Fats are essential for good health. They play important roles in maintaining cell membrane structure and producing nerve cells and certain hormones.Martini F., Nath J.L., Bartholomew E.F. Fundamentals of Anatomy and Physiology. San Francisco: Benjamin Cummings; 2012. People are embracing fats like there’s no tomorrow – we’re putting butter in our coffee and downing coconut oil by the spoonful in search of better health. Fats are the current panacea for all sorts of ailments but their benefits are often overstated, using a mixture of half-baked science and wishful thinking. So today we are going to delve into the science behind fats and give you the scoop on the evidence for some popular fats.
Which fatty acid is that?
Fats in general are made up of a glycerol unit (the ‘head’) and three fatty acid chains (the ‘tail’). It is the fatty acid chains that can differ between different types of fats, giving rise to different functions within the body. Fatty acids can be classified by the number of double bonds they contain or by the number of carbons it has. The number of carbons a fatty acid has, or its length, can change its function within our bodies. These are classified as either short, medium, long or extra long fatty acid chains.
Short chain fatty acids are 2 to 5 carbons in length and are produced when dietary fibre is fermented in the bowel. Medium chain fatty acids (MCFA) have between 6 and 12 carbons, however this definition is a conjecture and is still debatable. Published literature generally classify MCFAs as having between 8 and 10 carbons, and much of the research around the benefits of consuming such fats is based around this definition. Takeuchi H et al. The application of medium-chain fatty acids: edible oil with a suppressing effect on body fat accumulation. Asia Pac J Clin Nutr. 2008;17 Suppl 1:320-3
Suggested benefits gained from consuming MCFAs include increases in energy expenditure and fat oxidisation, which can lead to fat loss in the body independent of physical activity. For example, this 2003 study concluded that when diets of overweight but otherwise healthy men were manipulated so that the majority of the fat came from fatty acids with 8 or 10 carbons, participants lost significantly more weight than those fed longer chain fatty acids, such as olive oil. Similar methodologies and results were found in this 2002 study. These are two studies that are often cited by coconut oil enthusiasts, and I will try to explain the many reasons why this is a misnomer – sit tight.
Claim: Coconut oil is a wonder weight loss aid
Ah coconut oil, made famous by wellness warriors everywhere and Pete Evans who infamously and incorrectly stated that is it compromised primarily of monounsaturated fats on national TV. In recent years, many dubious health claims have been made about this oil – from weight loss to curing cancer. While most are dubious of the cancer claim, the myth that coconut oil will speed weight loss efforts persists. Studies such as those mentioned above have fuelled the hype, but is this evidence worthy of such hype?
Coconut oil is a peculiar oil, as it is solid at room temperature, opposing the general rule of oils being liquid at room temperature. The most abundant fatty acid in coconut oil is lauric acid which is 12 carbons long, making up about 47% of coconut oil’s fatty acids. As mentioned before, there is much confusion around whether this fatty acid is classified as a medium or long fatty acid chain. Even if we were to classify lauric acid as a MCFA, it is important to remember that the supposed benefits in the above mentioned studies came from the extracted fatty acids, not the various oils themselves – for which there is little evidence of efficacy. Additionally, this 2011 study found that a significant waist reduction was achieved with daily coconut oil consumption (30mL). But this was only found to be significant in men, and potential changes in diet during the study period were not assessed. Thus, we cannot conclude that the coconut oil was responsible for the weight loss.
Rarely do we eat nutrients/fatty acids in isolation, so it is perhaps far-fetched to suggest that coconut oil, which may contain some MCFAs, will help you lose weight.
Claim: coconut oil won’t give you heart disease
Coconut oil also contains mystiric (16.5%) and palmitic (7.5%) acids, which are 14 and 16 carbons long, respectively. Mystiric and palmitic fatty acids do not appear to have health benefits and may contribute to heart disease. Diet, Nutrition and the Prevention of Chronic Diseases, WHO Technical Report Series 916, Report of a Joint WHO/FAO Expert Consultation, World Health Organization, Geneva, 2003, p. 88 (Table 10)
Regardless of the length of the fatty acid chain, coconut oil is predominately a saturated fat, which has long been associated with heart disease. A 2014 position paper released by the Australian Heart Foundation did not shine a favourable light on coconut oil. The Australian Heart Foundation identified 5 studies that looked at the relationship between coconut oil consumption and triglyceride levels. Three studies found that coconut oil raised triglycerides, total cholesterol and LDL cholesterol in particular. The fourth study concluded that by replacing coconut oil with unsaturated fats, serum triglyceride levels were improved in Sri Lankan men. The fifth study looked at the effect of coconut flour on triglyceride levels, total serum cholesterol and LDL cholesterol, and found some benefit which the authors attributed to the high levels of fibre in the coconut flour. Eyres L. Coconut Oil and The Heart. Heart Foundation. 2014.
Some epidemiological evidence from the early 1980s and early 90s suggests that populations that consume a lot of coconut products have very low rates heart disease. This has been touted as proof of coconut oils’ inability to cause heart disease. Suggesting that these two factors are related is displaying a lack of critical thinking – as always we must remember that correlation does not equal causation.
Claim: butter is better
At around the same time that coconut oil was rising to fame, an old debate was resurfacing: butter vs. margarine. We are in an era where foods that are perceived as ‘natural’ are seen to be ‘better’ and ‘healthier’ than foods that have had more processing – and there is much consumer interest in eating foods that are as close to their natural state as possible. While this is a step in the right direction away from processed meats and overly-processed discretionary snack foods, natural foods are not inherently ‘better’ just because they’re ‘natural’ (‘natural’ is also a completely unregulated and contentious term, but that’s a whole other article waiting there). Believing that natural foods are better is referred to as a logical fallacy. I’ve discussed this on The Nutrition Press recently here, and you can read more about this fallacy over at Big Think here.
Cue the resurgence of butter. It’s seen to be more natural than margarine and healthier, presumably because it is made from milk and cream, which we get from cows. Margarine, on the other hand, has long been associated with plastic, for its supposed similar chemical structure. But as you can see here in this entertaining video, margarine and plastic are quite different.
Claim: butter is free from trans fats
Anti-margarine campaigners would also have you believe that margarine should be avoided because it contains the much dreaded trans fat. This is based on older, American research and isn’t applicable to the Australian margarine industry. Thanks to the Heart Foundation Tick, and responsible manufacturers, margarine has negligible trans fats, and this has been the case for a number of years. In contrast, butter is a source of naturally occurring trans fats. Margarine can also be fortified with plant sterols, which can be beneficial for people with high cholesterol.
The bottom line
Each of these fats have important roles in cooking. Coconut oil helps make a heavenly Thai curry and butter is essential for making crispy crumbly shortbread – try and replicate that with margarine and you will find that you can’t.
Fats are essential for good health, but none of them are miracle cure-alls. Australians eat too much fat, especially the saturated kind. Australian Dietary Guidelines recommend that no more than 35% of our energy comes from fat and that we keep saturated fat to below 10% of our daily energy. The 2012 Australian Health Survey: First Results indicate that 13% of males and 16% of females have a usual intake of fat above 35% of total energy.
The same health survey revealed that a tiny 6.8% of Australians eat enough vegetables, which have numerous health benefits. So, regardless of composition, it is unlikely that your health will be improved by eating more fat. Perhaps the answer to our health woes lies in the humble veggie?
References [ + ]
|1.||⇪||Martini F., Nath J.L., Bartholomew E.F. Fundamentals of Anatomy and Physiology. San Francisco: Benjamin Cummings; 2012.|
|2.||⇪||Takeuchi H et al. The application of medium-chain fatty acids: edible oil with a suppressing effect on body fat accumulation. Asia Pac J Clin Nutr. 2008;17 Suppl 1:320-3|
|3.||⇪||Diet, Nutrition and the Prevention of Chronic Diseases, WHO Technical Report Series 916, Report of a Joint WHO/FAO Expert Consultation, World Health Organization, Geneva, 2003, p. 88 (Table 10)|
|4.||⇪||Eyres L. Coconut Oil and The Heart. Heart Foundation. 2014.|