There are so many diets out there it’s tough to keep count. Most of them have the end goal of weight loss—though most of them aren’t ultimately effective or sustainable in achieving that. One of the most talked about diets this year, the alkaline diet, doesn’t necessarily focus on dropping pounds; rather, its alleged purpose is to reduce disease risk. The premise is that by eating foods that promote an alkaline pH in the body, you can optimize your pH and supposedly rid yourself of all the health woes brought on by an acidic, Western diet. That includes everything from cancer to obesity.
Does it work? Experts are extremely skeptical, but it’s not a total throwaway. There are some ways an alkaline diet can benefit your health—just probably not in the way it’s being advertised.
As you may remember from high school chemistry class, pH is a measure of how acidic or basic a substance is. Zero to 6.9 is acidic, 7 is neutral, and anything above that (up to 14) is basic. Basic and alkaline are synonyms. The pH of a healthy human’s blood is a little bit alkaline, at 7.4. The pH of stomach acid is naturally much lower, usually 3.5 or below.
Lauri Wright, Ph.D., R.D., L.D., assistant professor of nutrition at the University of South Florida, explains that the theory behind the alkaline diet is that when we metabolize food, we leave an "ash," or by-products, that are either acidic or alkaline. "The alkaline diet proponents say that acidic ash is unhealthy." But that's not clearly the case.
“Whether a food is considered to be acidic or alkaline depends on its overall effect on the body, or specifically its effect on urinary acid excretion,” not on whether it's acidic or basic to begin with, Lisa Cimperman, M.S., R.D.N., L.D., a clinical dietitian at University Hospitals Cleveland Medical Center and spokesperson for the Academy of Nutrition and Dietetics, tells SELF. For example, lemons are acidic foods with a pH of 2. But they are broken down into an alkaline substance in our bodies and give our urine a basic pH, so they're considered alkaline according to the diet's guidelines.
The alkalinity is measured along the PRAL scale, which stands for the potential renal acid load, aka how acidic they make your pee. Foods that have a negative PRAL score are considered alkaline. This includes lemons and most other fruits and vegetables. Foods with a positive score are considered acidic or acid-forming—this includes grains, animal proteins, and dairy foods, Cimperman explains.
Eating different foods on the PRAL scale may change the pH of your urine, but urine pH changes quickly and easily, is influenced by many factors, and “is a very poor indicator of body pH or health,” says Wright. Certain foods may also impact urine pH differently when combined with other foods, adds Cimperman, making a single food’s PRAL score irrelevant.
The alkaline diet's central claim that acidic foods have a negative impact on blood pH doesn't hold up. “The food we eat absolutely, unequivocally does NOT alter the pH balance of our blood,” says Cimperman. “Blood pH is tightly regulated by the lungs and kidneys. Abnormal blood pH is associated with severe and critical illnesses.” Basically, if your blood pH were “off,” you’d be really sick and probably in the hospital or on your way there.
One of the biggest claims of the alkaline diet is that it can prevent cancer cells from growing and multiplying. Both Cimperman and Wright say that there’s no scientific proof that cancer cells grow more when we eat acid-producing foods. There’s also no evidence saying that they don’t, so more research is definitely necessary to make a conclusion one way or the other. There’s all kinds of research that shows the myriad benefits of eating more fruits and vegetables. Ramping up your intake of these foods will make you healthier overall and likely reduce disease risk thanks to all the nutrients they pack. But the whole pH thing may or may not have anything to do with it.
“This type of diet is mostly plant-based, so it is healthy for cardiovascular health and weight,” Dana Hunnes, Ph.D., M.P.H., R.D., senior dietician at UCLA Medical Center and adjunct assistant professor at the Fielding School of Public Health, tells SELF. “It provides a lot of potassium, magnesium, and other trace vitamins and minerals that our bodies need.” A diet high in fruits and veggies is always a good idea. An alkaline diet will also be low in sodium, sugar, and fat—“inherently, there is nothing wrong with that!” she says.
The problem is that anytime you’re eliminating entire foods groups, you need to be cautious about getting the right nutrients elsewhere. “[The diet] excludes dairy, eggs, meat, and most grains,” Cimperman points out. Eggs are a good source of lean protein, among other vitamins. Lean meats can certainly be a part of a healthy, balanced diet and provide things like protein, iron, and B vitamins. And whole grains are an important source of fiber and B vitamins, she adds. “So bottom line, it can be nutritionally complete, but will take careful effort and planning. Also, people may be unnecessarily cutting out foods that they enjoy.”
Cutting out certain food groups will likely lead to weight loss—if that’s your goal—but you need to make sure you’re still getting the right macronutrients. “If you are trying to lose weight, you still want to make sure you’re eating enough calories and plant-based protein to maintain muscle mass while encouraging loss of fat mass,” says Hunnes. Also, this type of diet may not be sustainable for everyone, which means you may just gain the weight back when you start eating off-limits foods again. “If someone isn’t willing to adopt essentially a vegetarian/vegan lifestyle, it’s probably not the solution for them,” says Cimperman.
Eating less processed food, sodium, and added sugar, and eating more fruits, veggies, and legumes, is a pretty good way to boost health. But if you like eating dairy and lean meat as part of a balanced diet, you don’t need to eliminate these foods from your life for fear of how it alters your body chemistry. (Not to mention, whole grains are an important part of a healthy diet, and most experts would not recommend cutting them completely.) If you’re concerned about your diet and are looking for specific changes you can make to reduce disease risk, speak with a registered dietitian to come up with a plan that works for you and is sustainable.
