN) -- Advocates of a strict vegetarian diet showed off an advertising campaign attacking some of the touted benefits of milk on Tuesday.

The Physicans Committee for Responsible Medicine, which promotes a diet free of animal products, launched the campaign at a news conference. The group endorses a "vegan" diet, which rejects even dairy products and eggs.

The group's advertising claims "milk does not protect from broken bones" and is "useless against bone breaks." The group also claims that the body does not absorb the calcium in milk at acceptable levels, doing little to help fight against osteoporosis. The ads will appear in the Washington area, in medical journals and newspapers and on Web sites.

"Milk does not protect against bone breaks," said Patricia Bertron, a spokeswoman for the Physicians Committee for Responsible Medicine. "And Americans have always been told to drink milk, yet more than 25 million Americans have osteoporosis."

Osteoporosis is a disease which makes bones fragile and more likely to break. It affects approximately 28 million Americans, 80 percent of whom are women. Americans suffer about 1.5 million fractures of the spine, hip, wrist and other bones each year due to osteoporosis, the group estimates.

To back up its claims, which contradict the opinions of public health officials and osteoporosis prevention organizations, the committee cites two major studies: One is from the 78,000-person, 12-year Harvard Nurses' Health Study, the other from Australia.

"The studies that we found quite clearly show that increased consumption of milk and dairy products does not protect against bone fractures," said Lauri Chonko, another member of the vegetarian group. "So we're not saying that calcium isn't important, but we're saying that milk is not going to help protect your bones."

A spokeswoman from the Milk Industry Federation called the new campaign "irresponsible" and an "incorrect reading of the science."

The Physicians Committee, which in the past has promoted a diet free of meat and animal proteins and has for years urged Americans to stop drinking milk, says it hopes to educate people that there are "other excellent sources of calcium."

While most nutrition experts agree that there are sources of calcium other than dairy products, they argue that Americans tend not to consume those foods in large amounts. Those other sources include fortified orange juice, leafy green vegetables, beans and calcium supplements.

"You need to emphasize getting calcium from other sources, but you also need to focus on the exercise, alcohol consumption, smoking, those are other factors that have been implicated in that," Chonko said.