Food pairings: Working for or against you?

(Real Simple) -- Certain foods play well with others, while others lose strength in pairs.

Toothsome twosomes to watch out for:

DO mix grilled steak and Brussels sprouts

It turns out that certain compounds in Brussels sprouts (and other cruciferous vegetables, such as broccoli and cauliflower) may help rid the body of carcinogens that can form on meat during high-heat cooking.

That said, loading up on these vegetables doesn't give you license to char meat, chicken, or fish on the barbecue. "It's always best to cook meat or fish at low temperatures until it's done," says Kristin E. Anderson, Ph.D., a cancer epidemiologist at the University of Minnesota's School of Public Health and Cancer Center, in Minneapolis, Minnesota. "And if there are burned pieces, trim them off." Real Simple: No-fuss 30-minute meals

DO mix avocado and tomato

Tomatoes, which contain the antioxidant lycopene, are a super food. Eat some avocado at the same time and you've got a super super food -- the fat in the avocado helps the body absorb seven times more lycopene.

"Eating a steak or any fatty food with any vegetable can release its antioxidants," says Steven J. Schwartz, Ph.D., professor of food science at Ohio State University in Columbus. "But small amounts of healthy unsaturated fats are a better choice."

So add a little extra-virgin olive oil to your zucchini, spinach, and other dark green vegetables to unleash the carotenoid lutein, an antioxidant that may help protect against age-related macular degeneration. And instead of using fat-free dressing on your salad, drizzle on an olive oil--based one.

DO mix spinach and oranges

Although spinach has lots of iron, your body doesn't absorb it well when spinach is eaten alone. (Sorry, Popeye.) But with vitamin C by its side, this vegetable becomes a true standout.

That's because vitamin C converts the iron in spinach into a form that is more available to the body, says Liz A. Applegate, Ph.D., director of sports nutrition at the University of California, Davis.

This holds true for other vegetarian sources of iron, too, such as broccoli and tofu. It doesn't take a lot of C, either. One medium orange will do. You could also add to a spinach salad half a red pepper, several thick slices of tomato, or 1/2 cup of sliced strawberries -- all good sources of C. Real Simple: Grocery shopping strategies

DON'T mix alcohol and energy drinks

While you might not chase a vodka tonic with a Red Bull (like certain celebrity party girls), some teens you know might, and you should tell them it can do more than provide a sizable buzz: It can send them straight to the ER.

This unhealthy combo can cause heart palpitations and breathing difficulties. In severe cases, it could even lead to a heart attack or a stroke, says Roger A. Clemens, Dr. P. H., an associate director of regulatory science at the University of Southern California School of Pharmacy, in Los Angeles.

Overloading the body with stimulants like caffeine, which is found in many energy drinks, and alcohol, which is a depressant and a diuretic, puts tremendous stress on the central nervous system and heart. So put at least a few hours between your caffeine and alcohol consumption. Real Simple: Refreshing summer drinks

DON'T mix alcohol and diet soda

Yes, you'll reduce calories by asking for diet soda in your rum and Coke, but you might get drunk faster. In one recent study, it took just 21 minutes for half a diet cocktail to leave the stomach and reach the small intestine, where most alcohol is absorbed into the bloodstream, while the same amount of a non-diet concoction took 36 minutes.

"The calories provided by food or a sugary mixer slow the emptying of the stomach, so you get drunk less rapidly," says Chris Rayner, Ph.D., a gastrointestinal researcher who conducted the study at the Royal Adelaide Hospital, in South Australia.

If you still want to stick with sugar-free but don't want to get the spins, have a small snack beforehand, says Rayner. A few slices of cheese and a few crackers contain a good mix of fat, protein, and carbohydrates and should help slow stomach emptying.

DON'T mix coffee and breakfast cereal

Most cereals sold in the United States are fortified with iron. (A good thing, since 1 in 10 women has low iron levels.) Problem is, if you sip coffee while eating your Wheaties, polyphenols, an antioxidant in coffee, can hamper the body's ability to absorb the iron.

Coffee isn't the only offender. Black tea and some herbal teas (including peppermint and chamomile), which also contain polyphenols, have been shown to reduce iron absorption by as much as 94 percent, and hot cocoa cuts it by 71 percent.

The solution? Pour yourself a cup of java before or after your cereal. According to a study published in the American Journal of Clinical Nutrition, a cup of coffee one hour before an iron-rich meal didn't affect absorption. And if you choose to get your fix after breakfast, wait at least an hour or more.

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