Acidic foods, those with a pH of 4.6 or lower, can typically be part of a healthy, balanced diet, but they may cause discomfort for individuals with certain health issues.
For example, people with gastroesophageal reflux disease (GERD) may find that acidic foods like tomatoes and citrus fruits irritate the esophagus, leading to acid reflux.
Similarly, individuals with interstitial cystitis (painful bladder syndrome) may experience bladder irritation from these foods.
What is pH?
The pH scale measures how acidic or alkaline a substance is, ranging from 0 to 14. A pH of 0 is highly acidic, 14 is very alkaline, and 7 is neutral.
- Citrus Fruits
Citrus fruits such as lemons, oranges, and grapefruits have a pH between 3.0 and 4.3. Their tart taste comes from citric acid. 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
- Tomatoes
Tomatoes are mildly acidic, with a pH ranging from 4.3 to 4.9, depending on ripeness. Unripe tomatoes are more acidic, while overripe ones are less so. Commercially canned tomatoes may have added citric acid or lemon juice, lowering the pH for preservation. Tomato paste and juice have pH values as low as 3.5 and 4.1, respectively. Ketchup, made with tomatoes, sugar, and vinegar, is also acidic. - Coffee
Coffee is acidic, with pH levels ranging from 4 for lighter roasts to 4.3 for darker roasts. It contains various acids such as chlorogenic, quinic, and acetic acids. Those with GERD may experience fewer symptoms by switching from coffee to water. - Carbonated Drinks and Fruit Juices
Many carbonated beverages and fruit juices are acidic due to preservatives and flavorings. Phosphoric acid in sodas helps preserve freshness, while citric acid gives a tart flavor. Malic acid, found in apples and cherries, is commonly added for enhanced taste.
Examples of acidic drinks 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
- Fatty Foods
While 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 items, and fatty meats like bacon and sausage. - Yogurt
Yogurt is mildly acidic, with pH values 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 probiotics, which aid digestion. Some studies suggest yogurt doesn’t cause enamel erosion like other acidic foods. - Alcohol
Alcoholic drinks are generally acidic due to fermentation. Whiskey and rum have pH levels around 4.3 and 4.1, respectively. Wine ranges from 3.1 to 3.5, while beer has a pH between 3.9 and 4.5. - Pickled Foods
Pickled items such as cucumbers, sauerkraut, and olives are preserved in vinegar (acetic acid) and typically have pH levels between 3.4 and 4.2.
