Can man get adequate protein from a fruit diet? This is to ask: If a man were to attempt to live as a strict frugivore, could he be adequately nourished? We put this question in relation to the protein of this diet because there is no question about the ability of a fruitarian diet to supply adequacies of fats, carbohydrates, minerals and vitamins.

In an article entitled “Why I don’t eat Meat” by Owen S. Parrett, M.D., which has had wide distribution, the author says, “W.C. Rose of the University of Illinois, an authority in the field of protein, says that “less than twenty-five grams a day is all one needs.”

“If a man were to eat no meat, eggs or milk he would still get on the average 83 grams of protein a day. A woman would get 61 grams of protein a day. This fact was discovered in a research project made by Dr. Mervyn Hardinge of the College of Medical Evangelists under Dr. Frederick J. Stare of Harvard, well-known authority on nutrition.

Still, alarming amount of people decide to take protein supplements on top.

“Dr. U. D. Register, leading biochemist, and Dr. Hardinge, both active in the field of human nutrition, said to me that fruit alone, if amply supplied in sufficient variety, would provide people with enough protein to meet the actual body demand.”

Many efforts have been made to live upon a diet of fruits only, usually with only marked degree of success. It has usually been found that such diets are improved by the addition of green leafy vegetables. It is probable that this need has resulted from an insufficient variety of fruits. Certainly when we consider the wide range of food substances included under the term fruit, there would seem to be no necessity for inadequacies in the diet of the fruitarian. Nuts, which are fruits, are nearly all rich in protein of high biological value, capable of supplying adequacies of all the amino acids essential to growth and reproduction.

The biologist defines a fruit as “a ripened ovary with or without associated parts.” To make this a bit more complete, a fruit is the matured ovary of the flower, its contents and all intimately connected parts. Fruits are often more complicated than this description indicates.

In addition to the development of the ovary wall, the calyx may also become fleshy and envelope the ovary as in the apple and pear; or the end of the stem (receptacle) may enlarge and form a part of the fruit, as in the strawberry and blackberry. Tough shells or rinds may form for protection, as in nuts and lemons; or a delicious flesh may envelop a hard inner stone, as in the peach and plum. Some fruits, as the potato and peanut, are matured underground.

All of these developments serve to perform a few simple functions:

  1. They protect the ovules and seed while they are maturing
  2. They prevent loss of water.
  3. They provide for seed dispersal.

An animal eats the fruit and discards the seed at a distance from the parent plant. Edible fruits may thus be said to be the coin with which the plant compensates the animal for services rendered—that of dispersing the seed. A seed is a matured ovule enclosed in the fruit. Many fruits are merely mechanical devices to secure seed dispersal and are not edible. We need not consider these in our discussion of fruits.


A brief glance at the evolution of a fruit may help us in forming a clear picture of a fruit. The ovary grows as the seed develops, giving rise to a fruit. A fruit, in this sense, is not necessarily a fleshy edible product, but the seed-carrying organ of the plant. It is customary to include nuts in the category of fruits, although, it is the seed rather than the seed-carrying organ that we eat.

A fruit may consist of a single ovary with but one seed, as in grains, nuts, cherries, plums and peaches, or it may evolve from a single ovary which has several seeds, as the bean, pea, apple and orange. Then there are flowers which possess several ovaries which combine to form compound fruits like the strawberry or raspberry.

With the foregoing explanation in mind, it should not be difficult for each of my readers to answer himself the question: Is the tomato a fruit or a vegetable? Fruits are all produced by plants and, in this sense, they are all vegetables. But they are special parts of plants and are classed as fruits because of this. The tomato, as the matured ovary of the tomato flower containing seed, is quite obviously as much a fruit as the apple or orange. The cucumber squash, pumpkin and similar foods are fruits.

Confining ourselves, in this discussion to edible fruits, and ignoring those fruits that serve only as seed dispersers and have no food values, fruits are either dry or fleshy, simple or compound, depending on the character and development of the ovary which formed them.

  1. Examples of fleshy fruits are the apple, pear, cherry, peach, apricot, plum, nectarine, mango, banana, tomato, and gooseberry.
  2. Examples of dry fruits are legumes (beans and peas), acorn, hickory nut, pecan, walnut and almond.

Thus it will be seen that the term fruitarian may be used in a wider sense than is commonly thought. Indeed, in a biological sense, it may be made to include eating practices that probably should be foreign to man. This is to say that there may be more than one fruitarian category in nature. We are justified in classing the grain-eating birds as fruitarian, but it is doubtful that grains should form a part of the normal diet of man

There are fruits that are poisonous, some of them poisonous before ripening, others poisonous after ripening. These latter should be excluded from man’s diet. An excellent example of a fruit of this kind, one that is commonly eaten, is the cranberry. Sumac berries we refrain from eating, because, although tasty, they are toxic. Some plant substances are poisonous to some animals and not to others.

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An example is belladona, which, highly poisonous to man, is non-toxic to the rabbit after it is six weeks old. After this age the rabbit secretes an enzyme that enables it to digest the two toxins in the plant. Man produces no such enzyme.

In the same manner a fruit that may be poisonous to man may prove to be an excellent food for other animals. Nothing seems to eat the sumac berries. It may be possible that they are toxic to all forms of life. They are regarded as good herbal medicines, precisely because they are toxic. My readers should keep always in mind the rule of medicine: If the plant is non-toxic, it is food; if it is toxic, it is “medicine.”

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