Open Access Research

Comparison of two modes of vitamin B12 supplementation on neuroconduction and cognitive function among older people living in Santiago, Chile: a cluster randomized controlled trial. a study protocol [ISRCTN 02694183]

Hugo Sánchez1*, Cecilia Albala1, Lydia Lera1, José Luis Castillo2, Renato Verdugo2, Manuel Lavados2, Eva Hertrampf1, Alex Brito1, Lindsay Allen3 and Ricardo Uauy14

Author Affiliations

1 Public Health Nutrition Unit, Institute of Nutrition and Food Technology (INTA), University of Chile, El Libano 5524, Santiago, CP783490, Chile

2 Department of Neurology, Faculty of Medicine, University of Chile, Av. José Miguel Infante N° 553, Santiago, CP7500691, Chile

3 Department of Agriculture, Agricultural Research Services, Western Human Nutrition Research Center, University of California, Davis, CA, CP 95616, USA

4 Department of Nutrition and Public Health Intervention Research, Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK

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Nutrition Journal 2011, 10:100  doi:10.1186/1475-2891-10-100

Published: 27 September 2011

Abstract

Background

Older people have a high risk of vitamin B12 deficiency; this can lead to varying degrees of cognitive and neurological impairment. CBL deficiency may present as macrocytic anemia, subacute combined degeneration of the spinal cord, or as neuropathy, but is often asymptomatic in older people. Less is known about subclinical vitamin B12 deficiency and concurrent neuroconduction and cognitive impairment. A Programme of Complementary Feeding for the Older Population (PACAM) in Chile delivers 2 complementary fortified foods that provide approximately 1.4 μg/day of vitamin B12 (2.4 μg/day elderly RDA). The aim of the present study is to assess whether supplementation with vitamin B12 will improve neuroconduction and cognitive function in older people who have biochemical evidence of vitamin B12 insufficiency in the absence of clinical deficiency.

Methods

We designed a cluster double-blind placebo-controlled trial involving community dwelling people aged 70-79 living in Santiago, Chile. We randomized 15 clusters (health centers) involving 300 people (20 per cluster). Each cluster will be randomly assigned to one of three arms: a) a 1 mg vitamin B12 pill taken daily and a routine PACAM food; b) a placebo pill and the milk-PACAM food fortified to provide 1 mg of vitamin B12; c) the routine PACAM food and a placebo pill.

The study has been designed as an 18 month follow up period. The primary outcomes assessed at baseline, 4, 9 and 18 months will be: serum levels of vitamin B12, neuroconduction and cognitive function.

Conclusions

In view of the high prevalence of vitamin B12 deficiency in later life, the present study has potential public health interest because since it will measure the impact of the existing program of complementary feeding as compared to two options that provide higher vitamin B12 intakes that might potentially may contribute in preserving neurophysiologic and cognitive function and thus improve quality of life for older people in Chile.

Trial registration

ISRCTN: ISRCTN02694183

Keywords:
cobalamin; vitamin B12; cyanocobalamin; elderly; neurophysiology; cognitive disorders; nerve conduction; cluster randomized controlled trial; public health; Chile