[14] McCollum failed the general certification examination, but was allowed to enter high school provisionally based on his habit of extensive reading and his memorization of standard poetry.

[15] He fell in love with the school's Encyclopædia Britannica, purchased a set for $25 (about two months of his earnings), and used it for twenty-five years until he bought a new edition.

[17] In Wisconsin, McCollum was assigned to analyze cow feed and the animal's milk, blood, feces, and urine for the famous single-grain experiment, directed by department chief Stephen Babcock and his successor Edwin B. Hart.

[19] Babcock had studied for his Ph.D. at the University of Göttingen in Germany prior to working at the New York State Agricultural Experiment Station and then joining the staff in Wisconsin.

Due to discoveries by Justus von Liebig and others, they thought that any feed that contains a set amount of protein, carbohydrates, fats, salts, and water was equivalent to any other.

"[11] Searching for a breakthrough in human and animal nutrition, McCollum purchased all thirty-seven volumes of Richard Maly's Jahresbericht Über Die Fortschritte Der Tier-Chemie[23] so he could read them at home.

McCollum determined that he must find out what was lacking in their purified diets, and that he needed to experiment on animals with a short life span, finally deciding on rats.

The dean of the college of agriculture would not support experiments with what he feared was vermin, but Babcock, who was retired, understood the rats' importance and told McCollum to proceed.

In 1911 Osborne and Mendel criticized McCollum's hypothesis and his data, when they found that plant protein diets needed to be supplemented with protein-free milk.

[25] They concluded that rats stop growing until they are fed certain "ether extracts of egg or of butter", and that "there are certain accessory articles in certain food-stuffs which are essential for normal growth for extended periods".

[11] He thought that a professor succeeds with his students, "by his ability to make his conversations and lectures more interesting than song, dance, drink and fast driving".

[29] Looking at beriberi and the problem of polished rice, Christiaan Eijkman and Gerrit Grijns were trying to find the cause of polyneuritis (influenced by Louis Pasteur.

[3] McCollum and Davis's experiments with rat diets led to the discovery that Eijkman's and Grijns' anti-neuritic substance was the same as their water-soluble B[3] (B vitamins) in 1915.

They thought the prefix "vita" gave the substance too much importance, and that the ending "amine" means something specific in organic chemistry, but they only had scant evidence of one amino group.

[27] In 1917 the Rockefeller Foundation established a new Department of Chemical Hygiene at Johns Hopkins University,[16] and the unconventional founder's first two appointments were to non-medical scientists working for agricultural experiment stations.

His work was on fluorine and the prevention of tooth decay, vitamins D and E, and the effect of a slew of trace minerals in nutrition, including aluminum, calcium, cobalt, phosphorus, potassium, manganese, sodium, strontium, and zinc.

[11] While at Johns Hopkins, he was the leader of the National Dairy Products Corporation research laboratory and served as a consultant there, for one hour per day and one evening per week.

Developed by McCollum and marketed by Kraft Foods, Inc., the formula of concentrated milk contained all known vitamins necessary for "proper infant nutrition".

[46] McCollum's textbook The Newer Knowledge of Nutrition (1918) influenced many dietitians and went through multiple editions coauthored by Nina Simmonds and Elsa Orent-Keiles.

As a new member of the Food and Nutrition Board, McCollum was part of the decision in 1941 to enrich bread and flour with thiamine, niacin, and iron.

McCollum was critical of the decision; while he agreed that white bread has nutritional deficiencies, he felt that this action did not compensate for all of the nutrients that are stripped away by milling.

"[53] According to The New York Times, in 1936 he asked an audience of four hundred doctors at the Kings County Medical Society in Brooklyn to help investigate the "extravagant claims" being made for some medicinal preparations.

[11] After his 1944 retirement as professor emeritus, he spent ten years writing The History of Nutrition; he also wrote his autobiography, From Kansas Farm Boy to Scientist.

In 1951 Johns Hopkins held a two-day symposium called "The Physiological Role of Certain Vitamins and Trace Elements"; fifteen scientists delivered papers and many of his students and former colleagues returned to see him.

[11][12][58] While working with Olaf S. Rask ten years before he retired, McCollum began to search for ways to separate specific amino acids from protein hydrolysates.

[11] In 1965 he and his wife traveled so he could speak at the fiftieth anniversary of the appointment of Agnes Fay Morgan to the faculty of the University of California, Berkeley.

"[11] In her 1994 biography of Cornelia Kennedy for the Journal of Nutrition, former University of Minnesota graduate dean Patricia B. Swan writes "forgotten...are the women who worked with Elmer V. McCollum throughout his outstanding research career."

Semba cites an extraordinary 1918 letter written by Edwin B. Hart, chair of the University of Wisconsin department of agricultural chemistry, to the journal Science.

Hart states in this letter, which was published under the title "Professional Courtesy", that a paper co-authored by McCollum and Nina Simmonds, "A Study of the Dietary Essential, Water-Soluble B, in Relation to its Solubility and Stability Towards Reagents",[65] is actually the work of Harry Steenbock, who is mentioned only in a footnote and is thus the victim of a "gross injustice".

[63] Semba disputes McCollum and Davis's claim to the discovery of vitamin A, which was based on their observation that the unidentified substance was "fat-soluble", for three reasons: