Welcome to Straight Talk on Health I’m your host Dr. Chet Zelasko. Straight Talk on Health is a joint production with WGVU in Grand Rapids MI. I examine the practical application of health information. Nutrition. Exercise. Diet. Supplementation. I look at the science behind them, and let you know whether it’s something to consider or not. You can check out other things that I do on my website Drchet.com and sign up for my free emails.
As you might expect, I get a lot of questions. Over the years, I have been asked about vitamin B12 a lot. Usually, it’s about cyanocobalamin versus methylcobalomin forms of B12. Just to refresh your memory, there is no real difference. The methyl is actually made from the cyano form. They are functionally identical and no, you can’t get cyanide poisoning from the cyano form. One more thing, there is no natural form unless you eat meat or if you enjoy the yeast extract from making beer called Marmite. Let’s just say it's an acquired taste.
Once in a while, I get asked about serum vitamin B12 levels. It happens when someone to the doctor, the physician will check vitamin B12 levels, especially if a patient is saying that they have low energy levels. It's standard operating procedure. People are concerned if there is an issue with vitamin B12 levels elevated above the upper limit. The range for serum vitamin B12 levels are 190 picograms per mL on the low end with 950 pg/mL set as the upper limit for serum level.
I’ve read the entire document written by the Institute of Medicine who set the recommendations for the RDA now called the Dietary Reference Intake. I recently checked it out again to be sure nothing has changed. The IOM considers every published paper that researched vitamin B12. They never set an upper limit or UL for intake because they could never find any health issues by overconsuming vitamin B12.
Most of the time, people will maintain their serum levels in the normal range even if they consume many many times the DRI for vitamin B12. For those that happen to have very elevated levels, if they cut back on their vitamin B12 intake or they stop getting vitamin B12 shots from their physician, the numbers go back to normal relatively quickly, usually within a few days as vitamin B12 is a water soluble vitamin. With that in mind, I've never believed that high vitamin B12 levels could be an issue and that is still my interpretation of the research. The purpose of this podcast is to discuss a paper that indicates serum vitamin B12 may not be as benign as I think.
Before I do, if your vitamin B12 level happens to be a little over the upper limit, we have to understand the difference between hypervitaminosis and hypervitaminemia. What I described previously is hypervitaminosis. What that means is that for some people, they can have high vitamin B12 levels in their blood but it is completely reflective of intake, and that's it. Lower the intake of vitamin B12, and the blood levels of vitamin B12 returned within the normal range.
Where the difference lies is in hypervitaminemia. In other words, intake can be normal but for some reason vitamin B12 levels in the blood are excessively high. The body is not using vitamin B12 in its normal functions and so therefore, the blood levels increase. That's the type of high vitamin B12 level that may have pathological implications.
Exactly, what does vitamin B12 do in the body? Vitamin B12 is ubiquitous—that means it’s everywhere—as a coenzyme mainly involved in reactions leading to the synthesis of DNA and of making methionine from homocysteine. With that in mind, you can see how important vitamin B12 is to our health. The synthesis of DNA is involved in every cell in the body when those cells do what they do. Whether they are making hormones, insulin, blood cells, just about everything vitamin B12 is crucial to helping initiate that process. If for some reason it isn't able to do that, that can indicate that there may be something wrong.
In a review paper that I read published in 2013, several researchers combed through the scientific literature to see what, if any, conditions may be associated with elevated serum vitamin B12 levels. They were of the opinion that there was a difference between hypervitaminosis and hypervitaminemia and that the inability to use vitamin B12 could be related to pathologies.
There were several categories of diseases that could be related to elevated levels of vitamin B12. Again, let me remind you that we're not talking about elevated levels due to intake; we're talking about normal intake and the lack of use of vitamin B12 by the body. There were several categories of diseases and conditions associated with elevated vitamin B12.
Neoplasms, in other words cancers, were associated with elevated vitamin B12 levels. The primary organ target was the liver. However there were also relationships with breast, colon, stomach, and pancreatic tumors as well. I'm not going to pretend that I understand the disease process because it is complicated. But because cancer cells are able to reproduce, they may be able to do it without vitamin B12 necessary for DNA synthesis and therefore vitamin B12 levels will rise as a result.
Another category of conditions would be blood disorders such as leukemias. Let me give you an indication of elevated as it relates to one form of leukemia: chronic myeloid leukemia. There is a very strong association between elevated vitamin B12 levels and this form of leukemia. But, the elevation would be 10 times the normal value. So that means we're talking about levels close to 5000 picograms per mL and above. Another factor is that, with other forms of blood disorders, elevated levels of vitamin B12 were only associated in 1/3 to 1/2 of all the cases. The reason for giving you the numbers is to put things in perspective because we all have a tendency to overreact. An association Is not the same as cause and effect so keep that in mind
The other conditions associated with elevated vitamin B12 levels were liver disease and kidney disease. That makes sense. Vitamin B12 is used by the liver a lot because it is involved in so many chemical reactions that require the coenzyme action of vitamin B12. As vitamin B12 is excreted via the kidneys, it also makes sense that if there were problems breaking down vitamin B12 for excretion, that could lead to problems in the kidneys.
The overwhelming reason that this paper was written was to illustrate that elevated levels of vitamin B12 should one, be checked regularly whether someone has an energy issue or not and two, be a reason for looking at some of the conditions associated with it related to liver, kidneys and cancers. This was really an appeal to physicians to include it in their repertoire of diagnostic techniques because they felt too often it was overlooked. It also gives them some places to look to begin with.
For us, as consumers and potential patients, what it means to us is that overconsumption that results in hypervitaminosis is not significant. However, if our B12 levels go up even though our intake may be normal, that may be an indication there's something else going on and that we should pursue it with our physician to identify why the B12 levels increased. That's the path to better health. Until next time, this is Dr. Chet Zelasko saying health is a choice. Choose wisely today and every day.
Q J Med 2013; 106:505–515 doi:10.1093/qjmed/hct051
