It's a pitch Hollywood celebs love: that the alkaline diet – also known as the alkaline ash diet or alkaline acid diet – can help you lose weight and avoid problems like arthritis and cancer. The theory is that some foods, like meat, wheat, refined sugar, and processed foods, cause your body to produce acid, which is bad for you.
Eating specific foods that make your body more alkaline, on the other hand, can protect against those conditions as well as shed pounds. The alkaline diet really rocketed into the news when Victoria Beckham tweeted about an alkaline diet cookbook in January 2013.
Does It Work?
Maybe, but not for the reasons it claims.
First, a little chemistry: A pH level measures how acid or alkaline something is. A pH of 0 is totally acidic, while a pH of 14 is completely alkaline. A pH of 7 is neutral. Those levels vary throughout your body. Your blood is slightly alkaline, with a pH between 7.35 and 7.45. Your stomach is very acidic, with a pH of 3.5 or below, so it can break down food. And your urine changes, depending on what you eat – that's how your body keeps the level in your blood steady.
The alkaline diet claims to help your body maintain its blood pH level. In fact, nothing you eat is going to substantially change the pH of your blood. Your body works to keep that level constant.
But the foods you're supposed to eat on the alkaline diet are good for you: lots of fruits and vegetables, and lots of water. Avoiding sugar, alcohol, and processed foods is healthy weight-loss advice, too.
As to the other health claims, there's some early evidence that a diet low in acid-producing foods like animal protein (such as meat and cheese) and bread and high in fruits and veggies could help prevent kidney stones, keep bones and muscles strong, improve heart health and brain function, reduce low back pain, and lower risk for colon cancer and type 2 diabetes. But researchers aren't sure yet.
People who believe in the alkaline diet say that though acid-producing foods shift our pH balance for only a little while, if you keep shifting your blood pH over and over, you can cause long-lasting acidity.
What You Can and Can't Eat
Most fruits and vegetables, soybeans and tofu, and some nuts, seeds, and legumes are alkaline-promoting foods, so they're fair game.
Dairy, eggs, meat, most grains, and processed foods, like canned and packaged snacks and convenience foods, fall on the acid side and are not allowed.
Most books that tout the alkaline diet say you shouldn't have alcohol or caffeine, either.