Fat suffered a bad reputation for a long time and we were told to opt for low-fat options instead. But the tides turned eventually, prompting us to see fats in a new light.
Our lives became simpler. We learned how to avoid bad (saturated and hydrogenated) fats and eat good (unsaturated) ones to keep our tickers and arteries healthy.
Then the humble coconut came along in 2003, and the waters were once again muddied. Seen by some as a superfood but recently labeled by the American Heart Association (AHA) as part of the pool of unhealthful fats, the controversy goes on.
So, what are the scientific facts behind the coconut oil hype, and what are the latest developments?
Secret ingredient: 'Medium-chain' fatty acids
Many of the purported health claims surrounding coconut oil stem from research published in 2003 by Marie-Pierre St-Onge, Ph.D. — a professor of nutritional medicine at Columbia University in New York City, NY.
Prof. St-Onge found that in overweight women, consumption of medium-chain fatty acids — such as those found in coconut oil — led to an increase in energy expenditure and fat oxidation compared with women who ate long-chain or saturated fatty acids.
But Prof. St-Onge used a specially formulated fat diet in her study, not coconut oil, and she never claimed that coconut oil was the secret to the results seen in her research.
The rumor mill had begun to spin and coconut oil became widely hailed as a superfood.
In fact, a 2009 study involving 40 women showed that 30 milliliters of coconut oil — consumed daily for a 12-week period — increased good high-density lipoprotein (HDL) levels, accompanied by a reduction in waist circumference.
As more studies have followed, the picture became less clear-cut.
AHA and WHO advise to limit consumption
Despite the number of studies casting coconut oil in a favorable light, the AHA issued an advisory note on dietary fats and cardiovascular disease in June 2017, recommending that we replace saturated fats with more healthful unsaturated fats. This includes coconut oil.
As the World Health Organization (WHO) state, "[U]nsaturated fats (e.g. found in fish, avocado, nuts, sunflower, canola, and olive oils) are preferable to saturated fats (e.g. found in fatty meat, butter, palm and coconut oil, cream, cheese, ghee, and lard)."
The reason? Saturated fat is bad for our cardiovascular health. However, there is another twist to this fascinating tale.
While low-density lipoprotein (LDL) is generally thought of as "bad" cholesterol, the HDL type is widely accepted as being its "healthful" counterpart.
Yet in 2017, we covered three studies that potentially turn what we know about fats and cholesterol on its head. The first strudy found that saturated fats may not "clog" our arteries after all, while the second one uncovered a link between "good" HDL and mortality.
What is the latest?
One of the problems with the controversy surrounding coconut oil is the lack of good-quality, large-scale human studies. But adding to the body of evidence is a new study by the BBC's "Trust me I'm a Doctor" team.
Together with Dr. Kay-Tee Khaw, a professor of clinical gerontology, and Dr. Nita Gandhi Forouhi, a professor of population health and nutrition — both at the University of Cambridge in the United Kingdom — the team compared the effects of coconut oil, olive oil, and butter in 94 human volunteers.
Each study participant was asked to consume 50 grams of one of these fats daily for 4 weeks. The results came as a surprise.
Those who consumed coconut oil saw a 15 percent increase in HDL levels, while this number only stood at 5 percent for olive oil, which is accepted as being good for our cardiovascular system.
If we are working on the premise that HDL is good, then these results speak in favor of coconut oil.
It is important to note, however, that the results of this study have not been peer-reviewed and must be treated as preliminary.
Coconut oil: The verdict
So, is coconut oil healthful or not? As with many research areas, there is no straightforward answer.
If you are looking to lose weight, it's worth bearing in mind that coconut oil is very high in saturated fat and one tablespoon contains 120 calories.
If it's cardiovascular health that you are after, the official party line drawn by the AHA and WHO still puts coconut oil on the list of fats to limit. But who knows, maybe the tables will turn, and new guidelines will emerge.
In the meantime, coconut oil can be part of a healthful, balanced diet, if consumed in moderation.
However, it's worth looking out for coconut oil in packaged foods, especially partially hydrogenated coconut oil. This is a source of trans fats, which the Food and Drug Administration (FDA) say increase the risk of heart disease.