Vegetables Still Simple


On June 25, a paper published in the journal PLOS ONE revealed that Neanderthals included plants, tubers and berries in their diet. The authors, a group of American and Spanish scientists, analyzed prehistoric excrement from a roughly 50,000-year-old Neanderthal settlement and found the presence of a plant-based biomarker. Food was simple back then and primitive humans ate whatever fruits and vegetables were available, raw and fresh.

Today, it is common knowledge that vegetables are “good.” Food is not only linked to health, but also intertwined with psychology, politics and science. As such, there are many different opinions regarding vegetables, with the chief disagreement being how preparation, cooking or storage methods affect the nutrients in them.

A majority of people agree that most vegetables, when boiled, lose their nutrients to the waters, and others believe that cooking vegetables in microwaves also reduces their nutritional value. While almost every American household has one microwave oven, not many understand the way it works, but this knowledge is the key to understanding why microwave cooking takes less time, which in turn explains why more nutrients are actually preserved in the microwave oven.

The waves used by microwaves to cook food are similar to radio waves, but are faster in the frequency in which they oscillate. They are remarkably selective and only affect polar molecules like water, which has molecules with one positively charged end and one that is negatively charged. The microwave oven works by energizing (thus heating up) water molecules, which in turn energizes their molecular neighbors. These waves also penetrate more quickly than the heat from an oven or stovetop by immediately reaching molecules about an inch below the surface, in comparison to the slow conduction process of moving outside heat inward.

Food was also simple for prehistoric humans because they rarely had the luxury to think about what to do with leftovers. In modern society where time is short, those who have time to cook tend to cook more for later consumption. Some believe this practice to be deemed harmful for dark leafy vegetables, claiming that the nitrates in these vegetables are then converted to nitrites that are linked to cancers.

Nitrates and nitrites are used in curing meats and are usually blamed for the health risk from consuming processed meats, but many dark leafy greens contain high amount of these compounds, too. Bacteria indeed turns nitrates into nitrites in leftover vegetables, but the conversion from nitrates to nitrites occurs in other parts of the lifecycle of the vegetables. An enzyme within vegetables also does the conversion before cooking, and bacteria in the mouth and gut chemically do so during eating and digesting.

Harm is only done when nitrites react with certain dietary amines to produce nitrosamines, a known carcinogenic compound, and not just from the mere presence of nitrites. In order for this harmful conversion to happen, high heat such as frying or a high acidic environment, such as the condition in the human stomach, is needed. Vitamin C is shown to prevent this conversion, therefore vegetables which naturally pack many vitamins and minerals are themselves the antidotes to the formation of nitrosamines.

Although food was a simple matter before the appearances of microwave ovens and refrigerators and their associated confusions and concerns, vegetables still remain simple. Microwaving dark leafy greens and saving leftovers for the next day remains a healthy option.

By Tina Zhang


NBC Science News
The Harvard Medical School
Center for Food Safety
The American Journal of Clinical Nutrition
The Linus Pauling Institute

You must be logged in to post a comment Login