Coconut oil... healthy or not? — Premier

Merritt Drewery

Seventy-two percent of Americans consider coconut oil a healthy food but experts are on the fence,

In June 2017, a panel for the American Heart Association reviewed research focusing on the role of dietary fats in cardiovascular disease and released a statement encouraging the replacement of dietary saturated fats with unsaturated fats, with an emphasis on polyunsaturated fats, to reduce the incidence of cardiovascular disease [1]. Given the recent craze, coconut oil was given specific attention, and nutritional recommendations were made. In this entry, we review the nutritional aspects of coconut oil, compare popular health claims with evidence-based research findings, and discuss the recommendations of the American Heart Association panel with specificity to coconut oil.

Fatty Acid Profile of Coconut Oil

All oils are blends of saturated, monounsaturated, and polyunsaturated fatty acids and are typically classified based on their most abundant fatty acid. The saturated fat content of coconut oil is 82% [2]. For comparison, the saturated fat content of butter is 63%, and of beef fat is 50% [2]. Accordingly, coconut oil is classified as a saturated fat.

Saturated fat is commonly known as unhealthy fat detrimental to cardiovascular health. However, saturated fats are not equal in their relationships to cardiovascular health. Rather, cardiovascular implications of dietary saturated fats depend on their chain length. This is discussed in depth below, with specificity to circulating cholesterol levels. Saturated fats are classified as medium-chain (fewer than 12 carbons; also referred to as “medium chain triglycerides” or “MCTs”) or long-chain (greater than 12 carbons). For the purposes of this entry, it is important to note that the saturated fat fraction of coconut oil is primarily composed of long-chain fatty acids while medium-chain fatty acids represent approximately 13 – 15% [2].

Cardiovascular Claims

In making nutritional recommendations, the American Heart Association panel considered the saturated fat content of coconut oil (82%) and the association between coconut oil and heart disease [1]. To evaluate the latter, they considered data from seven human trials that compared the effects of coconut oil intake with those of monounsaturated and polyunsaturated oils (i.e., olive or canola oil). The panel found coconut oil significantly raises LDL (“bad”) cholesterol concentrations which is, in turn, related to increased heart disease risk. This is likely mediated by long-chain saturated fatty acids. Coconut oil, however, also boosts HDL (“good”) cholesterol [3-5]. In general, dietary fat increases HDL levels, but coconut oil is especially effective at doing so; this effect is likely attributable to medium-chain fatty acids [6]. However, dietary-induced changes in HDL cholesterol cannot be directly linked to cardiovascular disease and, therefore, effects on LDL cholesterol should be considered independently [1]. Given this evidence, the panel stated that there are no nutritional aspects of coconut oil that offset the downside of the saturated fat content and, as such, intake was advised against [1].

Supporters of the coconut oil industry commonly highlight that the traditional Polynesian diet, which is enriched in tropical oils including coconut, is associated with low rates of heart disease despite high LDL cholesterol levels [7,8]. While there is merit to this claim, other aspects of the Polynesian diet may be responsible for improving cardiovascular health, offsetting the LDL cholesterol-raising effects of coconut oil. Specifically, this diet is high in fiber, low in sodium, and high in omega-3 long-chain polyunsaturated fatty acids (fish oil) [9]. Other Polynesian lifestyle factors – non-smokers and physically active – also likely contribute to a lower incidence of heart disease in this population.

Weight Loss Claims

Dr. Oz, a registered Medical Doctor and television personality, called coconut oil the “miracle fat that fights fat”. However, when obese women cooked with two tablespoons of coconut oil daily for twelve weeks, they did not lose more weight than those who cooked with soybean oil [10]. As a hypocaloric diet and exercise regime were also introduced, these results cannot be directly attributed to the nutritional intervention. Furthermore, women cooking with coconut oil had increased peripheral insulin resistance [10], which is associated with the onset of type 2 diabetes mellitus.

Weight loss claims of coconut oil stem from a study that evidenced a role for medium-chain fatty acids in increasing weight and fat loss in overweight individuals, as compared to olive oil [11]. However, as noted above, coconut oil contains only 13 – 15% medium-chain fatty acids and the intervention used in the study was a special blend of 100% medium-chain fatty acids. A study by the same senior researcher was recently presented at a scientific conference and revealed that a lower dose of medium-chain fatty acids did not improve weight loss-related measures in overweight adolescents, although weight loss itself was not reported [12].

Cognitive Claims

Joseph Mercola, a registered Medical Doctor and internet entrepreneur, claims coconut oil may prevent Alzheimer’s disease. However, this claim is not scientifically backed.

The basis of coconut oil as “brain food” lies in ketosis. In a normal state, our brains are fueled by glucose. In fasting or starving conditions, we draw on fat stores for energy. Fat metabolism yields ketones which the brain can use as a replacement for glucose. The onset of cognitive disorders is commonly characterized by a decreased ability of the brain to use glucose, which essentially starves the brain. During this period, the brain can still utilize glucose. Therefore, the thought is that, if brain ketone levels are significantly increased, they will be used in place of glucose, and mental functions could be at least partially restored.

During medium-chain fatty acid metabolism, ketones are produced. However, the levels produced are not sufficient to support the processes discussed above, making the claim for coconut oil in brain health less viable. Furthermore, as noted, the medium-chain fatty acid fraction of coconut oil is less than 15% [2].

Before You Trash Your Coconut Oil…

While the American Heart Association panel warns against saturated fat consumption, a recent systematic review and meta-analysis of observational studies [13] suggested eliminating saturated fat from your diet does not necessarily translate to lower heart disease risk. This is a substitution result, as the void from the saturated fat intake is commonly filled with the consumption of sugar, white flour, and other “empty” calories. If saturated fat is replaced by whole grains, fruits and vegetables, or polyunsaturated fats (i.e., olive oil, sunflower oil), the risk of heart disease is lowered. Thus, it is not necessarily meaningful or accurate to label saturated fats as “good” or “bad” but, rather, focus should be placed on the nutritional value of the food replacing saturated fat.

Furthermore, the American Heart Association panel did not advise complete avoidance of saturated fat to reduce the risk of heart disease. Rather, the current American Heart Association and American College of Cardiology guideline is to decrease saturated fat intake to 5 – 6 % of daily caloric intake for individuals with elevated LDL cholesterol levels [14]. This translates to approximately 12 grams (0.8 tablespoons) of saturated fat per day, assuming an average daily intake of 2,000 calories. In line with this is the 2015 – 2020 Dietary Guidelines for Americans recommendation advising the general population to limit saturated fat intake to less than 10% of daily caloric intake [15]. With that said, the panel did advise against all intake of coconut oil [1].

The basis for the panel’s advisement against coconut oil intake resulted from the LDL cholesterol-raising effect of coconut oil and the emphasis placed on LDL cholesterol in the risk of heart disease. The association between cholesterol levels, subtypes of cholesterol (HDL vs. LDL), and heart disease is a blog entry in itself… but could it be that the AHA focused too heavily on LDL cholesterol? Inflammation is the root cause of heart disease [16-18]; approaching recommendations based on this may lead to different recommendations.

To conclude, coconut oil’s potent HDL cholesterol-boosting effect may make it more healthful than its saturated fat content alone would indicate, but there are better options among oils to reduce the risk of heart disease. Evidence-based research findings do not indicate a role for coconut oil in metabolic or cognitive health, despite claims touted by popular figures and the coconut oil industry.

Bio

Merritt Drewery is a native of Baytown, Texas. She holds a BS and MS in Animal Science, with a focus in Ruminant Nutrition, from Texas A&M University. Merritt recently received her PhD in Molecular and Clinical Nutrition from Louisiana State University, where her research evaluated the association between maternal nutrition during pregnancy and infant autonomic development. She recently transitioned into a position with Grober Nutrition, LLC in Auburn, NY where she develops milk replacers for young animals.

In her free time, she is probably playing with her very scruffy, disobedient dog or showing pictures of her nephews to anybody who feigns interest. She is terrified of her first winter in Upstate New York and welcomes your advice, along with any blog topic requests.

References

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