The "good" cholesterol increased only on the very-high-fat diet.
The long-held belief that saturated fats are unhealthy has been challenged by researchers at University of Bergen in Norway in a new study.
"These results indicate that most healthy people probably tolerate a high intake of saturated fat well, as long as the fat quality is good and total energy intake is not too high. It may even be healthy," said one of the researchers Ottar Nygard, Professor and cardiologist.
The researchers found strikingly similar health effects of diets based on either lowly processed carbohydrates or fats.
In the randomised controlled trial, 38 men with abdominal obesity followed a dietary pattern high in either carbohydrates or fat, of which about half was saturated.
Fat mass in the abdominal region, liver and heart was measured with accurate analyses, along with a number of key risk factors for cardiovascular disease.
"The very high intake of total and saturated fat did not increase the calculated risk of cardiovascular diseases," Nygard said.
"Participants on the very-high-fat diet also had substantial improvements in several important cardiometabolic risk factors, such as ectopic fat storage, blood pressure, blood lipids (triglycerides), insulin and blood sugar," he said.
Both groups had similar intakes of energy, proteins, polyunsaturated fatty acids, the food types were the same and varied mainly in quantity, and intake of added sugar was minimised.
"We here looked at effects of total and saturated fat in the context of a healthy diet rich in fresh, lowly processed and nutritious foods, including high amounts of vegetables and rice instead of flour-based products," PhD candidate Vivian Veum said.
"The fat sources were also lowly processed, mainly butter, cream and cold-pressed oils," Veum said.
Total energy intake was within the normal range. Even the participants who increased their energy intake during the study showed substantial reductions in fat stores and disease risk.
"Our findings indicate that the overriding principle of a healthy diet is not the quantity of fat or carbohydrates, but the quality of the foods we eat," Johnny Laupsa-Borge, another member of the research team, noted.
Saturated fat has been thought to promote cardiovascular diseases by raising the "bad" LDL (low-density lipoprotein) cholesterol in the blood.
But even with a higher fat intake in the diet intervention study compared to most comparable studies, the study -- published in the The American Journal of Clinical Nutrition -- found no significant increase in LDL cholesterol.
Rather, the "good" cholesterol increased only on the very-high-fat diet, the study said.
The researchers said future studies should examine which people or patients may need to limit their intake of saturated fat.
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