B vitamins

Older news items (pre-2010) brought over from the old website

Vitamin B12 may protect the brain in old age

A five-year study of 107 older adults (61—87) has found that those who had higher vitamin B12 levels were six times less likely to experience brain shrinkage compared with those who had lower levels of the vitamin in their blood, even though none of them had vitamin B12 deficiency. Vitamin B12 is found in meat, fish and milk, and is often deficient in older people.

http://www.eurekalert.org/pub_releases/2008-09/aaon-vbm090208.php

B-vitamin deficiency may cause vascular cognitive impairment

A new mouse study helps clarify the association between homocysteine, folate & B12, and cognitive impairment. The study found that mice fed a diet deficient in folate and vitamins B12 and B6 demonstrated significant deficits in spatial learning and memory compared with normal mice, developed plasma homocysteine concentrations that were seven-fold higher, and showed smaller capillary length and density in blood vessels in the hippocampus. Homocysteine is produced by the breakdown of a dietary protein called methionine; B-vitamins are required to convert homocysteine back to methionine. A third group of mice were fed a diet enriched with methionine. These mice showed similar, but less pronounced effects. The findings indicate that increased levels of homocysteine, produced by low intake of folate and B vitamins, impairs cognition through microvascular changes.

Full text is available at http://www.pnas.org/content/105/34/12474.abstract
http://www.physorg.com/news139574626.html

How food affects the brain

I’ve reported on quite a lot of studies finding beneficial effects of one food or another on the brain. Now a researcher has analyzed more than 160 studies about food's effect on the brain, and here’s the bottom line. He comes out for omega-3 fatty acids, as both improving synaptic plasticity and the expression of several molecules proteins to learning and memory, as well as protecting against attention-deficit disorder, dyslexia, dementia, depression, bipolar disorder and schizophrenia. He suggests it’s better to get it from food than supplements (which is always recommended). Salmon, walnuts and kiwi fruit are all good sources. They’re still working out which fatty acids are most important, but one is definitely docosahexaenoic acid, or DHA — which like vitamin C we’re not good at making for ourselves; we have to ingest it. He also concludes that diets high in trans fats and saturated fats are bad for cognition.
Studies also support the need for folic acid (found in spinach, orange juice and yeast), which is essential for brain function, and appears to reduce age-related cognitive decline and dementia. And BDNF, important for learning and memory as well as metabolic regulation (so there’s a connection there with obesity), is helped by omega-3 fatty acids and the curry spice curcumin, and also, it seems, smaller food portions.

Full text is available online at www.nature.com/nrn/journal/v9/n7/abs/nrn2421.html
http://www.eurekalert.org/pub_releases/2008-07/uoc--slh070908.php

Vitamin B12, folate, and cognitive function

Confirming earlier studies, a large epidemiological study has found that older people with normal vitamin B12 status and high levels of folate had higher scores on a test of cognitive function. The study clarifies some inconsistencies in earlier research by disentangling the interaction between these factors. It appears seniors with normal levels of vitamin B12 perform better if folate level is high, but when vitamin B12 is low, high levels of folate are associated with poor cognitive performance, as well as a greater probability of anemia. There are also indications that the combination might be a factor in some other diseases.

http://www.eurekalert.org/pub_releases/2007-02/tu-fab020907.php

Folic acid supplementation may improve cognitive performance

A study involving 818 older adults with raised homocysteine levels and normal vitamin B12 levels found that those given daily folic acid supplements (800 micrograms) for 3 years had lower homocysteine levels and improved cognitive performance compared to those given a placebo.

http://www.eurekalert.org/pub_releases/2007-01/l-fas011707.php

More evidence for value of folate for aging brains

Confirming a growing body of evidence, a study of 50-85 year old Boston-area men (members of the ongoing Normative Aging Study) found that men who obtained more folate in their diets showed significantly less of a decline in verbal fluency skills over the course of three years than did men with lower dietary folate intake. High folate levels also appeared protective against declines in spatial copying. The effects of folate were independent of its impact on homocysteine, which turned out to be more strongly associated with tests of memory. Folate is a B vitamin found particularly in leafy green vegetables and citrus fruit.

http://www.eurekalert.org/pub_releases/2005-09/tu-lgv092205.php

Preventing high levels of homocysteine may protect against age-related cognitive impairment

Previous studies have found a link between high levels of homocysteine and poor cognitive performance, but it has been difficult to work out just what the association is, in view of confounding factors such as cardiovascular risk factors and levels of folate, B12, and B6, all of which play a role in high levels of homocysteine. A new analysis has disentangled these factors, and has found that, in people over 60 (but not those under 60), higher levels of homocysteine are independently associated with lower levels of cognitive performance. Similarly, higher levels of vitamin B12 are associated with higher levels of cognitive performance. The researchers suggest vitamins B12, B6, and folate taken before 60 could help protect against later cognitive impairment.

http://www.eurekalert.org/pub_releases/2005-09/bu-atp092705.php

Folates more effective in limiting Alzheimer's disease risk than antioxidants, other nutrients

Analysis of data from the Baltimore Longitudinal Study of Aging has revealed that those with higher intake of folates, vitamin E and vitamin B6 had a lower risk of developing Alzheimer’s. When the three vitamins were analyzed together, only folates were associated with a significantly decreased risk. Those who had at least 400mcg of folates a day (the recommended daily allowance) had a 55% reduction in risk of developing Alzheimer’s. Unfortunately, most people who reached that level did so by taking supplements, suggesting the difficulty of doing so through diet alone. Folates are abundant in foods such as liver, kidneys, yeast, fruits (like bananas and oranges), leafy vegetables, whole-wheat bread, lima beans, eggs and milk; however, they are often destroyed by cooking or processing. No association was found between vitamin C, carotenoids (such as beta-carotene) or vitamin B-12 intake and decreased Alzheimer's risk.

Corrada, M.M., Kawas,C.H., Hallfrisch,J., Muller,D. & Brookmeyer,R. Reduced risk of Alzheimer’s disease with high folate intake: The Baltimore Longitudinal Study of Aging. Alzheimer’s & Dementia, 1 (1), 11-18.

http://www.eurekalert.org/pub_releases/2005-08/uoc--fme081105.php

Moderately high homocysteine linked to Alzheimer’s risk

A study of 83 Alzheimer’s patients, 78 patients with vascular dementia, 64 stroke patients, and 71 healthy controls, found that elevated levels of homocysteine were associated with a more than five-fold increase in the risk for stroke, a nearly five-fold risk for vascualr dementia, and almost triple the risk for Alzheimer's disease. High blood levels of homocysteine have been found to be associated with an increased heart attack risk in several studies. High levels of homocysteine have been found to be associated with deficiencies in vitamin B12 and folate, and also with smoking.

McIlroy, S.P., Dynan, K.B., Lawson, J.T., Patterson, C.C. & Passmore, A.P. 2002. Moderately Elevated Plasma Homocysteine, Methylenetetrahydrofolate Reductase Genotype, and Risk for Stroke, Vascular Dementia, and Alzheimer Disease in Northern Ireland. Stroke, 33, 2351 – 2356.

http://www.eurekalert.org/pub_releases/2002-10/aha-mhh092602.php

Study links high levels of homocysteine, and folic acid or vitamin B-12 deficiencies to cognitive decline

Current estimates suggest that more than one million elderly in Europe and about 750,000 elderly in North America become cognitively impaired each year. Recent research suggests that deficiencies of folate or vitamin B-12 and elevations of plasma homocysteine (tHcy) may be partly responsible. A British study of 331 participants in a longitudinal survey found significant negative effects on cognition in the elderly subjects who had deficiencies of folic acid or vitamin B-12 and elevated tHcy. In the older group (aged 76-78), increased levels of tHcy correlated both with lower serum folate and vitamin B-12 concentrations and with lower cognitive test scores. In the younger group (aged 61-63),higher folate concentrations correlated with higher scores on one of the assessment tests, but otherwise no effects of B vitamins or tHcy were apparent.
Green leafy vegetables, citrus fruits and juices, whole wheat bread and dry beans are good sources of folate.

Smith, A.D. 2002. Homocysteine, B vitamins and cognitive deficit in the elderly. American Journal of Clinical Nutrition, 75,785-6.

http://www.eurekalert.org/pub_releases/2002-04/ajoc-nsa041902.php

Folic acid possibly a key factor in preventing Alzheimer's disease

Experiments with mice bred with mutant genes that cause Alzheimer's disease found that those mice fed on a diet deficient in folate had fewer neurons in the hippocampus ( a brain region critical for learning and memory that is destroyed as plaques accumulate during Alzheimer’s disease), and elevated levels of homocysteine. Researchers suspect that increased levels of homocysteine in the brain caused damage to the DNA of nerve cells in the hippocampus. In the mice fed an adequate amount of folate, nerve cells in this brain region were able to repair the damage. But in those mice fed a folate-deficient diet, nerve cells were unable to repair this damage. A human study is being planned.
Green leafy vegetables, citrus fruits and juices, whole wheat bread and dry beans are good sources of folate. In the U.S., since 1998, the Food and Drug Administration has required the addition of folic acid to enriched breads, cereals, flours, corn meals, pastas, rice, and other grain products.

Kruman, I.I., Kumaravel, T.S., Lohani, A., Pedersen, W.A., Cutler, R.G., Kruman, Y., Haughey, N., Lee, J., Evans, M. & Mattson, M.P. 2002. Folic Acid Deficiency and Homocysteine Impair DNA Repair in Hippocampal Neurons and Sensitize Them to Amyloid Toxicity in Experimental Models of Alzheimer's Disease. Journal of Neuroscience, 22, 1752-1762.

http://www.eurekalert.org/pub_releases/2002-03/nioa-fap030102.php

High homocysteine levels may double Alzheimer's risk

Findings from the long-running Framingham study found people with elevated levels of homocysteine in the blood had nearly double the risk of developing Alzheimer’s disease (AD). This study is the first to tie homocysteine levels measured several years before with later diagnosis of AD and other dementias, and provides the most powerful evidence yet of the link between high homocysteine levels and AD.

Seshadri, S., Beiser, A., Selhub, J., Jacques, P.F., Rosenberg, I.H., D'Agostino, R.B., Wilson, P.W.F. & Wolf, P.A. 2002. Plasma homocysteine as a risk factor for dementia and Alzheimer's disease. The New England Journal of Medicine, 346, 476-483.

http://www.eurekalert.org/pub_releases/2002-02/nioa-hhl021202.php

Research ties vitamin B12 and folate deficiencies with Alzheimer's disease

People with low levels of B12 or folate may have a higher risk of developing Alzheimer's disease. A 3-year Swedish study of 370 people 75-years-old and older found that more than half (46 out of 78) of those diagnosed with dementia during the timeframe of the study had both low levels of vitamin B12 or folate and Alzheimer's type dementia. Low vitamin B12 and folate levels have long been observed in elderly people, and it has been theorized that this vitamin deficiency might be tied to neurological or psychiatric disorders. This study breaks new ground by connecting these deficiencies with Alzheimer's disease.
Vitamins B12 and folate (a form of water-soluble vitamin B) are found in common foods. Vitamin B12 is naturally found in animal foods including fish, milk and milk products, eggs, meat, and poultry. Leafy greens such as spinach and turnip greens, dry beans and peas, fortified cereals and grain products, and some fruits and vegetables are rich food sources of folate.

http://www.eurekalert.org/pub_releases/2001-05/AAoN-RtvB-0705101.php

High homocysteine levels are associated with decreased memory capability after age 60

Recent studies have linked Alzheimer disease and dementia after multiple strokes to extremely high serum homocysteine concentrations. A survey of 1299 men and women aged 60 and over, none of who had previously had a stroke, found an independent relationship between very high homocysteine levels and poor performance on cognitive tests. The folate status of the participants was checked as folate has been shown to significantly modify homocysteine levels. Story recall was worse among subjects with a combination of low folate and high homocysteine than in those whose homocysteine levels were normal or low. Homocysteine levels increased with age and were accompanied by a comparable decline in folate status. The researchers found independent associations between the highest levels of homocysteine and poorer recall. Among subjects with the highest level of homocysteine, the odds of passing a word delayed-recall test were identical whether their folate status was high or low.

http://www.eurekalert.org/pub_releases/2001-04/AJoC-Hhla-2504101.php