Plant Protein Producers

By Dr. Royal Lee

Summary: Mushrooms and yeasts take center stage in this article. The high protein content of mushrooms (button mushrooms contain over ten amino acids) as well as their wealth of enzymes and fat-metabolizing compounds (betaine, choline, lecithin) make them an historically prized edible. Yeasts, of course, are responsible for the fermentation processes used to make bread, cheese, and the like, but they are also “superior food sources of valuable nutrients,” says Dr. Lee. “The Oriental food pattern differs from ours because…most of the protein they eat is from plants. They accomplish this largely by the use of molds and yeasts, which produce foods high in quality vegetable proteins.” From Let’s Live magazine, 1958.

[The following is a transcription of the original Archives document. To view or download the original document, click here.]

Plant Protein Producers[spacer height=”20px”]

Mushrooms have been cultivated commercially for over 400 years and served as a delicacy for over 2000 years, gracing the tables for the feasts of Caesar, where epicurean tastes elevated these plants to high places. We do not think of mushrooms we buy in a store as molds, yet there is little essential difference between the common molds we find in breads and the common mushroom. Also of the same family are the yeasts and fungi. The common characteristics of the some 80,000 different kinds of these plant growths is that they have no chlorophyll; they produce spores and are parasites. That is, they produce no food supply of their own but must find a preexisting live host for their metabolic needs.

Use to Mankind

In addition to other things, it is this property of living on preexisting food supplies that makes these plants useful to man. For example, the “rising” of bread is caused by the escape of the bubbles of carbon dioxide evolving from the fermentation action of yeasts on carbohydrates; another fungus can change the alcohol of fermenting substances such as apple juice into acetic acid and so produce cider vinegar. This same action also produces many kinds of cheese. Various cheeses are inoculated with species [of the genus] Penicillium to produce the characteristic green-veining and improvement of flavor such as we find in the popular Roquefort cheese. It is interesting to note that some old-time medical books recommended Roquefort cheese for many ailments now treated by penicillin.

Edible Toadstools

While present day botanists shy away from the term “toadstools,” the descriptive nature of the term recalls the storybook pictures of our youth. Many will recall the mushroom hunters who gathered in farm pastures where the ground was enriched with manure and gathered the fleshy morsels, priding themselves on their botanical know-how in being able to differentiate the poisonous varieties.

Today, mushrooms are grown commercially on a vast scale. This is an occupation that requires great skill, since mushrooms are very demanding as to their environment and food supply. They require proper ventilation and need an adequate supply of oxygen and are inhibited by an excess of carbon dioxide. All of this accounts for the relatively high market price of this prized edible.

High Food Value

After the water is removed, the remainder of the mushroom solids run about 30 percent protein. More than twelve amino acids have been reported, including arginine, methionine, tryptophan, glutamic acid, and valine. Betaine, choline, and lecithin—the well-known lipotrophic factor—have also been reported. During the course of their growth, mushrooms produce urea, an essential constituent of the body fluids that helps promote osmosis and is instrumental in elimination of wastes in the urine. (For more on urea, see Vitamin F and Carbamide in Calcium Metabolism, Lee Foundation Reprint No. 20.)

According to Food Toxicology and Food Products, 43 to 62 grams (about 2 ounces) of mushroom protein is sufficient to maintain nutritional balance in a healthy person of 154 pounds. Over six enzyme groups have been reported in mushrooms, including the important copper-bound group (tyrosinase), which is also found in potatoes and is considered to be an important member of the ever-increasing vitamin C complex group. The copper is bound to the protein in a manner analogous to its linkage in hemocyanin, the blood pigment of certain lower animals.

Mushrooms eaten raw offer a compatible source of raw protein in the diet and are quite tasty. They should only be eaten raw, however, if in a wholly fresh and wholesome condition.

Yeast in China

Yeasts are also superior food sources of valuable nutrients. Many readers will recall the great interest that was aroused a few years back when beneficial results from the daily use of baker’s yeast were reported in the treatment of boils, acne, constipation, and other gastrointestinal and skin diseases. While the publicity has since died, there are many people who continue the practice to this day and continue to report beneficial results.

The Chinese have used yeasts and mold in their diet for over 2000 years. Soy sauce (a rich source of amino acids) and cheese-like food made from soybeans and rice are considered essential components of the Chinese diet. The Oriental food pattern differs from ours because it is one in which little protein is obtained from animal foods; most of the protein they eat is from plants. They accomplish this largely through the use of molds and yeasts, which produce foods high in quality vegetable proteins. Today, we know that brewer’s yeast is a superior protein food, even compared with meat proteins, on a quantitative basis.

Nutrition from Yeast

In 1945 some 871,000 pounds of calcium gluconate were produced in the United States, most of it from the action of fungus fermentation. Brewer’s yeast was placed on naval life rafts during the war as emergency rations because of its keeping qualities and its complete protein nature. Malted barley is widely used as a source of diastase, which converts starch into maltose and dextrose that are used as yeast food.

The nutrition from yeast may be classified into five basic effects:

  1. Source of mineral salts, particularly sulfates, phosphates, and potassium
  2. Source of carbon-bound molecules, particularly glucose, fructose, and mannose (natural sugars)
  3. Energy requirements
  4. Source of nitrogen—as protein
  5. Growth factors

The nation’s farmers are now only 6 percent of our total worker force, while world population grows ever larger. Many authorities have offered the suggestion that our best chance of supplementing the increasing demand for protein supply is by the cultivation of the various yeasts and molds and fungi as supplemental food sources. Of the over two billion forms of life in the world, these yeasts and molds offer our best chance for solving a problem that threatens to become catastrophic.

By Dr. Royal Lee. Let’s Live, 1958.


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