Have you ever wondered why some people seem to get away with eating anything they want and others develop diabetes just by walking past a doughnut shop. The relatively new science of nutrigenomics offers a number of answers to these kinds of questions, and no genetic abnormality has been more thoroughly studied than a group of mutations that affect the way the body makes an enzyme called MTHFR.
What is MTHFR?
The acronym MTHFR stands for methylenetetrahydrofolate reductase. It's an enzyme your body has to have to activate vitamin B9, commonly referred to as folate or folic acid, into a form that it can use.
Why Does Folic Acid Need "Activating"?
Folic acid is just one of multiple forms of the compound we know as vitamin B. The B9 group is found in leafy greens, foliage, as:
- Monoglutamyl folates, and
- Polyglutamyl folates.
Folic acid is a synthetic form of the vitamin. The folic acid form of the vitamin is added to flour to prevent a deficiency that can cause birth defects like spina bifida and cleft palate.
The body can't use folic acid in the form in which it is added to food very efficiently. To be readily absorbed by cells or to cross the blood-brain barrier so it can enhance brain health, folic acid has to be transformed to methylfolate. This process requires the enzyme methylenetetrahydrofolate reductase.
If you don't, your body can use tiny amounts of the vitamin slowly, but at the cost of a variety of metabolic dysfunctions that cause:
- The previously mentioned birth defects, plus a greater risk of miscarriage, even when the mutation is from the father ,
- Anemia (low red blood cell count) ,
- Chronic fatigue ,
- Diarrhea, especially in older people , and
- Irritability .
These are symptoms that can occur to anyone who has any of the MTHFR mutations. However, there's more than one kind of MTHFR mutation, and more than one set of long-term consequences to having one of these mutations without making appropriate changes in diet.
What Are the MTHFR Mutations?
DNA (almost always) is a sequence of just four base pairs, adenine (A), cytosine (C), guanine (G), and thymine (T). These base pairs are the "letters" that in groups of three spell out codons or "words" that place amino acids in the right order to make a function protein. In the case of the MTHFR gene, the result is an enzyme.
There are two places in the strand of DNA that codes this enzyme that tend to go wrong. One is at position number 677, the 677th A, C, G, or T in the stand of DNA that codes MTHFR. The nucleotide at this position is supposed to cytosine (G). However, sometimes there is a mutation that substitutes thymine (T). The right coding is expressed as C677C. Both strands of DNA have cytosine where it's supposed to be. However, one or both of your parents may have passed down DNA that has thymine (T) where there's supposed to be cytosine (C). If you have one "misprint," your DNA is said to be heterozygous for this mutation, or C677T. If you have two "misprints," your DNA is said to be homozygous, or T677T. Because just one base pair is involved, this kind of mutation is known as a single nucleotide polymorphism, or SNP, pronounced "snip."
Another place that DNA can be miscoded is position 1298. Here there is supposed to be adenine (A) on both strands of DNA. However, sometimes there is a mutation that substitutes cytosine (C) for adenine. Non-mutant DNA here is termed A1298A. A heterozygous mutation would be A1298C, and a homozygous mutation would be C1298C.
Homozygous mutations are more serious than heterozygous mutations. They cause more symptoms. "Compound" mutations, mutations at both locations, are more serious still.
What Can MTHFR Mutations Do?
Australian nutritionist Joe Leech explains the importance of MTHFR mutations this way:
Your genetics load the gun. Your diet pulls the trigger.
Just having an MTHFR mutation without treating it is enough to endanger a pregnancy or cause chronic fatigue. However, it takes a combination of MTHFR mutations and lifestyle choices to cause these potentially deadly results:
- Athletes who have C677T or T677T genotypes need to pay close attention to their intake of methylfolate, B6, and B12 for optimum performance .
- People who have the A1298C or C1298C genotypes and who drink too much alcohol without getting enough methylfolate in their diets have approximately double the risk of a certain kind of tumor in breast, colon, esophageal, ovarian, pancreatic, or prostate cancer .
- Even though MTHFR mutations regulate folic acid metabolism, women who have the C677T or T677T genotypes and who don't get enough vitamin B6 during pregnancy are at greater risk of miscarriage .
- People who have the T1298T genotype who don't get methylfolate, B6, and B12 are at two to three times greater risk for heart disease .
- Any form of MTHFR mutation increases the risk of age-related hearing loss  as well as diabetic neuropathy and diabetic retinopathy .
- C677T and T677T mutations are associated with increased risk of bipolar disorder  and schizophrenia  (although there are other important genetic factors), as well as gout  and kidney disease .
All of these conditions may be ameliorated or even prevented by choosing the right diet and supplements. However, different diets and supplements are required for different genetic mutations. That's the reason it's important for anyone who has chronic fatigue, fertility issues, or any of the conditions listed above, or who has them in the family, to get an MTHFR test.