Classifying The Acidification Potential of Foods

Tuesday, October 20, 2009  |  4 Comments

by Christopher Vasey

Christopher Vasey, N.D

Not all foods are uniformly alkalizing, acidifying, or acid. For example, both rice and millet are acidifying foods, but millet is much more acidifying than rice. To fine-tune an optimal diet, we need to refine these classifications.


The classification of fresh fruits is valid only for those who are unable to metabolize acids properly. For everyone else, all fruits have an alkalizing effect.

Because a fruit's acidifying properties depend on how ripe it is - the more ripe, the less acid - the classification assumes the fruits listed are in their ripest state. But just what is a ripe fruit, exactly?

Most people today do not have gardens or orchards, so they depend on grocery stores for their produce. But for economic reasons, most fruit sold in stores is harvested long before it reaches maturity, because fruit is less fragile (and therefore easier to ship) when still hard and green. The spoilage rate is therefore greatly reduced, and the fruit can survive the elaborate handling that takes place at the level of the producer, the wholesaler, the retail seller, and finally the consumer. Picking fruit when it is unripe also permits better management of inventory, as the flow of merchandise can easily be adapted to the needs of the market.

The harmful result of this premature harvesting is that fruit never reaches the full ripeness that makes it soft, aromatic, sweet, and juicy. If you have ever had the opportunity to taste a fruit that has ripened on the tree in the open air, bathed in the rays of the sun, you know how much more delicious it is than what you usually eat.

Aside from the question of taste, the natural ripening of fruits brings about very significant reduction in their acid content, much more than takes place in fruits harvested before they are ripe. One of my patients, who could not metabolize acids properly, loved oranges but could not eat them without experiencing discomfort. To his great surprise, when he took a trip to an orange-producing region just at the time the fruit was ripe, he found he could eat a pound or more of oranges daily without the least bit of distress. Having attained their full maturation under the sun rather than sitting in a warehouse since they were green, these oranges now contained only a very small amount of acids, which were quite easy for him to metabolize.

Every fruit is a complete entity in and of itself and should whenever possible be eaten in its entirety, skin and seeds and all. Of course, apricot kernels and cherry stones are too large to be swallowed easily and too hard to be digested. But apple, orange, and grape seeds, among others, contain elements that are of great benefit to the body and are useful to its metabolism of the fruit. Furthermore, the skin of fruits contains numerous minerals and enzymes that facilitate neutralization of the acid contained in the fruit pulp. It is thus a mistake to peel apples and pears and to get rid of the skins of figs, grapes, prunes, and so forth. Only orange and citrus fruit peel, melon rind, and pomegranate skin should be thrown away, even if they have not been treated with pesticides and other chemicals.

Fresh fruits can be eaten as they are or shredded or chopped in a fresh fruit salad. Fresh fruits are naturally sweet, so adding sugar should be avoided, because sugar is an acidifying agent. It is also best not to eat fruits along with cereal grains-for example, in granola or muesli-because the combination of fresh fruit and cereal flakes is hard to digest and encourages fermentation, which is a great producer of acid toxins.

Cooking fruit does not reduce its acidity. When cooking compotes and pies, it is important to use ripe apples and not green apples that have fallen prematurely.

Shredding or slicing fruit makes it more alkaline, because the contact of the pulp with air allows some of its acid content to oxidize.

The only alkalizing fruit, the banana, is not easily digested by everyone. This is usually because it has been picked before it has become truly ripe. A ripe banana has very sweet, soft flesh. Its sugar content can be increased by mashing it into a puree with a fork or spoon and allowing it to sit out in the air for ten to twelve minutes before eating it.

Another way to neutralize the aggressive nature of fruit-based acids is to eat them with soft white cheese, fresh cheese, or cream. This is common in many cuisines, as it is to eat smaller fruits such as strawberries and raspberries with creme fraiche or sour cream.


Dried fruits have lost the greater portion of their water content, and thus their juice, after having been set out to dry under the sun or in an oven. Dates are an exception; they are naturally low in water, and the way they appear in the stores ready for consumption is exactly how they look when ripening on the tree.

Because dried fruits are naturally quite sweet, they usually do not have sugar added to them before they are sold, with the exception of some dates that are packed in a sweet syrup.

Of course, the riper and sweeter a fruit is before it is dried, the higher its alkaline content after this process. The acidity of the fresh fruit is reduced in any event by the drying process thanks to oxidation.

Dried fruits playa very small role in the average diet of most people, and many people never eat them. Because they are alkalizing, however, their consumption ought to be encouraged. They allow individuals with a high sensitivity to the acids of fresh fruits to eat fruit in a form suitable for their particular needs.

Dried fruit is extremely concentrated, and some people have trouble digesting it. Soaking the fruit in water for twelve to twenty-four hours before eating it makes it more easily digestible. It can be eaten with or without its soaking liquid.

Soaked dried fruit can also be made into delicious desserts by blending the fruit and its soaking liquid with a fromage blanc or cream cheese.


As the name suggests, oleaginous fruits are rich in oil. Half their weight, in fact, consists of oil. Many people consider them to be incidental rather than staple foods and only eat them occasionally when they are part of a cake or cookie.

Of all the oleaginous fruits, only two are truly alkaline: almonds and Brazil nuts. But the alkalizing benefits of almonds are so strong that people suffering from acidification should eat them on a regular basis. Black olives are equally alkalizing, in contrast to green olives, but only if they have been preserved in oil and not in a brine or vinegar preparation.

Oleaginous fruits can be eaten just as they are, either one variety at a time or in combination, or along with dried fruits. Because of their high concentrations of basic nutrients it is better not to mix too many different kinds together, as this can make them difficult to digest. Crushed, slivered, or grated oleaginous fruits can be added to fruit salads, green salads, and raw-vegetable platters, or can be spread on bread like butter. Many different kinds of nut butters and pastes are readily available in supermarkets, groceries, and gourmet and health food stores. Peanut butter sandwiches, of course, are a lunchbox staple. Non-sweetened almond paste can also be used to make almond milk. Tahini, or sesame paste, is an ingredient in many popular Middle Eastern dishes, such as hummus and baba ganoush.


Except for tomatoes and eggplants, which are quite acidifying, all vegetables are alkalizing and should make up a significant portion of your diet if you are suffering from problems caused by acidification. Some vegetables are very alkalizing, however, and others are less so. The latter have been listed in a second column under the heading "Slightly alkaline"; these are chiefly white (endive, celery, cauliflower, etc.) and sulfurous vegetables.

Sulfurous, or cruciferous, vegetables (broccoli, Brussels sprouts, radishes, onions, peppers, etc.) can restore minerals to the depleted physical internal environment of a person suffering from acidification, but they also contain sulfur, which itself is acid. Among sensitive individuals the sulfur not only has a slightly acidifying effect but is also an irritant to the mucous membranes of the digestive system, as well as to the respiratory mucous membranes and the skin when the acid is eliminated, organs that are already weakened and sensitive in people suffering from acidification. But this is of concern only if you are overly sensitive to acids, and only when you consume too large a quantity of the vegetables in question.

White and sulfurous vegetables can therefore be eaten, but to guarantee a good supply of minerals it is best to eat primarily green and colored vegetables, potatoes, and certain fruiting vegetables (cucumber, sweet pepper, etc.)

Vegetables can be eaten raw, cooked, in soup, or in juice. When you eat them raw with a dressing, be sure the dressing is not so acidic that it destroys their beneficial alkalizing qualities. Too often, such dressings contain so much vinegar or lemon juice that they not only drown out the flavor of the vegetables, but are also strongly acidifying if you are unable to metabolize acids properly. In that case you need to measure your intake of vinegar or lemon juice in teaspoons, not tablespoons. (Experiments have shown that vinegar is less acidifying than lemon juice.)

Cooked vegetables contain smaller amounts of vitamins than raw vegetables, because cooking destroys some of their vitamin content. However, the mineral content-which is most important in terms of restoring a healthy acid-alkaline balance-is not altered when vegetables are braised, steamed, or roasted. Boiling draws minerals from the vegetables into the cooking water, which is generally thrown away after use, along with these valuable elements.

Vegetables can make up part or all of a single meal. Homemade vegetable soup is highly recommended, especially in winter, for not only does it replenish the body's mineral content (soup contains the vegetables' mineral-rich cooking liquid), but its warmth counteracts one of the most common symptoms of acidification, the feeling of always being cold (due to the depletion of minerals).

Homemade vegetable juice has more benefit than canned, since it is fresh. Commercial vegetable juices vary in freshness, depending how they are preserved. If you have trouble metabolizing acids you should avoid juices that have been lactofermented, because they are slightly acidic.

If you make your own vegetable juice you can use a single vegetable or make a vegetable cocktail out of several different varieties. If possible, use organic produce so as to avoid ingesting chemicals. If the juice is too strong for your taste, you can dilute it with water without losing any of the alkalizing benefits. (Water has a neutral pH except when chlorinated, a process that makes it more acidic.)


There are countless ways to prepare cereal grains. They can be eaten whole (rice, spelt, etc.), ground (polenta, couscous, bulgur), crushed into cereal flakes, or ground into flour to thicken sauces and soups and to make bread, biscuits, and crackers, or very finely ground to be used in cakes and pastas.

With the exception of corn, all cereals and their by-products are acidifying. Their acidity increases in proportion to their refinement; white rice, for example, is much more acidifying than brown rice.

Of all the cereal grains, millet is the most acidifying. This is important to know, as it is often recommended for its excellent ability to replenish minerals in the case of hair loss, rheumatism, and so on because of its high silica content. However, silica is an acid mineral that is usually found in the form of silicic acid. Millet's ability to restore minerals to the body is undeniable, but people with problems digesting acid should avoid it, because its silica content is more than their bodies can deal with.

White bread is more acidifying than whole-grain or dark breads because, stripped of vitamins, trace elements, and enzymes to make it more easily digestible, it produces-like white sugar-numerous acids. Yeast breads have also been included with acidifying foods, because the yeast that makes dough rise also makes it acidic, as can easily be verified by tasting it. It is still excellent bread, but it is difficult to metabolize for many people, especially those who are acid sensitive.

Toasting or grilling bread facilitates its digestion, because cooking cereal grains is the equivalent of predigesting them. Bread crust is more easily digested than the center portion, as the crust is more thoroughly cooked. Toasting bread slightly reduces its acidifying quality. For this same reason, crackers, which are all crust, are also less acidifying than freshly baked bread. Stale bread is less acidifying as well.

Cereal flakes that are crunchy (such as corn flakes) are less acidifying than those that are not (such as the oats used in muesli), because the former have been toasted.

The acidifying quality of pastas is typically made worse by the customary tomato sauce, tomatoes being the most acidifying vegetable. Pasta-preferably made from whole-grain flour-served plain, or with a white sauce or a little grated cheese, is a healthy alternative to pasta with tomato sauce.

Fruit pies and tarts combine several acidifying ingredients: flour, sugar, and fruit. The fruit used is often not ripe. It is better to eat such pastries only on occasion, and only when they have been made with ripe fruit. It is also a good idea to include grated or shredded almonds or cream to compensate for the acidity.


Whole milk, whether raw or pasteurized, is alkalizing, but it becomes acidifying when it is sterilized, ultra-pasteurized, homogenized, and otherwise processed, because it then becomes increasingly difficult to metabolize. Although milk is naturally alkalizing, most adults have lost the digestive capacity they had as children to make milk curdle. Milk may be safely drunk in the form of a fruit-based milkshake or smoothie, because the acidity of the fruits causes the milk to curdle in the stomach. When chocolate and/or sugar are added, milk becomes an acidifying beverage.

Cheeses with either a hard or soft crust are acidifying. Their acidity increases in proportion to their fat content, their age, and how strong they are.

Well drained and eaten in moderation, cottage cheese and other soft unripe cheeses are slightly alkalizing. On the other hand, the more whey they contain, and the older they are, the more acid they become. (Large-curd cottage cheese tends to be better drained and thus more alkalizing than small-curd cottage cheese.) Furthermore, not only will their acidity increase, but their originally lactic levogyre L+ acids will be transformed into lactic dextrogyres D- acids. These acids are much harder to metabolize by the body, which cannot oxidize them properly due to the lack of the specific enzyme necessary to transform them. The greatest part of these acids is neither assimilated nor utilized by the body, but is directly eliminated in the urine in the hours immediately following their consumption. This elimination does not come without cost, however, since in order to neutralize the acidity, alkaline elements must be expended. Foods containing these kinds of lactic acids thus have a tendency to deplete the body's mineral content.

L+ lactic acid, in contrast, is very much in harmony with the body's physiology. The body transforms lactose to this form of lactic acid, and it is also what the muscles produce when burning sugar. When present in excess, L+ lactic acid causes aches and pains. The body does possess the necessary enzymes to transform L+ acid, so this substance does not have an acidifying effect.

In making yogurt, the proportion of L+ lactic acids can change completely depending on the method of fermentation used. Elevated levels of L+ lactic acid are found in the new varieties of yogurt that contain live cultures. Of course, the substantial amounts of sugar added to flavored yogurts make them acid.

Fresh butter, eaten raw and in moderation, is alkalizing, but it loses this advantage when eaten in large quantities or after being subjected to heat in cooking.

Eggs are slightly acidifying. Eaten alone, the yolk is alkalizing, however.


Meats can be divided into two basic groups: white and red. The latter contain a higher quantity of toxins, blood, and fat, from which their deeper color is derived. But they also have a much higher acidifying effect on the body, the worst culprit being delicatessen meats and cold cuts. Fish is not much less acidifying than meat. Crustaceans (shrimp, crayfish), however, are even more acidifying, as are the majority of shellfish. Oysters are the one exception. Their high mineral content - minerals of all sorts, not simply alkaline minerals - make them an excellent source of minerals for building up the body's stores.


Leguminous plants are highly concentrated foods. They contain little water and consist almost entirely of proteins, lipids (fats), and glucides (carbohydrates). Peanuts, for example, contain 35 percent protein, 48 percent fat, and 25 percent glucides, leaving a mere 2 percent for water and mineral salts.

Leguminous plants are extremely potent acidifiers due to their high concentration of acidifying nutrients, and because they are rich in purines. For the body to eliminate this toxin it has to transform it into uric acid. One ounce of soybeans contains as many purines as two ounces of pork. Tofu and soy milk are much less acidifying because the process used to manufacture them makes them easier to metabolize.


Water - which should be the basic drink of every human being-generally has a pH of 7, but this can vary quite a bit depending on its origins. Tap water is usually acidic because it is most often chlorinated, and chlorine is an acid. Bottled mineral waters typically have a pH of 7, but if carbonated gas is added, as is the case with many popular brands, it becomes acidic. Slight carbonation decreases water's normal pH of 7 to 6 or 5.5, and high carbonation decreases it even further, to 5.

The most alkaline mineral waters I have found (this is by no means an exhaustive list) are Contrexeville (France), with a pH of 7.1; Evian (France), with a pH of 7.2; Henniez bleue (Switzerland), with a pH of 7.5; and Limpia (Italy), with a pH of 7.5 (although it is officially 7.99 right at the springs). The label on the mineral water bottle will indicate the water's pH. You can make your own alkaline water by purchasing pHion Booster drops. This option is much less expensive than purchasing bottled water. These pH drops will also increase the pH of your water to 9.5, which is 500 times more alkaline than 7.

The water filters sold commercially to purify tap water filter out the calcium and consequently acidify the water. Nevertheless, acidification of the body's internal environment is much less dependent on consumption of water-even of slightly acid water-than it is on other factors.

Coffee, tea, and chocolate drinks are acidifying because of their purine content. Herb teas and plant-based infusions such as mint, verbena, or linden blossom are alkalizing, except for those containing rose hips, fruit peels, and birch leaves. Horsetail, which is rich in silicic acid, like millet, has an acidifying effect on people whose metabolisms cannot cope with acids.

Juice made from ripe sweet fruits like mangoes or peaches is alkalizing if drunk in small quantities (one small glass a day). Other juices-mainly grapefruit and orange-have an acidifying effect on individuals whose metabolisms are deficient in dealing with acids.

Vegetable juices are alkalizing as a rule, unless they are preserved by lactofermentation. Tomato juice is always acidifying, however.

As noted earlier, whey is alkalizing or not depending on its age.

Commercial sodas, commercial brands of lemonade, and similar beverages are very acidifying because of their high sugar content.


The Acid-Alkaline Diet for Optimum Health
Christopher Vasey

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