A new investigative study claims that saturated fats may not be as bad for human health as previously believed.

Foods that are high in saturated fats include palm and coconut oil, butter, rendered animal fats, dark chocolate, fish oil, cheese and processed meat, among others. Health experts have long-believed that over-consumption of these products could increase one's risk of heart disease, stroke, and even cancer, but such a stance remained controversial.

Investigative reporter Nina Teicholz wrote a book titled The Big Fat Surprise: Why Butter, Meat & Cheese Belong in a Healthy Diet, which discussed how saturated fat helps people stay healthy and why the low-fat, all fruit and vegetable diet may not be that beneficial to the body.

"When the dietary recommendations came out in 1961 saying that saturated fat causes heart disease, that was based on total cholesterol," Teicholz told CNN. "But our understanding of heart disease has evolved enormously."

Teicholz explained the belief began six decades ago when heart attack became the number one killer in America. During that same period, Dr. Ancel Keys, a scientist from the University of Minnesota, conducted his study on seven countries involving 13,000 men about the effects of saturated fats and sugar in one's diet. The findings of that study became the foundation of most diet guidelines we have today.

But Teicholz and other experts disagreed with the findings of Keys' study, arguing that it focused on selected countries including the United States, Netherlands, Italy, Greece, Japan and Yugoslavia. Keys failed to include countries known for their high consumption of fats but had low records of heart attack in West Germany, Sweden and Switzerland.

Keys's study called for people to adapt to the Mediterranean diet, a diet consisting of fruits, vegetables, pasta, dairy, fish and olive oil. But Teicholz warned that consuming too much fruit was not a good idea.

"I think too much fruit is probably not a good idea. Fruits have also been bred over the last century to be much sweeter. There are also some fruits that are much higher in sugar than others like pineapple, watermelon are higher in sugar than blueberries. Certain vegetables are very starchy and that starch breaks down to glucose," Teicholz said in an interview with Mashable.