The ‘Right’ Way To Eat Your Vegetables?

By now, most people know they should be eating more vegetables. But are there ways to get more from the vegetables you already eat? A growing body of research shows that when it comes to vegetables, it’s not only how much we eat, but how we prepare them, that influences the amount of phytochemicals, vitamins and nutrients that enter our body.

The benefits are significant. Numerous studies show that people who consume lots of vegetables have lower rates of heart disease, hypertension, diabetes, eye problems and even cancer. The latest dietary guidelines call for 5 to 13 servings - that is two and a half to six and a half cups a day. For a person on a 2,000-calorie-a-day diet, this translates into nine servings, or four and a half cups a day. But how should they be served?

Surprisingly, raw and plain vegetables are not always best. In The British Journal of Nutrition, researchers report a study involving 198 Germans who strictly adhered to a raw food diet, meaning that 95 percent of their total food intake came from raw food. They had normal levels of vitamin A and relatively high levels of beta carotene. But they fell short when it came to lycopene, a carotenoid found in tomatoes and other red-pigmented vegetables that is one of the most potent antioxidants. Nearly 80 percent of them had plasma lycopene levels below average. “There is a misperception that raw foods are always going to be better,” says Steven K. Clinton, a nutrition researcher and professor of internal medicine in the medical oncology division at Ohio State University. “For fruits and vegetables, a lot of times a little bit of cooking and a little bit of processing actually can be helpful.”

No single cooking or preparation method is best. Water-soluble nutrients like vitamins C and B and a group of nutrients called polyphenolics are often lost in processing. Studies show that after six months, frozen cherries have lost as much as 50 percent of anthocyanins, the healthful compounds found in red and blue fruits and vegetables. Fresh spinach loses 64 percent of its vitamin C after cooking. Canned peas and carrots lose 85 percent to 95 percent of their vitamin C.

Fat-soluble compounds like vitamins A, D, E and K and carotenoids are less likely to leach out in water. Cooking also breaks down the thick cell walls of plants, releasing the contents for the body to use. That is why processed tomato products have higher lycopene content than fresh tomatoes. In January, a report in The Journal of Agriculture and Food Chemistry concluded that boiling was better for carrots, zucchini and broccoli than steaming, frying (the worst choice)or serving them raw.

A March 2007 study in The Journal of Food Science looked at the effects of cooking on the nutrients in broccoli. Steaming and boiling caused a 22 percent to 34 percent loss of vitamin C. Microwaved and pressure-cooked vegetables retained 90 percent of their vitamin C.

What accompanies the vegetables can also be important. Studies at Ohio State measured blood levels of subjects who ate servings of salsa and salads. When the salsa or salad was served with fat-rich avocados or full-fat salad dressing, the diners absorbed as much as 4 times more lycopene, 7 times more lutein and 18 times the beta carotene than those who had their vegetables plain or with low-fat dressing. Because nutrient content and taste can vary so widely depending on how a vegetable is prepared, the main lesson is to eat a variety of vegetables prepared in a variety of ways. “Putting on things that make it taste better — spices, a little salt — can enhance your eating experience and make the food taste better, so you’re more likely to eat vegetables more often,” Dr. Clinton said.

Gil GradisarPresident, PrevaHealth