Medium-Chain Fatty Acids (MCFA)

What are medium-chain fatty acids?

Medium-chain fatty acids (MCFA) contain 6-12 carbon (C) atoms.

MCFA Examples:

• Hexanoic or caproic acid (C6)
• Octanoic or caprylic acid (C8)
• Decanoic or capric acid (C10)
• Dodecanoic or lauric acid (C12)

All the above short-chain fatty acids are saturated. They provide 8.3 Calories per gram ^[4].

Foods High in MCFA

Foods high in MCFA ^[1,2]:

• Coconut milk (1/2 cup, 120 mL): 15 g
• Palm-kernel oil (1 tbsp, 13.6 g): 8 g
  
• Coconut oil (1 tbsp, 13.6 g): 8 g
• Cheese, feta (100 g): 3 g
• Butter (1 tbsp, 14 g): 1.2 g

Chart 1. Composition of coconut oil (One tablespoon of coconut oil contains 12.8 g of fatty acids)
SATURATED FA (11.8 g)		MONO-UNSATURATED FA (0.8 g)	POLY-UNSATURATED FA (0.2 g)
Medium-chain FA (7.9 g)	Long-chain FA (3.8 g)
-Lauric acid (6.1 g)	-Myristic acid (2.3 g)	-Oleic acid (0.8 g)	-Linoleic acid (0.2 g)
-Caprylic acid (1 g)	-Palmitic acid (1.1 g)
-Caproic acid (0.8 g)	-Stearic acid (0.4 g)

Chart 1 reference: SELFNutritionData ^[14]

MCFA Absorption

MCFA can be quickly absorbed from the small intestine, even in the absence of the digestive enzyme pancreatic lipase (in this case MCFA are absorbed as triglycerides – the form as found in foods) and even when bile salts are less available (in liver disease or bile duct stones); this is why MCFA are a useful source of calories in disorders with fat malabsorption ^[4]. In patients with surgically removed small intestine, MCFA can be absorbed in the colon ^[5].

MCFAs as Food Additives

Free MCFAs, such as caproic acid, have an unpleasant odor, but MCFA esters, such as caproate, have a pleasant odor and may be used as food flavors.

MCT Supplements

Medium-chain triglycerides (MCT) in the oil form are available without prescription (over-the-counter). They are semi-synthesized from palm or coconut oil.

Special MCT supplements to be used as part of MCT ketogenic diet are available by prescription.

Medium-Chain Fatty Acids Supplements Benefits

MCFA are EFFECTIVE in providing calories for patients fed by intravenous nutritional infusions ^[20].

MCFA are POSSIBLY EFFECTIVE in:

• Increasing satiety (more than long-chain fatty acids) ^[17]
• Preventing certain types of seizures in children ^[4,6,19,20]
• Preventing the rupture of lymphatic vessels in primary intestinal lymphangiectasia or Waldmann’s disease (in combination with a low-fat diet) ^[18].
• Preventing muscle breakdown in critical illness (when given as an intravenous infusion) ^[20].
• Providing calories to patients with fat malabsorption due to liver or bile duct disease, cystic fibrosis, pancreatitis, celiac disease, Crohn’s disease, or after extensive surgical removal of the small intestine ^[16].
• Treating hereditary hyperlipidemias, such as hyperlipoprotein lipase deficiency ^[4].

MCFA are POSSIBLY INEFFECTIVE in preventing weight loss in HIV/AIDS and increasing athletic performance ^{[10,11,15,20]}.

There is INSUFFICIENT EVIDENCE about the effectiveness of MCFA in prevention or treatment of Alzheimer’s disease, fatty liver ^[13], chylothorax (a rare lung disorder) ^[20] and ischemic heart disease or in decreasing body fat, improving the absorption of calcium and magnesium, decreasing high cholesterol ^[7], increasing lean muscle or promoting weight loss ^{[4,7,8,9,10,12]}.

It is not clear, if coconut oil has any harmful or protecting effect on heart. Health authorities, such as Harvard Medical School and American Heart Association recommend avoiding regular use of coconut oil (and palm and palm-kernel oil) because it increases the blood levels of total and LDL cholesterol.

MCFA Safety: Side Effects, Toxicity

MCFA are PROBABLY SAFE for most adults. Side effects may include nausea, vomiting, abdominal bloating, diarrhea, essential fatty acid deficiency ^[20].

Who should not take MCFA supplements?

• Pregnant and breastfeeding women and individuals with a liver disease ^[20]
• Diabetics. MCFA tend to produce ketones and metabolic acidosis ^[20].
• Patients with liver cirrhosis ^[4]

MCFA and Cooking

MCFA have a low smoking point and easily foam, so oils high in MCFA, such as coconut and palm-kernel oil, are not suitable for deep frying ^[3].