Food Affecting Blood pH
The big problem with the claims made by alkaline diet proponents is that they’re based on a misunderstanding of pH and how the body regulates blood pH. The relative alkalinity of the foods you eat doesn’t generally affect the alkalinity or acidity of your blood.
Acids are continuously being produced in the body during normal metabolic processes, but they don’t influence overall bodily pH in healthy individuals. Your body works hard to keep that 7.35–7.45 blood pH range, which is slightly on the alkaline side. If there’s too much acid or base in your system, built-in physiological buffers get rid of it through your urine.
Changing your diet might change the pH of your saliva or urine, but it’s practically impossible to affect the pH of your blood by what you eat. The only times that blood pH is affected is in the case of an acid-base disorder such as advanced stages of shock, diabetic ketoacidosis, or kidney failure — all of which are medical emergencies and not the result of not eating enough alkaline foods.
Focusing on the Wrong Benefits
Not only does the alkaline diet theory misunderstand the mechanisms through which your body regulates its pH, but the narrow focus on this one attribute of plant-based foods ignores the many benefits of plant-based eating that are actually backed up by science. A whole food, plant-based diet supplies an abundance of powerful antioxidants, fiber, and a rainbow of health-promoting phytochemicals. The alkaline diet’s health benefits are real, but they likely have little to do with pH.
Confusing and Restrictive
With a focus mostly on pH and choosing the most alkaline foods, there’s a risk of dietary restriction to the point of nutrient deficiency. It’s easy to get confused about what you are and aren’t supposed to eat, as there’s a lack of consistency in the recommendations, which vary widely. Some lists, for example, say that mushrooms are highly acidic, while others tell us that they are alkalizing.
Little to No Scientific Backing
Mst problematic of all, there’s minimal scientific evidence to support the alkaline diet’s biggest claims around diet alkalinity protecting against chronic disease or affecting blood pH.
One 2010 study found that low urine pH predicted neither low bone density nor bone fractures, while another from the same year discovered no correlation between dietary acid load and bone mineral density in older women. A 2011 study found no correlation between dietary acid load and lower bone density, except possibly in older men.
And a 2016 review of over 8,000 published articles relating to dietary pH and cancer found a single clinical trial on the topic. This trial found no relationship between the acid load of the diet and bladder cancer. The researchers concluded, “Despite the promotion of the alkaline diet and alkaline water by the media and salespeople, there is almost no actual research to either support or disprove these ideas.”
The Bottom Line
The alkaline diet, which focuses on pH balance, is a popular diet with many adherents and proponents. It is inherently whole food, plant-based, which can be great, and it’s been shown to be helpful for chronic kidney disease. But beyond that, there’s little to no scientific evidence to support its other health claims. In fact, it’s likely that its benefits have more to do with all of the known advantages that come with a whole food, plant-based diet that steers clear of added sugars, highly processed foods, and animal products.