Michael Mosley and Coconut Oil

Dr Michael Mosley (Trust Me, I’m a Doctor) instigated a trial to determine the impact of coconut oil on cardio-vascular health.

94 participants were randomly assigned to one of three groups. They were asked to consume an additional 50g of fat – either coconut oil, butter or olive oil, daily for a period of four weeks.[1]

The main measure was the change in total cholesterol.

Below is Mosely’s conclusion.

Dr Mosley says that, as predicted, the LDL levels of butter eaters increased by about 10 per cent on average while their good cholesterol, HDL, rose by around five per cent. The volunteers who downed olive oil saw a non-significant reduction in LDL cholesterol and a five per cent rise in good cholesterol. Meanwhile, the people in the controversial coconut oil group experienced – on average – no increase in LDL levels. Instead, there was a 15 per cent rise in their good cholesterol.[2]

Note that the emphasis is on the amount of change rather than the more important absolute values.

Below are cholesterol and systolic blood pressure at the start and the end of the trial.

Baseline valuesCoconut oilButterOlive Oil
LDL-cholesterol (mmol/L)
Total cholesterol (mmol/L)
Systolic blood pressure (mm Hg)131.4136.5133.1
Results at 4 weeksChange from baselinePairwise comparison
(First value – second value)
Coconut oilButterOlive oilCoconut vs OliveButter vs CoconutButter vs Olive
LDL-cholesterol (mmol/L)-0.090.33-0.06-0.040.420.38
Total cholesterol (mmol/L)0.220.420.
Systolic blood pressure (mm Hg)0.18-3.79-3.673.91-3.220.69
  • Adding 50g of fat to a diet a high-fat diet is not healthy dietary modification.
  • All diets were 36-37% fat (by energy) which is higher than the US average of 33%.
  • The average total cholesterol for all diets was 5.9-6.0 – which is very high. The Framingham Risk Assessment accumulates risk points above the value of 4.1.
  • Systolic blood pressure is also high. Optimal systolic blood pressure is less than 120.
  • Change from baseline for all groups for both total cholesterol and systolic blood pressure was not sufficient to have any impact at all on health.
  • Adding 50g of fat daily for four weeks is detrimental.
  • Not all authorities agree that HDL cholesterol is a valid indicator of cardio-vascular health.

A change in cholesterol is not the only impact that a high-fat diet and high saturated fat diet has on health. High-fat diets have a multitude of adverse health outcomes.

A single high-fat meal has a significant impact on endothelial function which takes several hours to recover – just in time for your next high-fat meal.[3] [4]

The fluidity of the cell membranes is decreased and the permeability is increased with an increase of saturated fats, as well as increasing the viscosity of the blood and increasing the adhesiveness of blood cells. Having blood components sticking together and sticking to blood arteries is not conducive to good health.

An alternative view is that three high-fat, unhealthy diets have a similar unhealthy impact on not only cardio-vascular but overall health.



  1. Khaw, K.-T. et al. (2018) Randomised trial of coconut oil, olive oil or butter on blood lipids and other cardiovascular risk factors in healthy men and women. Open Access. 8 (e020167), 15.
  2. Noone, Y. (2018) Why Dr Michael Mosley now thinks that coconut oil may be good for you [online]. Available from: https://www.sbs.com.au/food/health/article/2018/02/26/why-dr-michael-mosley-now-thinks-coconut-oil-may-be-good-you.
  3. Vogel, R. A. et al. (1997) Effect of a Single High-Fat Meal on Endothelial Function in Healthy Subjects. American Journal of Cardiology. [Online] 79 (3), 350–354.
  4. Jakulj, F. et al. (2007) A high-fat meal increases cardiovascular reactivity to psychological stress in healthy young adults. The Journal of nutrition. 137 (4), 935–939.

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