Low levels of the mineral selenium may increase the risk of anaemia in older people, according to a new study from the United States.
Writing in the European Journal of Clinical Nutrition, researchers from the Johns Hopkins Medical Institutions and the National Institute on Aging report that people with the lowest selenium levels were 11.4 per cent more likely to have anaemia, compared to people with the highest levels..
“This study raises a potentially important public health question: has selenium deficiency been overlooked as a cause of anaemia among older adults? This study may represent a first important step toward determining whether selenium deficiency is a potential cause of anaemia among older adults,” wrote lead author Richard Semba.
Being the first such study of its kind, the researchers were cautious about the recommendation of selenium supplements, or selenium-rich foods, noting that it is not known whether improvements in selenium intake would have a direct impact on anaemia in older people – related to haemoglobin levels.
Anaemia, the most common blood disorder, can affect anyone, but the highest occurrence is in elderly women, women of childbearing age (due to menstruation), children and teenagers. According to the Semba and his co-workers, the prevalence of the disorder increases with age.
The researchers studied data on 2,092 adults over the age of 65 taking part in the third National Nutrition Examination Survey, Phase 2 (NHANES III). Blood samples were used to evaluate selenium levels and the incidence of anaemia, defined using the WHO levels of less than 12 grams of haemoglobin per decilitre of blood (g/dL) for women, and 13 g/dL for men.
Almost 13 per cent of the participants were classified as anaemic, while the average selenium blood levels of selenium were lower in people with anaemia than in people without the disorder. Increasing selenium levels were associated with a reduced risk of anaemia, said the researchers.
Is it biologically plausible?
The researchers noted that the mineral is involved in maintaining optimal concentrations of an antioxidant enzyme called glutathione peroxidise, which protects haemoglobin against oxidation
However, considering the flip side to this argument, they said that there is negligible biological evidence that anaemia could cause low selenium blood levels.
“Further work is needed to corroborate these findings in other populations, provide evidence for longitudinal causal associations, identify underlying biological mechanisms and determine whether improving selenium status has an impact upon anaemia in older adults,” said Semba and his co-workers.
Source: European Journal of Clinical Nutrition
2009, Volume 63, Pages 93-99; doi:10.1038/sj.ejcn.1602889
“Low serum selenium is associated with anemia among older adults in the United States”
Authors: R.D. Semba, M.O. Ricks, L. Ferrucci, Q.-L. Xue, J.M. Guralnik, L.P. Fried