Don’t go Coconuts about this Heartily Hyped Oil!

Although coconut oil is no way near as bad for cardiovascular health as previously thought, it is not that amazing either. Multiple studies have shown that replacing coconut oil with unsaturated fat sources such as olive and safflower oil lowers the risk of heart disease due to reductions in total and ‘bad’ cholesterol levels. 

Coconut oil is being heavily promoted as a miraculous Super-Food that can help in the prevention and treatment of uncountable conditions, but the reality is that we have almost no evidence to support most of these health claims. For most conditions we simply have no evidence to suggest whether consumption of this oil is beneficial or detrimental, but in the case of cardiovascular disease we have a number of studies that looked at the effects of coconut oil on blood cholesterol levels and other predictors of cardiovascular health. Although most of these interventions involved small numbers of people, they constantly revealed the same result: that coconut oil caused the greatest increases in total cholesterol (TC), good cholesterol (HDL-C) and bad cholesterol (LDL-C) levels compared to all other given vegetable oils.

A group of researchers compared the effects of coconut oil, butter and safflower oil on blood lipid parameters in 41 healthy individuals during a 5 week intervention (figure 1). In accordance to previous studies, butter raised TC and LDL-C to a greater extent than safflower oil, with coconut oil sitting in between the two. However, it is worth noticing that coconut oil was superior to both butter and safflower oil at increasing HDL-C levels. 

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Figure 1. 41 healthy individuals from Pacific ethnicity were divided into 3 intervention groups and were either given butter, coconut oil or safflower oil for a period of 6 weeks. Blood tests were performed at the start of treatment, during the 3rd week and at the end of the study. It was revealed that subjects in the coconut oil group had the highest levels of HDL-C, while those in the safflower group had the lowest levels of TC and LDL-C levels. Meanwhile, individuals in the butter group reported the highest levels of TC and LDL-C. 

It is interesting to note that although coconut oil contains far more saturated fat than butter (figure 2), studies constantly show that the former is better for cholesterol levels. This is explained by the fact that a large proportion of fat in coconut oil is in the form of medium chain triglycerides that are rapidly absorbed and metabolised, having a reduced impact on blood cholesterol levels. Also, it is important to realise that butter contains a small amount of trans-fats which are known to greatly decrease HDL-C and boost LDL-C levels. Nevertheless, this study demonstrated that safflower oil had a better impact than both coconut oil and butter on cholesterol levels and therefore it is a better bet for cardiovascular health.

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Figure 2. Fatty acid composition in Coconut Oil (blue) vs. Butter (red): Coconut Oil is composed almost entirely of saturated fat (92%), whereas butter contains around 67% of saturated fat and 26% of mono-unsaturated fat. Meanwhile, poly-unsaturated fat only makes up less than 2% of total fatty acid composition in both coconut oil and butter. The unexpected higher cholesterol levels produced with butter are likely caused by the presence of harmful trans-fats (5%) and to the lower amounts of medium chain triglycerides contained compared to coconut oil (not shown).   

Furthermore, a crossover study in 25 healthy subjects showed detrimental effects on blood cholesterol levels upon feeding coconut oil compared to soybean oil. Individuals were given coconut oil for the first 8 weeks, after which they returned to their normal diets for 3 weeks before incorporating soybean oil for the remaining 8 weeks. Researchers found great reductions in TC (-17.5%) and LDL-C levels (-23.1%) when soybean oil replaced coconut oil feeding. More importantly, the ratio of TC to HDL-C cholesterol (a strong predictor of heart disease) was higher with coconut oil, indicating that this oil was more likely to cause heart complications on the long term than the highly unsaturated soybean oil.

In a similar investigation, olive and coconut oil were given to 45 young Malaysian adults during 10 weeks (figure 3). In this trial, every individual incorporated olive oil into their diets for the first five weeks and then replaced it with coconut oil for the remaining five weeks. Along the course of treatment, blood cholesterol levels were measured when fasted and after having a meal. The researchers found that coconut oil raised TC levels by 6.5% and LDL-C by 7.9% compared to olive oil. Nevertheless, coconut oil also increased HDL-C levels compared to olive oil by 6.2%, thereby helping to transport more cholesterol from the blood to the liver where it gets degraded. Ultimately, when the scientists looked at the ratio of TC to HDL-C they found no difference between the oils.

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Figure 3. 45 young Malaysian adults were given diets containing fixed amounts of protein (20%), fat (30%) and carbohydrate (50%). For the first 5 weeks they obtained 67% of their total fat intake from olive oil. After this period the subjects stopped taking olive oil and instead they were given 67% of total fat from coconut oil for the last 5 weeks. The blood samples revealed that replacement of olive oil with coconut oil significantly raised TC, LDL-C and HDL-C levels.

Overall, most of the evidence we have so far shows that substituting coconut oil with unsaturated rich oils improves cholesterol levels and possibly decreases cardiovascular risk. However, it is also evident that despite the really high saturated fatty acid content of coconut oil, you are much better choosing it over other highly saturated fats like lard and butter.

References

Eyres, L., Eyres, M.F., Chisholm, A. & Brown, R.C. (2016). Coconut oil consumption and cardiovascular risk factors in humans. Nutrition Reviews, 74(4), 267-80.

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