Sunday, March 5, 2017

Increased intake of vitamin B12 reduces risk of cancer:
CSIRO Thursday, 6 January 2000

New CSIRO research shows that eating three times the recommended daily intake of vitamin B12 and folate reduces DNA damage, which could lessen the risk of heart disease and cancer. Vitamin B12 is found in meat, fish, liver, kidneys and chicken, while folate is found in wholegrains and leafy green vegetables. The study found that after three months of boosting the folate and vitamin B12 intake of people with above average rates of DNA damage, there was a 25 per cent reduction in chromosome damage. The CSIRO's Michael Fenech says this suggests that taking care of one's DNA increases the chances for longevity and reduces the risk of cancer.

The link between acid suppressing medication and vitamin B12 deficiency
Monday 24 March 2014 5:30PM
Researchers in California found that the long-term use of commonly prescribed drugs to lower the acid in our stomach, particularly for treating heartburn and acid reflux, may be linked to vitamin B12 deficiency.

David Spence:  So we said let’s look at what happens if we exclude these people who got the B12 injections and while we’re at it we’ll also exclude the people who had kidney failure.  The reason we did that wasn’t for what turned out to be probably the right reasons, we excluded them because we thought they would not respond to vitamin therapy.  So in this sub-group analysis we had about two thirds of the patients from the VISP trial and in that group we showed a very significant reduction of strokes, heart attacks and death, there was a 34% reduction in strokes, heart attacks and death.
Norman Swan: So this is between those who had high vitamin B12 versus those who had low?
David Spence:  Yes, that study suggested that vitamin B12 is probably pretty important in all this and we never realised that excluding the renal failure was the key to the benefits.  So we published last year in JAMA a study in patients with diabetic kidney problems and we used a higher dose of B12 than we used in the VISP and we randomised these patients who had diabetic kidney disease to high dose vitamins versus placebo and when we got the results I was completely gobsmacked.
I thought we must have reversed the randomisation code because the high dose vitamins actually made things worse.  The kidney function declined more quickly and they were twice as likely to have cardiovascular events, so death, myocardial infarctions, stroke, progression to dialysis and amputation, those were all combined.  This meant that in patients with kidney failure the vitamins made things worse, so on the one hand in the VISP sub-group analysis where we excluded patients with kidney failure vitamins it made things better, but in patients with kidney failure vitamins made things worse.
Norman Swan:  I apologise if this is making you go cross eyed but it’s really important stuff.  You see to go back to the beginning of this story it’s still about homocysteine levels and the risk of blood clots and artery damage.  It’s just that in a country like Canada or Australia where we have folic acid in flour, vitamin B12 becomes the main way to bring homocysteine down.  And if David Spence is right the kind of vitamin B12 you take is critical.
David Spence:  But it’s not just quite that simple. It’s also another factor called ADMA, asymmetric dimethylarginine, and it depends on which B vitamin.  The B vitamin that’s harmful is high dose folic acid which increases the blood levels of this antagonist of the good stuff called nitric oxide which is increased in people who have high doses of folic acid and poor kidney function.  And on the other hand the vitamin B12 that was used in all these trials was the usual form which is called cyanocobalamin, which has cyanide in it and it turns out that some work in Japan had shown about ten years ago that it if you give cyanocobalamin to patients with kidney failure they get a build up of cyanide and cyanide consumes a factor that is good for the arteries called hydrogen sulphide.  And resarchers showed that if you give a different form of B12 called methylcyanocobalamin, not only does it lower the levels of homocysteine but it also lowers the levels of asymmetric dimethylarginine, ADMA.  You probably need to be using methylcobalamin in people with impaired kidney function, whereas in the VISP sub-group analysis we showed that ordinary B12 was beneficial  when we excluded people with renal failure.

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