Eating an alkaline diet got a big boost a few years ago when celebrities touted it as a way to stay slim and muscular. But, while there are health benefits to eating non-acidic foods, especially if you have kidney disease, that doesn't mean you should avoid acidic foods altogether.
If you're considering eating non-acidic foods, check with your doctor and make sure you aren't missing any essential vitamins and minerals.
Non-Acidic Fruits and Vegetables
When you focus on low acid foods, you are really looking for foods with a low-acid load. That means they produce a negative acid load response in your body. This is mostly fruits and vegetables.
Here are some vegetables that produce more of an alkaline response in your body, according to a May 2017 study in the Journal of Renal Nutrition, and an older, but still highly regarded study from October 2011 in the Journal of Environmental and Public Health:
- Brussels sprouts
Fruits, fruit juice and nuts that produce a negative acid load include:
- Apples and apple juice
- Black currants
- Grape juice
- Black currants
This list of least acidic fruits and vegetables is certainly not a complete list. Most fruits and vegetables when metabolized produce alkali, which neutralizes acid through the kidneys, according to the Journal of Renal Nutrition.
Read more: What Is an Alkaline Diet?
What Is the pH Scale?
The pH scale measures the acidity or alkalinity of a solution, according to Science Buddies. Scientists use a logarithmic scale to measure pH levels, based on 14, with 7 being the middle, or neutral. A solution that can produce, or donate, hydrogen ions is considered acidic, with a pH of 1-6.9. A solution that can accept hydrogen ions is considered alkaline, or base, with a pH higher than 7.
Pure water is neutral, neither acidic nor alkaline, Science Buddies says. But fluid produced in food can vary along the scale. Any food may measure acidic but may produce an alkaline reaction in your body. So if you're seeking a lower acid diet, you want to look for alkaline-producing foods.
The human body produces fluids that also vary along the pH scale, according to the Journal of Environmental and Public Health. Bile, for example, is typically 7.6 to 8.8 along the pH scale, so it's neutral to slightly alkaline. Your skin is slightly acidic, between 4.6 and 6.5. Urine ranges from 4.6 to 8, depending on what you eat, while gastric fluid, which breaks down protein, is 1.35 to 3.5, which means it's pretty acidic.
Why Low Acid?
The typical low-alkaline or non-acidic diet often specifies no meat, no dairy, no gluten and no sugar. There can be some health benefits to diets that cut out some of these acid-producing foods, especially for your kidneys, says the Polycistic Kidney Disease Foundation, specifically by reducing your risk of kidney stones. A review first published in 2012 in the Journal of Environmental and Public Health that is still frequently cited found that there are health benefits in focusing on foods that are more alkaline in the body.
There's no evidence that an alkaline diet improves bone health or prevents osteoporosis, the authors concluded. It may benefit your bones in other ways, however. The authors added that there is benefit to bone health in eating more fruits and vegetables in an alkaline diet.
The study said, "Increased fruits and vegetables ... may benefit bone health, reduce muscle wasting, as well as mitigate other chronic diseases such as hypertension and strokes." The authors added that eating foods that are alkaline in the body help to increase growth hormone, which in turn helps with heart, memory and cognitive health.
A November 2012 study published in the journal Osteoporosis International concluded that there is a small but significant increase in muscle mass for healthy women who eat a diet rich in alkaline-producing foods. Although protein is important for muscle mass, the study said, fruits and vegetables with potassium and magnesium are also important.
Fruits and Vegetables
Rather than focusing on low acidic foods and non-acidic fruits, nutritionists at the T. Colin Campbell Center for Nutrition Studies at Cornell University suggest choosing a diet rich in alkaline-producing foods like fruits and leafy green vegetables and limiting or eliminating foods that produce a higher acid load, like cheese, meat, chicken and fish.
So instead of focusing on changing your body's pH level, it's more important to focus on a healthy diet rich in vegetables, fruits, legumes and whole grains to maintain optimal bloodstream pH levels. You'll help your kidneys, too. In the May 2017 study in the Journal Renal Nutrition, the authors concluded, "Reducing the acid load of the diet offers an exciting new approach to treating patients with CKD (chronic kidney disease)." A 2016 study in the Iranian Journal of Kidney Diseases agreed that a more acidic diet helps to prevent chronic kidney disease.
The American Institute of Cancer Research agrees. Home test kits measuring the pH of your urine don't provide reliable information about the body's pH level. Instead, focus on eating a variety of fruits, vegetables, whole grains and beans, and keep to a minimum the amount of red meat and processed meats that you eat.
Read More: Top 10 Healthiest Fruits and Vegetables
If you've decided to focus on plant-based foods, you will probably decrease the total amount of acid neutralized by your kidneys, according to the May 2017 study in the Journal of Renal Nutrition. That's good for kidney health, even if you don't have chronic kidney disease.
Researchers in the study found that if soya protein replaces meat protein, the amount of ammonium excreted in the urine falls significantly, even in people without CKD. Ammonium is highly acidic. According to the study, a more vegetable-based diet alters the gut flora, which may increase the alkaline production in the gut. This diet may also help lower blood pressure, which can slow the progression of kidney disease.
There are some fruits and vegetables that do have a lower alkalizing effect on the body. Spinach, for example, can add acid to the body, the Journal of Renal Nutrition researchers found. So does beetroot and chard. Cranberries, prunes, plums and some berries increase acid secretion, according to the study. So if you're looking to lower the alkalizing effect of food, focus on the effect rather than least acidic fruits and vegetables.
Researchers said more studies need to be done on fruits and vegetables and acid absorption by the body. This absorption may also be affected by the cooking process, according to the study in the Journal of Renal Nutrition. So until more is learned, the authors suggest only limiting fruits and vegetables that are known to add acid secretion. So lentils, beans, chickpeas and almonds, which increase acid secretion slightly, are encouraged as a good alternative to animal protein.
- Journal of Renal Nutrition: "Reducing the Dietary Acid Load: How a More Alkaline Diet Benefits Patients With Chronic Kidney Disease"
- Journal of Environmental and Public Health: "The Alkaline Diet: Is There Evidence That an Alkaline pH Diet Benefits Health?"
- Osteoporosis International: "A Higher Alkaline Dietary Load Is Associated With Greater Indexes of Skeletal Muscle Mass in Women"
- American Institute for Cancer Research: "Alkaline Diets"
- T. Colin Campbell Center for Nutrition Studies: "The Myth of Alkalizing Your Body"
- Iranian Journal of Kidney Diseases: "Dietary Acid-Base Load and Risk of Chronic Kidney Disease in Adults: Tehran Lipid and Glucose Study"
- Baylor Medicine: "Not Just Another Celebrity Diet: Benefits of an Alkaline Diet"
- Science Buddies: "Acids, Bases and the pH Scale"
- Polycistic Kidney Disease Foundation: "The Alkaline Diet"