Brands catering to Hispanic culture or Hispanic consumers are never too quiet about touting their supposed authenticity.

El Pollo Loco boasts Mexican food that's "steeped in tradition," Corona beer-maker Constellation Brands flexes its lead among Hispanic drinkers, while Chipotle labels itself a "Mexican Grill."

And yet, in taking a closer look at who exactly leads these "Hispanic" companies at the highest level, a Yahoo Finance review revealed a shockingly low representation of Hispanics among their respective boards — echoing a larger diversity problem for the entire Fortune 500.

Mexican fast casual chains Del Taco (TACO) and Chipotle (CMG) each only have one Hispanic board member among their ranks. Constellation Brands (STZ) lists two Hispanic board members, while El Pollo Loco (LOCO) continues to lack any Hispanic representation at all.

At an average of just 12% Hispanic board representation, those companies only marginally top the disproportionally low representation among Fortune 500 boards. According to an annual review by Deloitte and The Alliance for Board Diversity, only about 4% of all board seats at Fortune 500 companies are held by Hispanic directors.

Adjusting for U.S. adult population demographics, Hispanics are by far the least represented in the board room for any racial or ethnic group. White Americans, meanwhile are overrepresented in the board room, with 82.5% of all Fortune 500 board seats despite comprising just 64% of the adult U.S. population.

The lack of Hispanic representation in the board room has persisted for years and only recently started to see marginal signs of improvement, according to Esther Aguilera, CEO and president of the Latino Corporate Directors Association. The operative word there is "marginal" since she says there is still such an enormous gap to close. Even in California, where a new law requires at least a minimum level of diversity representation on boards, Latinos still only comprise 2.5% of company board seats despite making up the state's largest demographic cohort with 39.4% of California's population.

"The numbers are awful," she said. "Though there was a four fold increase in [board] appointments, in the first six months of this year, it's still less than what we're seeing with other communities."

Part of the slow change, Aguilera says, has stemmed from slow board turnover, and a misconception that there aren't qualified Hispanic candidates that could be fit to fill board seats. Part of the Latino Corporate Directors Association's push to bring awareness to the lack of representation has been augmented by linking up companies with qualified candidates — a combo that has resulted in dozens of director hirings.