Good cholesterol vs bad cholesterol: should we stop worrying about bacon?

For decades the government has branded cholesterol as a killer. Foods high in cholesterol (eggs, butter, bacon) and saturated fat levels (coconut oil, red meat) should be avoided. However, recent advances in scientific research suggests that this premise lies on false grounds. Research in the British Medical Journal says the current government guidelines should be challenged, and that they should strongly reconsider the current recommendations for replacing saturated fat with carbohydrates.

Cholesterol is a fat biosynthesised by all animal cells and is essential for life. However, high fat levels in the bloodstream (including cholesterol) are strongly correlated with heart disease. It was suggested in the 1970s that to reduce the risk of heart disease by elevated cholesterol levels, fat should make up no more than 30% of daily food intake.

Dr Ron Rosedale has said ‘cholesterol is the hero, not the villain’ it is portrayed to be. Instead of limiting the amount of cholesterol consumed through foods, scientific evidence suggests creating a positive energy balance from your diet and avoiding processed foods, trans fats and sugars.

The levels of fats in the blood pose the true danger to human health, not cholesterol itself. As cholesterol will not mix with water, it needs help travelling through the bloodstream by lipoproteins (fat and proteins). So when we refer to cholesterol we are usually referring to these lipoproteins. However, these proteins are far from just being cholesterol.

These lipoproteins are often referred to as good (HDL) and bad (LDL) cholesterol. Often the term ‘good vs. bad cholesterol’ arises, but what does it mean? High-density lipoprotein (HDL) aids in the removal of cholesterol by transporting it to the liver. Low-density lipoprotein (LDL) does not assist in the process, instead LDL transports cholesterol onto the vessel wall, this can cause a build-up in plaque and narrow the arteries.

It is widely accepted that increasing HDL and lowering LDL reduces the risk of heart disease. However, there are different sub-fractions of LDL which complicate this black and white picture. The density and size of the LDL particle is important. Small, dense LDL particles lodge in the arteries easier, heightening an individual’s risk of heart disease, contrasting to those with large LDL particles. It is now considered that oxidised-LDL and these small LDL particles are the biggest risk factor for clogged up arteries.

Guidelines on how to increase HDL and reduce LDL usually involve: exercise, good body composition and decrease saturated fat intake. Health experts have been arguing that there is no link between foods high in saturated fat and dietary cholesterol with dangerous levels of LDL.

Saturated fat consumption leads to a rise in LDL levels according to numerous short-term feeding trials. And the government further recommends saturated fats should supply less than 11% of daily calories. These guidelines lacked any solid evidence and should not have been introduced, suggests Dr Aseem Malhotra, a London based cardiologist. Dr Malhotra wrote in the British Medical Journal, ‘it was time to bust the myth of the role of saturated fat in heart disease'. Studies have shown that saturated fats do not increase your risk of heart disease. In fact, they can lower the risk of heart disease by shifting small, dense LDL to large LDL.

Research at The University of Hull’s department of Sport, Health and Exercise Science has been investigating the effects of saturated fats on triglyceride levels (a type of fat in the blood strongly correlated with heart disease). They found that virgin coconut oil (roughly 90% saturated fat) and exercise significantly reduced triglyceride levels and increased HDL while LDL remained the same following a high-fat meal. This suggests that even in small doses, virgin coconut oil enhances the removal of fats in the blood, a protective mechanism against heart disease. Of note, these results are not yet published. Another study in the European Journal of Applied Physiology found exercise has beneficial effects in reducing fats in the blood following a very high-calorie meal.

Research in Japan found that reducing saturated fat consumption had inverse effects on the risk of cardiovascular disease. The paper concluded that saturated fat decreased the risk of stroke mortality and cardiovascular disease.

In recent years awareness concerning saturated fat has been gathering momentum. Numerous short-term and long-term feeding trials have concluded the benefits saturated fat can have on health and that previous guidelines are circumspect. A meta-analysis found in a 5-23 year period, totalling 347,747, saturated fat consumption was not linked with heart disease. Additional long-term feeding trials concluded similar findings.

The US Department of Agriculture has indicated that it will submit to recent advances in research and amend its dietary guidelines. The department plans to no longer advise people to avoid foods high in cholesterol. Almost 40 years of dietary guidelines and public health issues about eating cholesterol-laden foods will be undone. The research that warned us off eating high-cholesterol food (coconuts, eggs, bacon, butter) might have been flawed. This U-turn comes after years of division in the medical community.

Will guidelines on saturated fat be amended next? Doctors appear to be moving away from warnings about foods high saturated fat (nuts, animal fats, fish oils) and cholesterol, instead focusing on processed foods and sugar being the main dietary threat. Or is it the sedentary lifestyle we lead today the biggest threat?

Craig Scott is a Postgraduate Student in Sport, Health and Exercise Science at University of Hull