In today’s pop culture vernacular, it’s an insult to be called basic — the opposite of cool and trendsetting. But in the nutrition world, being basic, as in alkaline, is aspirational, with popular books, websites and celebrities all endorsing a pH approach to eating. There is some serious science to back this trend, so it is worth paying attention to, but (surprise, surprise) there is a lot of confusing misinformation and hyperbole out there, too.
The concept of the alkaline diet centers on the well-established fact that different foods affect our body’s pH balance differently. As a rule, fruits and vegetables promote alkalinity, whereas meats, dairy and grains have an acidic effect. It’s not the acid content of the food itself that matters here; it is the way the food impacts our pH once it is metabolized. For example, even though oranges and tomatoes are acidic foods, they have an alkaline impact on our bodies.
Let’s get one thing straight right away, though: The pH of our blood never varies much. Our kidneys and lungs work hard to keep that tightly regulated at about 7.4, because even a small variation in blood pH is life-threatening. So ignore statements such as the one I found on an influential TV doctor’s website, proclaiming that the “typical American diet is full of foods like meat and dairy products that tend to increase the acidity of your blood.” (Sigh.)
Although the acid-base balance of our blood is constant, the pH inside our cells has a somewhat broader range, from slightly acidic to slightly alkaline. Our cells function best when they are on the alkaline side, and the way you eat impacts that balance. In a 2012 review published in the Journal of Environmental and Public Health, researchers noted that alkaline diets lead to higher levels of magnesium in cells — a mineral that is required for many enzyme systems, as well as for activating vitamin D, for example. The study also points to documented benefits of an alkaline diet, including preservation of muscle mass with aging.
The pH of our urine varies widely, as our urinary tract is on the front line of keeping our bodies in acid-base balance. Animal protein, grains, soda, beer and sodium all produce high acid loads for our kidneys to process. That acid can be neutralized by the potassium and minerals from fruits and vegetables, but if we don’t get enough of those alkaline foods, our urine can wind up chronically acidic, which can contribute to kidney stones and necessitate that our bones’ stores of neutralizing minerals be continually tapped, ultimately depleting and weakening them.
But the acid-base equation is only part of the bone-health story, and research has been mixed as to how an alkaline diet affects our bones. Besides plenty of acid-balancing potassium and minerals needed to spare their stores, healthy bones also depend on adequate protein. Strict alkaline diets may limit protein-rich foods because of their acid effect, which is a negative for bone health. Focusing on boosting your produce consumption while getting enough protein appears to be the better path to take.
Although there is some solid science indicating that pH matters, many of the benefits touted by alkaline diet proponents, such as healthier bones, reduced risk of chronic disease and weight loss, can be directly traced to the well-known dietary advice to consume more colorful produce and vegetable protein and fewer fatty meats, sweets, refined carbs and sugary drinks. The alkaline diet may sound cutting-edge and innovative, but the most sensible versions boil down to the same advice found in the U.S. Dietary Guidelines.
If considering the pH impact of your food helps you focus on improving your eating habits, then go for it. But remember to keep it in perspective. Many of these plans categorize foods as good (alkaline) or bad (acidic) without taking into account overall nutritional balance. And there is always a risk in taking just a single factor into account when making food decisions. Going by acid-alkaline value alone (you can find a list on acidalkalinediet.com), you’d deem white bread better for you than shrimp, for example, and mushrooms on par with sugar. Clearly, the pH of a food does not tell the whole story.
Krieger is a registered dietitian, nutritionist and author. She blogs and offers a biweekly newsletter at elliekrieger.com. She also writes weekly Nourish recipes in The Washington Post’s Food section.