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Vitamin B12 May Prevent Brain ShrinkageElderly people who have vitamin B12 levels at the high end of normal may have a decreased risk of brain shrinkage, a new study reports.
Vitamin B12 One of the major roles of B-group vitamins is as assistants to enzymes; enzymes are substances that catalyse chemical reactions, their assistants are called coenzymes. Vitamin B12 is required for the function of the folate-dependent enzyme, methionine synthase. This enzyme is required for the synthesis of the amino acid, methionine, from homocysteine. An insufficient supply of vitamin B12 can lead to an accumulation of homocysteine, which has been associated with an increased risk of cardiovascular diseases; in addition methionine is required for the synthesis of S-adenosylmethionine (SAM), which has a major role in regulating gene expression. Vitamin B12 is also required by the enzyme that catalyzes the synthesis of succinyl-CoA; this reaction plays an important role in the production of energy from fats and proteins. Succinyl CoA is also required for the synthesis of hemoglobin, the oxygen carrying pigment in red blood cells.
The absorption of vitamin B12 occurs in a unique way. Vitamin B12 is released from food by digestion, especially by stomach acid. The vitamin B12 binds with intrinsic factor produced in the stomach; the resulting complex travels to the small intestine for absorption. Absorption is very poor unless the intrinsic factor is present; secretion of intrinsic factor decreases substantially with age. Deficiency of vitamin B12 is associated with pernicious anaemia and damage to a fatty substance surrounding nerves called myelin; myelin ensures effective transmission of signals between nerve cells.
The Study 107 healthy people aged 61-87 had brain scans and gave blood samples once a year for up to five years. All participants were found to have normal levels of B12; however the researchers found that those in the upper third of vitamin B12 levels were 6 times less likely to experience brain shrinkage than those in the lowest third. The authors conclude that: "Low vitamin B(12) status should be further investigated as a modifiable cause of brain atrophy [wasting] and of likely subsequent cognitive impairment in the elderly." The study follows work associating low B12 status and elevated homocysteine with accelerated cognitive decline.
Click here to read the study abstract. |