Teeth whitening is the No. 1 requested cosmetic service, and its popularity continues to soar, according to a 2011 survey by the American Academy of Cosmetic Dentistry.

Typically, we pay cosmetic dentists $200 to $500 for at-home tooth whitening and $500 to $1,000 for in-office procedures.

Outside the dentist’s office, it’s every bit as popular. Americans spend billions every year on over-the-counter teeth-whitening products.

But there’s an easier, cheaper and natural approach: the right diet.

‘Toothbrush foods’ to eat

Apples, fresh green beans, cauliflower, carrots, celery and other crunchy fruits and vegetables help whiten by gently scrubbing the teeth. That’s why crudités — sliced, fresh, raw veggies — are a great snack, says New York City cosmetic dentist Timothy Chase. Bonus: Fibrous fruits and vegetables are low in calories, high in nutrients and massage gums and promote blood flow to help keep gum tissues healthy. They also increase flow of saliva, “the magic fluid” that helps protect oral health.

Strawberries and oranges work to polish teeth. Strawberries also contain an enzyme called malic acid that helps keep teeth whiter, adds Vincent Mayher, a spokesman for the Academy of General Dentistry.

Cheese and other dairy foods, such as yogurt and milk, contain a type of lactic acid that helps prevent decay. Hard cheeses also scrub teeth, Chase says.

Staining foods to avoid

You know the worst stainmakers: tea, coffee, blueberries, red wine, soy sauce, colas. Here are some surprises:

White wine can promote staining because it contains tannins and acids that etch tooth surfaces, notes Mark Wolff, professor and chairman of the Department of Cariology and Comprehensive Care at New York University College of Dentistry. Spirits are generally not acidic, he says, unless mixed with acidic beverages in cocktails such as screwdrivers (vodka and orange juice) and cosmopolitans (vodka with cranberry and lime juice).

Sports drinks and sodas, regardless of whether they’re regular or sugar-free, are also high in stain-promoting acids.

If you do eat foods that stain

Many people — including the dentists we talked to — won’t give up staining foods. What then?

Water works to reduce staining. Drink water with meals and rinse your mouth with water after eating, Chase advises. That’s not a dentist’s-office-style “rinse and spit” maneuver — just sip and give a final swish (and swallow) after a meal.

Sugar-free gum can help clean teeth “in a pinch,” Chase says, when you won’t be able to brush for a while. Xylitol (artificial sweetener) in some sugar-free gums also helps prevent decay.