Do I have a B12 defficiency?

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Do I have a B12 defficiency?

Postby AndrewBurns » Sun Jul 15, 2012 7:38 pm

Hey all, here's my problem. I did my longest ever ride at 155km today and it was tough, especially because I didn't bring enough food, but I'm having some other strange symptoms now that lead me to believe I might have a B12 deficiency, or at least that I do now after my intense ride. A few details:

- I eat a vegetarian diet
- I developed very sore leg muscles during the ride (not unexpected with the distance I guess), got a lot better after I had lunch
- I've felt very tired and weak all afternoon (I usually do after 80+ km rides)
- Today after the ride I've been experiencing intense pain in my soft pallet when eating, the action of chewing forces food against the roof of my mouth, the pressure of which causes a strong burning feeling.

The last point is what had me looking around for causes, I initially thought it might be some kind of allergy but it's happened with a few different foods I've had this afternoon and I did read that such pain can be caused by a B12 deficiency. I also read that B12 can be a problem with a vegetarian diet which might have been made worse by the length and intensity of the exercise I did today and the fact that I didn't eat enough before or during.

Has anybody experienced something like this? Any suggestions? I could get a blood test done but I'm not sure it would be representative unless it was after intense and long exercise like I had today, assuming that depletes B12...

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Re: Do I have a B12 defficiency?

Postby KonaCommuter » Sun Jul 15, 2012 7:42 pm

I’m no expert but I have heard that many meat eaters are deficient in B12 so it’s not just vegetarian / vegans (and those of us working towards that end).
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Re: Do I have a B12 defficiency?

Postby DoogleDave » Sun Jul 15, 2012 8:45 pm

I am also no expert and excuse the personal question but when you go to do number 1's is the colour clear like water or more yellow like olive oil?

Not sure how much water you drank during your 155km ride today (other than the sports drink you mentioned), however it may be a case of dehydration amongst a possible low level of B12, etc.

Eating and drinking properly during long rides are an absolute must....especially when your ride goes beyond the 3+ hour mark.
During shorter rides your body can sustain itself using its own reserves but once you get past a couple of hours of riding your glycogen levels start diminishing to a point that it needs topping up. If you don't keep refilling your tank after that point you will hit the wall (known as "bonking"), as your energy runs out and if you still don't refill the tank your body will start converting proteins (from muscle etc) into energy - which is inefficient and not good - something you want to avoid.

I dare say most cyclists that start doing longer rides experience bonking and soon learn that its much better to eat and drink properly rather than go through that again...

Nothing worse than rolling slowly up the driveway at home after your ride as you almost fall off your bike, eat everything that isn't nailed down, have a huge drink (or three) and then lie down and feel like you're about to die.

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Re: Do I have a B12 defficiency?

Postby coffeeandwine » Sun Jul 15, 2012 9:04 pm

Talk to your doctor about it. Simple blood test will give you the answer, nothing to stop you going for a ride first. :)

Easy to treat once you have the answer but you really do need to speak with your doctor first. Good luck.
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Re: Do I have a B12 defficiency?

Postby martin_12 » Mon Jul 16, 2012 8:48 am

I am pretty sure I have B12 deficiency caused by poor absorption, so I have done some reading on this subject. I have found that most GPs don't know much about it.

B12 blood tests are extremely unreliable, specially in people who do regular exercise.

This a good article in the subject:

This article says that B12 requirements and physiology in recreational athletes are probably different from sedentary people.

There are no known adverse effects of B12 supplements, so if you think you may be deficient you should take them. Many experts say that vegetarians should take supplements regardless.

You can buy 1000 microgram B12 (cyanocobalamin) tablets in supermarkets. If your problem is diet rather than poor absorption, then you may be able to get away with smaller doses.

If you decide to take B12 regularly you should get methylcobalamin which doesn't have the cyanide component.

Edit: According to the two articles cited above (and many others) the most reliable test for detecting B12 deficiency is methylmalonic acid. Not all labs do it and Medicare may not fund it so you may have to pay for it, but a genuine B12 deficiency can cause devastating consequences (like irreversible peripheral neuropathy, irreversible degeneration of central nervous system), so it is very important to find out. If you get a methylmalonic acid test you should have it done before you take any B12 supplements.

B12 was discussed in the ABC Health Report in February this year.

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Re: Do I have a B12 defficiency?

Postby Lizzy » Sun Aug 19, 2012 8:40 pm

martin_12 wrote:I am pretty sure I have B12 deficiency caused by poor absorption, so I have done some reading on this subject. I have found that most GPs don't know much about it.

Snap - interesting thread, will have to take a good look through that info. I'm waiting on my latest lot of test results. About a year and a half ago I got my B12 checked in a routine 30-whatever workover and it was so low my GP recalled me and said "Shots. Now, you're in the neurological damage zone". I'm also being treated for hypothyroidism, and have been checked out for coeliac & Addisons in case one of them is an underlying factor in both; neither were, so for now I'm just getting banged up with it once a month (when I remember; sigh). I'm not a big meat eater but there is no dietary reason for me to be deficient in anything (I <3 my food :P)

I wouldn't have rated my activity levels as that much higher than average so as to skew test results, but hmmmm ... :idea:
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Re: Do I have a B12 defficiency?

Postby martin_12 » Tue Aug 21, 2012 5:32 pm

B12 blood tests are unreliable in everyone, but, according to that Herrmann study, even less reliable in people who do endurance exercise regularly.

A problem is after you have started B12 injections or oral supplements, a methylmalonic acid test is likely to be normal and you won't know whether that is due to the supplementation or because you never were deficient.

Coeliac disease is just one possible cause of B12 deficiency. Your GP should be doing tests for intrinsic factor and gastric parietal cell antibodies that can affect B12 absorption. Helicobacter pylori infection is another possible contributory factor. There are probably others that I can't remember.

30-something is quite young to be B12 deficient, unless you are a vegan or vegetarian.

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