Like most businesses, health and life insurance companies are out to make a buck, and one way they augment their income is by investing in other industries.

But a new study has found that $1.88 billion from this industry is backing the top five publicly traded fast food chains. Excessive consumption of this sort of food has been repeatedly linked to a host of health problems, including obesity and diabetes.

"Life and health insurance firms profess to support health and wellness, but their choice of financial investments has raised doubts," wrote Arun Mohan and his coauthors, all at the Department of Medicine at Cambridge Health Alliance and Harvard Medical School, in an article published online April 15 in the American Journal of Public Health

The largest burger backer was Northwestern Mutual, which had invested $422.2 million in publicly traded fast food corporations, including $318.1 million in McDonald's, according to Mohan's research.

It's already common knowledge that the insurance industry has made even bigger investments in tobacco (handing over almost $4.5 billion, according to a 2009 study), but evidence is mounting that obesity and other dietary diseases are becoming as much of a burden on health—both individual and national—than smoking. People who live near fast food restaurants are more likely to have a stroke than residents living farther away, according to another 2009 study. And high-fat foods have been shown to be rather addictive, at least in animal models.

The researchers conceded that "fast food can be consumed responsibly," but Mohan and his colleagues asserted that "the marketing and sale of products by fast food companies is done in a manner that undermines the public's health."

Although most companies—and many individuals—hand their investment portfolios over to financial firms (or separate company departments) to manage, the authors argued that, "insurers ought to be held to a higher standard of corporate responsibility."

"Our data illustrate the extent to which the insurance industry seeks to turn a profit above all else," Wesley Body, senior author of the study, said in a prepared statement. "Safeguarding people's health and well-being take a back seat to making money."

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