The study of nutrition dates back to the 18th century, when the French
chemist Lavoisier discovered a relationship between our metabolism of food
and the process of breathing. By the early 20th century, scientists had
found that diseases — such as beri beri, rickets, scurvy, and pellagra —
were associated with certain diets. By 1912, the Polish chemist Casimir Funk
had found a substance (vitamin B1) that actually prevented beri beri, and he
named it “vitamine.” Later it was found that these diseases were caused by
the lack of specific nutrients — vitamin B1 (thiamine), vitamin D, vitamin
C, and vitamin B3 (niacin) respectively.

In the early 1940s, the National Research Council set Recommended Dietary
Allowances (RDAs).

Researchers and scientists continue to find out more about how individual
nutrients can help prevent and treat disease. But they are also learning how
whole foods may allow nutrients to work together. For example, antioxidants
like beta carotene, selenium, vitamin E, and vitamin C, when consumed in
foods, appear to protect against the development of heart disease, cancer,
and other chronic degenerative diseases. More recent studies have resulted
in the discovery that common deficiencies in vitamin D result in immune
system compromise.

The old RDAs have been replaced by Dietary Reference Intakes (DRIs), which
show how much of a nutrient we need every day to maximize health and lower
the risk of chronic disease (in contrast to RDAs, which listed the minimum
amount needed to prevent a deficiency). The field of clinical nutrition is
now increasingly incorporated into mainstream medical treatment.