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Medium chain acyl-CoA dehydrogenase deficiency

Does your blood sugar crash when you don’t eat for a day? Do you find that coconut oil in your coffee doesn’t work well for you? It could be that your body has trouble using medium-chain fatty acids for energy.

What is medium-chain acyl-CoA dehydrogenase deficiency?

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is an “inborn error of metabolism” which impairs the body’s ability to break down medium-chain fatty acids for fuel.

In a nutshell, the body can use either glucose (through glycolysis) or fatty acids (through beta-oxidation) as the basis for producing energy in the mitochondria. MCAD deficiency affects the body’s ability to efficiently use medium-chain fatty acids for energy.

MCAD deficiency in infants and children:

MCAD deficiency is a fairly rare genetic disorder, and it is usually only diagnosed in children who carry two copies of mutations in the ACADM gene (some are listed below).

Symptoms of MCADD generally occur when an infant or child hasn’t eaten, often due to being sick with a cold, ear infection, or the flu. Because the body can’t utilize fatty acids efficiently for energy, children with MCAD deficiency can have severe hypoglycemia (low blood sugar), which can progress into a serious metabolic crisis.[ref]

Not every child that has genetic mutations for MCAD deficiency ends up having problems with MCAD deficiency. Newborn screenings are now being done to identify infants with MCAD deficiency.[ref]

Carrying one copy of an MCADD mutation:

It is now being recognized that people who carry one copy of an ACADM gene mutation may also have problems with hypoglycemia during times of intense exercise, fasting, surgery, or illness — basically, the times when your body may rely only on fatty acids instead of glucose for energy. People with one copy of the mutation may have no problems at all under normal conditions since fatty acid oxidation should still work — just at a less-than-optimal level.[ref][ref][ref][ref]

One study sums up with this: “As in other metabolic disorders, the distinction between “normal” and “disease” in MCAD deficiency is blurring into a spectrum of enzyme deficiency states caused by different mutations in the ACADM gene potentially influenced by factors affecting intracellular protein processing.”[ref]

MCADD Genotype Report:

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Nutrition and lifestyle considerations:

If you are a carrier (heterozygous) for one of the MCAD deficiency mutations, you may find that a higher carb/ lower fat diet may work better for you. In this era of carbs being demonized, MCAD carriers may need to buck the low-carb trend — or at least be alert for signs of hypoglycemia if eating a low-carb diet.

Blood sugar drops:
The key is to keep an eye out for signs of low blood sugar. If you exercise hard, eating before a workout may be beneficial.

Anecdotally, drinking a lot of alcohol without eating anything can also cause hypoglycemia in people with one copy of the MCAD mutation.

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About the Author:
Debbie Moon is the founder of Genetic Lifehacks. Fascinated by the connections between genes, diet, and health, her goal is to help you understand how to apply genetics to your diet and lifestyle decisions. Debbie has a BS in engineering and also an MSc in biological sciences from Clemson University. Debbie combines an engineering mindset with a biological systems approach to help you understand how genetic differences impact your optimal health.

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