Ah, the age-old question continues. Do eggs or more specifically, does dietary cholesterol raise cholesterol levels in our blood? Just when we thought the question had been answered and the door was closed on this topic, a new study has appeared this year to confuse us once again.
Let’s start with what we do know.
What is cholesterol?
Cholesterol is a fat found in your blood which is produced naturally in your body, mainly by the liver. You can also get cholesterol from some food sources such as: eggs, shellfish, meat and dairy products.
Are there different types of cholesterol?
Yep! There are actually two main types of cholesterol found in our blood.
Low-density lipoprotein or LDL cholesterol – often called the ‘bad cholesterol’ due to its role in the build-up of plaque which causes blockage in the arteries.
High density lipoprotein or HDL cholesterol – often called the ‘good cholesterol’ as it helps to remove other forms of cholesterol from your blood and reduce the build-up of plaque in the arteries.
Does eating fatty foods cause high cholesterol?
In a word, yes. However, what’s most important are the type of fats we choose to eat. These can be grouped into either saturated or unsaturated fats.
Saturated or trans fats are directly linked to an increase in LDL cholesterol and can be found in animal foods, such as fatty meat, dairy products, coconut products and palm oil.
Poly- or monounsaturated fats help balance the cholesterol in your blood by decreasing LDL and increasing HDL cholesterol. Unsaturated fats can be found in plant foods, such as olive and vegetable oils, nuts and seeds, as well as oily fish.
Basically, what this means is that to improve your cholesterol levels through diet you must work to improve your ratio of fats. This can be done by reducing the regular food sources of saturated fat in your diet and increasing the healthier, unsaturated fats.
And finally, does dietary cholesterol effect blood cholesterol levels?
Previous research has proven that cholesterol in food only has a small effect on the level of cholesterol in your blood. This has been the general consensus amongst researchers and health professionals for some time now, with the Australian Heart Foundation stating – ‘When it comes to blood cholesterol levels, cholesterol in food is less important than eating less saturated and trans fats, and more healthy fats.’
This year however, a new study was published which concluded that higher consumption of dietary cholesterol or eggs leads to a higher risk of heart disease and cardiac related deaths.(1) The study analysed data from 6 previous studies. These studies collected data over a 30-year period and pooled a total of 29,615 participants. When they analysed the data, the researchers found an association between egg consumption as reported at the start of the study and participants’ risk of developing cardiovascular disease. As their egg consumption rose, so did their risk. With that being said, there are a number of limitations to this study.
- A large number of the egg eating participants were also undertaking other unhealthy lifestyle habits such as: smoking, high red and processed meat intake and low intake of fruit and vegetables. Therefore, difficult to blame eggs alone.
- At the start, participants filled in questionnaires detailing the foods they ate. They were not asked about their diets again; long term dietary patterns are unclear.
- This type of study can only show an association, rather than cause and effect. More research is needed to understand the reasons behind this link
For now, let’s focus on the fact that eating healthily is all about balance. If you’re eating too much of one thing it leaves less room in the diet for other foods that may have more health benefit. Stay tuned for our next blog where we delve deeper into a heart healthy diet.
- Zhong VW, Van Horn L, Cornelis MC, Wilkins JT, Ning H, Carnethon MR, et al. Associations of Dietary Cholesterol or Egg Consumption With Incident Cardiovascular Disease and Mortality. JAMA. 2019;321(11):1081-95.