CREDIT: JOEL BEZ
The nutritional content of vegetables drops significantly when boiled.

Since we were little, our mothers always told us to eat our vegetables in order to be healthy. In the old days, little thought went into how food was prepared and the impact it would have on the nutritional value of it. Today, there is much controversy in the media about the nutritional content of cooked foods versus raw foods, processed food and other methods used when storing and transporting foods. With every TV show, newspaper article and magazine telling you something different, it can be quite confusing to understand what the science actually says about what we should do with our food before it is consumed. In this article, I'll try to clear up some of the mystery surrounding food preparation.

Firstly, it must be mentioned that our body needs a variety of vitamins and minerals to be healthy, according to the Centers for Disease Control; many of these nutrients are found in the fruits and vegetable servings recommended by Canada's Food Guide. People consume fruits and vegetables a number of ways: frozen, dried, cooked, boiled and drained, and reheated after cooking.

The most common methods of preparing vegetables is cooking or boiling then draining. Cooking your vegetables can cause you to lose as much as 40 per cent of your minerals and 70 per cent of your vitamins. According to NutritionData, boiling and draining can cause a loss of up to 70 per cent of your minerals and 75 percent of your vitamins! This means that if you buy frozen vegetables and then boil them, there is almost no nutritional value left in them at all! In addition to this, reheating previously cooked vegetables can cause a loss of 10 to 40 per cent of the remaining vitamins, although it does not seem to affect mineral content. (For a full list of nutrient losses, check out nutritiondata.self.com/topics/processing.)

What about frozen fruits and vegetables? Research shows that some vitamins and minerals (riboflavin, niacin, B6, B12, iron, magnesium and copper) are not lost at all during freezing; however certain vitamins like vitamin C can show as much as a 30 per cent reduction after being frozen. In addition, some minerals like copper and potassium are lost at a rate of 10 per cent when frozen. Other vitamins and calcium are lost at a rate of 5 per cent.

Studies conducted on dried fruits and vegetables show that minerals aren't typically lost during the drying process, but most vitamins are lost at a rate of 50 per cent! In the case of vitamin C, a typical loss during drying is 80 per cent.

So we should eat all of our fruits and vegetables raw then, right? WRONG! Studies show that while cooking vegetables shows a reduction in the mineral content, eating fruits and vegetables raw makes it tough for our bodies to extract some vitamins in them, particularly beta carotene or vitamin A and other carotenoids, according to an article in the Journal of Nutrition. Carotenoids are very important nutrients because they are anti-oxidants, which neutralize free radical in the cells (electrons that cause damage) and fight some diseases like cancer, according to an article on beyondveg.com. Research in the Journal of Nutrition suggests that lightly heating or steaming vegetables makes it easier to extract these carotenoids. Since steaming still reduces some vitamins like vitamin C, according to an article in Scientific American magazine, it would make sense to eat a combination of cooked and raw fruits and vegetables in order to receive optimal nutrients.

As the old saying goes, "variety is the spice of life"; this is definitely true when it comes to food preparation. It is important that you not only have a variety of foods, but also that they are prepared in a variety of ways.

In closing, it should also be mentioned that the food preparation techniques discussed are for optimal nutrient absorption, however when certain barriers are present (time, access to fresh fruits and vegetables, etc.), the important thing is just that you are eating. Remember, some nutrients are better than NO nutrients; however, the more nutrients you absorb on a daily basis, the higher the chance that your body can fight off certain diseases like cancer.

Jason Doyle is a Fitness and Health Promotion student at Fanshawe College.