Combining Foods for Optimal Digestion1

©Copyright 1997 by Robert Chuckrow, Ph.D.


This subject is crucial because habitually disregarding its principles can lead to allergies and autoimmune conditions (links are at end of article).

During the late 1960s, I became interested in reading about diet- and health-related subjects and began eating only natural, raw foods. I went to a health-food store and bought a variety of nuts, seeds, and dried fruits. After eating them I had a virtuous feeling, followed by intestinal gas and, then, severe diarrhea. I began to notice that whenever I ate raw, nutritious food, I experienced a similar digestive upset.

One book explained that it takes your body a while to adjust to unrefined, “live” foods after years of eating devitalized, “dead” foods. However, no scientific reason was given for this assertion, nor was any remedy offered.

One day, I was in a health-food store, and a booklet entitled Food Combining Made Easy, by Herbert Shelton,2 caught my eye. The first few pages described my dilemma and addressed it in what appeared to be a refreshingly scientific manner. Until then, I was frequently dismayed at the unscientific approach of the numerous “underground” books I had read on the subject of health. Here was one that aroused my optimism.

The digestive upset that I experienced resulted from the haphazard combinations of the “health foods” I was eating. Once I obeyed the rules of food combining, not only did the digestive distress disappear, but the general health of my stomach improved.

The basic premise of food combining is that combinations of starch and protein, sugar and starch, and sugar and protein take longer to digest than if the components of each of these pairs were eaten alone. Not only is sugar a medium for the growth of yeast, but eating sugar along with starchy or high-protein foods hampers their digestion. Sugar inhibits the secretion of ptyalin, an enzyme in the saliva for the digestion of starch. Sugar also inhibits the stomach's secretion of hydrochloric acid (HCl), which is necessary for the digestion of protein. Ptyalin is chemically basic and would be neutralized by HCl. Thus, when starch is eaten alone, little HCl is secreted. However, when a protein and starch are eaten in the same meal, the starch soaks up the HCl meant for the protein, arresting its digestion and slowing the digestion of the protein.

The reason that it is more critical to properly combine natural, raw foods is that their high nutritive value and lack of preservatives make them much more susceptible to bacterial decomposition in the gut than devitalized foods. Over the past thirty-five years, I have had ample opportunity to apply these basic concepts and confirm their validity.

Keep in mind that food combining need not be perfectly strict. Once you learn about and directly experience the effects of eating proper and improper combinations, you will be able to decide how strict you need to be in any given situation. Consider the following related anecdote:

As an amateur harpsichordist, I had the opportunity years ago to take some private lessons with Gerald Ranck (1948–2014), a highly accomplished concert harpsichordist. When I played a Bach prelude for him, he exclaimed, “You are playing the entire piece legato. You must vary your playing with alternations of legato and staccato. Otherwise, even though it is Bach, it will become boring. I want you to practice the piece entirely staccato—every note!”

During that week I practiced the prelude, playing every note staccato. Next lesson, I proudly played the piece as practiced. He stopped me, saying, “What are you doing? Why is every note staccato?”

I immediately realized that just because he suggested I use a tool to improve or perfect a certain skill, that did not mean I should use it indiscriminately or exclusively. Similarly, with food combining, one must first practice it strictly in order to understand the underlying principles and effects. Afterward, you can apply the principles reasonably and temper them as required.

Green and Non-Starchy Vegetables

Arugula Chicory Lettuce Sorrel
Asparagus Collard greens Mung bean sprouts Spinach
Bamboo shoots Cucumber Mushrooms Sweet pepper
Beet greens Dandelion greens Mustard greens Sweet corn
Bok choy Eggplant Okra Swiss chard*
Broccoli Endive Onion Turnip
Broccoli rabe Escarole Parsley Turnip greens
Brussels sprouts Fennel Radishes Watercress
Cabbage Garlic* Rhubarb* Yellow summer squash
Cauliflower Green beans Scallion Zucchini
Celery Kale Seaweed (all)  
Chard* Kohlrabi Snap beans  

*not recommended as foods

Starches and Sugars

Starches Mildly Starchy Sugars
All cereals Cauliflower Brown sugar
Beans† Beets Maple syrup
Chestnuts Carrots Honey
Corn Rutabaga Malt syrup
Peas Salsify Rice syrup
Potatoes (all kinds) Parsnip Turbinado sugar
Peanuts   White sugar
Winter Squash    
Jerusalem Artichokes    

†Note that the protein content of beans is low in quantity and very low in biological value. Therefore, beans have been classified here as a starch. By contrast, soybeans (below) are high in excellent-quality protein and contain no starch.


Almonds Fish Pecans
Avocado Flax seeds Pignolia nuts
Black walnuts Fowl Pilinuts
Brazil nuts Hickory nuts Pinon nuts
Cashews Lentils Pistachios
Cereals (all) Meat Pumpkin seeds
Cheese Milk‡ Sesame seeds
English walnuts Olives Soybeans
Filberts Peanuts Sunflower seeds

‡Note that milk is a combination of sugar and protein.


Sweet Fruits Sub-Acid Fruits Acid Fruits
Banana Apple** Citrus Fruits (all)
Grapes Apricot Dried Fruits (all)
Mango Cherries** Pineapple
Plantain Peach** Tomato
Guava Pear  
Lychee** Plum**  
Kiwi** Mango  
Pomegranate** Nectarine  

**When sour, these fruits are classified as acid.

Food-Combining Chart

*Cheese or nuts are fair with acid fruit.
Starches are fair with sub-acid fruits, bad with everything else.
Melons are fair with sweet or sub-acid fruit.
Fats are good with everything except melon.
Avocado is good with acid fruit or green vegetables.
Milk should be taken alone.
Yogurt is fair with all fruit other than melons.

Additional Aspects of Digestion

Digestion Times

It is of value to know roughly how long each type of food takes to be digested before it leaves the stomach. Water and fruit and vegetable juices take approximately half an hour. Starches take about two hours. Proteins and fats take about four hours. Once the tissues of your stomach become free of irritation and your awareness of digestion develops, you will feel when the stomach empties and know the wonderfully comfortable feeling of an empty stomach.

Sample Meals

Breakfast: one grapefruit

4 oz. raw Brazil nuts
steamed broccoli
large tossed salad

carrot juice (then wait 30 minutes)
brown rice with flax oil or melted butter
steamed hiziki (seaweed)
large tossed salad

Breakfast: apple and banana

4 oz. raw sunflower seeds
steamed broccoli
large tossed salad

baked chestnuts and butter
steamed kale
large tossed salad with carrot and raw sweet potato

Breakfast: nectarines and cherries

tuna salad
steamed green beans
large tossed salad with sweet red pepper

baked potato in skin with butter
steamed cauliflower
large tossed salad with raw turnips

See also:

Hunger Pangs—What They are and How to Alleviate Them

Factors Affecting Digestion

A Link Between Incomplete Digestion and Degenerative Disease

Flatulence and Halitosis

Heartburn, Acid Reflux, and Antacids

The Difference Between True and False Hunger

Therapeutic Fasting

1From Robert Chuckrow, The Intelligent Dieter’s Guide, Rising Mist Publications, Briarcliff Manor, NY, 1997.
2Herbert Shelton, Food Combining Made Easy, Willow Publishing, Inc., San Antonio, TX, 1994.

©Copyright 1997 by Robert Chuckrow

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