[5] Throughout his career, Holst made many other contributions, writing numerous medical books and articles related to sanitation, health and practical hygiene.

Holst and Frølich suspected a nutritional deficiency for scurvy in the Norwegian fishing fleet, then called "shipboard beriberi," and thought to be a variant of beri-beri.

Holst and Frølich established an animal model that allowed systematic study of factors that led to the ship-related dietary disease, as well as the preventive value of different substances.

[6][7] Substituting guinea pigs for pigeons (a traditional beriberi research model) as the experimental animal for these studies was a lucky coincidence, as the guinea pig was later shown to be among the very few mammals capable of showing scurvy-like symptoms, while pigeons, as seed-eating birds, were later shown to make their own vitamin C in the liver, and could not develop scurvy.

However, in the later work which led up to the isolation of vitamin C as the antiscorbutic factor in 1932-33, Holst and Frølich's guinea pig model of scurvy proved to be the key biological assay which allowed identification of the chemical substance (hexuronic acid, later called ascorbic acid) which was ascorbutic vitamin.