As coconut oil has gained in popularity, articles written on
the possible health benefits of this oil have skyrocketed. Coconut oil has been
labeled as everything from a weight loss supplement to a cure for cancer and
facial moisturizer. Yet, the numbers of reliable clinical trials to back up
these claims are scarce. In this post I am going to focus on a claim targeted
towards athletes: “coconut oil improves athletic performance”… doesn’t it?
Coconut oil is primarily made up of saturated fats. There
are three categories of saturated fats: short chain fatty acids, medium chain
fatty acids, and long chain fatty acids. The length of chain refers to the number
of carbon atoms present, 6 or fewer (short), 8-10 (medium), or 12 or more
(long). Coconut oil contains 63% medium chain saturated fatty acids, 30% long
chain saturated fatty acids, and 7% long chain unsaturated fatty acids.
Primarily made up of saturated fats, this composition sets coconut oil apart
from other oils, especially in the oil’s medium chain triglyceride (MCT)
content. Many researchers believe the MCT content is what gives coconut oil
health-boosting properties.
The abbreviation, MCT, may sound familiar. Like coconut oil,
MCT oil has emerged as a dietary supplement. While MCTs are naturally present
in coconut oil, palm oil, human breast milk, and full fat cows or goats milk,
pure MCT oil is hydrolyzed from palm and coconut oil.
Medium chain triglycerides are more readily absorbed in the
intestines compared to long chain triglycerides. For this reason, MCT
supplementation is commonly prescribed to cystic fibrosis or epilepsy patients,
and those with conditions that affect nutrient absorption in the intestines.
Some scientists claim that replacing long chain
triglycerides with MCTs in one’s diet can aid in weight loss through fat
oxidation and improved thermogenesis. Compared to LCTs, a meta-analyses
published in the Journal of the Academy
of Nutrition and Dietetics found a diet including MCTs over an average of
ten weeks reduced total body fat, subcutaneous fat, and visceral fat as well as
waist and hip circumferences. However, no significant difference in blood
lipids was found between diets containing LCTs or MCTs. While a diet high in MCTs may actually help with fat loss, MCTs are
just as high in calories as other fats. Therefore, if not consumed in
moderation, MCTs can cause weight gain.
With easier absorption plus increased fat oxidation and
thermogenesis, can MCT oil improve athlete performance? Many internet articles
claim MCT oil to be beneficial to endurance athletes. Websites such as
rebootedbody.com want to convince you that MCT oil supplementation is a must
for athletic performance; however, four published clinical trials say
otherwise.
The first study published in the International Journal of Sports Nutrition and Exercise Metabolism
measured the respiratory exchange ratio (RER) and maximum aerobic capacity
(VO2) in eight ultra-endurance cyclists. The cyclists performed at timed
intervals on two separate occasions. During the first set of timed intervals,
the cyclists were given either 75g of carbohydrate or 32g of pure MCT oil,
followed by 200mL of a 20% carbohydrate solution or a 4.3% MCT + 10%
carbohydrate solution every 20 minutes during the intervals. Results found no
difference in RER or V02 between the MCT and carbohydrate trials. GI symptoms
occurred in 50% of the MCT trials.
The second study published in the American Journal of Clinical Nutrition included seven cyclists that
performed four separate exercise trials while consuming either a 10%
carbohydrate solution, 10% carbohydrate-electrolyte + 5% MCT solution, a 5% MCT
solution, or a placebo. Results found no differences in performance between the
carbohydrate, carbohydrate + MCT, and placebo solutions. However, the MCT
solution had a negative effect on performance with a 17-18% lower rate than the
other solutions. Plus, the carbohydrate + MCT and MCT-only solutions did not
raise the rates of fat or carbohydrate oxidation or utilization. GI symptoms
occurred in association with MCT solutions.
The third study published in the Journal of Sports Medicine and Physical Fitness assessed trained
runners that performed a maximal and endurance treadmill test after consuming a
dietary supplement containing either 56g of corn (LCT) oil or 60g of MCT oil
for two weeks. After the tests, the runner’s blood was taken to measure blood
concentrations of lactate, glucose, beta-HBA, free fatty acids, glycerol, and
triacylglycerols. Respiratory exchange rate (RER) was measured during exercise
and performance was measured by length of run before exhaustion. Results found no difference in blood
concentrations between the LCT and MCT trials. No significant difference in RER
or performance was found between the two trials.
The fourth study published in the International Journal of Sports Nutrition measured blood concentrations
of free fatty acids and beta-HBA, and exercise performance in 9 cyclists
consuming either a 10% carbohydrate solution, 10% carbohydrate + 1.72% MCT, or
10% carbohydrate + 3.44% MCT solution. Cyclists consumed 400ml at the start of
exercise and an additional 100ml every 10 minutes. Results found the
consumption of MCT solutions raised blood concentrations of free fatty acids
and beta-HBA. There was no difference in performance between the carbohydrate
and carbohydrate + MCT groups. No gastrointestinal symptoms were reported.
The bottom line: coconut oil is a 90% saturated oil with a
high MCT content. MCTs have potential health benefits, and can be hydrolyzed
from coconut oil to produce pure MCT oil. Currently, research does not support
that coconut oil or pure MCT oil supplementation enhances athletic performance.
This post written by: Ellen Wittneben, RDKate Dietetic Intern
Your Nutrition Coach,
RDKate
Did
the low-fat era make us fat? PBS. 2008. Available at:
http://www.pbs.org/wgbh/pages/frontline/shows/diet/themes/lowfat.html. Accessed
March 17, 2016.
St-Onge,
M-P, Bosarge, A, Goree, LLT, Darnell, B. Medium Chain Triglyceride Oil
Consumption as Part of a Weight Loss Diet Does Not Lead to an Adverse Metabolic
Profile When Compared to Olive Oil. Journal of the American College of
Nutrition. 2008;27(5):547–552.
Goedecke,
JH, Clark, VR, Noakes, TD, Lambert, EV. The effects of medium-chain
triacylglycerol and carbohydrate ingestion on ultra-endurance exercise
performance. International journal of sports nutrition and exercise
metabolism. 2005;15(1):15–27. Available at: http://www.ncbi.nlm.nih.gov/pubmed/15902986.
Accessed March 17, 2016.
Jeukendrup,
AE, Thielen, JJ, Wagenmakers, AJ, Brouns, SF, Saris, WH. Effect of medium-chain
triacylglycerol and carbohydrate ingestion during exercise on substrate
utilization and subsequent cycling performance. American Journal of Clinical
Nutrition. 1998;67(3):397–404. Available at:
http://www.ncbi.nlm.nih.gov/pubmed/9497182. Accessed March 17, 2016.
Misell,
LM, Lagomarcino, ND, Schuster, V, Kern, M. Chronic medium-chain triacylglycerol
consumption and endurance performance in trained runners. Journal of Sports
Medicine and Physical Fitness. 2001;41(2):210–215.
Goedecke,
JH, Elmer-English, R, Dennis, SC, Scholss, I, Noakes, TD, Lambert, EV. Effects
of medium-chain triaclyglycerol ingested with carbohydrate on metabolism and
exercise performance. International Journal of Sports Nutrition.
1999;9(1):35–47.
Mumme,
K, Stonehouse, W. Effects of Medium-Chain Triglycerides on Weight Loss and Body
Composition: A Meta-Analysis of Randomized Controlled Trials. Journal of the
Academy of Nutrition and Dietetics. 2015;115(2):249–263.
