Estimating the prevalence of Vitamin B12 deficiency in vegetarian out patients between 18 and 60 years of age presenting to a tertiary care hospital

INTRODUCTION : Vitamin B12 is an essential nutrient that is used by the body to act as cofactors in certain key reactions within the cells. Cobalamin along with folate is needed for synthesis of DNA required in cells undergoing rapid turnover, such as haematopoetic and enteric lining cells. The physiological consequences of a deficiency in any of the above nutrients are increased homocysteine, reduced methionine and impaired formation of tetrahydrofolate. These changes ultimately lead to the characteristic neurological and haematological manifestations, not to mention certain events like vascular thromboses that may be seen even in the absence of overt vitamin B12 deficiency. Animal products provide the only dietary source of vitamin B12. Vegetarianism is a well known risk factor for vitamin B12 deficiency. Other important etiological considerations are pernicious anaemia and malabsorption. The treatment is simply supplementing the vitamin in the body with extremely satisfying results at minimum costs and adverse effects. AIMS : The primary aim of this study was to determine the prevalence of vitamin B12 deficiency among vegetarian out patients, between the age groups of 18 and 60 years, visiting the internal medicine out patient department of a tertiary level teaching hospital in South India, and to study their clinical profile along with the risk factors and clinical associations of this condition. OBJECTIVES : The study was designed to accomplish the following six objectives: 1. To determine the prevalence of vitamin B12 deficiency among vegetarian patients (between the ages of eighteen and sixty years) coming to the internal medicine out patient department of Christian Medical College and Hospital, Vellore. 2. To study the clinical manifestations of vitamin B12 deficiency in vegetarians. 3. To study the risk factors associated with the development of vitamin B12 deficiency among vegetarians. 4. To study the awareness of vegetarians about vitamin B12 deficiency and the need for exogenous supplementation. 5. To study the different neuropsychiatric manifestations and the anxiety and the depression levels of the vitamin B12 deficient population 6. To make a preliminary observation as to the prevalence of surrogate markers for pernicious anaemia in the study population. MATERIALS AND METHODS : Study design: This study was carried out based on the principles of a cross sectional study design. It involved observation and obtaining scientific readings at a particular point in time, with no follow up, either prospectively or retrospectively. A cross sectional study is amenable for the analysis of prevalence data and that being our primary objective, this particular study design was chosen. Study population: A prevalence study for any factor is best done in the community – in a lot of situations that would reduce the bias of a hospital study. This being a hospital study has its own limitations. However as far as possible we wanted to choose a population in our hospital survey that would most closely reflect the community or the general population at large. Hence for our study, we excluded people who were significantly ill or people with multiple interacting problems. We also excluded the elderly as in that population there would be the elements of age, poor absorption and poor nutrition confounding the results. Thus we ended up with the following: Inclusion criteria: 1. Vegetarian patients coming to the out patient department of the Internal Medicine Department of Christian Medical College, Vellore, India. 2. Consenting males and females between 18 and 60 years of age. 3. First visit to Christian Medical College, Vellore. 4. Ambulant patient. Vegetarian patients were defined as patients that had been consuming a diet devoid of any form of meat, at least for three completed years prior to the date of recruitment. Exclusion criteria: 1. Patients on supplementation with vitamin B12 either orally or parenterally. 2. Patients with overt features of malabsorption. 3. Patients with chronic diarrhoea. 4. Patients with severe hepatic, renal, pulmonary, cardiac or neurological disease. 5. Patients with advanced malignancy. 6. Patients with dementia. RESULTS : A total of 118 subjects were interviewed of which a total of 10 subjects were excluded owing to the fact that they were on vitamin B12 supplementation. Hence a total of 108 subjects were included in the analysis. LIMITATIONS : There were a few important limitations to this study: 1. The hospital based population selection has its inherent biases and problems of extrapolation of the results to the community. 2. The design of the study being cross-sectional, analysis of risk factors and drawing up associations including causal associations might not be without its problems. 3. The small numbers may not have been adequate to bring out the statistical significances of certain studied factors. 4. The high rates of anxiety and depression may have been owing to the inherent selection bias of this hospital based cohort. The screening tools may also have contributed to this. 5. The analysis of pernicious anaemia antibody screens was not complete owing to various constraints. CONCLUSIONS : This was a cross sectional study among vegetarian out patients where we found the following: 1. There was a high prevalence of vitamin B12 deficiency (61%) in the study population. Another 23% had borderline vitamin B12 levels. Most of them were not overtly symptomatic. 2. The most common clinical features were glossitis and paresthesias. Subacute combined degeneration of the spinal cord was rare. 3. Macrocytosis (MCV>100fl) was seen in 19.7% of B12 deficient patients and in 4% of the borderline B12 group. An MCV higher than 100fl and a folate level less than 9.5ng/mL predicted vitamin B12 deficiency. Also, the folate levels correlated very well with the vitamin B12 levels. 4. Etiology of vitamin B12 deficiency in the population is unlikely to be purely dietary and could be multi-factorial including malabsorption and pernicious anaemia. 5. Awareness about B12 deficiency was extremely low. 6. There was a high prevalence of neuropsychiatric symptoms in the entire study population – there were no significant differences between the B12 categories in terms of anxiety and depression scores. 7. Within a small subgroup of the study population, an unusually high level of pernicious anaemia antibody positivity was found, that could not be adequately handled statistically owing to small numbers. Overall, there were a number of clinical and statistical possibilities that emerged from this small study, that require further investigation in larger studies in the future.