You don’t always get a chance for a “do over.” But when researchers took a second look at a large study that examined vitamin B use among stroke victims, they found something important that was missed the first time.
And here’s the good news: The results of the follow up study offer victims of non-disabling strokes a course of action that may help prevent future strokes and cardiac events.
The middle way
The name of the study says it all: Vitamin Intervention for Stroke Prevention trial (VISP). When the VISP research was first reported last year, researchers found that high doses of vitamins B-6, B-12 and folic acid given to 3,680 patients who had experienced non-disabling strokes only moderately lowered homocysteine levels. (Homocysteine is an amino acid that promotes plaque buildup in blood vessels.) The conclusion: Risk of another “vascular event” remained the same.
But researchers at the Stroke Prevention and Atherosclerosis Research Centre (SPARC) in London, Ontario, analyzed the study and found several variables that may have skewed the results.
The SPARC team began by excluding subjects who started off the study with very high or very low levels of vitamin B-12 (which is known to reduce homocysteine). The idea was to remove two types of subjects: 1) Those who were already taking vitamin B-12 supplements, and 2) Those who likely had B-12 absorption problems (more on that in a moment).
This created a subgroup of more than 2,150 subjects with an average age of 66. And the results in this subgroup were dramatically different from the first group. When the data concerning ischemic stroke, coronary disease and death was analyzed, those who took the highest dosage of B-6, B-12 and folic acid reduced their risk of those conditions by more than 20 percent. The worst outcomes were seen in subjects who had the lowest intake of vitamin B-12.
Writing in the November 2005 issue of the journal Stroke, researchers noted that higher doses of B-12 and other treatments to lower homocysteine might be needed for some stroke patients in order to avoid further strokes and heart attacks.
Blocking the flow
Nowback to the B-12 absorption issue.
As we age we’re generally more likely to develop a B-12 deficiency because older people produce less of a protein known as intrinsic factor, which is essential for proper B-12 absorption. In addition, other factors can interfere with the assimilation of vitamins. In an HSI Members Alert we sent you in September 1999, we told you how pharmaceuticals sometimes hamper nutrient absorption from foods. For instance, acid blockers (such as Prilosec, Nexium, etc.) have been shown to significantly decrease absorption of – wouldn’t you know it? – vitamin B-12.
Fortunately, getting B-12 into your diet is easy, as long as you’re not a strict vegetarian. Meat, eggs and shellfish are the foods most abundant in B-12. So it’s no surprise that in addition to the elderly, B-12 deficiency is also a typical problem among vegetarians.
Send in the supplements
In addition to B-12, folate and vitamin B-6 also help metabolize homocysteine to keep levels down. These B vitamins are found in asparagus, lentils, chickpeas, most varieties of beans, and especially spinach and other leafy green vegetables. But as with B-12, the other Bs are not well absorbed, so a B complex supplement is often required to keep homocysteine levels in check.
HSI Panelist Allan Spreen, M.D., recommends folate supplements of 1.6 mg (1600 mcg) per day, and as much as 5 mg for those who want to address cardiovascular problems. Dr. Spreen points out that, “Folate isn’t effective in low doses except in a limited percentage of cases.” As for B-12, he recommends 1mg (1000 mcg) per day in sublingual form (dissolved under the tongue). And the form you choose is important too. Dr. Spreen: “Use methyl-B-12, instead of cyano- or hydroxo-B-12. It’s harder to find and more expensive, but worth every penny.”
In addition, Dr. Spreen suggests that to get the most out of folate, 100 mg per day of B-6 is also necessary, as well as 400-500 mg of magnesium per day (to make the B-6 more effective).
As I mentioned above, the SPARC team noted that other treatments beyond B vitamins may be needed to lower homocysteine levels. According to several studies, supplements of the antioxidant amino acid N-acetylcysteine (NAC) may also help bring those levels down.
“Vitamin Intervention For Stroke Prevention trial: An Efficacy Analysis” Stroke, Vol. 36, No. 11, November 2005, ncbi.nlm.nih.gov