While the quintessential pairing of ripe tomatoes and lettuce is certainly enjoyable, a good salad can be so much more. Adding fruits, nuts, and other well-chosen ingredients offers a welcome change. More importantly, incorporating a few more nutritious ingredients is an easy way to serve a more healthful dish.

Salad building blocks

These components add significant nutritional benefits. Choose among them to suit your palate and your needs.

Greens

What they add: Most leafy greens contribute folate, the B vitamin critical to red blood cell health and the

reduction of neural tube birth defects like spina bifida. Also, they provide generous amounts of vitamin A and the antioxidants lutein and zeaxanthin, which may help protect against macular degeneration. CookingLight: Test your nutrition know-how

Good to know: Lutein is better absorbed when combined with a splash of oil, particularly olive oil, according to a 2007 preliminary study with animals from the Journal of Agriculture and Food Chemistry. So a classic vinaigrette not only tastes great on your salad, but it may also help you absorb more nutrients. MyRecipes:Sautéed tuna and green onion stalks on romaine

Fruits

What they add: All fruit provides abundant good nutrients (vitamin C and potassium, in particular) and a laundry list of disease-fighting chemicals in a package that's naturally low in fat, sodium, and calories. Blueberries contain polyphenol (a phytochemical linked to heart disease and cancer prevention) compounds called anthocyanins and proanthocyanins that may play a role in preserving memory. Grapes also offer polyphenols.

Good to know: The fiber in fruits can help lower blood cholesterol levels and reduce risk of heart disease. For example, one cup of blueberries has nearly four grams of fiber, and one medium apple yields five. MyRecipes: Mesclun with berries and sweet spiced almonds

Nuts and seeds

What they add: One-fourth cup of nuts or seeds adds nearly five grams of high-quality protein, as well as generous amounts of vitamin E, fiber, minerals, and arginine, a compound that helps blood vessels to function. Nuts are high in fat, the healthful unsaturated kind. CookingLight: In search of the perfect food

Good to know: A report in Harvard Men's Health Watch suggests that as little as two ounces of nuts per week might lower your risk of heart disease. "Adding nuts to a balanced, healthful diet can take you one step away from heart disease," says editor Harvey B. Simon, MD, an associate professor of medicine at Harvard Medical School. MyRecipes: Arugula, grape, and sunflower seed salad

Tomatoes

What they add: With plenty of vitamin C, some blood pressure--lowering potassium, and folate, tomatoes also impart the plant chemicals flavonoids (potential cancer fighters) and phytosterols (which may help lower cholesterol).

Good to know: Lycopene, an antioxidant in tomatoes, is under question as a cancer fighter. The 2006 Prostate, Lung, Colorectal, and Ovarian Cancer Trial found no protective benefits from a greater lycopene intake. Harvard researcher Edward Giovannucci, MD, still thinks there's plenty of evidence to tag this favorite salad fruit as a "probable" cancer fighter and suggests tomatoes may have other beneficial ingredients "and, conceivably, complex interactions among multiple components may contribute to the anticancer properties." MyRecipes: Mixed herb salad

Onions

What they add: Onions are plentiful sources of disease-fighting phenols and flavonoids, both potential cancer fighters and weapons against some chronic diseases. The richer its phenolic and flavonoid content, the better an onion's protective effect, according to Rui Hai Liu, MD, PhD, an associate professor of food science at Cornell University. CookingLight: All-star foods that fight for health

Good to know: In a 2004 study, Liu looked at 10 varieties of onions and found shallots have six times the phenolic content of sweet Vidalia onions, the lowest on the scale. Pungent yellow onions and red onions also measured high. MyRecipes: Escarole-arugala salad with roasted peppers and marinated onions

Vegetable oils

What they add: Liquid vegetable oils are rich in vitamin E and unsaturated fats (monounsaturated and polyunsaturated), which don't clog arteries. Olive oil is particularly rich in phenol antioxidants.

Good to know: Look for virgin or extravirgin varieties of olive oils, states a report last August in Mayo Clinic Women's HealthSource. The freshest oils (check to verify that the bottling date is less than a year old) and virgin or extravirgin olive oils tend to be richest in antioxidants. MyRecipes: Mixed greens with blueberry vinaigrette

Seafood and other proteins

What they add: Fatty fish like salmon or tuna offer omega-3 fats, which help lower the risk for heart disease. The American Heart Association suggests eating at least two three-ounce cooked servings of fish per week.

Good to know: Fish, skinless chicken, or small amounts of cheese can also help boost the protein content of salads. According to a 2007 study from Purdue University, increased protein improves satiety at meals.