After writing a promotional pamphlet for a milk company in 1932, she wrote two non-published treatises:
Optimum Health (1935) and
You Can Stay Well (1939). In 1942 Davis wrote a 524-page, forty-one chapter nutrition textbook for
Macmillan, Inc.,
Vitality Through Planned Nutrition. But she received public acclaim with her subsequent books written for the general public: ''Let's Cook it Right
(1947); Let's Have Healthy Children
(1951); Let's Eat Right to Keep Fit
(1954); and Let's Get Well'' (1965). By 1974, when she died, her books had sold over 10 million copies. Davis wrote her consumer books over a 40-year career, revising some in the 1970s. She saw herself as an "interpreter", not merely a researcher. "I think of myself as a newspaper reporter, who goes out to libraries and gathers information from hundreds of journals, which most people can't understand, and I write it so that people
can understand." She reviewed scientific literature in the biochemical libraries at U.C.L.A., for instance. Her references for ''Let's Get Well
totaled almost 2,500, many from cases during her nutrition practice, and she was upset when the publisher of Let's Have Healthy Children'' eliminated the 2,000 references from the 1972 revision, according to author
Daniel Yergin. Her first book, ''Let's Cook it Right
(1947), was an effort to update and improve on the popular guide, Joy of Cooking'' (1931), by including scientific facts about nutrition. In the book she also criticized obstetricians and pediatricians for being ignorant about nutrition, which leads them to prescribe harmful diets for both mother and child. She said that "the chapter on canned foods will make your hair stand on end". Her third book was ''Let's Eat Right to Keep Fit'' (1954; updated 1970), which was written as a basic primer on nutrition for the layperson. In it she includes numerous documented case histories from her practice and from footnoted medical journals. Another stated that Davis "indulges in amateur diagnosis which is both unconvincing and dangerous ... which cannot be recommended because of its inaccuracies and the over-dramatic manner in which the material is presented." ''Let's Get Well'' (1965) was her final book, in which she tried to convince the reader that before most diseases develop there were likely nutritional deficiencies that people were not aware of. She discussed nutritional therapy for hundreds of ailments, including heart disease, high cholesterol, ulcers, diabetes, and arthritis, often contradicting the dietary advice given by many physicians. The book is documented with over 2,000 footnoted references to studies reported in medical journals and books.
Social concerns about nutrition Davis believed many of America's dietary problems were due to most doctors not being well informed about nutrition. She believed few medical schools offered nutrition courses and physicians had little time to read the hundreds of medical journals published to keep up with new findings. Davis criticized the food industry for promoting bad eating habits with misleading advertising. "It's just propaganda," she said, "that the American diet is the best in the world. Commercial people have been telling us those lies for years." In a television interview she said that a "great deal of sickness is caused by refined foods". She states that "We are literally at the mercy of the unethical refined food industry, who take all the vitamins and minerals out of food." She was also worried about the welfare of society in general, warning in 1973 that "nutrition consciousness had better grow or we're going under...We're watching the
fall of Rome right now, very definitely, because Americans are getting more than half their calories from food with no nutrients. People are exhausted." In her opinion, according to Yergin, "entire civilizations rise and fall on their diets". She felt that one of the reasons Germany easily defeated France in World War II was due to the Germans' healthier diets. "Ominously, she warns that the Russians eat much less of the illness-breeding refined foods than do Americans."
Public appearances Davis's works gained further popularity from speaking on the lecture circuit on college campuses as well as in Latin America and Europe, and she eventually became sought after for guest appearances on television talk shows. ==Modern influence and critics==