If you have gastrointestinal issues like acid reflux or GERD, your doctor may recommend eating low-acid foods, which can help keep acid reflux at bay.
Even if you're not managing a specific health condition, many low-acid foods are considered healthy picks (as they're primarily fruits and vegetables) and can be valuable to your daily diet.
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While there are health benefits to eating non-acidic foods, especially if you have GERD or kidney disease, that doesn't mean you should avoid acidic foods altogether. A food's pH value will determine whether a food is acidic or non-acidic (neutral or more alkaline) and where it lies within the spectrum.
What Is the pH Scale?
The pH scale measures the acidity or alkalinity of a solution, according to the U.S. General Survey (USGS). Scientists use a logarithmic scale to measure pH levels, which generally range from 0 to 14.
- Basic/Alkaline: A pH of more than 7 indicates that the subject is basic.
- Acidic: A pH of less than 7 indicates that the subject is acidic. The closer to 0, the more acidic.
- Neutral: A pH of 7 indicates that the subject is neutral.
While pure water is neutral, neither acidic nor basic, the 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 October 2011 research in 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 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.
Low-acid foods just happen to be mostly fruits and vegetables. And a food’s pH may give you a good indication of its acidity. But there are exceptions: Lemon has a pH closer to 2 (acidic) yet has buffering (alkaline-forming) properties, per an August 2019 review in Nefrologia.
Don't get confused: Low-acid foods will still fall on the "acidic" side of the pH scale, with the pH value of 4.6 dividing low from high-acid foods. The greater the pH number, the less acidic the fruit, per Oklahoma State University.
Some examples of low-acid fruits include, per Oklahoma State University:
- Persimmons (pH 5.4-5.8)
- Cantaloupe (pH 6.17-7.13)
- Olives, black (pH 6.0-6.5)
- Honeydew melon (pH 6.3-6.7)
- Dates (pH 6.3-6.6)
- Papaya (pH 5.2-5.7)
- Watermelon (pH 5.2-5.8)
- Figs, Calamyrna (pH 4.6)
- Bananas (pH 4.5-5.2)
Some examples of low-acid vegetables include, per Oklahoma State University:
- Asparagus buds (pH 6.7)
- Mushrooms, cooked (pH 6.2)
- Brussels sprouts (pH 6-6.3)
- Corn (pH 6-7.50)
- Carrots (pH 4.9-5.2)
- Radishes (pH 5.8-6.5)
- Celery (pH 5.7-6)
- Artichoke, hearts of palm (pH 5.7-6)
- String beans (pH 4.6)
- Cauliflower (pH 5.6)
- Spinach, cooked (pH 6.6-7.2)
- Eggplant (pH 4.5-5.3)
- Okra, cooked (pH 5.5-6.4)
- Potatoes (pH 6.1)
- Parsnip (pH 5.3)
- Cabbage (pH 5.2-6)
- Yellow Squash (pH 5.8-6)
- Cucumbers (pH 5.1-5.7)
If you are considering a low-acid diet, check with your doctor or consult with a dietitian to make sure you aren't missing any essential vitamins and minerals.
There is no conclusive scientific evidence to support the central claim of the alkaline diet, as neither food nor drink can change your blood's tightly controlled pH, according to a June 2016 review in BMJ.
However, current studies support cutting back on some of those acid-producing foods (i.e. red meats) while filling your diet with more veggies. In fact, decreasing animal meat in favor of more fruits and vegetables helps reduce urine acidity, a culprit in promoting kidney stones, per the National Kidney Foundation. And a May 2016 study in the Iranian Journal of Kidney Diseases suggests that a low-acid diet is tied to a lower risk of chronic kidney disease.
Emphasizing more vegetable protein in lieu of red meat may even help manage heartburn symptoms and issues related to GERD. Vegetable proteins are associated with fewer incidents of acid reflux within the first hour after eating, according to an April 2018 study in Gastroenterology Research and Practice.
"High-fiber food helps with the movement of contents in the stomach through the digestive tract," Madathupalayam Madhankumar, MD, a gastro surgeon, says. "The food which is stuck in the stomach for a long time causes acid generation and pressure on the esophageal sphincter, which will result in acid reflux."
Lemon juice, garlic, and onion are common GERD trigger foods. So if you're managing GERD, swap out the lemon juice for lemon zest and simply omit the onion and garlic.
Is a Low-Acid Diet Right for You?
Low-acid diets may be necessary for GERD treatment. As previously mentioned, highly acidic foods — in addition to spicy foods, caffeinated foods and drinks and alcohol — can irritate the throat and esophageal tissue.
GERD can lead to Barrett's esophagus, a precancerous condition, according to Memorial Sloan Kettering Cancer Center. Only a small percentage of people with Barrett's esophagus end up with esophageal cancer.
Unless it is medically advised, you don't have to worry about determining the acidity of every single food. Most people don't need to be so pH-specific. Instead of becoming pH-obsessed, it's more important to focus on a healthy diet rich in vegetables, fruits, legumes and whole grains.
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.
- 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?"
- 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"
- Science Buddies: "Acids, Bases and the pH Scale"
- Clemson University: "pH Values of Common Foods and Nutrients"
- Nefrologia: "Dietary Acid Load: Mechanisms and Evidence of Its Health Repercussions
- BMJ: "Systematic Review of the Association Between Dietary Acid Load, Alkaline Water and Cancer
- National Kidney Foundation: "Kidney Stone Diet and Prevention"
- Gastroenterology Research and Practice: "Vegetal and Animal Food Proteins Have a Different Impact in the First Postprandial Hour of Impedance-pH Analysis in Patients with Heartburn
- Journal of Diabetes Investigations: "Lower Vegetable Protein Intake and Higher Dietary Acid Load Associated with Lower Carbohydrate Intake are Risk Factors for Metabolic Syndrome in Patients with Type 2 Diabetes: Post-hoc Analysis of a Cross-sectional Study"
- Memorial Sloan Kettering Cancer Center: "What I Should Know About Barrett's Espophagus and Risk for Esophageal Cancer"
- Nutrients: "The Potential for Plant-Based Diets to Promote Health Among Blacks Living in the United States"
- USGS: "pH Scale"
- Oklahoma State University: "The Importance of Food pH in Commercial Canning Operations"