By now, most people are familiar with the golden rule of vegetable consumption: five a day. Although, when it comes to getting the most out of those veggies, many are still stumped. Boil, steam, bake, fry or dry? The options are limitless, but the nutritional differences can be profound — at least that’s what AM found when we looked at different way’s to prepare veggies.
Is raw always best?
Most nutritional scientists will agree that eating vegetables raw is the most efficient way to preserve vitamins, minerals and other important nutrients, but is raw always best? It appears the answer is no. A study published last year in the British Journal of Medicine followed 198 subjects who adhered to a strict raw food diet and found that the participants had low levels of lycopene, an important cancer-fighting antioxidant found in tomatoes, guava, watermelon and red bell peppers. The solution? Heat. Cooking tomatoes for 30 minutes or more has been shown to significantly increase the amount of lycopene compared to raw tomatoes, because the heat breaks down the tomato’s thick cell wall, facilitating the release of this important compound. However, heating isn’t always the solution.
On one hand, cooking veggies such as carrots can increase levels of beta-carotene, a carotenoid that is converted by the body to vitamin A, which plays an important role in vision, reproduction, bone growth and regulating the immune system. On the other hand, canned carrots or peas have been shown to lose up to 95% of their vitamin C from cooking. What’s more, delicate veggies such as spinach break down in no time at all, even at low temperatures. The dilemma of whether or not to cook is therefore far from settled. The issue is even further muddied when trying to decide which cooking method is best.
Which cooking method is best?
Steaming, boiling, microwaving, pressure cooking, and frying are all acceptable methods of cooking your veggies, but when it comes to deciding which is best, the truth is that no single method is tops, and the choice is largely left up to the individual. In January of 2008, a report in The Journal of Agriculture and Food Chemistry concluded that boiling was best for carrots, zucchini and broccoli, better than steaming, frying or even serving raw. Frying was by far the worst, as it can lead to the creation of free radicals — highly reactive compounds that can injure healthy cells. However, a November 2007 study in the same journal found that heating broccoli damages the enzyme myrosinase which is important for the production of sulforaphane, a potential cancer-fighting and ulcer-preventing compound. Making matters even more befuddling, a March 2007 study in The Journal of Food Science touted microwaving as tops, at least when it came to preserving vitamin C. This study found that microwaving and pressure-cooking led to only a 10% loss in vitamin C levels in broccoli, while steaming and boiling caused upwards of a 34% loss. Although — surprise, surprise — a November 2007 study in The Journal of Agricultural and Food Chemistry found quite the opposite.
The bottom line
There are countless examples of studies that flip-flop on which cooking method is best, depending on which veggies are examined and which specific nutrients are being measured. The point then is to enjoy variety. Food is cooked so it tastes better. If it tastes better, you’ll eat more. The same principle applies to adding spices or fatty dressings to food. According to a May 2008 study in The American Journal of Preventive Medicine, one of the largest barriers to young adults eating their greens was taste. If it tastes better, you’ll eat more (and fat may even improve the absorption of certain nutrients). Does all this uncertainty mean that it’s time to throw your hands up in despair? Maybe, or you can just enjoy the idea of mixing things up. If you need a little more specificity, try a few of these tips:
Food For Thought
- Generally, cook foods in the shortest amount of time possible and at lower temperatures; however, as mentioned before, change things up once in a while.
- If boiling, microwaving or steaming, use minimal amounts of water.
- Unless you’re worried about your weight or other health condition, don’t be afraid to add some fat-rich avocados, full-fat dressings or spices to your veggies, so long as it ensures you eat more.
- Leave edible skins on vegetables when possible (important nutrients may be lurking within).
- Lastly, save the water used when boiling vegetables and use it in soups, stews, gravies, and sauces.