Medium Chain Triglycerides: A Magic Bullet?
Coconut products have skyrocketed to superfood fame practically overnight. Or, to be more specific: coconut oil consumption in the USA jumped by 34% between 2004 and 2014. These changes in consumer behavior were accompanied by an impressive array of marketing campaigns claiming that coconut oil is easy to digest, reduces cholesterol, protects against heart attack, and promotes weight loss. At the same time, there’s been exponential growth in the number of scientific articles concerning coconut products.
How much is hype, and how much is sound science?
Even when scouring the scientific literature, it’s difficult to say. Many findings are inconclusive, divergent, and often contradictory. There are plenty of reasons for this lack of clarity:
- Variability in the products used in research (virgin vs. refined vs. hydrogenated trans fats),
- lack of long-term randomized clinical trials, l
- ack of rigorous trial replication,
- insufficient duration of clinical trials,
- challenges with subject compliance in long-term restrictive dietary protocols,
- and failure to differentiate between dietary fat types in testing.
The simple answer to the question of the long-term effect of MCTs in the body is “we don’t know.” And we probably won’t get definitive answers any time soon.
The squabbles surrounding dietary fat guidelines essentially boil down to a lack of valid scientific research. Considering the long-term nature of the communicable diseases that dietary fats are theorized to exacerbate/improve, the complexity of human diet, the unique properties of dietary fats, not to mention individual physiological and pathological variations, this isn’t an easy problem to solve.
As Forouhi et al., authors of the article “Dietary fat and cardiometabolic health: evidence, controversies, and consensus for guidance,” published in 2018 by the BMJ write, “This controversy might be resolved by longer term clinical trials, but the cost and methodological and ethical challenges of such dietary trials suggest they may never be done.”
To make matters worse, as Anahad O’Connor writes in his New York Times article “More Evidence That Nutrition Studies Don’t Always Add Up,” “nutrition research is plagued by a credibility problem.” Cherry-picked data, weak and skewed statistics, and pressure to publish papers geared to “go viral” are the embarrassing earmarks of most nutrition research.
O’Connor adds, “Plenty of other factors that influence health can also blur the impact of diet, such as exercise, socioeconomic status, sleep, genetics and environment. All of this makes the most popular food and health studies problematic and frequently contradictory.”
It’s a mess.
Saturated Fats and Heart Disease — Erroneous Conclusions
And the issues don’t stop there. The most hotly contested topic in the field of nutrition, and health in general, is probably dietary fat. Of all the fats, saturated fat is the most maligned. That means it’s no easy task to evaluate health claims made about saturated fat supplements.
Forouhi et al., face the problem squarely, writing:
In past decades, dietary guidance has almost universally advocated reducing the intake of total and saturated fat, with the emphasis shifting more recently from total fat to the replacement of saturated fat with polyunsaturated fats and the elimination of trans fat. These recommendations and the link between fat consumption and the risk of cardiovascular disease have been among the most vexed issues in public health: are dietary fats “villains,” are they benign, or are they even “heroes” that could help us consume better overall diets and promote health? And, which dietary fats fit into which category?
You’d think you could trust an organisation like the American Heart Association to give you sound medical advice, but they’ve made recommendations inconsistent with ongoing scientific research, and their dietary saturated fat recommendations have been denounced as “draconian.”
Everyone thinks saturated fat is evil. But dietary fat is not the greatest contributor to saturated fat in the body. Indeed, the liver readily converts carbohydrates to saturated fat. In other words, the amount of saturated fat in the body is determined predominantly by, not fat, but carbohydrate consumption.
Furthermore, it’s a widely accepted untruth that high fat intake causes heart disease. Fat, or even cholesterol, for that matter, don’t cause heart disease or atherosclerosis; inflammation does.
One major problem with coconut oil research is that most studies on the effects of coconut oil measure cholesterol, and extrapolate those levels to risk of heart disease. Researchers have found that a superior marker for coronary artery diseases is the ratio of total cholesterol to HDL cholesterol, as opposed to the single value of LDL (“bad”) cholesterol alone. Incidentally, oils rich in lauric acid have been found to decrease the ratio of total to HDL cholesterol, which indicates preferrable cardiovascular outcomes.
Indeed, the whole history of dietary fat research is a bit awkward.
The oils used by many researchers were hydrogenated and likely contained trans fats, which are recognized to elicit adverse health effects. Furthermore, in several rodent studies, animals were fed coconut oil as the sole dietary fat. They were found to have higher cholesterol levels, and were less healthy than those fed corn or soybean oil. Mike Foale, a retired agronomist at Australia’s Commonwealth Scientific and Industrial Research Organization (CSIRO), points out that these studies were flawed because coconut oil lacks essential omega fatty acids. The animals fed coconut oil were thus suffering from a dietary deficiency, as opposed to the proposed “negative” effects of the oil itself.
“In the real world, coconut users of the tropics generally eat fish, which are rich in omega-3 fatty acids,” says Foale. “So the combination has always been a healthy one, and heart disease isn’t an issue among traditional coconut users.” Consider: Polynesians and Bicolanos, populations that consume large volumes of coconut products, demonstrated favorable lipid profiles (viz. cholesterol and LDL/HDL ratios), low rates of atherosclerosis, and low incidence of heart disease.
A comprehensive investigation of the history, politics, and intrigue behind the stigma against saturated fat is, fascinating as it is, beyond the scope of this article. For the whole scoop, refer to Laura Cassiday’s excellent article “Big fat controversy: changing opinions about saturated fats.”
MCT Science: What We Think We Know
Caveats aside, studies have been conducted, and based on those findings, here’s what we think we know about MCTs. They:
- Promote a metabolic pathway of fatty acid oxidation (energy production) over storage.
- Increase satiety, thereby decreasing caloric consumption. One study showed that MCT oil induced greater satiety than whole coconut oil. A caveat: this study was conducted with just 24 subjects over the course of three days. Further research is needed to confirm these findings.
- Improve insulin sensitivity and decreases insulin resistance risk factors.
- Are readily digestible, indicated in people with severe malabsorption issues like celiac or Crohn’s disease.
- Beneficial in pancreatic insufficiency. This is due to the fact that MCTs don’t require pancreatic enzymes (lipase) or bile salts to absorb them. MCTs may be more absorbable for people with impaired bile production, or who have had their gallbladder removed.
There’s some evidence that MCTs augment memory and reduce oxidative stress in rats via enhanced cholinergic activity and increased antioxidant activity. This suggests a potential role in the prevention and treatment of Alzheimer’s.
MCT metabolites known as ketone bodies have been found to exert neuroprotective effects. Ketonemia — the increased presence of ketone bodies in the bloodstream — is promoted by habitual MCT ingestion and may be beneficial in Alzheimers.
What is Ketosis?
Achieving ketosis is a significant motivator for many consumers of MCT oil. Let’s take a moment to understand what it is, and why people are chasing it.
Ketosis is an adaptive metabolic state induced by the body under conditions of glucose deprivation. Glucose is the preferred cellular fuel of the body, and when carbohydrate consumption tanks (typically an intake of less than 50g/day, though this value varies by individual), then the body compensates by turning to different fuel sources. In addition to diet changes, fasting and strenuous aerobic exercise can achieve the same effect.
Under these conditions, glucose is tapped from its storage form of glycogen, and glucose is produced in the body from non-carbohydrate sources like lactic acid, glycerol, and certain amino acids. Once these sources are depleted, the metabolic process of ketogenesis kicks into gear.
In ketogenesis the body metabolizes fatty acids to ketone bodies which replace glucose as the primary source of energy. Ketosis refers to the metabolic state in which ketone bodies are generated and used as cellular fuel. Ketone body production depends on resting basal metabolic rate (BMR), body mass index (BMI), and body fat percentage.
Ketone bodies are readily used for energy production by the heart, muscle tissue, and kidneys. They can also cross the blood-brain-barrier and act as an alternative energy source for the brain. Conversely, red blood cells don’t have mitochondria, and cannot use ketone bodies to produce energy. Similarly, the liver lacks a crucial enzyme — diaphorase — and cannot use ketone bodies as a fuel source.
Ketone bodies produce more ATP (cellular energy) than glucose, leading folks to designate it a “super fuel.” This quality of ketones enables the body to efficiently produce fuel, even during a caloric shortfall.
There are several advantages to being in a state of ketosis:
- The absence of glucose feedback results in reduced insulin secretion.
- Ketone bodies decrease free radical damage and enhance antioxidant capacity.
- In Alzheimer’s, where glucose uptake in the brain is impaired, ketone bodies may be a functional alternative fuel source.
Importantly, ketosis is induced by severely limiting carbohydrate and protein consumption. This diet is considered unsustainable for most people in the long term, and, depending on body type, may be difficult to actuate. MCTs can be metabolized to ketone bodies, but that does not mean that consuming MCT oil will induce ketosis. A concerted dietary protocol must be followed to coax the body into this carb-starved metabolic state.
MCT ingestion does, however, elicit a state of mild-to-moderate ketonemia, which may have health-promoting effects for certain conditions.
One human study found that MCTs have varying levels of keogenicity, or capacity to produce ketone bodies. Under acute metabolic test conditions, caprylic acid was found to be three times more ketogenic than capric acid, and about six times more ketogenic than lauric acid. Caprylic acid was significantly more ketogenic than coconut oil alone. The observed ketogenic effect was substantially higher in the absence of a meal, indicating its increased efficacy during fasting.
Notably, the dose of caprylic acid used in the study was able to produce a mean daily plasma ketone concentration sufficient to fuel the energy-deprived regions of the brain of someone with Alzheimer’s.
MCTs and Weight Loss
MCT oil is predominantly marketed for its purported weight loss properties. This is because MCTs are significantly less likely to be stored in adipose tissue, don’t generate ‘ectopic fat’ metabolites that promote insulin resistance and inflammation, and may be less prone to activate inflammatory macrophages.
Some proponents of MCT oil laud it’s “fat burning” properties, and cite animal studies from the ‘80s as evidence. These claims center around thermogenesis, the processes whereby mammals generate body heat directly from body fat. Thermogenesis has been linked to weight loss, and is considered a mechanism for the prevention of obesity.
MCT oil is generally considered to be thermogenic. Several short-term studies (24 hours to 14 days) found that MCTs increase thermogenesis compared with LCTs. Then again, a more recent study observed that coconut oil given to obese adolescents did not enhance thermogenesis relative to corn oil. Concrete conclusions are hard to come by, and long-term studies are distinctly lacking.
A 12-week randomized double-blind clinical trial involving 40 women found that a diet supplemented with coconut oil decreased waist circumference, while a comparison group supplemented with soybean oil exhibited increased waist circumference. In this trial supplementation with coconut oil did not induce dyslipidemia and reduced abdominal obesity.
Some studies have observed benefits when dietary LCTs are replaced with MCTs, such as increased energy expenditure, faster satiety, and facilitated weight control. There’s also evidence that MCFAs are beneficial in diabetes. One animal study found that a high-fat coconut oil diet over the course of four weeks reduced adiposity and preserved insulin action in muscle and adipose tissue. Lauric acid was found to exert the strongest antidiabetic activity of the saturated fatty acids.
MCFAs may also be protective against type 2 diabetes by regulating the adaptive catabolic process of autophagy. Another mechanism by which MCTs may ameliorate obesity-related diseases like inflammation and diabetes is via modification of the gut microbiome. MCTs are thought to optimize the intestinal ecosystem, thereby promoting healthy metabolism.
It all sounds promising, but take it with a grain of salt. As researchers Lima and Block write in their 2019 article “Coconut oil: what do we really know about it so far?”, “Clinical trials studying the relationship between the consumption of CO and weight reduction are still scarce in the literature.”
An Oil for Every Occasion
Hype aside, there is a time and place for each of these products.
MCT oil: Use if you have pancreatic insufficiency, impaired lymphatic chylomicron transport, or issues with fat malabsorption. If this is the case, you’re likely working with a medical professional to get the nutritional support you need.
If you don’t have major malabsorption issues, use MCT oil with a healthy dose of realism. People attracted to MCT oil might be seeking a one-shot fix for their health woes, and swallow a spoonful of MCTs thinking “job done.” Instead, consider building a wholesome healthy lifestyle with a balanced diet, sleep hygiene, stress management, and exercise.
Researchers Katz and Meller hit the nail on the head in their article “Can we say what diet is best for health?” They write, “Guidance that places an exaggerated emphasis on the exclusion or inclusion of any one food or nutrient is ill-advised.”
MCT oil as a product also suffers from being more processed, more expensive, and lacking in anti-inflammatory polyphenols and, in most cases, lauric acid.
Some side effects have been reported in association with high levels of MCT oil consumption. These are rare, and primarily of a gastrointestinal nature: bloating, cramping, diarrhea, nausea, and vomiting. Notably, these symptoms were found in people with extremely high-fat diets (90% of daily calories), or people who took MCT oil on an empty stomach. Most studies report that MCT oil, when taken with food in moderation, is well-tolerated.
If MCT oil strikes you as a beneficial supplement, consider these general guidelines for use:
No more than 4-7 tbs/day to prevent gastrointestinal distress. Start at the lower threshold and work your way up. Divide doses between meals. Importantly, MCT oil should not be your only dietary fat source — the body needs polyunsaturated long chain essential fatty acids; fish is an excellent source of omega 3s. MCT oil should not be heated over 150°C or it will oxidize.
Virgin coconut oil: Best choice for higher-heat cooking. VCO has a long tradition of usage as food and medicine, and is less expensive and less processed than fractionated coconut oil.
VCO contains health-promoting lauric acid, which is typically absent in fractionated coconut oil.
VCO is also rich in active polyphenol compounds, which are strong inhibitors of lipid peroxidation, a key driver of inflammation. Researchers theorize that VCO’s polyphenols are responsible for the oil’s antioxidative, anti-inflammatory, and neuroprotective properties. Significantly, polyphenols are known to ward off the neurotoxic effects of β-amyloid, the peptide implicated in Alzheimer’s. Refined MCT oil and other fractionated coconut oils, due to their manufacturing processes, likely lack comparable levels of polyphenols.
Fractionated (non-edible) oil: This oil shines in topical applications as a massage oil or vehicle for aromatherapy. It’s odorless, lighter in texture, and more absorbable than VCO. Remains liquid at most temperatures; favored for lotions and rollerball blends.
Liquid coconut oil: Best for cooking, if you crave the convenience of a habitually liquid product. Use liquid coconut oil instead of VCO if you’re oil pulling for dental health and want to spit down the drain without mucking up the plumbing.
Where Do We Go From Here?
It’d be great if we could guzzle one product and have perfect health, but alas, as always, it’s going to be an integrated effort involving a well-rounded diet, stress management, sleep hygiene, and exercise (I know, I know… boooooring).
But in the end, there are no magic bullets. Beware marketing hype that claims otherwise. Take traditional diets as a guide: cultures that used coconut products as a staple likewise consumed high amounts of fish, fruits, and vegetables.
Dr. Krauss, an NIH-funded researcher who studies dietary fat, blood cholesterol, and heart disease risk at the UCSF Benioff Children’s Hospital Oakland, echoes these sentiments. He advises, “Diets should be limited as much as possible in simple sugars and highly processed grain products. And diets that are rich in plant-based food sources are desirable. A third recommendation would be to avoid high intake of red meat and substitute fish, which has been associated with reduced heart disease risk. And an overall principle is to avoid over-consumption of calories.”
We have to wonder how much we’re letting research and media affect our common sense. In 2010 Krauss published a massive meta-analysis that found higher intake of saturated fat was not associated with increased risk of coronary heart disease, stroke, or cardiovascular disease. When sensational headlines hit the press spurring folks to load up on triple cheeseburgers, Krauss was crestfallen.
“That’s not the message,” Krauss clapped back. “The message is to make food choices that are balanced in the overall diet and not to consider any given food the salvation of health or the kiss of death.”