Caprylic Acid (C8 MCT): Benefits, Dosage & Use in Sports Nutrition
Caprylic acid, also known as C8, is a medium-chain fatty acid that your body converts to ketones faster than any other dietary fat. Here we break down what science actually shows and how to get practical benefit from C8.
TL;DR
- C8 (caprylic acid) is an 8-carbon MCT fatty acid metabolized directly in the liver into ketones
- More efficient than C10 or C12 for ketone production (Vandenberghe et al., 2017)
- Dose: 5-15 ml (1-3 tsp) per day, start low
- Useful on keto diets, during intermittent fasting, and for endurance training
- GI distress is the main side effect from excessive dosing
What Is Caprylic Acid?
Medium-chain triglycerides (MCTs) are fatty acids with chain lengths of 6-12 carbon atoms. Caprylic acid is the 8-carbon variant (C8), the most efficient ketone producer among MCTs.
Unlike long-chain fatty acids, C8 does not require bile acids for digestion. It travels via the portal vein directly to the liver, where it is rapidly oxidized into ketone bodies (Bach & Babayan, 1982). This means a fast energy source that does not depend on glycogen reserves.
Why C8 Is Special Among MCTs
Not all MCTs are equal. Coconut oil, often marketed as an "MCT source," is primarily lauric acid (C12), which behaves metabolically more like a long-chain fatty acid.
| MCT Type | Chain Length | Ketone Production | Share in Coconut Oil |
|---|---|---|---|
| C6 (caproic acid) | 6C | Fast but bad taste | ~1% |
| C8 (caprylic acid) | 8C | Most efficient | ~7% |
| C10 (capric acid) | 10C | Moderate | ~6% |
| C12 (lauric acid) | 12C | Slow | ~49% |
Vandenberghe et al. (2017) demonstrated that C8 raised plasma ketone levels 3 times more effectively than coconut oil at an equivalent dose.
Science-Backed Benefits
Rapid Energy Source
C8 converts to ketones within 15-30 minutes of consumption. This is valuable for athletes training fasted or needing quick energy without carbohydrates (St-Pierre et al., 2019).
Cognitive Support
Ketones cross the blood-brain barrier and provide the brain with an alternative fuel. Studies show improved cognitive performance, especially at low blood sugar levels (Cunnane et al., 2016).
Body Composition
MCTs increase thermogenesis and satiety compared to long-chain fats. A meta-analysis found that MCT consumption reduced body weight and body fat percentage compared to long-chain fats (Mumme & Stonehouse, 2015).
Antimicrobial Activity
Caprylic acid has in vitro antimicrobial effects against Candida species (Omura et al., 2001). While clinical evidence is limited, it is commonly used in gut health protocols.
Practical Usage Guide
How to Start
1. Week one: 5 ml (1 tsp) per day — on an empty stomach in the morning
2. Week two: 10 ml (2 tsp) — split between breakfast and lunch
3. From week three: up to 15 ml (1 tbsp) — according to tolerance
Popular Uses
- In coffee ("bulletproof coffee") — add 1-2 tsp to morning coffee
- In smoothies — blend with protein powder and berries
- Pre-workout — 30 minutes before endurance training on an empty stomach
- In baking — replace some fat with MCT oil (up to 165C)
Side Effects and Warnings
- GI distress is common when starting too fast — cramping, nausea, diarrhea
- Always start with a small dose and increase gradually
- Diabetics should consult a physician, as ketones affect blood sugar regulation
C8 MCT vs Regular MCT Oil
| Property | Pure C8 | MCT Oil (C8+C10) | Coconut Oil |
|---|---|---|---|
| Ketone production | Highest | Moderate | Low |
| Flavor | Neutral | Neutral | Coconut |
| Price | Higher | Moderate | Lowest |
| GI tolerance | Good | Good | Best |
| Price in Estonia | 15-30 EUR/500ml | 10-20 EUR/500ml | 5-12 EUR/500ml |
Common Mistakes
1. Equating coconut oil with MCT — coconut oil is primarily C12, which does not produce ketones quickly
2. Starting with too large a dose — start with 5 ml, not a tablespoon
3. Expecting weight loss from MCT alone — MCT does not cancel out a caloric surplus
4. Using above 165C — breaks down at high temperatures
Frequently Asked Questions
Is C8 suitable for a keto diet?
Yes, C8 is an ideal keto partner. It accelerates reaching ketosis and maintains higher ketone levels throughout the day.
Is MCT oil vegan?
Yes. MCT oil is typically derived from coconut or palm oil and is entirely plant-based.
Can I take C8 on an empty stomach?
Yes, but start with a small dose (5 ml). Fasted consumption accelerates ketone production, but may initially cause digestive discomfort.
How to identify quality MCT oil?
Check that the label specifies the percentage of C8 (caprylic acid). Quality C8 MCT oil contains at least 95% caprylic acid.
Estonia-Specific Notes
MCT and C8 oil are available in Estonia at sports nutrition stores and online. Pure C8 oil typically costs 15-30 EUR per bottle. Estonian winter conditions, when energy and motivation can dip, make MCTs particularly useful as part of a morning energy routine.
References
1. Bach AC, Babayan VK. (1982). Medium-chain triglycerides: an update. American Journal of Clinical Nutrition, 36(5), 950-962.
2. Vandenberghe C, St-Pierre V, Pierotti T, et al. (2017). Tricaprylin alone increases plasma ketone response more than coconut oil or other medium-chain triglycerides. Current Developments in Nutrition, 1(4), e000257.
3. St-Pierre V, Vandenberghe C, Lowry CM, et al. (2019). Plasma ketone and medium chain fatty acid response in humans consuming different medium chain triglycerides during a metabolic study day. Frontiers in Nutrition, 6, 46.
4. Cunnane SC, Courchesne-Loyer A, Vandenberghe C, et al. (2016). Can ketones help rescue brain fuel supply in later life? Frontiers in Molecular Neuroscience, 9, 53.
5. Mumme K, Stonehouse W. (2015). Effects of medium-chain triglycerides on weight loss and body composition. Journal of the Academy of Nutrition and Dietetics, 115(2), 249-263.
6. Omura Y, O'Young B, Jones M, et al. (2001). Caprylic acid in the effective treatment of intractable medical problems. Acupuncture & Electro-Therapeutics Research, 36(1-2), 19-64.
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