Science - June 2, 2005

Elderly need megadoses B12

One in ten, and possibly even one in five, elderly people has a vitamin B12 deficiency, and as a result, an increased chance of mental deterioration and depression. A piece of Wageningen research suggests that it is practically impossible to compensate for the shortage by paying more attention to diet. Only high levels of supplements are likely to help.

Vitamin B12 is only found in animal products, and mainly in meat. The vitamin is vital for the functioning of enzymes that regulate metabolism and deactivates the otherwise potentially dangerous amino acid homocysteine. As a result of the ageing process the human body starts to use the vitamin less efficiently. Studies have shown that over the age of fifty the concentration of the vitamin in the blood starts to decline.

Researchers at the sub-department of Human Nutrition examined 120 healthy people over seventy who had a mild B12 deficiency. They divided their subjects into five different groups, and each group received a different amount of the vitamin in the form of capsules. The lowest dose was three micrograms per day, the recommended daily amount. The highest dose was one thousand micrograms per day.

The researchers measured the concentrations of homocysteine and methylmalonic acid in their subjects and found that the greater the B12 deficiency, the higher the concentration of these two substances. According to the measurements, the subjects in the experiment needed a minimum daily dose of 600 micrograms of B12 to normalise their situation.

‘Our research shows that far higher doses of B12 are required to eliminate a deficiency of the vitamin than we previously thought,’ the Wageningen researchers write. ‘The lowest dose that led to an improvement of a mild deficiency was two hundred micrograms more than the presently recommended daily dose.’

The research results have been published in the Archives of Internal Medicine. The research was funded partly by the EU and the manufacturer Kellogg’s.
/ WK

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