8 Most Acidic Foods

For people with gastroesophageal reflux disease (GERD), acidic foods like tomatoes and citrus fruits can irritate the esophagus, leading to acid reflux.

These foods can also aggravate the bladder in those with interstitial cystitis (painful bladder syndrome).

What is pH?

The pH scale measures the acidity or alkalinity of a substance, ranging from 0 to 14. A pH of 0 is extremely acidic, 14 is very alkaline, and 7 is neutral.

1. Citrus Fruits

Citrus fruits, such as lemons, oranges, and grapefruit, have a pH between 3.0 and 4.3. Their tart flavor is due to citric acid, which contributes to their acidity. Sour fruits like lemons and limes can have even lower pH levels, down to 2.

Other acidic fruits include:

• Grapes: pH 2.8–3
• Plums: pH 2.8–3.4
• Strawberries: pH 3–3.9
• Blueberries: pH 3.1–3.3
• Raspberries: pH 3.2–4
• Apples: pH 3.3–4
• Peaches: pH 3.3–4
• Apricots: pH 3.3–4.8
• Pineapple: pH 3.2–4
• Prunes: pH 3.6–3.9

2. Tomatoes

Tomatoes are mildly acidic, with pH values ranging from 4.3 to 4.9, depending on ripeness. Unripe tomatoes have lower pH levels, while overripe ones are less acidic. Commercially canned tomatoes often have added citric acid or lemon juice, lowering their pH for better preservation. Tomato paste and juice can have pH values as low as 3.5 and 4.1, respectively. Ketchup, made with tomatoes, sugar, and vinegar, is also acidic.

3. Coffee

Coffee is acidic, with pH levels ranging from 4 for lighter roasts to 4.3 for darker roasts. It contains several acids, such as chlorogenic, quinic, and acetic acids. People with gastroesophageal reflux (GERD) may experience fewer symptoms when they switch from coffee to water.

4. Carbonated Drinks and Fruit Juices

Many carbonated drinks and fruit juices are acidic due to added preservatives and flavorings. Phosphoric acid in sodas helps preserve freshness, while citric acid adds a tart taste. Malic acid, found in apples and cherries, is often added to enhance flavors.

Examples of acidic beverages include:

• Lemon juice: pH 2.3
• Cranberry juice: pH 2.6
• Lemonade: pH 2.6
• Energy drinks: pH 3.1
• Other sodas: pH 3.1
• Sports drinks and flavored water: pH 3.3
• Pineapple juice: pH 3.4
• Flavored tea: pH 3.5
• Apple juice: pH 3.6
• Orange juice: pH 3.9

5. Fatty Foods

Though not highly acidic, fatty foods can worsen heartburn and acid reflux. They relax the lower esophageal sphincter, allowing stomach acid to flow back into the esophagus. Foods to avoid include full-fat dairy, fried foods, and fatty meats like bacon and sausage.

6. Yogurt

Yogurt is mildly acidic, with pH levels between 4 and 4.4. During fermentation, lactose is converted to lactic acid, lowering the pH. Despite its acidity, low-fat yogurt may help with acid reflux due to its probiotic content, which supports digestion. Some studies suggest that yogurt doesn’t cause enamel erosion like other acidic foods.

7. Alcohol

Alcoholic beverages are generally acidic due to the fermentation process. Whiskey and rum have pH values around 4.3 and 4.1, respectively, while wine ranges from 3.1 to 3.5, and beer is between 3.9 and 4.5.

8. Pickled Foods

Pickled foods, such as cucumbers, sauerkraut, and olives, are preserved in vinegar (acetic acid) and tend to have pH levels between 3.4 and 4.2.