Guideline to drink 8 glasses of water daily is a myth, study says

CAMBRIDGE, Mass. — Eight 8-ounce glasses of water a day keeps the doctor away — or does it?

Researchers out of Harvard revealed it may be best to forget everything we've always known about proper hydration, according to a new report in the Harvard Health Letter. In fact, the commonly accepted guideline was never based on scientific evidence and may actually be harmful to some, according to the study.

The first revelation — the optimal water target is actually 30 to 50 ounces a day, or about four to six glasses instead of eight ounces, researchers said. Additionally, if water isn't really your jam, there are other ways to get your daily fluids.

"It's really about fluids in general. Doesn't necessarily have to be water," Dr. Sharmeela Saha told CBS News. "Lettuce, spinach, fruits in general, soups ... Those are all things that are going to have a lot of water in them as well."

One surprising food group that's great for hydration: meat, which can contain up to 60 percent water, according to WebMD. Hamburger and chicken breast are both excellent ways to meet your daily fluid goals.

When it comes down to it, however, water still stands alone as the single best way to hydrate, researchers said. Listen to your body when it tells you to reach for that glass.

"There's been a real water revolution in this country. Water is non-caloric, it plumps up your skin and it hydrates your muscles," Dr. Kathleen Zelman told WebMD. "Water is non-caloric, it plumps up your skin and it hydrates your muscles. Water is the staff of life, and now it's everywhere."

Water flushes your body of toxins, carries nutrients to cells and keeps your ears, nose and throat healthy, according to the Mayo Clinic.

Researchers noted that while it's crucial to stay hydrated — especially when temperatures rise during the summer — it's best to do so gradually throughout the day instead of gulping down a large amount of water all at once.