There was a time, in the distant past, when studying nutrition was a relatively simple science.
In 1747, a Scottish doctor named James Lind wanted to figure out why so many sailors got scurvy, a disease that leaves sufferers exhausted and anemic, with bloody gums and missing teeth. So Lind took 12 scurvy patients and ran the first modern clinical trial.
The sailors were divided into six groups, each given a different treatment. The men who ate oranges and lemons eventually recovered — a striking result that pointed to vitamin C deficiency as the culprit.
This sort of nutritional puzzle solving was common in the pre-industrial era. Many of troubling diseases of the day, such as scurvy, pellagra, anemia, and goiter, were due to some sort of deficiency in the diet. Doctors could develop hypotheses and run experiments until they figured out what was missing in people’s foods. Puzzle solved.
Unfortunately, studying nutrition is no longer that simple. By the 20th century, medicine had mostly fixed scurvy and goiter and other diseases of deficiency. In developed countries, these scourges are no longer an issue for most people.
Today, our greatest health problems relate to overeating. People are consuming too many calories and too much low-quality food, bringing on chronic diseases like cancer, obesity, diabetes, and heart disease.