Alkaline Diet: What to Know Before Trying It

By Sonya Collins
WebMD Feature

Reviewed by Louise Chang, MD

Trying out the latest diet is practically an American pastime. The more health benefits the diet supposedly provides, the better. We don't just want to lose weight; we want to cure arthritis, diabetes, and cancer, and slow the aging process, too. Some web sites touting the alkaline diet claim it does all these things and more.

Is it true? Here's what you need to know.

First, some background information. Our pH is the measure of exactly how acidic or alkaline we are. A pH of 0 is completely acidic, and a pH of 14 completely alkaline. A pH of 7 is neutral.

You don't just have one pH level. For example, the stomach has a pH ranging from 1.35-3.5. It must be acidic to aid in digestion. However, blood must always be slightly alkaline, with a pH of 7.35 to 7.45.

The theory of the alkaline diet is that eating certain foods can help maintain the body's ideal pH balance to improve overall health. But the body maintains its pH balance regardless of diet.

For instance, your diet may affect the pH level of your urine. But what you eat does not determine your blood's pH level.

What's in the Alkaline Diet

The alkaline diet is mostly vegetarian. In addition to fresh vegetables and some fresh fruits, alkaline-promoting foods include soy products and some nuts, grains, and legumes.

Web sites promoting the alkaline diet discourage eating acid-promoting foods, which include meat, fish, poultry, dairy products, processed foods, white sugar, white flour, and caffeine.

The alkaline diet is basically healthy, says Marjorie Nolan, RD, an American Dietetic Association spokeswoman.

"It's a diet of fresh fruits and vegetables, plenty of water, avoiding processed foods, coffee, and alcohol, which are all recommendations for a generally healthy diet anyway," Nolan says. "But our body regulates our pH between 7.35 and 7.45 no matter how we eat."

Potential Benefits

Diets that include a lot of animal protein can lower urine pH and raise the risk forkidney stones. So eating a diet rich in vegetables, as with an alkaline diet, can raise urine pH and lower the risk for kidney stones, says John Asplin, MD, a kidney specialist who is a fellow of the American Society of Nephrology.

Researchers have speculated that an alkaline diet might slow bone loss and muscle waste, increase growth hormone, make certain chronic diseases less likely, and ease low back pain. However, that hasn't been proven.

There is also no concrete evidence that an alkaline or vegetarian diet can prevent cancer. Some studies have shown that vegetarians have lower rates of cancer, particularly colon cancer, according to the American Cancer Society. But vegetarians often have other healthy habits, such as exercise and abstaining from drinking and smoking, so it is difficult to determine the effects of diet alone.

"Clinical studies have proved without a doubt that people who eat more fresh fruits and vegetables and hydrate properly do have lower rates of cancer and other diseases," Nolan tells WebMD, "but it probably has nothing to do with blood pH."