Tag: blood clots

October 31, 2005

After Americans enriched their diet with folic acid in 1996, the frequency of blood clots in the brain was reduced by 15%. Now research shows that added supplementation of Vitamin B12 will markedly lower this risk even further.

Immediately, it sounds simple: People with high levels of the amino acid homocysteine in the blood have an increased risk of blood clots in the brain and in the heart. You also know that you can lower homocysteine with folic acid and, to a lesser extent, with B6 and B12 vitamins. When the Americans began to enrich cereal products with folic acid from 1996, both the average American’s homocysteine and the rate of blood clot in the brain decreased by about 15% in three years.

“The money fits”, and then the result is almost obvious in advance, if you want to conduct a lottery experiment, where every other participant gets folic acid, B6 and B12 vitamins. Of course, they get fewer blood clots in the brain.

But the reality is more varied. In Norway, such an experiment (NORVIT) was conducted with 3,750 patients who had just survived a blood clot in the heart. For 3.5 years, they were supplemented with either folic acid (0.8 mg), vitamin B6 (40 mg), both or blind tablets (placebo). Among those who only received folic acid, mortality decreased approx. 10%, but not statistically certain. But in the other two groups the death tolls were increased, not statistically certain either.

Perhaps it is too late to start taking supplements when you are already severely calcified. Or, as will appear, perhaps it was more decisive that the Norwegians “forgot” to give the participants vitamin B12.

An experiment has also been carried out in the USA (VISP). It was with people who had recovered from a blood clot in the brain, but had an increased risk of a new one. Admittedly, the Americans did not initially find any effect either. Supplementation of folic acid (2.5 mg), vitamin B6 (25 mg) and vitamin B12 (0.4 mg) did not reduce or improve mortality or risk of blood clots in the brain. Therefore, the experiment was simply stopped after two years. It was useless, they thought.

B12 is useful if it is absorbed
A close explanation could be the aforementioned enrichment of cereal products with folic acid. After all, the average homocysteine had already fallen by approx. 15% in the Americans. During the trial, it only dropped a further 2%.

But the Americans have since studied the numbers more closely. In doing so, they discovered one important source of error in particular: Many of the 3,680 elderly participants had reduced absorption of vitamin B12 from the gut and therefore had relatively little B12 in their blood (less than 250 pmol/l). This is often seen in the elderly, and it is now known that these elderly need supplements of at least 1,000 micrograms of vitamin B12 per day. But the participants had only received 400.

What would it look like if you now disregarded these participants and concentrated on those with normal B12 uptake? It was decided to investigate. At the same time, participants with reduced kidney function were disregarded, as they also respond sluggishly to these supplements. Finally, participants who were previously receiving medical treatment with B12 were naturally disregarded.

There remained 2,155 people who had no problems absorbing B12. In this large group, the supplements both lowered homocysteine further and reduced the overall risk of death, blood clot in the heart or blood clot in the brain – by 21%! The treatment helped anyway; even a lot when the ability to absorb B12 was intact.

As stated, it appears that the fortification of cereal products with folic acid has reduced the Americans’ risk of blood clots in the brain by approx. 15%. Now it seems that a solid supplement of vitamin B12 on top of that can reduce it significantly more – but the many elderly people, who absorb vitamin B12 poorly, presumably need larger supplements.

This is the result at the moment. It must be verified before it is approved. But the indications are there.

By: Vitality Council

References:
1. Toole JF, et al. Lowering homocysteine in patients with ischemic stroke to prevent recurrent stroke, myocardial infarction, and death: the Vitamin Intervention for Stroke Prevention (VISP) randomized controlled trial. JAMA. 2004 Feb 4;291(5):565-75.
2. Bonaa KH. NORVIT: Randomized trial of homocysteine-lowering with B-vitamins for secondary prevention of cardiovascular disease after acute myocardial infarction. Program and Abstracts from the European Society of Cardiology Congress 2005; September 3-7, 2005; Stockholm, Sweden. Hot Line II. Iflg. Linda Brooks. NORVIT: The norwegian vitamin trial. Medscape sept. 2005. (Ikke publiceret i trykt medie)
3. Spence DJ et al. Vitamin intervention for stroke prevention trial. An efficacy analysis. Stroke 2005;36:2404-2409.

jama.ama-assn.org
www.medscape.com
stroke.ahajournals.org
www.iom.dk