For today’s nutrition scientists, one plus one equals three. It’s not just about eating the right foods any more: the “superfoods,” such as broccoli, sweet potatoes, almonds and blueberries. These days, it’s also about how you put them together.

Food synergy is a new concept in the field of nutrition science, and it stems from recent research that suggests the nutritional values of some foods can be enhanced through particular food combinations.

“It’s not that one nutrient doesn’t work; it’s that two or three work better,” says dietitian Elaine Magee, author of “Food Synergy” (Rodale, $19.95).

The amount of a nutrient that can be usefully absorbed from a particular food is known as bioavailability. Food synergy deals with the combinations of biochemically cooperative foods that increase bioavailablity.

Increasing the bioavailability of iron, a mineral essential to human health, is a good example of how synergistic combinations work. The World Health Organization lists iron deficiency as “the most common and widespread nutritional disorder in the world,” and it estimates that nearly a third of the global population is anemic.

Most of us know that spinach is a good source of nutritional iron, as are most dark leafy greens. But the iron in vegetables is harder for the body to absorb than the iron in meats and eggs. By adding a few orange or grapefruit segments to a spinach salad, the bioavailability of the iron in spinach gets a significant boost.

“The iron in meats, fish and eggs (heme iron) is more readily absorbed than the iron in plants (non-heme iron),” says Carol Gilmore, assistant director of food and nutrition at Lawrence Memorial Hospital. “Citrus, or vitamin C in some form, sets up conditions within the body that can allow for increased absorption of non-heme iron.”

Coffee and tea, it should be noted, have the opposite effect.

With the addition of a healthful fat — olive oil, nuts or avocado — the nutrient bioavailability of your spinach-citrus salad jumps yet another notch. Ironically, a fat-free salad dressing actually inhibits absorption of the iron in your spinach salad, while a healthful fat acts as an efficient carrier for nutrients.

Sorting through all the new research to find the right food combinations can be a bit daunting. Here are some proven synergistic food pairings:

• Broccoli and tomatoes: Both contain cancer-fighting properties, but a study at the University of Illinois indicates that the tumor-inhibiting effects are greatly enhanced when broccoli and tomatoes are consumed together.

• Good fats with raw salads and vegetables: Small amounts of good fats — olive oil, avocados and avocado oil, and nuts and nut oils (especially walnut) — facilitate the body’s absorption of antioxidants and other essential nutrients.

• Rosemary with grilled foods: The high heat of grilling activates cancer-causing compounds (HCAs) in ground beef and other meats. A 2005 study at Kansas State University found that adding rosemary to grilled meats can reduce HCA formation by up to 80 percent.

• Whole-grain breads and peanut butter: The amino acids that are lacking in wheat are available in peanut butter. The combination of the two supplies all the amino acids the body needs for efficient protein synthesis.

• Apply heat to tomatoes: Tomatoes contain lycopene, a potent form of antioxidant that combats aging, stroke and heart disease. Cooking or canning tomatoes, or using tomato paste, can increase the bioavailability of lycopene by 500 percent.

Most food synergists recommend “a colorful plate”: three different colors of vegetables accompanied by a small amount of protein and a healthful fat, advice in keeping with tried-and-true nutritional knowledge.

“Eat a varied diet,” Gilmore says. “A variety of nutrients increases the supporting mechanisms that aid in absorption.”