Not all saturated fats increase the chances of developing diabetes - and some actually protect against the disease, a study has shown.
The kind of saturated fat found in dairy products such as yoghurt is likely to reduce type 2 diabetes risk, say scientists.
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But other types obtained from red meat and fried food, or generated after consuming carbohydrates or alcohol, may be harmful.
The differences depend on the number of carbon atoms chain-like saturated fatty acid molecules contain, according to the research.
Those with an even number - 14, 16 and 18 - were associated with a higher risk of type 2 diabetes, the most common form of the disease affecting almost three million people in the UK.
Molecules with odd numbers of carbon atoms, 15 and 17, led to a protective effect.
Saturated fat is typically found in fatty animal products such as butter, cheese and red meat.
It is generally considered unhealthy and linked to high levels of cholesterol and heart disease, as well as type 2 diabetes.
Lead researcher Dr Nita Forouhi, from the Medical Research Council Epidemiology Unit at Cambridge University, said: "Our findings provide strong evidence that individual saturated fatty acids are not all the same. The challenge we face now is to work out how the levels of these fatty acids in our blood correspond to the different foods we eat.
"Our research could help trigger new directions in experimental studies and basic research so we can better understand the biology."
She added: "These odd-chain saturated fatty acids are well-established markers of eating dairy fats, which is consistent with several recent studies, including our own, that have indicated a protective effect against type 2 diabetes from eating yoghurt and other dairy products.
"In contrast, the situation for even-chain saturated fatty acids, such as 16:0 and 18:0, is more complex. As well as being consumed in fatty diets, these blood fatty acids can also be made within the body through a process which is stimulated by the intake of carbohydrates and alcohol."
Copyright AAP 2014
