by Bonnie Kaplan, PhD & Julia Rucklidge,

Human knowledge of the relationship between nutrition and mental function probably goes back many thousands of years, but it has been documented for ‘only’ about 2700 years. So join us now for a fun ramble through history, which we will present here in the form of Q&As.

  1. When was the first report of a clinical trial on the impact of nutrition on mental/cognitive health? You can read about it yourself in the Bible, in the first part of the Book of Daniel. During the Babylonian Exile that lasted about 50 years until about 538 BCE, Assyrians sacked much of Israel, captured the people and took them back to the areas of present-day Syria, Iraq etc. During the period of this Exile, King Nebuchadnezzar proposed a clinical trial: he wanted all the Israelis to eat the same food as the youth from the royal families for 3 years. We don’t know why. Daniel, a leader of the Israeli youth, did not like the idea of ‘defiling’ his body with royal food, which we can only guess might have been rich in meat and alcohol. So Daniel made a counter proposal: a 10-day trial in which the Israelis would be given only pulse (chickpeas, lentils, beans) and water. The result, variously translated, was that after 10 days the King found that “in all matters of wisdom and understanding, that the king inquired of them, he found them ten times better” than the royal youth. In other words, diet affected brain function! (Side note: many Christians now recommend a ‘Daniel diet’ for weight loss and health - google it!)
  2. What was the view of the ancient Greeks toward food and nutrition? Is there any quotation more frequently attributed to Hippocrates than this one? “Let food be thy medicine, and medicine be thy food.”
  3. Do we know how people in the modern era viewed nutrition and mental health prior to the explosion of pharmaceuticals in the mid-20th century? Mrs. Beeton’s Book of Household Management, first published in 1861, provided a guide to running a household in Victorian Britain. This 1112-paged tome mostly contains recipes but also has sections on how to manage children, the servants and properties, as well as a section dedicated to how to keep well (a large portion of which discusses the role of food). A section devoted to “invalid” cookery shows the wisdom of the time about the importance of diet: “Diet can often cure where drugs are useless or worse. Diet is always harmless where drugs are usually dangerous. Every year diet plays a larger part in the skilled treatment of disease. And yet we often see unskilled women, who would hesitate before changing their children’s diet from roast meat and milk puddings, more than before pouring down their throats all manner of powerful medicines. For the majority of common ailments, some slight change of diet is by far the best remedy.” For the most part, Mrs. Beeton was talking about the treatment of physical ailments; however, she also appreciated the role that food played in the expression of psychological symptoms: “If we consider the amount of ill-temper, despondency, and general unhappiness which arises from want of proper digestion and assimilation of our food, it seems obviously well worth while to put forth every effort, and undergo any sacrifice, for the purpose of avoiding indigestion, with its resulting bodily ills.”
  4. Are there North American examples of Mrs. Beeton-type wisdom from prior to the current age of pharmaceuticals? Thanks to a miraculous ‘find’ by a former research assistant, we know this: mental illness was believed to be due to (and this is adirect quote!) “imperfect nutrition.” We found this information in a major reference used throughout the American west of the 19th century, and the prairie provinces of Canada of the same period. The 1910 book is called the People’s Home Library: it was a source of in-depth, practical knowledge, especially for those homesteading and living far from health care for themselves or their livestock. In three volumes, the People’s Home Library taught you how to cook, treat various medical ailments, make soap, increase your supply of breast milk, build a house, care for your livestock, and much more. When we found a copy in rural Alberta about ten years ago, we were curious to know about mental illness. In the index, we found ‘acquired insanity,’ pointing to text that said: the number one cause of acquired insanity is imperfect nutrition. And by the way, we mentioned above that there were three volumes. One of them is entirely recipes (the other two are about medical and livestock issues). Food was always known to be important, including for mental health.
  5. Has ‘processing’ of food always resulted in a poorer diet? Perhaps some of us heard our grandparents talk about how they ate prior to World War II, before processed food became widely available. Some will recall their attitude that food processing (in particular, preservation by canning and freezing) improved our nutrition enormously. It enabled the population-at-large to eat vegetables all year round that otherwise were available only in the summer. But the early days of ‘processing’ that broadened accessibility of fruits and veggies gradually gave way to packaged food. And in a future post, we will review some of the research comparing the mental health of people who eat mostly processed food to the health of people who eat a traditional diet.

So are we saying that our ancestors already knew that nutrition was a big part of the mental health picture? YES.  In fact, we would go so far as to say that it was only the pharmaceutical era that really eclipsed the rich historical knowledge that our ancestors had about the importance of food for maintaining good mental health.

First published in Mad In America

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