Prospectus

Issue date: 4/15/09 Section: News

Media Credit: Chrissie McKenney

Once upon a time, food was just food. You got hungry: you ate. Although an appreciation of the relationship between diet and health dates back at least as far as Hippocrates ("Let food be thy medicine, and medicine thy food"), no one really understood what was good for you or why, at least not in a physiological, scientific way. Physicians attempted to prescribe diets as remedies for illness, but the process was more like astrology than medicine. Foods were classified as hot, cold, wet, or dry based on an association with one of the four classical Greek elements: fire, air, water, earth. There was a belief that these qualities of food interacted to create "humors" within the body. For example, cold and dry interact to create "black bile" (a humor), which was blamed for liver problems and would be treated with a diet of hot and wet foods. Nutrition science continued in this way for many centuries.

Fast-forward to the modern era. Currently we understand our diet as the source of 6 major nutrients: carbohydrates, fats, proteins, water, vitamins, and minerals. Carbohydrates and fats provide most of the energy. Protein provides building blocks for growth and repair, as well as some additional energy. Water is involved in every stage of digestion and is also necessary for nearly everything else that goes on in the body. The first four categories of nutrients are clearly very important, but our bodies can't use them very well without the last two, the vitamins and minerals. They work with other molecules in our body to allow us to digest and make use of carbohydrates, proteins, and fats.

A shortage of vitamins and minerals in the diet can lead to a range of diseases and disorders, such as goiter (iodine), scurvy (vitamin C), rickets (vitamin D), night blindness (vitamin A), anemia (iron), and pellagra (niacin, a B vitamin). All of these are easily prevented or cured with a little extra dose of the missing nutrient in the diet. Because of this, many foods are now fortified with vitamins and minerals (like adding vitamin D to milk or iodine to table salt).

In trying to understand the relationship between diet and health, nutrition scientists also discovered that a diet high in fruits and vegetables is associated with a lowered risk for chronic disease and some cancers. It seems that, apart from providing many essential vitamins and minerals, as well as a good dose of fiber, plants produce a wide range of compounds that have health-promoting effects in the human body. We call these compounds phytochemicals (phyto = plant).

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