Dietary fats: The good, the bad and the ugly...

Is fat really the enemy? For many years it was suggested that 'low fat' was healthier. But has this low fat culture unfairly demonised one of the major constituents of our food? After all, there are good fats as well as bad ones.

To much fanfare​ (and some criticism), food retailers and manufacturers in the UK recently signed a pledge to cut saturated fat levels in their products. Yet some of the same retailers and manufacturers have so far failed to sign up to similar pledges to cut overall calories in foods. In this special edition article, FoodNavigator asks how much we really know about the different types of fat in the diet - and whether fat is getting a raw deal when it comes to consumer and industry perception.

According to many experts it is the type of fats you eat that is more important to health than the total amount of fat in the diet. For example, consuming foods rich in plant and fish oils, and avoiding foods that are rich in trans fat, may reduce the risk for heart disease and type 2 diabetes.

Below we take a look at some of the key issues, benefits, and risks, associated with the major groups of fats.

The good...​

It is important to remember that not all fats are bad. In fact there are several fats that come with a raft of health benefits and are absolutely essential to life. Unsaturated fats - like omega-3 essential fatty acids - are healthy fats that have been linked to better heart health and could help lower bad  (LDL) cholesterol levels in the blood and increase levels of good (HDL) cholesterol.

The long chain omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are essential to our functioning and have several suggested health benefits. DHA, for example, is a primary structural component of the human brain, cerebral cortex, skin, and retina. As such, there has been great interest in whether increased intakes of the fatty acid can aid in the development if the brain  - and whether higher intakes can help to protect against cognitive declines in older age.

Omega-3 fatty acids can also help lower blood triglyceride levels, prevent blood from clotting and maintain a regular heart rhythm.

The bad?​

If unsaturated fats are the good guys, does that mean saturated fat is the enemy? There are about 24 different saturated fats - and not all of them are equally bad for your health.  Indeed some may not be bad at all.

The saturated fat found in butter, whole milk, cheese, and other dairy products is suggested to increase LDL levels the most, followed by the saturated fat in beef, while stearic acid, found in pure chocolate, is more like unsaturated fat in that it lowers LDL levels.

Certain vegetable oils - such as palm oil and coconut oil - contain saturated fat.

Writing in the British Medical Journal​ last week​, cardiologist Aseem Malhotra claimed that advice to cut saturated fat has actually increased cardiovascular risk – and that high fat dairy and red meat have been unfairly demonised. Malhotra, of Croydon University Hospital in London, said that too much focus on saturated fat​ and government obsession with cholesterol had meant other dietary components – like sugar – had been overlooked, and statins had been over-prescribed.

“Recent prospective cohort studies have not supported any significant association between saturated fat intake and cardiovascular risk,”​ he wrote. “Instead, saturated fat has been found to be protective.”​

“…It is time to bust the myth of the role of saturated fat in heart disease and wind back the harms of dietary advice that has contributed to obesity.”​

... the ugly?​

While there may be mixed messages on the status of saturated fat, there is very little doubt when it comes to trans fats. Artificial trans fatty acids in the form of partially hydrogenated vegetable oils are attractive to the food industry because they are solid at room temperature, inexpensive, and can increase the shelf life of foods. However, in recent years they have been found to increase levels of LDL (low density lipoprotein, or ‘bad’) cholesterol in the blood, while simultaneously lowering levels of HDL (high density lipoprotein, or ‘good’) cholesterol, thereby contributing to heart disease.

The World Health Organisation (WHO) recommends that trans fat should account for less than 1% of total dietary calories. Indeed, a recent WHO review  looked at international efforts to reduce trans fat in foods, including national and local bans, as well as labelling regulations and voluntary measures.

“National and local bans were the most effective,”​ said the WHO team. “Although significant progress has been made with labelling regulation in countries such as Canada and the United States, TFA [trans fatty acid] levels need to be reduced more, particularly in margarines and bakery products.”​

In particular, Denmark’s national ban on TFA’s has led to complete elimination of artificial trans fats from the food supply, while voluntary measures in the Netherlands led to a 20% reduction in trans fat consumption.