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Hemochromatosis gene may give athletes an edge

What is Hemochromatosis?

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Hemochromatosis is a rare genetic disease that causes iron to accumulate in the body.  Too much iron can have devastating effects.  People with hemochromatosis can develop “iron overload”.  We need iron to form hemoglobin and carry oxygen to our tissues, but too much can lead to cellular damage, diabetes, cardiovascular disease and possibly cancer.  The gene that causes hemochromatosis is called the HFE gene.  A mutation in this gene results in a protein that makes iron absorption very efficient.  In order to get hemochromatosis you need to have two mutated copies of the HFE gene.  The most common form of hemochromatosis (p.c282y) appears in about 2-5 people per thousand among Caucasians.  It is more common in some areas (1-2% in Ireland).  More people have a single mutated hemochromatosis gene.  About 5-14% of Western Europeans carry one.  About 6-7% of non-Hispanic White Americans carry it.

Benefits of a Hemochromatosis gene mutation?

It is possible that having a single Hemochromatosis gene is beneficial.  Studies have shown that women with a single copy are less likely to be anemic and less likely to be iron deficient (Datz et al. 1998).  People with two copies of the hemochromatosis also absorb more zinc, copper and manganese.  At present, it is unknown if people with single hemochromatosis genes do as well.  If yes, people with a single hemochromatosis gene may be protected from several nutritional deficiencies.  In any case, it looks like people with single copies may have an advantage in that they have some protection from iron deficiency.   Iron is critical to life.  It is also critical to athletic performance.   Having that HFE gene may protect an athlete from low iron or anemia.  It may be significant.  A recent study of French Olympic Rowing, Judo or Nordic Skiing Champions (Hermine et al. 2015) found that 80% of them had a single copy of the hemochromatosis gene mutation.  The frequency of a single HFE mutation was 50% for Olympic athletes who did not medal.

Genetics may help, but hard work, smart training and good nutrition are key.

Elite athletes may have “better” genetic profiles for sports than the general population.  But once they are at the elite level, they are separated coaching, training, nutrition, personality and luck (Santiago et al. 2010).  These factors will be what matter most for those without “better” genetic profiles as well. If the results of the French study (Hermine et al. 2015) are typical, 20% of Olympic Champions and 50% of Olympic athletes may be “just average” people. At least as far as the HFE gene is concerned.  If you have a great genetic profile, be grateful, but don’t forget you can still get your ass kicked by an average Joe or Jane.

Low iron is sometimes overlooked in athletes.  Intense training can speed iron loss.  Combine that with a poor diet or under-eating to make a certain weight and you may find your athlete struggling.  It can be a problem, especially for young women, that more training or another rest day may not solve. Female athletes who have stopped having periods seem to be prone to anemia (as well as bone thinning).  Click here to get info on tests for anemia.  Eat well my friends.  Train well.  Be reasonable.



Barton JC, Edwards CQ, Acton RT.  2015.  HFE gene: Structure, function, mutations and associated iron abnormalities.  Gene.  574: 179-192. 

Hermine O, Dine G, Genty V, Marquet LA, Fumagailli G, Tafflet M, Guillem F, Van Lierde F, Rousseaux-Blanchi, Palierne C, Lapostolle JC, Cervetti JP, Frey A, Jouven X, Noirez P, Toussaint JF.    2015.  Eighty percent of French sport winners in Olympic, World and Europeans competitions have mutations in the hemochromatosis HFE gene.  Biochemie.  119: 1-5. 

Santiago C, Ruiz JR, Munjesa CA, Gonzalez-Friere M, Gomez-Gallego F, Lucia A.  2010.  Does the poygenic profile determine the potential for becoming a world-class athlete? Insights from the sport of rowing.  Scand J Med Sci Sports.  20(1): e188-94. 

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Obesity Genetics and Bacteria: Another Piece of a Strange Puzzle

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Obesity genetics and bacteria are strange bedfellows.  The causes of obesity are far more complicated than we thought just a few short years ago.  Diet and exercise are important, for sure.  But scientists are discovering that genetics and the gut microbiome are be key factors too.  The gut microbiome, if you didn’t know, are the trillions of bacteria that reside in our digestive tracts.  New research has uncovered a piece of how genetics and bacteria interact to increase the chances that someone will become obese, or develop diabetes.

Obesity Genetics and Bacteria Nutshell

Most of us will remember that people can’t digest plant fiber.  That is why we don’t bother to eat grass.  Or leaves.  Or at least most leaves . . . the kind on trees.  Or shrubberies.  Cows and other hoofed animals can eat these things because their stomachs are designed differently.  Bacteria in a cow’s stomach have time to ferment grass and such and break down all those long cellulose chains into useable starch for the cow.  It turns out, however, that some gut bacteria in humans can break down plant fiber into short chain fatty acids.   Humans can then take these fatty acids and convert them into fat.

Obesity and Genetics.

Here comes the genetics part:  While we host trillions of bacteria, we also control their populations.   Overgrowth of bacteria is controlled by a gene called TLR5.  People whose TLR5 doesn’t work that well cannot control gut bacteria as well.  About 10% of our population has a mutated TLR5 that just doesn’t work.  At all.   Having this mutation increases your risk of metabolic syndrome: obesity, diabetes and cardiovascular disease.  Having this mutation also increases fat deposits in the liver.  If you are incredibly geeky (happy emoticom) you can read this “just out” article on genetics and obesity and bacteria here.  If you are less technically oriented, hopefully this information will of help as it is.  If you are struggling with your weight and trying to stay healthy, keep up the good work.   It actually is harder for some people than it is for others.   Different people can actually eat the same thing, and get different amounts of calories out of it.

Back in the old days having this mutation might have been beneficial.  You would have been able to extract more energy from food, which would have been great in times of famine.  But we now live in a time of excess.

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Folate, Cardiovascular disease, migraine, depression and MTHFRs

What is a MTHFR?

MTHFR is a gene.  It is a section of DNA that is responsible for producing an important enzyme.  Enzymes are proteins that drive many biochemical reactions.  Enzyme function is essential for your function as a living entity.  MTHFR is also pronounced (Mother @#$!% by graduate students.  And by younger faculty when they think tenured faculty are not listening.)    The enzyme is called Methylenetetrahydrofolate reductase.  It is key to converting folate (Vitamin B9) to a form that the body can use.

If you had no methylenetetrahydrofolate reductase you would be screwed.  Fortunately this is extremely rare.  Possibly because few would survive long enough to be born.  However, life being complicated . . . there are several different forms of the MTHFR gene.  The different forms produce slightly different kinds of enzyme.  The “normal” form is found in most people.  About 70% of the general population. The other 30% have mutations. Chances are high that someone you know is a mutant.  You may be a mutant too.   And there are different kinds of mutants.  “Normal” has two copies of the gene that makes high function enzyme.  Someone could have one normal and one mutant.  This person would make less high functioning enzyme.  But more than someone with two mutant copies.  About 10% of the population is thought to have two mutant copies.  There are also different types of mutations.  So there is probably a range going on here.  In terms of how much methylenetetrahydrofolate reductase is circulating in people.

What does it mean health-wise for MTHFR mutants?

MTHFR mutants can’t convert folate to its useable form as well as MTHFR normals.  They are more likely to be folate-deficient.  This can lead to greater risk of some birth defects.  For example: spina bifida and anencephaly. (not having a brain).  Mutants are much more likely to get migraine headaches.  The kind of headache with aura.  They are also more likely to get cardiovascular disease.  Even if they do everything else right.  Other bad things are:

  • More severe forms of schizophrenia (not all MTHFR mutants have this! Or so says a very reliable voice)
  • More likely to suffer from depression
  • Greater risk of high blood pressure
  • Greater risk of pre-eclampsia
  • Greater risk of some cancers
  • Greater risk of birth defects including heart defects and spina bifida

Some good things about being a MTHR mutant are:

  • Less risk of colon cancer
  • Less risk of leukemia

What are the chances that I am a MTHFR mutant?

A lot of research is still being done.  So far it looks like there are 24 different polymorphisms.   So far it looks like people of Mediterranean descent and Hispanics are more likely to have a MTHFR mutation.  General Caucasions are next.  MTHFR mutations seem to be least frequent in people of African ancestry.  See this article (page 12 for a chart).  If you look at the chart you will see that MTHFR mutations are not uncommon at all.  So don’t feel bad if you are one.  You will need to be more careful about heart disease.  If you are a young woman of childbearing age you should make sure your diet contains enough folate.  If you are low in folate AND a MTHFR mutant you may be more likely to have health problems.

Is there anything I can do about my mutation (Does CrossFit fix mutations)?

Possibly yes.  Methylenetetrahydrofolate reductase is only one step in the conversion of folate to its useable form.  There are now folate supplements you can take in which the folate is already partly converted.  These are available by prescription.  Some people are taking them to help combat depression.  It will be interesting to see if such supplements will also control migraine headaches.  And cardiovascular disease.  And birth defects.  Very exciting. Oh.  CrossFit will not help with this.

What about diet? Are people on the Paleo diet protected?

People who have the MTHFR mutation may need more folate than others.  Regardless of what diet they follow.  Increasing folate intake may protect them from heart disease.  And other problems.  Beans and whole grains are major sources of folate.  Fruit, vegetables and liver are good sources too.  People who drink alcohol regularly will need more folate than others.  So will young women.  People who follow the Paleo diet (or Paleolithic diet) may also have low folate intake. That is because the paleo diet excludes grains and beans.  High vegetable intake should help.   The paleo diet is popular with CrossFit athletes.

Here are a few citations. For more check pubmed.

Liu A, Menon S, Colson NJ, Quinlan S, Cox H, Peterson M, Tiang T, Haupt LM, Lea RA, & Griffiths LR (2010). Analysis of the MTHFR C677T variant with migraine phenotypes. BMC research notes, 3 PMID: 20663228

Gong D, Gu H, Zhang Y, Gong J, Nie Y, Wang J, Zhang H, Liu R, Hu S, & Zhang H (2012). Methylenetetrahydrofolate reductase C677T and reduced folate carrier 80 GA polymorphisms are associated with an increased risk of conotruncal heart defects. Clinical chemistry and laboratory medicine : CCLM / FESCC, 50 (8), 1455-61 PMID: 22868813

Khandanpour N, Willis G, Meyer FJ, Armon MP, Loke YK, Wright AJ, Finglas PM, & Jennings BA (2009). Peripheral arterial disease and methylenetetrahydrofolate reductase (MTHFR) C677T mutations: A case-control study and meta-analysis. Journal of vascular surgery, 49 (3), 711-8 PMID: 19157768