I wrote this for another site a few years ago, I believe it to be relevant until you are adapted(was written for the lay public):
To MCT or to LCT????? That is the question………...
“Tomorrow, I start my diet!” With a hint of pre-emptive triumph this affirmation is stated millions of times each year. The reason tomorrow always seems to win over today: dieting is generally regarded as a time of deprivation, restriction and a healthy reduction in one’s gastronomic indulgence. The Very-Low-Carbohydrate Ketogenic Diet (VLCKD) is notorious for an initiation period that can lead to symptoms dubbed the “Keto-Flu.” In years past you either suffered through it or bailed on the diet altogether.
Cliff J. d C. Harvey and colleagues at AUT University in Aukland, New Zeland, may have a third choice for keto dieters. With their recent published research, “
The Effect of Medium Chain Triglycerides on Time to Nutritional Ketosis and Symptoms of Keto-Induction in Healthy Adults: A Randomised Controlled Clinical Trial,” Harvey and company have given ketogenic dieters the research to support MCT use in order to reduce keto-flu symptoms and decrease time taken to reach nutritional ketosis.
Very-low-carbohydrate ketogenic diets offer specific health benefits for those suffering from certain diseases, such as neurological disorders, diabetes, cancer, obesity and other metabolic conditions. (1-11) Research supports the effectiveness of ketogenic dieting and some individuals simply feel better with such a diet when compared to a low-fat reduced calorie program. (18) One of the major drawbacks to a VLCKD is the induction period. During this period the body transitions from using primarily glucose and stored muscle and liver glycogen to using fats and ultimately ketones as its primary fuel source. During the induction/transition period the infamous “keto-flu” may hit dieters, potentially derailing success before they even get started.
Keto-flu manifests with symptoms such as constipation, headache, halitosis(bad breath), muscle cramps, diarrhea, general weakness, and rash.(12) Keto-flu is a result of increased natriuresis, kaliuresis, and diuresis. Reductions in blood glucose during the adaptation period can also result in a temporary shortage of fuel for brain function, and thus a feeling of mental dullness with lack of clarity. The severity of the aforementioned symptoms vary from person to person, but almost everyone experiences some degree of effects during the adaptation period of the ketogenic diet.
Suffer Less you say? Tell us more…..
“The aim of the present study, therefore, was to investigate, in a randomized, double-blind, placebo-controlled trial, whether MCTs reduce time to nutritional ketosis and symptoms of keto-induction and mood in a classic ketogenic diet. The primary outcome measured was the time taken to achieve NK. Secondary outcomes were symptoms and mood.” (13)
The researchers recruited participants as shown in table 1 below.
| Table 1: Demographic characteristics of participants. |
| | | | | MCT | LCT |
| | | | Gender (M/F) | 1/11 | 1/10 | | Age (years); mean (range) | 40 (33 to 47) | 40 (32 to 48) | Ethnicity  | European (5) | European (11) | | NZ Maori (2) | | | | Pacific Island (3) | | | | Chinese (1) | | | | Other Asian (1) | | |
| | |
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| MCT: medium chain triglyceride; LCT: long-chain triglyceride; M: male; F: female. |
Once recruited and divided, the study participants were placed on a VLCKD with a 4:1 lipid to non-lipid ratio. Females were allowed 1800 kcal per day while the men received 2200 kcal per day. Both the men and women consumed 80% of their daily calories from fat, which included the supplemental oils. The remainder of calories were allocated as 13-17% protein and 3-6% from carbohydrates. (13)
Participants were randomly assigned to receive either MCT oil(comprised of 65% caprylic acid C:8 and 35% capric C:10) or sunflower oil. Both oils were dosed at 30g, three times per day, for 20 days. The researchers arrived at this dose based on a previous study performed by Ivy et al. in which they discovered 100% of participants experience gastric distress with dosages of 50 and 60g of MCT, with only a small GI effect noted at 30g.(14)
Participants were instructed to measure their beta-hydroxybutyrate (BOHB) and blood glucose(BG) levels upon awakening. Participants were furnished a FreeStyle Neo” blood-prick ketometer/glucometer (Abbott Industries) in order to perform said tests. For the purpose of this study, the researchers choose a blood level of ≥0.5 mmol·L−1 BOHB to determine a participant having reached a state of ketosis. In addition to blood tests, volunteers also completed a symptom questionnaire as well as a mood evaluation. (13)
Results
“Supplementing MCT resulted in consistently higher blood levels of BOHB in our cohort of healthy adults relative to LCT treatment, with higher BOHB at all time points in the MCT group (Figure 2).” (13)
The researchers also a negative effect of BOHB on glucose in both groups. That is, higher BOHB levels resulted in lower glucose levels. This was further indicated by a very large, significant, inverse relationship of glucose to BOHB for both MCT and LCT groups” (13)
Ok, so we get higher blood levels of BOHB with lower levels of blood glucose using MCT’s, but this is always the result of a keto diet right? So why use MCT’s at all?
It all comes back to the potentially troublesome induction period with the dreaded keto-flu. Do MCT’s help us endure the keto-flu or perhaps even shorten it all together? The results and data are encouraging:
“Overall, time to ketosis was more rapid with MCT supplementation. The achievement of NK within the first three days was higher with MCT versus LCT……Supplementation with MCT versus control resulted in
lower symptoms associated with keto-induction.” (13)
Statistical Significance
By day three, the initial advantage MCT had shown in hastening NK had ceased. From day three on participants entered NK at the same rate. It should be noted that the MCT group saw 100% of its members reach NK while the LCT group had one person unable to obtain NK at the end of day twenty. So when it comes to reaching NK there may not be a statistically significant advantage after a few days…...but……
Real Life-Significance
The MCT group had 17% of its members in NK by DAY ONE vs 0% for LCT! On day two MCT had 33% of users in NK vs 18% for LCT. So if one uses MCT during the first two days of a VLCKD there is up to a 33% chance you will be in NK. Anyone who has dieted can appreciate the difference one or two days less of suffering would make. One or two days may be the difference between a successful induction period or abandoning the VLCKD altogether.
MCT’s are generally regarded as safe and ketogenic.(15-17) There is a clear and significant effect on BOHB levels when MCT supplementation is compared to LCT consumption.(13) While there was not a significant effect on time to NK with MCT vs LCT, certain participants were able to achieve NK two whole days earlier with MCT’s.
Two days can be a lifetime when dealing with brain fog, cramping, bad breath and general weakness, aka the keto-flu. Simply put, when subjecting one’s self to voluntary suffering two days may be the difference between success and failure.
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