Genetic Variants Associated with Vitamin B12

Discussion in 'Fibromyalgia Main Forum' started by tansy, Nov 13, 2008.

  1. tansy

    tansy New Member

    Nutrigenomics study reveals surprising genetic predictor of blood levels
    of vitamin known to be deficient in some elderly people

    For immediate release: September 7, 2008

    Boston, MA - Researchers at the Harvard School of Public Health (HSPH)
    and their collaborators at Tufts University and the National Cancer
    Institute (NCI) have identified a common genetic influence on B12
    vitamin levels in the blood, suggesting a new way to approach the
    biological connections between an important biochemical variable and
    deficiency-related diseases.

    "The news here is the discovery of a robust genetic predictor of vitamin
    B12 levels," said <>
    David Hunter, the Vincent L. Gregory Professor of Cancer Prevention and
    director of the Program in Molecular and Genetic Epidemiology at HSPH
    and senior author of the study. "This is an example of the way we're
    going to understand more about how levels of vitamins and other
    nutrients in the body are partially determined by genetic factors as
    well as by what we eat."

    Other studies have found rare gene mutations with dramatic effects on
    people's ability to digest, absorb, and use vitamin B12. This paper
    found more common variations of a gene that has a much smaller effect by
    itself, but it may belong to an important biological pathway whose
    careful study may lead to clinically useful strategies and therapeutic

    The researchers first found the gene, called FUT2, in a genome-wide scan
    of 1,658 women of European ancestry who participated in the Cancer
    Genetic Markers of Susceptibility (CGEMS) project. They replicated the
    findings in another 1,059 women from the Nurses' Health Study.

    "This provides a framework for further nutrigenomics studies and for
    exploring gene-diet interactions with cancer and other diseases," said
    <> Aditi Hazra, HSPH
    instructor and lead author of the study. The paper was published in the
    Sept. 7 advance online
    <> Nature

    Other studies have linked B12 deficiency with pernicious anemia,
    cardiovascular disease, cancer, and neurodegenerative disorders. Lower
    B12 levels have been associated with cognitive impairment. A key player
    in the B-vitamin pathway, B12 helps maintain healthy nerve cells, form
    red blood cells, and synthesize DNA.

    In the diet, B12 comes from meat, fish, dairy, other animal products,
    and fortified breakfast cereals. As many as one-quarter of the elderly
    may have mild B12 deficiency. Strict vegetarians, who avoid meat, and
    vegans, who avoid all animal products, are also at risk of B12

    "This is an unexpected finding. We thought we had already learned
    everything about the absorption of vitamin B12," said co-author Jacob
    Selhub, director of the Vitamin Metabolism Laboratory at the USDA Human
    Nutrition Research Center on Aging at Tufts University. He has conducted
    many of the studies linking B12 status in the elderly with cognitive
    impairment, anemia, and bone marrow density and osteoporosis.

    Anything in the stomach that affects the normal acidity and digestive
    processes, ranging from infections to acid reflux medicine to aging, may
    also interfere with B12 absorption, studies suggest. B12 is first
    separated from food by stomach acid and then escorted from there by a
    protein called intrinsic factor to the small intestine, where the
    complex is absorbed and B12 is released into the blood.

    Until further studies are conducted, the most plausible explanation is
    the potential preventive effect of the gene variant on factors known to
    cause B12 malabsorption, such as H. pylori infection, the researchers

    Hazra and her colleagues had been investigating the genetic and
    epigenetic links between colorectal cancer and adenoma and the B-vitamin
    pathway, also known as the one-carbon metabolism pathway, including
    folate, vitamins B6 and B12, and homocysteine. Ultimately, she hopes to
    identify different gene variants that work together and create a
    nutrigenomics predictor score to assist in future individual cancer
    prevention strategies.

    Evaluating more than 528,000 genetic variants, the strongest signals
    came from variants in FUT2. The gene variant associated with the highest
    B12 levels has previously been determined to protect the stomach from
    infection by the Norwalk virus and ulcer-causing H. pylori bacterium.

    In the study, the FUT2 genetic variant accounted for about three percent
    of the variation in B12 plasma levels, Hazra said. The researchers do
    not have direct evidence that people who carry the gene variant suffer
    from any cognitive or other adverse affects of low B12 levels.
    This study was supported by the National Cancer Institute of the
    National Institutes of Health.

    Co-authors of this study include Aditi Hazra, Peter Kraft, Edward L.
    Giovannucci, and David J. Hunter of HSPH; Jacob Selhub of Tufts
    University; and Gilles Thomas, Robert N. Hoover, Stephen J. Chanock of

    "Common Variants of FUT2 are Associated with Plasma Vitamin B12
    Levels," Hazra et al., Nature Genetics Advance Online publication, Sept.
    7, 2008, doi:10.1038/ng.210.
    For more information, contact:
    Christina Roache

    <> Harvard School of Public Health is
    dedicated to advancing the public's health through learning, discovery,
    and communication. More than 400 faculty members are engaged in teaching
    and training the 1,000-plus student body in a broad spectrum of
    disciplines crucial to the health and well being of individuals and
    populations around the world. Programs and projects range from the
    molecular biology of AIDS vaccines to the epidemiology of cancer; from
    risk analysis to violence prevention; from maternal and children's
    health to quality of care measurement; from health care management to
    international health and human rights.