The balance of acidity and alkalinity in your body allows essential chemical reactions to take place in cells and tissues.

Not all parts of the body are equal, pH-wise: For example, the stomach, with its fluctuating digestive juices, is more acid than the brain or blood, which are slightly alkaline (at about 7.1 and 7.4, respectively). The balances are maintained via various proteins, minerals, and kidney and lung functions. In addition, everything you eat or drink affects pH balance, for good or for ill. Even breathing regulates pH: Inhaling brings alkaline oxygen into the system, and exhaling removes acidic carbon dioxide.

To function properly, cells need to be slightly alkaline; most Americans, however, suffer from an abundance of acidity. Stress, medications, illness, and highly strenuous exercise promote acid production; so do many of the foods favored in the typical Western diet. Fatty, high-protein fast foods like cheeseburgers and french fries trigger the stomach to secrete extra amounts of acidic digestive juices. Refined flour and sugar (in this instance, the bun and ketchup) reduce to acid compounds once they're metabolized. And that extra-large cola is extremely acidic. Considering that too much acidity is associated with many degenerative diseases, from colitis to rheumatoid arthritis, this "value meal" isn't such a bargain after all.

Buffer Breakdown
Age is also a contributing factor. "Acid-alkaline balance is relatively easy to maintain when we're young and our regulating mechanisms are in good working order," explains Lark. "But with each passing decade, starting in our 40s or even earlier, the efficiency of our buffering systems begins to decline." According to Lark, only 6 percent to 8 percent of the population produce naturally high alkaline levels well into old age; these people have excellent digestive function and lung capacity, and are more likely to be energized and healthy as the years go by.

To find out whether your system tends to be acid or alkaline, answer Lark's questionnaire (below) or self-test your saliva or urine using pH test paper. If you're troubled by over-acidity, rebalance your diet to include more alkaline foods.

"What a person eats can have a huge impact on pH," says Lark. Limit your intake of animal products, refined flours, and sugars, and put more alkaline vegetables on the menu.

Conversely, if you are overly alkaline ( very rare), focus on acidic foods. To stay your healthiest, choose whole foods in this group, rather than nutrient-poor white flour and sugar. You can fine-tune your grocery list further by knowing which items within each food category are relatively more acidic or alkaline.

As macrobiotic instructor and chef Cynthia Briscoe advises, "The acid-forming foods are not just refined carbohydrates like white flour and sugar, but dishes that give you concentrated amounts of protein and fat." She suggests reducing animal protein and increasing vegetable content by changing the format of a given meal. For example, instead of a grilled steak for dinner, prepare a salad topped with a few slices of the meat. 

You'll know when your natural balance has been restored because you'll start feeling better. Briscoe recalls a student who after three days of classes and eating balanced meals, told her, "I woke up today with a happy little feeling in the middle of my stomach that I hadn't felt for years!" Start thinking in terms of the acid-alkaline balance at mealtime, and see if that happy feeling is yours as well.


Are You Unbalanced?
To find out whether your system is generally alkaline or overly acid, you can have some fun running informal tests at home. One option is to use pHydrion litmus paper, which turns color when it comes in contact with saliva. For greatest accuracy, take the test immediately upon awakening. Tear off an inch of the paper and place it on your tongue for about 10 seconds, then check the results against the enclosed color chart. According to nutritionist Nancy Appleton, Ph.D., a reading between 6.6 and 7.0 indicates acid-alkaline balance while a reading below 6.6 indicates over-acidity and a need to eat more alkalizing foods.  Another option is plastic pH strips, which can be easier to read because the chemical reagent is affixed to the strips and tends not to bleed; find them at ph-ion.com.

When testing pH, keep in mind that readings can be affected by factors such as stress or any foods or liquids you've consumed. To offset these influences, test yourself several times over a week or two.

Because there are so many variables, Susan Lark, M.D., prefers to rely on personal health histories to identify over-acidity. The following yes/no questionnaire is condensed from Lark's book, The Chemistry of Success.

1. After consuming fried foods, red meat, fast food, colas, or desserts, I don't feel my best.
2. I eat refined foods like white flour and sugar regularly.
3. I regularly take aspirin, antibiotics, or unbuffered vitamin C.
4. Vigorous exercise often leaves me feeling exhausted.
5. After an hour of work at my desk, I'm mentally and physically tired.
6. My muscles often feel stiff and sore.
7. I have a history of osteoporosis, arthritis, or gout.
8. I've already had my 50th birthday.
9. I frequently catch a cold or the flu.
10. I am especially susceptible to sore throats, canker sores, or food allergies.

1. For breakfast, instead of orange juice, coffee, and a bagel for breakfast, have a slice of melon, herbal tea or a grain-based coffee substitute, and whole-grain toast.
2. At lunch, opt for bean or vegetable soup rather than tomato soup.
3. Add crunch and color to your salads with celery and sweet red peppers rather than tart cucumber and tomatoes. And instead of an acidic vinaigrette, prepare a dressing using tahini : In a medium bowl, combine 1/4 cup tahini (sesame paste), 1/4 cup water,  beating together with a fork. Stir in 1 tablespoon finely chopped parsley, and season to taste with freshly ground black pepper.
4. Choose fish--it's more alkalizing than red meat.
5. Iced ginger tea has the pleasing bite of a cola drink without the high acidity.
6. For a calcium fix, choose a small wedge of cheese (typically 5.0 to 6.1 pH) over yogurt (3.8 to 4.2). Yogurt with sugar-sweetened fruit may be even more acidic; once sugar is metabolized, it ends up as acid in your system.
7. To make a less acidic fruit salad, use guava, papaya, watermelon, cantaloupe, pear, banana, figs, and dates.
8. Raise a glass filled with a favorite beer instead of a tart wine to make a toast.
9. Avoid acidity triggers. Food sensitivities can bring about symptoms of over-acidity. Some common culprits include wheat, dairy, nuts, and seafood.