Ever since coconut oil became the new black in healthy living, it’s had its skeptics. And they got joyfully noisy over a recent “Presidential Advisory” from the American Heart Association.
But while dramatic headlines about “unhealthy” coconut oil grabbed attention, the advisory doesn’t actually discredit coconut oil at all.
What it does say is only what we’ve been hearing from the AHA for years:
Replacement of saturated with unsaturated fats lowers low-density lipoprotein cholesterol, a cause of atherosclerosis, linking biological evidence with incidence of CVD in populations and in clinical trials. Taking into consideration the totality of the scientific evidence, satisfying rigorous criteria for causality, we conclude strongly that lowering intake of saturated fat and replacing it with unsaturated fats, especially polyunsaturated fats, will lower the incidence of CVD.
Yet research has consistently challenged this “diet-heart hypothesis.” For instance, a 2010 study in the American Journal of Clinical Nutrition noted that while “replacement of saturated fat by polyunsaturated or monounsaturated fat lowers both LDL and HDL cholesterol,” replacing that fat with carbohydrate gave much more cause for concern.
On top of that,
An independent association of saturated fat intake with CVD risk has not been consistently shown in prospective epidemiologic studies, although some have provided evidence of an increased risk in young individuals and in women.
But then came the 2013 paper which re-evaluated data from the Sydney Diet Heart Study, originally conducted from 1966 to 1973.
In this cohort, substituting dietary linoleic acid in place of saturated fats increased the rates of death from all causes, coronary heart disease, and cardiovascular disease. An updated meta-analysis of linoleic acid intervention trials showed no evidence of cardiovascular benefit. These findings could have important implications for worldwide dietary advice to substitute omega 6 linoleic acid, or polyunsaturated fats in general, for saturated fats. [emphasis added]
A related paper by some of the same authors reinforced these findings. And the next year, a review of more than 70 studies on fat consumption and coronary disease found no association between fat consumption and heart disease risk.
Current evidence does not clearly support cardiovascular guidelines that encourage high consumption of polyunsaturated fatty acids and low consumption of total saturated fats.
Since news of the new AHA advisory broke, there have been lots of great commentaries discussing these and other doubt-casting studies – see here and here, for instance. But perhaps the best is Gary Taubes’ essay at MedPage Today.
Taubes points out the tendency for people to believe what they want to believe, even rejecting scientific evidence to satisfy their preconceptions – such as those collectively held by the AHA.
Ultimately this AHA document is a recapitulation of what the AHA experts have been arguing for decades. The only reason to publish it is because it’s been taken heat lately from folks like me and Nina Teicholz and a host of others who point out that we’re dealing with a pseudoscience here and the public deserves far better. Those of us who have become critics may indeed be biased about what we believe now – I certainly am — but ultimately we’re arguing for better science. This kind of post-hoc analysis of clinical trials, whether subgroup analysis or otherwise, can only be hypothesis generating. What the AHA experts are doing here is saying that their assessment of the data leads to what they consider a compelling hypothesis: replacing SFA with PUFA should reduce heart disease by 30%. But that’s all they can say. By deciding what data to include and what not based on their preconceptions of what’s true and what’s not, they cannot say this is a fact, as they claim, only that it’s still a reasonable hypothesis and has yet to be refuted.
As for coconut oil, it’s worth noting that its benefits aren’t restricted to diet. It’s well-known for its antibiotic and moisturizing properties when used topically. It also appears to be quite effective for oil pulling. One study of 60 teens who practiced coconut oil pulling for 30 days found significant improvement in plaque and gingival scores after just one week.
So no, coconut oil is not suddenly “bad.” There is no new, earth-shattering evidence here – no proof that should make you stop using the stuff right this moment.
We could use an end to dramatic and inaccurate headlines, though.