The Saccharine, the Oily, and the Albuminous: Food Groups

In 1753, James Lind demonstrated that eating citrus fruit can prevent scurvy. A few decades later, in 1816, French physiologist François Magendie showed that nitrogen in food is essential for good health. By 1842, Justus von Liebig identified the importance of proteins. In 1895, Dutch physician Christiaan Eijkman discovered that what is later called vitamin B protects against the disease beriberi.

In the 1910s, Polish biochemist Casimir Funk discovered vitamins, paving the way for a deeper understanding of nutrition. Then, in the 1950s, physiologists and nutritionists began to explain how excess fat and sugar can cause heart disease.

By the early 19th century, it was clear that life depends on chemical processes and that certain chemicals in food play a key role in health. In the 1820s, British physician William Prout's investigations into the chemistry of digestion led to his discovery of the main food groups. Analyzing the gut contents of animals such as rabbits and pigeons, Prout observed that they contained just a few basic substances made from carbon, hydrogen, and oxygen. His discovery of hydrochloric acid in the stomachs of several animals further convinced him of the chemical nature of digestion.

In 1827, Prout published the first of three papers on chemicals in food, which he referred to as “alimentary substances.” He classified foods into three “principles”: saccharine (carbohydrates), oily (fats), and albuminous (proteins). This was the first clear exposition of the three main food groups.

Nowadays, carbohydrates are understood to be sugars and starches made from carbon, hydrogen, and oxygen; they provide the basic energy for cells. Fats and oils (lipids)—also composed of carbon, hydrogen, and oxygen—are utilized by the body for backup energy, vitamin storage, hormone production, and organ protection. Proteins serve multiple roles, from building muscles to defending against infections. They are constructed from 20 or so amino acids, which, in turn, are built from carbon, hydrogen, nitrogen, oxygen, or sulfur.