Eating foods that contain large amounts of saturated fat has long been associated with cardiovascular diseases with health experts themselves advising to stay away from foods that are high in saturated fat such as red meat and cheese.

Investigative journalist Nina Teicholz, however, has set out to challenge the decades-old medical advice claiming that saturated fat is not at all that bad for the health and neither are fruits and vegetables as healthy as we think.

In her book "The Big Fat Surprise", Teicholz revealed how a study conducted by University of Minnesota scientist Ancel Keys between the 1950s and 1960s influenced current dietary recommendations. Keys' study which became known as the "Seven Countries study" involved nearly 13,000 men between 40 and 59 years old from the United States, Finland, the Netherlands, Italy, Greece, Yugoslavia, and Japan to examine the association between diet and coronary heart disease.

Findings of the study, which became the basis of current nutritional guidelines, show that countries with diet that contain high amounts of saturated fat tend to have higher prevalence of heart disease. The findings of his study prompted Keys to promote the Mediterranean diet which is composed of high amounts of fruits and vegetables, bread, pasta, olive oil, fish and dairy.

The Seven countries study, however, is criticized as Keys did not include countries that are known for their rich fatty foods but have low heart disease rates such as Sweden, West Germany and Switzerland leading Teicholz, a New York-based journalist who has written for The New Yorker, The Economist, The New York Times and Gourmet magazine, to conclude that there was not enough evidence to prove that saturated fats are the main culprit that causes heart disease.

"There were other ideas at the time, but Ancel Keys got that idea and planted it into the American Heart Association... and it's like, the rest is really history from there," Teicholz said. "It had never been tested."

Teicholz's contentions may have found support particularly from some of the book's readers but health experts warn people to take her revelations with a grain of salt and not to make drastic changes to their diet just yet.

Walter Willett, from the department of nutrition at the Harvard School of Public Health, said that although the effects of saturated fat may not seem very damaging when you consider everything else in a person's diet, it does not mean that saturated fat is not at all bad.

"It's like an orchestra - you have to have all the pieces there and have to have it in the right balance," Willett said. "Not one factor is going to solve your health issues."