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Ulster Research Probes Low-Dose Folic Acid Effectiveness

30 December 2010

A LOW DOSE of folic acid roughly equal to the added intake from food  fortification policies in the  USA and elsewhere can lower homocysteine  levels as effectively as doses two to four times higher, according to University of Ulster research.

Research by Professor Helene McNulty and colleagues found that over 26 weeks, daily doses of 0.2, 0.4, or 0.8 mg of folic acid  reduced homocysteine concentrations by 14.3%, 14.2%, and 18.3%,  respectively, with no significant between-group differences.

The equivalent efficacy of the lower dose is at odds with most  previous studies exploring the issue, they reported in the just-published January 2011 issue  of the American Journal of Clinical Nutrition.

"Previous trials may have overestimated the folic acid dose required  because of too short an intervention period to observe a more complete  response to lower doses," the researchers said.

Fortification of food with folic acid  -  introduced in the U.S. in  the late 1990s  - is aimed at reducing neural tube defects. But folic  acid also reduces homocysteine levels.

Identifying the lowest effective dose of folic acid is important,  according to the researchers, is important because of concerns that high doses may  increase the risk of cognitive impairment in older people with low  vitamin B12 levels, mask the anemia of vitamin B12 deficiency, and  enhance colorectal tumorigenesis in people with preexisting lesions.

The trial was conducted in Northern Ireland, which does not have a mandatory folic acid fortification policy.

After controlling for baseline homocysteine concentration  --  which  was higher in the patients who had ischaemic heart disease  --  the  response to folic acid was similar across the study participants, who  were combined for the analyses.

All three doses of folic acid reduced homocysteine levels, regardless of baseline concentration. "The results are timely," the researchers said, "because population-wide  fortification with folic acid on a mandatory basis (introduced over 10  years ago in North America) is under consideration by various  governments worldwide."

The study was supported by the Northern Ireland Chest Heart and Stroke Association.

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