Can butter and whole milk prevent diabetes? Although we've been told for more than 50 years to avoid foods high in fat, a new study found that a specific type of saturated fat called heptadecanoic acid found in fish and whole-fat dairy products, could actually reverse metabolic syndrome, the precursor to Type 2 diabetes.

The CDC estimates that 1 in 3 American adults have metabolic syndrome — more than 86 million.

Researchers at the National Marine Mammal Foundation (NMMF) found that bottlenose dolphins can develop metabolic syndrome, even in the wild, that is similar to humans. But unlike humans, they can easily switch in-and-out. Scientists believed that by exploring what propels the development of metabolic syndrome in dolphins might have implications for humans.

"To better understand what may be a driver for metabolic syndrome in dolphins, we started exploring their diet, which is primarily fish," said the study's lead author Dr. Stephanie Venn-Watson, director of NMMF's Translational Medicine and Research Program.

Since so many humans supplement their diets with fish-based omega-3 fatty acids, the researchers measured fatty acid blood levels in 49 dolphins as well as in the fish they ate.

"We were surprised to find that among the 55 fatty acids studied, the saturated fat heptadecanoic acid appeared to have had the most beneficial impact on dolphin metabolism," said Venn-Watson. "Dolphins with higher levels of heptadecanoic acid in their blood had lower insulin and triglycerides."

When dolphins with low levels of heptadecanoic acid were fed fish high in the nutrient, symptoms of metabolic syndrome, such as high insulin, glucose, and triglycerides, became normal within six months. In addition, levels of ferritin, which is a measure of iron in the blood, decreased within three weeks.

Heptadecanoic acid, also known as margaric acid or C17:0, is a saturated fat. It's found in dairy products, rye, and some fish. The study found no detectable heptadecanoic acid in nonfat dairy products, but did find some in low-fat products. The greatest amounts were found in whole milk and yogurt, with butter containing the highest levels. The fish containing the highest levels of heptadecanoic acid was mullet.

Venn-Watson said that the move from whole fat dairy products may have created unexpected deficiencies in heptadecanoic acid. "In turn, this dietary deficiency may be playing a role in the global diabetes pandemic," she said.

The study was published in the journal PLOS One.