Clinical trials are a crucial part of the modern scientific method. Yet the earliest recorded clinical trial, which incidentally dealt with food, was conducted around 2600 years ago, in ancient Babylon. There were no scientific journals back then, but we know about the study because it was reported in a book that is revered by Jews, Christians, and Muslims. I’m talking about the Book of Daniel, which is part of the Hebrew Bible and the Christian Old Testament.
The Book of Daniel is about the Babylonian Captivity, when Nebuchadnezzar II of Babylon conquered Judah and Jerusalem and sent the Jews into exile, in roughly the year 600 BC. During this period, it would have been customary to take some of the sons of prominent people from the conquered lands and hold them hostage in court. This explains how Daniel and several other Hebrews ended up in Nebuchadnezzar’s court. They weren’t there voluntarily. Later on, Psalm 137 described this period as follows:
For there they that carried us away captive required of us a song; and they that wasted us required of us mirth, saying, Sing us one of the songs of Zion. How shall we sing the Lord’s song in a strange land?
One of the biggest problems that Daniel and his fellow captives faced in the court of Nebuchadnezzar was the fact that they would have been expected to eat the food that was being served in court. For devout Jews, of course, this was nothing short of blasphemy. To eat the food at court meant that they would be eating meat from animals that had been sacrificed to pagan gods and drinking wine that had likewise been offered to foreign gods. In other words, by eating the food at court, they would be violating their own religion and taking part in the religion of their captors. To refuse to eat the food at court would thus be a risky act of civil disobedience.
Daniel’s challenge was to figure out some way in which he could get permission for himself and the other Hebrews to avoid offending either God or Nebuchadnezzar. He decided that he and his friends should eat only “food that comes from seeds” (i.e., vegetables and fruit and grains and pulses, such as peas) and drink only water. Thus, they would avoid the meat and wine that were ritually unclean because they had been used in rituals for pagan gods. The overseer in charge of Daniel and his friends was reluctant to let them follow this strict diet. He was afraid it would ruin their health, thus landing him in big trouble. So Daniel suggested a simple experiment. He and his friends would eat plant foods and water for 10 days, and afterward their health would be compared with that of the people consuming meat and wine.
According to the Book of Daniel, after 10 days Daniel and his friends looked healthier than the youths who had been eating the king’s food. It also says that they were “fatter,” but it’s more likely that they would have been thinner than the people who were pigging out on “the king’s dainties.” It’s easy to gain too much weight on a meaty diet, but it’s hard to get fat on a starchy, high-fiber diet. However, that small inaccuracy probably resulted from the fact that the study report was published roughly four centuries after the study itself was completed. As a recent article on this study noted, “Daniel perished, then published.”  With tongue firmly in cheek, the article also noted that the methodological weaknesses of the study include “probable selection bias, ascertainment bias, and confounding by divine intervention.”
About 2600 years after Daniel’s experiment, a group of researchers in the United States did roughly the same experiment, this time comparing Daniel’s diet with the standard dietary recommendations of the American Diabetes Association, which allows people to eat controlled portions of “the king’s dainties.”  This study differed in several ways from the study reported in the Book of Daniel. The modern study involved people with type 2 diabetes, which is a disease that is known to be linked to obesity and a fatty diet. The subjects were randomly assigned to either the Daniel-type diet or the ADA diet. Also, the trial lasted longer than 10 days, to show improvements in the subjects’ glycosylated hemoglobin levels (HbA1c) and to provide a clear picture of how much weight they lost and how many prescription drugs they could stop taking.
I was not at all surprised to see that a diet like Daniel’s was far more effective than the ADA’s standard recommendations at improving the health of people with type 2 diabetes. What surprised me was that the participants were more successful at sticking to the Daniel-style diet. This success probably stemmed from the fact that although people’s food choices were limited, their portions were not. The ADA dietary recommendations are about portion control, which most people can’t achieve. The Daniel diet lets people eat to their heart’s content, while still losing weight.
1. Grimes DA. Clinical research in ancient Babylon: methodologic insights from the book of Daniel. Obstet Gynecol. 1995;86(6):1031–1034.
2. Barnard ND, Cohen J, Jenkins DJ et al. A low-fat vegan diet improves glycemic control and cardiovascular risk factors in a randomized clinical trial in individuals with type 2 diabetes. Diabetes Care. 2006;29(8):1777–1783.
Photo by diff_sky