Vegetarian diet as a risk factor for tuberculosis in immigrant south London Asians.

Abstract

Background -In a previous retrospective study of tuberculosis in south London among Asian immigrants from the Indian subcontinent Hindu Asians were found to have a significantly increased risk for tuberculosis compared with Muslims. This finding has been further investigated by examining the role of socioeconomic and lifestyle variables, including diet, as risk factors for tuberculosis in Asian immigrants from the Indian subcontinent resident in south London. Methods -Using a case-control study technique Asian immigrants from the Indian subcontinent diagnosed with tuberculosis during the past 10 years and two Asian control groups (community and outpatient clinic controls) from the Indian subcontinent were investigated. Cases and community controls were approached by letter. A structured questionnaire concerning a range of demographic, migration, socioeconomic, dietary, and health topics was administered by a single trained interviewer to subjects (56 cases and 100 controls) who agreed to participate. Results -The results confirmed earlier findings that Hindu Asians had an increased risk oftuberculosis compared with Muslims. However, further analysis revealed that religion had no independent influence after adjustment for vegetarianism (common among Hindu Asians). Unadjusted odds ratios for tuberculosis among vegetarians were 2-7 (95% CI 1-1 to 6.4) using community controls, and 4-3 (95% CI 1-8 to 10.4) using clinic controls. There was a trend of increasing risk of tuberculosis with decreasing frequency of meat or fish consumption. Lactovegetarians had an 85 fold risk (95% CI 1-6 to 45.4) compared with daily meat/ fish eaters. Adjustment for a range ofother socioeconomic, migration, and lifestyle variables made little difference to the relative risks derived using either community or clinic controls. Conclusions -These results indicate that a vegetarian diet is an independent risk factor for tuberculosis in immigrant Asians. The mechanism is unexplained. However, vitamin D deficiency, common among vegetarian Asians in south London, is known to affect immunological competence. Decreased immunocompetence associated with a vegetarian diet might result in increased mycobacterial reactivation among Asians from the Indian subcontinent.

Susceptibility to mycobacterial infections: the importance of host genetics

“…Vegetarian diet may predispose to vitamin-D deficiency, and among immigrant south London Asians vegetarianism has been found to be a risk factor for tuberculosis. 110 Serum 25(OH)D 3 levels have been found to be lower among untreated tuberculosis patients than controls in the UK and to be associated with disease severity in tuberculosis patients in Indonesia. 111,112 Vitamin D exerts its effects via the vitamin-D receptor (VDR) which is present on monocytes and activated T and B lymphocytes.…”

Risk of coronary heart disease in Hindus and Muslims from Indian subcontinent is similar

“…We have shown that the susceptibility to both osteomalacia and tuberculosis in immigrant Asians from the Indian subcontinent is significantly greater in Hindu than Muslim subjects living in south London 3 4. For both osteomalacia and tuberculosis the increased risk seems to be explained by the higher prevalence of vegetarianism among Hindus.…”

“…With the help of an Asian dietitian we identified all Asian names and categorised them as probable Hindu, probable Muslim, or other. This method has been shown to be accurate 4. Patients who were admitted more than once during the two years were counted only once.…”

Intra-urban health differentials in London - urban health indicators and policy implications

“…It is also associated with a vegetarian diet (32) in south Asian Hindus, thought to be the result of a deficiency of vitamin D to fight infection. (33) Asthma and respiratory diseases were significantly associated with a number of different environmental factors. Hospital admissions for asthma are shown in Figures 1 and 2.…”