The results of a study released last week into guidelines for fat consumption were music to the ears of many.

Headlines announced “Fat guidelines lacked any solid scientific evidence” and “Butter ISN’T bad for you after all!” But after decades of being told by public health authorities to limit saturated fat and stick to healthy margarine spreads, why do we have this sudden u-turn and what on earth are we supposed to eat now?

The story behind the headlines goes right back to the 1960’s and two well known scientists; Ancel Keys and John Yudkin. Both men offered theories as to the cause and development of heart disease; Keys pronounced that high cholesterol levels were at the root of cardiovascular disease and recommended a low fat, cholesterol-lowering diet.

Yudkin on the other hand promoted the link between sugar consumption and heart health. Unfortunately, he was not as influential as Keys and his theory did not catch on. So, for the next 40 years, public health advice in the UK and USA was founded upon the idea that low-fat, low-cholesterol diets were the best option for promoting cardiovascular health.

The problem here is that despite decades of low-fat advice, levels of heart disease and obesity have continued to sky rocket and the theory has proven unsound.

Cholesterol does make up part of the fatty plaques and clots found in atherosclerosis and heart disease however it is there because of an underlying problem – inflammation.

Your body uses cholesterol as a sort of first aid ‘sticking plaster’, sending it to any part of the body that has been damaged or is inflamed. Blaming cholesterol for heart disease is a bit like blaming the fire brigade for fires; they are always there at the scene of a fire so therefore they must have caused it!

The dietary advice based on Keys theory also ignored another important factor; only 20-25% of your cholesterol comes from your diet, the rest is made by your liver, with production being tightly controlled by various hormones and signals within the body.

Once food manufacturers began producing low-fat foods to they soon realised that something else needed to be added to their products to replace the fat and maintain the standards of taste and texture – they chose sugar.

For the past 40 years, people have taken fat out of their diets, replaced it with sugar laden alternatives and inadvertently proven John Yudkin’s theory that sugar, not fat, is the main contributing factor to cardiovascular disease!

The one type of fat we do know to be linked with cardiovascular disease is trans fats; these are chemically altered fats found in margarine and various baked goods. Your body cannot process these fats and they are proven to contribute to a host of health issues including heart problems.

So, is butter back on the menu? In my kitchen, yes! The key is moderation and to include a range of other healthy fat-rich foods such as oily fish, seeds and nuts too.

- Sally Duffin is a nutritional therapist and writer based in Holgate, York.