A Brief History of Nutrition Science

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).

Some phytochemicals may be valued for their potential to treat certain conditions (allicin from garlic for heart disease, hypericin from St. John's wort for depression), but overall, we get excited about them because they are antioxidants. Antioxidants protect our bodies from damage by free radicals, which are compounds that are produced in the body as a result of aging and from exposure to toxins, pollution, and ultraviolet radiation. They can cause cell damage and illness. Antioxidants protect our bodies from free radicals by neutralizing them.

Now that we have been introduced to the wonders of antioxidants, we just can't get enough of them. Good news: If you are consistently getting a balanced diet with plenty of fruits and vegetables, you should be set up for a long life of health and vitality, promoted by sufficient nutrients and antioxidants. Bad news: Most Americans don't get a balanced diet with plenty of fruits and vegetables. They still want the phytochemicals, just not the foods that produce them.

This has lead to a boom in the dietary supplement industry. They extract the nice antioxidants for us and put them in capsules or add them to breakfast cereals, fruit juice, ice cream-wherever they'll fit. People stock up on these products in the hope that it will make up for their various dietary infractions. Even people who do eat a reasonably balanced diet often assume that more is better and include antioxidant fortified foods and supplements. The thing is, more may just be more, and might even be harmful. A recent review of studies on the effects of several antioxidants on the survival of cancer patients, found that some antioxidants not only were unhelpful in improving patient health, but they were also associated with a greater risk of mortality.

Jane Valentine, RD, an instructor in the Natural Sciences and Health Professions departments at Parkland, worries about the consequences of consuming too many antioxidant-fortified foods or supplements. "My concern is foods that are enhanced with herbal supplements or individual amino acids can actually cause more harm than good. These tend to interfere with different medicines either making them more reactive or less [reactive]... There is very little scientific evidence to back up many of the claims that supplement companies use."

A vitamin pill can be a useful supplement to a reasonable diet, but it is no substitute for healthy eating. The same is true of antioxidants. They are vital and wonderful, but taken alone, without a balanced diet, they benefit the companies that sell them more than the people who take them.