Older individuals with low levels of vitamin B12 seem to be at increased risk of having brain atrophy or shrinkage, new research suggests. Brain atrophy is associated with Alzheimer's disease and impaired cognitive function.
Although the study, published in the Sept. 8 issue of Neurology, can't confirm that lower levels of B12 actually cause brain atrophy, they do suggest that "we ought to be more aware of our B12 status, especially people who are vulnerable to B12 deficiency [elderly, vegetarians, pregnant and lactating women, infants], and take steps to maintain it by eating a balanced and varied diet," said study co-author Anna Vogiatzoglou, a registered dietician and doctoral candidate in the department of physiology, anatomy and genetics at the University of Oxford, in England.
"It's worth looking at B12 levels. It's a simple blood test," affirmed Dr. Shari Midoneck, an internist at the Iris Cantor Women's Health Center in New York City. "It doesn't hurt to take B12."
Good sources of the vitamin include meat, fish, milk and fortified cereals.
According to the study authors, vitamin B12 deficiency is a public health problem, especially among older people.
This study involved 107 volunteers aged 61 to 87 who were cognitively normal at the beginning of the study. All participants underwent annual clinical exams, MRI scans and cognitive tests and had blood samples taken.
Individuals with lower vitamin B12 levels at the start of the study had a greater decrease in brain volume. Those with the lowest B12 levels had a sixfold greater rate of brain volume loss compared with those who had the highest levels of the vitamin.
Interestingly, none of the participants were deficient in vitamin B12, they just had low levels within a normal range.
"They all had normal B12 levels, yet there was a difference between the higher levels and the lower levels in terms of brain shrinkage, which is new information which could potentially change what we recommend to people in terms of diet," said Dr. Jonathan Friedman, an associate professor of surgery and neuroscience and experimental therapeutics at Texas A&M Health Science Center College of Medicine and associate dean of the College of Medicine, Bryan-College Station campus.
Other risk factors for brain atrophy include high blood pressure, diabetes and high cholesterol.
Not only might B12 levels be a modifiable risk factor for cognitive decline, it might also be a clue to help clinicians assess cognitive problems earlier on.
Right now, it's not clear what the biological mechanisms behind the link might be, nor is it clear whether added B12 would avert brain atrophy.
"We are doing a clinical trial in Oxford in which we are giving B vitamins [including B12] to elderly people with memory impairment," Vogiatzoglou said. "In this trial, we are doing MRI scans at the start and the end, and so, we will be able to find out if taking B vitamins really does slow down the shrinking of the brain. The trial will be completed in 2009."
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A balanced complex of the B vitamins is essential for energy and for balancing hormone levels. Vitamins are involved in biochemical processes throughout the body and appear to be involved in protecting and enhancing cognitive function. In particular, the B vitamins play an integral role in the functioning of the nervous system and help the brain synthesize chemicals that affect mood.
Vitamin B-12 deficiency increases with age due to stomach changes that reduce the ability to absorb the vitamin. Thus, the B-12 deficiency develops despite normal amounts of B-12 in the diet.
Vitamin B12 deficiency is estimated to affect 10%-15% of individuals over the age of 60. Studies typically find that about 15 percent of those older than 65 have poor B-12 status. This percentage increases with age and is typically greater in institutionalized older people.
The most common causes of vitamin B12 deficiency are: 1) an autoimmune condition known as pernicious anemia and 2) food-bound vitamin B12 malabsorption. Although both causes become more common with increasing age, they are separate conditions
Vitamin B-12 deficiency increases with age due to stomach changes that reduce the ability to absorb the vitamin. Thus, the B-12 deficiency develops despite normal amounts of B-12 in the diet.
A study by American Journal of Clinical Nutrition suggested that it is well established that the clinical manifestations of overt, severe vitamin B-12 deficiency include both hematologic (macrocytic or megaloblastic anemia) and neurologic (subacute combined degeneration of the spinal cord, peripheral neuropathy, cognitive impairment) sequelae. The neurologic consequences are of particular concern, because they can occur in the absence of hematologic symptoms and can become permanent if vitamin B-12 replacement therapy is not initiated within a year of the onset of symptoms. It therefore is incumbent on clinicians to recognize vitamin B-12 deficiency at an early stage, before the neurologic health of a person is irreversibly affected.
Inadequate intake of vitamin B-12 is much more common than previously thought. A new study in the elderly showed that 40% had low or marginal levels of B-12 considered necessary for good health. Another study showed that up to 18% of 40- and 50- year old persons had low B-12 levels. Lack of B-12 damages the nervous system resulting in loss of feeling and balance, and can also lead to dementia. The Institute of Medicine recommends that all people 50 and older take a B-12 supplement or eat vitamin B-12 fortified foods.
Another study published in the American Journal of Psychiatry in December 2002 examined the association between low levels of vitamin B-12 and depression in 3,884 older adults. The study reported that older adults with vitamin B-12 deficiency were more likely to have depressive symptoms than those who were not deficient in vitamin B-12.
Screening for vitamin B12 deficiency in the elderly can yield a high number of abnormal results even in the absence of anemia. Vitamin B12 deficiency may result from malabsorption or lack of hydrochloric acid common in the elderly. Measurements of serum methylmalonic acid and homocysteine are more sensitive methods for confirmation of B12 deficiency than radioisotope assays or serum B12 levels. In one study of 86 B12 deficient patients who responded to cobalamin therapy, neuropsyciatric abnormalities were noted in 28%, many times in the absence of anemia.
Vegetarians are another group prone to B-12 deficiency. Since only animal foods contain significant amounts of vitamin B-12, people consuming vegan and macrobiotic diets are also at high risk for deficiency. Studies on these groups have reported poor B-12 status in as many as 90 percent of the study participants.
Sources:
http://www.cspinet.org
http://ods.od.nih.gov/factsheets/vitaminB12.asp
http://www.nutritionatc.hawaii.edu
http://www.ajcn.org
http://www.mayoclinic.com
http://www.drhoffman.com
http://lpi.oregonstate.edu
http://lifeextensionvitamins.stores.yahoo.net
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