As far back as 1936, Senate Document 264 warned Americans that the soils used to grow fruits and vegetables were seriously deficient in needed minerals. Continuous cropping and the ravages of pollution even then were robbing the soils of the minerals needed to sustain life.
These are Verbatim Unabridged extracts from the 74th Congress 2nd Session:

"Our physical well-being is more directly dependent upon minerals we take into our systems than upon calories or vitamins, or upon precise proportions of starch, protein or carbohydrates we consume."

"Do you know that most of us today are suffering from certain dangerous diet deficiencies which cannot be remedied until depleted soils from which our food comes are brought into proper mineral balance?"

"The alarming fact is that foods (fruits, vegetables and grains) now being raised on millions of acres of land that no longer contain enough of certain minerals are starving us - no matter how much of them we eat. No man of today can eat enough fruits and vegetables to supply his system with the minerals he requires for perfect health because his stomach isn't big enough to hold them."

"The truth is that our foods vary enormously in value, and some of them aren't worth eating as food...Our physical well-being is more directly dependent upon the minerals we take into our systems than upon calories or vitamins or upon the precise proportions of starch, protein or carbohydrates we consume."

"This talk about minerals is novel and quite startling. In fact, a realization of the importance of minerals in food is so new that the text books on nutritional dietetics contain very little about it. Nevertheless, it is something that concerns all of us, and the further we delve into it the more startling it becomes."

"You'd think, wouldn't you, that a carrot is a carrot - that one is about as good as another as far as nourishment is concerned? But it isn't; one carrot may look and taste like another and yet be lacking in the particular mineral element which our system requires and which carrots are supposed to contain."

"Laboratory test prove that the fruits, the vegetables, the grains, the eggs, and even the milk and the meats of today are not what they were a few generations ago (which doubtless explains why our forefathers thrived on a selection of foods that would starve us!)"

"No man today can eat enough fruits and vegetables to supply his stomach with the mineral salts he requires for perfect health, because his stomach isn't big enough to hold them! And we are turning into big stomachs."

"No longer does a balanced and fully nourishing diet consist merely of so many calories or certain vitamins or fixed proportion of starches, proteins and carbohydrates. We know that our diets must contain in addition something like a score of minerals salts."

"It is bad news to learn from our leading authorities that 99% of the American people are deficient in these minerals, and that a marked deficiency in any one of the more important minerals actually results in disease. Any upset of the balance, any considerable lack or one or another element, however microscopic the body requirement may be, and we sicken, suffer, shorten our lives."

"We know that vitamins are complex chemical substances which are indispensable to nutrition, and that each of them is of importance for normal function of some special structure in the body. Disorder and disease result from any vitamin deficiency. It is not commonly realized, however, that vitamins control the body's appropriation of minerals, and in the absence of minerals they have no function to perform. Lacking vitamins, the system can make some use of minerals, but lacking minerals, vitamins are useless."

"Certainly our physical well-being is more directly dependent upon the minerals we take into our systems than upon calories of vitamins or upon the precise proportions of starch, protein of carbohydrates we consume."

"This discovery is one of the latest and most important contributions of science to the problem of human health."

Senate Document No. 264, 1936.