She wrote an early textbook on nutrition in 1942, followed by four best-selling books for consumers which praised the value of natural foods and criticized the diet of the average American.

"[3] She was raised with her sisters on the family's farm by her father and an elderly aunt, where among her duties were pitching hay, plowing corn fields, and milking cows.

[2] From age ten to eighteen, she was also an active member of the 4-H Club, an organization which helped youths reach their fullest potential.

[2] During her time with the club she won numerous ribbons for her breads, canned fruits and vegetables, which she had entered at state and county fairs.

[2] After returning from Europe, Davis moved to Oakland, California in 1931 and worked as a consulting nutritionist for doctors at the Alameda County Health Clinic.

She promoted the benefits of whole grains and breads, fresh vegetables, vitamin supplements, limits on sugar, and avoidance of packaged and processed foods.

[2] The book offers nutrition advice for pregnant women as well as for infants and young children, including explaining the benefits of breastfeeding and when to introduce solid foods.

[2] She denounced prepared baby foods due to their high concentrations of additives and pesticide residue, which made her opinions controversial among doctors.

[12] She argued that women who did not eat well during pregnancy were more likely to suffer from numerous medical problems and that their infants might have hearing and vision abnormalities, rickets and anemia, and do poorly in school, and that such mothers were settling for mediocre children when they could have superior ones.

[14] 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.

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.

[2] In her book Exploring Inner Space which was published in 1961 under the name of Jane Dunlap, she described her experience in taking the hallucinogenic drug LSD.

"[4] 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.

[3] She felt that one of the reasons Germany easily defeated France in World War II was due to the Germans' healthier diets.

"[3] 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.

[17] One historian described Davis as the "most widely read nutritionist of the postwar decades ... [whose work] helped to shape Americans' eating habits, their child-feeding practices, their views about the quality of their food supply, and their beliefs about the impact of nutrition on their emotional and physical health.

Her celebrity was demonstrated by her repeated guest appearances on The Tonight Show Starring Johnny Carson, as she became the most popular and influential nutritionist in the country.

[17] A significant portion of Davis's appeal came from her credentials, including her university training, and her apparent application of scientific studies and principles to her writing, with one book totaling over 2100 footnotes and citations.

Senator Patrick Leahy commended her views in 1998 as well, in remarks supporting a law protecting free speech on food safety from the threat of lawsuits.

The child was pale and chronically ill because her mother, who was an adherent of Davis's nutrition, was giving her large doses of vitamins A and D plus calcium lactate.

[5] She attributed her getting cancer to her early years in college, where she ate junk food before learning about its negative effects on health, and to a number of X-rays she underwent.