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Two new studies have put Vitamin B12 in the headlines this week, reaffirming the important role of this nutrient across the generations.
On March 2, Pediatrics published a study directed by Anne Molloy of Trinity College Dublin’s School of Medicine, that illustrated the importance of B12 for women in childbearing years. The researchers found that women with low levels of Vitamin B12, before and after conception, showed a greater risk of giving birth to babies with neural tube defects (NTDs).
The researchers examined B12 concentrations in blood samples drawn from pregnant women for three earlier studies. Taken at an average of 15 weeks gestation, the original blood was collected during a time when few pregnant women in Ireland took vitamin supplements.
The first group included samples from 95 women whose pregnancy was affected by neural-tube defect plus 265 control subjects. The second group included samples from 107 women who had a previous neural-tube–defect birth, but whose current pregnancy was not affected, and 414 control subjects. The third group included samples from a different group of 76 women during an affected pregnancy and 222 control subjects.
The research team found that the mothers of children affected by neural tube defects showed significantly lower levels of Vitamin B12 in their blood. In fact across the three groups, the odds of having a neural-tube defect was two to three times higher among women with the lowest B12 quartiles compared to the highest. The analysis determined that blood B12 concentrations of less than 250 nanograms/litre during pregnancy were associated with the highest risk of a birth defect.
A member of the B complex family, Vitamin B12 is an essential nutrient for the normal production of DNA, the maintenance of healthy nerves and the growth of all cells, including blood cells. Vitamin B12 also helps metabolize nutrients — proteins, carbohydrates and fats — and turn them into energy. In support of heart health, Vitamin B12 reduces blood levels of homocysteine, an amino acid by-product of metabolism that can accumulate on arterial walls.
Spinal bifida and anencephaly are the two most common birth defects of the brain and spinal cord. According to the March of Dimes, each year an estimated 2,500 babies are born with spinal defects in the United States alone, a statistic that does not reflect the number of pregnancies that end in miscarriage or stillbirth. For years, the U.S. Public Health Service has recommended that all women of childbearing age receive 400 micrograms of folic acid each day, which the study authors note, has reduced the rate of neural tube defects by as much as 70%. Past studies have connected a mother’s low B12 blood level to the incidence of NTDs, but as the authors conclude: “our objective was to quantify the effect of low B12 status on neural-tube–defect risk in a high-prevalence, unfortified population.”
A separate study, authored by William G. Christen (Sc.D.) from Brigham and Women’s Hospital and Harvard Medical School, has found that women taking folate, Vitamin B6 and Vitamin B12 supplements had a 34 percent lower risk of developing age-related macular degeneration (AMD) and a 41 percent lower risk of visually significant AMD.
AMD is the leading cause of irreversible vision loss for seniors. Previous observational studies have found an association between lower homocysteine concentrations in the blood and a lower risk of AMD. Other intervention studies have shown that folic acid, Vitamin B6 and Vitamin B12 may lower homocysteine levels. But until now, there was no study examining the effect of B vitamin supplementation on the risk of AMD.
Part of the Women’s Antioxidant and Folic Acid Cardiovascular Study (WAFACS), the randomized, double-blind, placebo-controlled trial followed more than 5,000 women healthcare professionals, age 40 or older. Participants received a placebo or a combination of folic acid (2.5 mg/day), Vitamin B6 (50 mg/day) and Vitamin B12 (1 mg/day). After just two years, the trend to beneficial effects was evident among women taking B vitamins. After 7.3 years, the women taking supplements had a 34 percent lower risk of any AMD and a 41 percent lower risk of visually significant AMD.
“This is very promising news for the millions of older people who may be at risk for age-related macular degeneration,” said Andrew Shao (Ph.D.), Vice President, Scientific and Regulatory Affairs, for the Council for Responsible Nutrition in Washington. “Currently, there are very few treatment options for AMD and so prevention is key. The results of this study suggest that B vitamins could be combined with other supplemental nutrients, including antioxidants, Vitamins C and E and beta-carotene and lutein, which have also been shown to lower the risk of AMD.”
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