If you're like most consumers trying to do the right thing, you have probably spent time pondering the nutritional merits of many foods.

Are Cheerios better than shredded wheat? Is whole-wheat bread more nutritious than rye or pumpernickel? How does orange juice stack up against pomegranate and V8? And if the choice at the vending machine is between a bag of pretzels, trail mix or a granola bar, which do you buy?

Nutrition scientists are stepping up to the plate to help make your food choices easier, and perhaps healthier, with nutrient profiling.

"If you want sweets and fats, which ones should you choose?" asks Adam Drewnowski, a University of Washington professor who heads the Nutrient Rich Foods Coalition (www. nutrientrichfoods.org), one of the U.S. groups developing nutrient profiling. "If you want cuts of meat, should it be ground beef or ground turkey? We're going back to this notion of helping the consumer decide within the categories."

Think of it as eating by numbers. And it goes beyond counting calories. Here's how it works. Researchers use mathematical calculations to score foods based on their nutritional merit. The more nutrients a food has, the better it rates. Accordingly, foods that have added sugar, salt, trans fat and other less healthy ingredients lose points.

Fruit and vegetables get stellar scores -- as long as they aren't deep-fat fried or loaded with added sugar. Other nutritional standouts include dried beans, brown rice, skim milk, salmon, skinless chicken breasts, lean flank steak and unsalted nuts.

Olive and canola oils snag better scores than butter, which contains saturated fat. And they all rate higher than partially hydrogenated oils -- a source of artery-clogging trans fat.

But what about the thousands of other products, from applesauce to frozen dinners? What's the best way to rate those? Should whole-grain blue corn tortilla chips prepared with canola oil rank as a healthier choice than baked chips made with highly processed white potatoes? Are eggs better to eat than pepperoni? Where does cost factor in? And what symbol or number should be used to best guide consumers to smart choices?

Those are the kinds of variables that scientists are weighing as they measure the pluses and minuses of various nutrients.

The Nutrient Rich Foods Coalition -- sponsored by 12 commodity food groups, including the California Avocado Commission, the Egg Nutrition Center and the Florida Department of Citrus -- scores food not just on nutrients, but also by serving size. Cost is also part of the group's scoring.

"We want to reflect the total nutrient package," says Drewnowski, whose advisory board includes the head of the 2005 U.S. Dietary Guidelines and a former Department of Agriculture undersecretary. "We are going for simplicity and transparency."

Designers of the Overall Nutritional Quality Index (www.onqi.com) have taken a different approach. Led by David Katz, director of the Yale Griffin Prevention Research Center, this group of scientists was assembled in secrecy to avoid outside influence. Funded initially by foundation money, Katz has now gotten funding from Topco Associates, a group of 62 supermarkets, food wholesalers and food service companies with 13,000 stores.

The ONQI (pronounced "on-key") equation has not yet been made public, but Katz says that it uses 30 nutrients to rate food from 1 to 100. "We have scored 20,000 foods at this point," he says. ONQI is slated to be rolled out in about 1,000 Topco member stores in August.

Working well in New England

Nutrient profiling is already working well at Hannaford, a New England chain of grocery stores that launched a "Guiding Stars" program in 2006 to help consumers make smart choices. Developed by a team of scientists from leading institutions, the program is based on U.S. and international nutrition guidelines.

Foods with good nutritional value get one star; better nutritional value, two stars, and best nutritional value, three stars. At the deli counter, meats and cheese go starless but garlic and herb tortellini get one star, cranberry walnut side salad snags two stars and tabbouleh gets three.

Based on buying patterns, consumers seem to like it. In the program's first year, sales of packaged foods with stars rose 2.5 times more than those without them. Breakfast cereals and yogurt with stars increased 3.5 times compared with products with no stars. Sales of higher-fat ground beef without stars declined by 5 percent, while packages with stars rose by 7 percent.

"This is just the opening of the door," says Drewnowski, who envisions a day when consumers may be guided by their PDA or cell phone to the best food choices for their tastes and budget. He imagines someone telling their handheld device: "I want to have the most nutritious foods I can and I have only $10 for dinner."

You can subscribe to the free Lean Plate Club e-mail newsletter at www.leanplateclub.com. Sally Squires is a writer for the Washington Post.