Sandwiches aren't just an important part of the American diet; they are essential to it. And lucky for hungry consumers, sandwiches are undergoing exciting flavor and quality upgrades on every level -- carriers, fillings and condiments.

New sandwich trends are driven by artisan and sustainable ingredients, American regional and global flavor profiles, and even better nutrition, according to the "Sandwiches: Culinary Trend Mapping Report" from theCenter for Culinary Development(CCD) and market research publisherPackaged Facts.

"The role of sandwiches in people's lives is huge," says Kimberly Egan, CEO of CCD. "It makes sense that redefined sandwiches reflect the same values consumers are embracing in their lives."

These values include supporting artisan and sustainable food production, eating more seasonally and nutritionally, and celebrating regional and global foods and flavors.

Study authors say today's top sandwich trends include:

The "Fine Fast" Sandwich Shop: Gourmet sandwich shops helmed by chefs feature high-quality, artisan and locally source ingredients along with a wide range of house-made condiments and toppings.

The Asian Sandwich Invasion: Chinese bao sandwiches and Vietnamese bahn mi are crossing over and attracting adventurous eaters craving new flavors.

The Reinvented Jewish Deli:Traditional delis are re-inventing themselves with more sustainable and ethical raw ingredients.

Glamorous Grilled Cheese: This American classic is getting an overhaul with artisan bread and cheese plus sophisticated flavorings.

The Great Sandwich Shop Takeover: Fast-casual sandwich and bakery chains are innovating with more healthful offerings, global flavor profiles and even some local ingredients.

Pulled Pork Sandwiches and Better Burgers: While the North Carolina classic goes national, the beloved burger explodes with new styles of beef, a variety of tasty buns and a host of exotic toppings.

The Center for Culinary Development, San Francisco, is a food and beverage strategic innovation company specializing in consumer insights, trends and marketing expertise.

Packaged Facts, New York, N.Y., is a division of MarketResearch.com. Packaged Facts publishes market intelligence about consumer goods and retailing, foods and beverages, demographics, pet products and services, and financial products.