Caprylic Acid (C8): Impact on Blood Ketone Levels and Evaluating Current C8 Products

Caprylic Acid (C8): Impact on Blood Ketone Levels and Evaluating Current C8 Products

This article outlines the benefits of caprylic acid (C8) vs medium-chain triglyceride (MCT) oil and coconut oil. C8 products are refined forms of coconut and/ or palm oil that contain only caprylic acid triglycerides.

Purported benefits of C8 products range from increased energy, increase in blood ketone levels and associated reduction in blood glucose levels, reduced body-fat, antimicrobial activity and even possibly reduced risk of certain metabolic diseases.

Read on to learn more about what exactly caprylic acid is, how it functions, what research has to say about it, and which C8 products we feel are worth your money.

Caprylic Acid Overview

Fatty acids come in two forms: saturated and unsaturated (caprylic acid being the former). Chemical classification of saturated fatty acids takes into account how many carbon atoms are in the hydrocarbon chain:

  • Less than 6 carbons denotes short-chain fatty acids (SCTs)
  • 6-11 carbons denotes medium-chain fatty acids (MCTs);
  • more than 11 carbons denotes long-chain fatty acids (LCTs);
  • and more than 22 carbons denotes very long-chain fatty acids.

Caprylic acid (C8) falls into the MCT category and is found primarily in food products like coconut and butter.

However, caprylic acid isn’t the same as other medium-chain fatty acids because it has fewer carbons compared to capric acid (C10) and lauric acid (C12).

C8 products are derived from MCT and coconut oil products by filtering out the capric and lauric acid components, resulting in an oil composed purely of caprylic acid. Caproic acid (C6) is also a medium-chain fatty acid found mainly in various animal fats and is generally excluded from MCT oil products.

What is & What Isn’t Caprylic Acid? Clearing Up Naming Confusion

A few different names are used when referring to Caprylic Acid, which can be confusing, although they are all the same C8 fatty acid.

Caprylic acid’s hydrocarbon chain contains 8 carbon atoms, so it is often referred to as C8 or octanoic acid/ octanoate. Octo, of course, referring to the number 8.

The name Caprylic Triglyceride or Caprylic acid triglycerides are also sometimes used. These are in fact slightly different molecules, but with similar properties. They contain a glycerol molecule bonded with caprylic fatty acids. The pancreas secretes an enzyme – called lipase – that breaks down triglycerides into its component three fatty acids and a glycerol molecule.

The C8 found in MCT oil products is technically derived from triglycerides, so it is common to see the term caprylic acid used interchangeably with caprylic triglyceride; functionally, they are the same.

Purported Caprylic Acid Benefits & Supporting Literature

Research has shown that caprylic acid ingestion increases ketone body production significantly1,2. Even a modest increase of 1mMol in plasma caprylic acid levels was shown to increase ketone body production fivefold. Intuitively this is just what keto dieters would want since ketones are their primary source of energy.

Moreover, despite the presence of moderate amounts of blood glucose (such as when you’ve been eating carbohydrates or higher amounts of protein), caprylic acid is still readily absorbed from the gastrointestinal tract and rapidly oxidized3. This means the C8 is converted into ketones regardless of whether you are in ketosis and following a ketogenic diet or not.

Other research has demonstrated that caprylic acid does indeed have strong antibacterial, antiviral, and antifungal activities4. Caprylic acid has also been shown to be effective at improving blood lipid profiles of hypertensive rats, though data in humans remains limited5.

However, there is little evidence supporting the postulation that caprylic acid is superior to a mixture of medium-chain fatty acids in reducing body-fat. Research on the performance-enhancing benefits of caprylic acid is also limited at this time, so hopefully this will be explored in future studies.

Caprylic Acid (C8) Products

Caprylic Acid (C8) vs. MCT Oil Products

Something to consider is that most MCT oil products are generally a mixture of caprylic acid and capric/ decanoic acid (C10) and sometimes lauric acid (C12). he exact ratio of each varies by product and typically contains between 50 to 75% caprylic acid).

MCT oil has accumulated a healthful amount of research literature over the past few decades, and it is safe to assume that many of its benefits are derived from caprylic acid (since caprylic acid generally constitutes the majority / 50% of the mixture). That being said, MCT products are not identical to pure caprylic acid products so be careful not to confuse the two.

Typical Fatty Acid Composition of Oil Products (MCT, Coconut, Palm, C8)

C8 Fatty Acid  in Oil Products

Note: Values in chart are averages for product type. Coconut oils and palm oils differ in fatty acid makeup according to location sourced from and farming, while MCT oil products differ based on refinement process used and quality goals of product manufacturers.

C8 products are essentially a refined version of MCT oils that have had the capric acid (C10) and lauric acid (C12) filtered out, leaving only caprylic acid as the fatty acid component.

This is thought to improve GI tolerability, a significant inconvenience associated with MCT oil (i.e. GI distress, indigestion, and diarrhea can result for the less experienced or if doses over a tablespoon are taken). Caprylic acid has a shorter hydrocarbon chain than capric and lauric acids, and thus is rapidly shuttled out to the liver for digestion. This helps elude any GI distress issue.

How & When to Use Caprylic Acid

To maximize the potential benefits of using Caprylic Acid follow these guidelines:

  • Since caprylic acid is readily digested by the liver and used for energy it would be ideal to take it before training (roughly 30-45 minutes pre-workout) without a meal (especially for those on keto diets). If taken with a meal, give yourself at least an hour before training. The same advice goes for other energy boosting goals, e.g. mental or work related.
  • C8 can be taken with meals that are higher in carbs and/or protein to reduce blood glucose spikes. Mechanistically this appears to be because insulin levels rise after ingestion of caprylic acid, due to increases in ketone body production, which increases glucose clearance.
  • It can also be utilized at pretty much any other time of the day to fulfill your fat intake needs, however, C8 is a very “pricey” source of dietary fat.
  • For antimicrobial use follow the directions on the product label and apply to the treatment area.

Caprylic Acid Dosage: How Much Should You Use?

Generally, one to two tablespoons (15 – 30mL) of pure caprylic acid oil at a time is sufficient6. Some individuals will go up to three tablespoons at a time, but the added benefits of such a high dose at one time are questionable; it would be ideal to spread several modest doses over the day as opposed to “loading” at one time.

Caprylic Acid (C8) Products Currently Available

Product Size (ml) Price (£) Price per 15ml Dose Purity Other Comments
Bulletproof Brain Octane
(in UK known as “Upgraded Octane”)
475 £16.95 £0.54 N/A* Sourced from Coconut Oil
945 £32.95 £0.52
58 (in 60 Softgels) £19.99 £5.13
KetoPerformance Pure C8 MCT 500 £15.49 £0.46 99.3% Sourced from Palm and Coconut Oil, Certificate of Analysis made available
1000 £29.66 £0.44
KetoSports Keto8 355 £19.97 £0.84 N/A* Sourced from Palm Kernel Oil
MiCkey T Eight
(Currently not available in UK)
945 £32.95 £0.52 99.01% Sourced from Palm and Coconut Oil
(Currently not available in UK)
945 £40.00** £0.63 99% Sourced from Coconut Oil
KetoMCT Oil
(Currently not available in UK)
945 £39.99** £0.63 97.79% Sourced from Coconut and Palm Oil
* Purity information is not made publicly available by all companies.
** Prices estimated based on typical US to UK conversion pricing.
Notes: Current UK prices are updated monthly and are the recommended retail price (RRP) set by the product owners. Amazon prices are typically higher than the RRP due to Amazon commissions being incorporated into pricing.

Structurally/ functionally speaking, the source from which these products derive their fatty acids is not an issue, but there are environmental concerns of products that rely on palm oil. Palm oil production has led to the deforestation of many previously tropical areas and accounts for upwards of 10% of CO2 emissions in the world.

Since greenhouse gasses are a large contributor to global warming, it’s safe to say that coconut oil is the most eco-friendly source from which C8 products are produced. In addition, there are concerns over the burning and killing of Orangutans, which have been falling in number as they live in the trees which are burnt down in Indonesia, for example.

The Main Takeaways

Caprylic acid (C8) is a substrate that shows promising potential for individuals following a keto diet. When compared to generic MCT oil, pure caprylic acid oil products are better bang for your buck since capric acid (C10) and lauric acid (C12) are not proven to increase ketone body production. Thus they also don’t appear to be as readily oxidized for energy as caprylic acid.

However, more research is needed to confirm whether or not many of the metabolic health benefits derived from MCT oil (such as reduction of abdominal fat and performance enhancement benefits) are mediated mostly or solely by caprylic acid rather than the other fatty acids.

Caprylic Acid (C8) Product Recommendations

KetoPerformance Pure C8 MCT is currently the most cost-effective caprylic acid oil product in the UK. If you are concerned about sustainability and sourcing of palm kernel, Bulletproof Upgraded Octane is slightly more expensive, but now made from 100% coconut oil.


  1. McGarry, J. D., & Foster, D. W. (1971). The Regulation of Ketogenesis from Octanoic Acid THE ROLE OF THE TRICARBOXYLIC ACID CYCLE AND FATTY ACID SYNTHESIS. Journal of Biological Chemistry, 246(4), 1149-1159.
  2. Miles, J. M., Haymond, M. W., Nissen, S. L., & Gerich, J. E. (1983). Effects of free fatty acid availability, glucagon excess, and insulin deficiency on ketone body production in postabsorptive man. Journal of Clinical Investigation, 71(6), 1554.
  3. Schwabe, A. D., Bennett, L. R., & Bowman, L. P. (1964). Octanoic acid absorption and oxidation in humans. Journal of applied physiology, 19(2), 335-337.
  4. Nair, M. K. M., Joy, J., Vasudevan, P., Hinckley, L., Hoagland, T. A., & Venkitanarayanan, K. S. (2005). Antibacterial effect of caprylic acid and monocaprylin on major bacterial mastitis pathogens. Journal of dairy science, 88(10), 3488-3495.
  5. Kim, B. H., Sandock, K. D., Robertson, T. P., Lewis, S. J., & Akoh, C. C. (2008). Dietary structured lipids and phytosteryl esters: blood lipids and cardiovascular status in spontaneously hypertensive rats. Lipids, 43(1), 55-64.
  6. Scalfi, L., Coltorti, A., & Contaldo, F. (1991). Postprandial thermogenesis in lean and obese subjects after meals supplemented with medium-chain and long-chain triglycerides. The American journal of clinical nutrition, 53(5), 1130-1133.