Nutritional immunology is the study of how nutrition affects the immune system and the body's ability to fight off infection and disease. It has long been known that food provides humans and animals with necessary vitamins and nutrients for healthy bodily function. Those studying nutritional immunology seek to take this concept a step further by looking at how malnutrition might affect the immune system. The theory is that malnutrition leaves the body weak and prone to disease, while proper nutrition allows the body to remain strong and healthy. Studies of this kind have been done for thousands of years.
According to historical documents, the Greek physician Hippocrates is credited with the quote “Let food be thy medicine and medicine be thy food.” This statement shows a remarkable understanding of the role nutrition plays in the health of the body. It is very likely that Hippocrates observed that those who had access to a steady and varied supply of food were less prone to illness than those who struggled to find each meal. His observations were probably some of the first studies of nutritional immunology.
Other ancient physicians also noted this pattern. Indian, Egyptian, Chinese, and Celtic medical practices all recommended certain herbs, spices, fruits, and vegetables be eaten to ward off certain diseases and conditions. Ancient doctors understood that a certain kind of diet helped promote longevity, even if they didn’t understand why. Their observations were generally only surface-based. An ancient Indian physician, for instance, might not understand why those who ate oranges experienced illness less often than those who didn’t. All he could do was make the surface correlation.
Support for nutritional immunology seemed to increase around 1810, with scientist J.F. Menkel’s discoveries. Menkel was able to draw a correlation between disease and the condition of the thymus, a gland located at the base of the throat. The thymus regulates many of the functions of the lymphatic system, which controls immunity. When examining malnourished patients, Menkel discovered that many of these people were not only prone to illness, but also showed atrophied thymus activity.
This discovery was incredibly important, but Menkel never quite understood why malnutrition affected the thymus this way. It wasn’t until the 20th Century that doctors and scientists discovered that foods contain vitamins. It was during this time that studies of nutritional immunology really took off. During the 1920s and 1930s, medical scientists were able to isolate the vitamins in foods and create some of the first vitamin supplements. These supplements were often used to treat diseases until vaccines became popular during World War II.
World War II is often called the vaccine era in medical studies. Vaccines, and later antibiotics, became the primary treatments for most conditions until a reemergence of nutritional immunology in the 1960s. From there, these studies continued to gain ground, with minor starts and stops along the way. Many modern doctors examine a patient’s diet and combine improved nutrition with prescription drugs for a lasting and holistic treatment plan.