Seth Perlman / AP file A farmer harvests corn near Farmingdale, Ill.

Newly disclosed documents in a legal battle over the taste buds and wallets of sweet-toothed American consumers show that some of the nation’s largest agri-business companies forged ahead with a plan to rebrand high-fructose corn syrup as “natural … corn sugar” despite misgivings among some senior executives.

Emails outlining the reservations were included in a half-million-page trove of previously confidential court documents made public in advance of a procedural hearing Thursday in a pair of high-stakes federal lawsuits pitting the corn syrup manufacturers against sugar companies.

The sugar companies, led by the Western Sugar Cooperative, sued the Corn Refiners Association in 2011, alleging that giant food makers -- including Archer Daniels-Midland, Cargill Inc., and Tate & Lyle – engaged in a $50 million ad campaign to promote high-fructose corn syrup as “corn sugar,” while describing it as “natural” and “nutritionally the same as sugar.”

The corn refiners filed a counter claim in September 2012, alleging that the sugar companies were themselves deceiving consumers by engaging in what they called a decade-long “spin and smear conspiracy” aimed at damaging corn syrup’s reputation.

Hundreds of millions of dollars could ride on the outcome, depending on whether public attitudes shift as a result of the case. While high-fructose corn syrup remains a mainstay in soft drinks and many other sweetened food products, particularly baked goods, some makers have been returning to sugar after some studies linked consumption of high-fructose corn syrup to health problems such as diabetes and obesity.

At the center of the court dispute is a “Sweet Surprise” print, online and television ad campaign launched by the Corn Refiners Association in June 2008, which touted high-fructose corn syrup as natural and equivalent to sugar. Corn refiners argue that the campaign was intended to educate the public after sugar firms tricked consumers into believing the former was a safer, more healthful alternative to high fructose corn syrup.

But emails included in the newly revealed court records show some executives in the corn syrup camp debated the wisdom of making the “natural” case to consumers.

"I think we're unnecessarily asking for trouble by using the ‘natural’ language," Archer Daniels-Midland spokesman David Weintraub wrote in a previously "confidential" Feb. 3, 2010, memo that included the term "Marketing Ploy" in the subject line.

"I don't think we really gain much in the mind of the audience or customers and I think it provides a point to ridicule the ads and the industry comes off as being disingenuous ("How can something that comes from a big chemical factory really be natural?" said Maddow/Olberman/whomever.) Weintraub added that while the “claim is true,” that “doesn’t mean we have to say it … and I don’t think it gets us much.”

Several months later, Weintraub described the name change in an email as "dishonest and sneaky."

About the same time, a Tate & Lyle executive Matthew Wineinger expressed “concerns” over two upcoming corn sugar television ads, referencing a separate and unrelated lawsuit by the sugar manufacturers against the makers of Splenda that was resolved in a settlement for an undisclosed amount.

“Knowing and understanding how the sugar industry sued Splenda Sucralose over their tagline several years ago, do you have any concerns about how we use Sugar here?” the company official said.

Stephen D'Amore, an attorney representing the corn syrup manufacturers, said the emails merely reflect a healthy debate among pariticpants over the campaign.

“What the emails clearly show is the corn refiners engaged in a rigorous internal discussion about the public relations aspects of what HFCS is called, while never wavering in their core belief that high fructose corn syrup is both natural and nutritionally equivalent to sugar,” he said.

A different concern was aired by in an April 2009 email by Audrae Erickson, then president of the Corn Refiners Association.

In the email, Erickson defended the campaign, noting that it was not surprising “that the food and beverage industry would want to defend this highly versatile ingredient that is highly prized and widely used in the food and beverage supply.”

But she also noted that it was important that the Corn Refiners Association remain out of the limelight, saying, “Our sponsorship of this campaign (should) remain confidential.” (Erickson did not immediately respond to a request for comment from NBC News.)

The industry followed its ad campaign by petitioning the U.S. Food and Drug Administration in September 2010 to be allowed to change the name of high-fructose corn syrup to “corn sugar.” That request was rejected in May 2012.

By that time, the sugar industry already had taken the corn refiners to court, alleging false and misleading advertising for using the term “corn sugar” and claiming that there was no difference between high-fructose corn syrup and sugar, despite “numerous scientific publications that have reached the opposite conclusion.

The corn refiners, in their countersuit, accused the sugar industry of using a “discredited study” to tie high-fructose corn syrup to the national “obesity crisis.”

The interlocking cases are a long way from resolution.

Adam Fox, an attorney representing the sugar manufacturers, said late Wednesday that for his side, the next chapter in the case revolves around removing what he described as “broad, indiscriminate confidentiality designations made by the defendants and their allies.”

“People can form their own conclusions about why the defendants followed this strategy,” Fox said.

As for the corn syrup camp, D’Amore indicated that his team would focus on undercutting some of the science cited by the sugar manufacturers.

“The Sugar Association … scientist internally warns that certain studies are ‘totally flawed’ and should not be cited, yet the Sugar Association and its operatives go ahead and use those studies as part of a 10-year attack campaign against high fructose corn syrup,” he said. “… The Sugar Association and its operatives seek to attack high fructose corn syrup as a means to boost profits.”

Stan Goldman, a professor at Loyola Law School in Los Angeles, said the dispute boils down to the legal question of whether the corn syrup campaign was educational or commercial.

“It’s clearly connected to commerce in one form or another, and there’s a reason why,” he said. “With respect to commerce, the U.S. Supreme Court generations ago allowed the government to have greater authority and latitude from potentially harmful commercial speech as compared to political or other forms of speech.”

Whatever the outcome, he said, the documents made public as a result of the lawsuits may ultimately benefit the public by shedding light on the efforts to influence their eating habits.

“Even when you have a battle of titans of industry, occasionally the public ends up benefiting,” Goldman said. “Not always, but sometimes.”

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