Common Acidic Foods

Acidic foods should comprise 20 to 25 percent of the ideal diet, according to Ruthann Russo in "The Raw Food Lifestyle." Acidic foods contain little oxygen, which led Nobel Prize winner Otto Warburg to implicate them as a cause of cancer. Warburg supported this argument by demonstrating that cancerous cells thrive without oxygen, which won him the Nobel Prize. Accordingly, Warburg and other dietitians urge people to limit the consumption of acidic foods.

Moderately Acidic Foods

Meat, poultry and fish are innately acidic, but become more acidic when cooked. Corn, grains, nuts and beans are also acidic, but acidity greatly decreases in nuts and beans when they sprout. Tea and coffee are also acidic, although mineralized water can help to neutralize them. Fruits such as plums, prunes, cranberries, tomatoes and derivatives are acidic, as well. Moderate intake of acidic fruits or counterbalance them with alkaline fruit, such as bananas and oranges.

Very Acidic Foods

Some foods are highly acidic and can cause health problems such as acid reflux-related disorders in some individuals when eaten immoderately. Eggs, gravy, broth and organ meats are examples of highly acidic foods that appear as dietary staples. Common snacks and additives that contain a low pH include yogurt, buttermilk, sour cream and fermented foods -- including cheese and alcoholic beverages.

Contributors to Acidity

There are several contributors to acidity, the primary being sugar. Adding sugar to any food, especially in the form of glucose, sharply lowers its pH. This exacerbates the acidity of foods such as coffee and tea, which typically include sugar. Moreover, soft water, or water that has a low mineral content, tends to be more acidic. As a result, foods containing soft water are more likely to have a low pH. B complex vitamins contribute to acidic environments throughout the digestive tract. Finally probiotic bacteria create acidic environments in the stomach and intestines. Bearing these facts in mind, dangerously acidic foods can be easily identified, such as ketchup made with real tomatoes, as it also contains sugar, or sweetened yogurt.