Zinc status of rural and tribal women of reproductive age in Central India

Abstract

In India, there are currently no national data on zinc intake or serum zinc concentration to estimate the proportion of the population who are at elevated risk of zinc deficiency. Rural and tribal women are particularly vulnerable to zinc deficiency, given the high intake of cereals and legumes in the diet and high prevalence of iron deficiency in India. Notwithstanding, very few studies have examined the zinc status in these women. This study investigated the biochemical zinc status and dietary zinc intake of rural and tribal women in central India.

Rural and tribal non-pregnant women 18-30 years (n=109; rural n=53; tribal n=56) were selected using proportion to population sampling in Ramtek block, Nagpur district, India. Over a two-day period socio-demographic, biochemical, clinical and dietary data were obtained from the participants between April and September 2007. Blood samples were collected and analysed using the standardised International Zinc Nutrition Consultative Group (IZiNCG) protocols. A one-day interactive 24-hour recall was conducted on each participant (n=103) and food intakes converted into nutrient intakes primarily using the Indian food composition tables. As many zinc and phytate values were missing from the Indian food composition tables, values were imputed from other food composition databases. In addition, zinc values were adjusted for nutrient losses during cooking as the Indian food composition tables were given as raw values.

Socio-demographic characteristics indicated that women in tribal and rural areas were very poor, surviving on approximately $973 US dollars per household per year. The majority of these women (63%) had BMI <18.5 which is defined as chronic energy deficiency (CED);of those who had CED, ~ 47% had severe CED (i.e. BMI <16). Although 72% of women identified as non-vegetarian, most were in fact practicing vegetarianism due to limited financial resources. The median (1st, 3rd quartiles) energy intake was 5.4 (4.2, 6.7) MJ/day. The median (1st, 3rd quartiles) zinc intake was 5.3 (3.8, 7.0) mg/day, below the EAR of 9mg/day for women aged 18 years and 7mg/day for women aged ≥19 years of age. The phyate:zinc molar ratio was 26, which is considered to be high by IZiNCG and which would affect the bioavailability of zinc in the diet. The proportion of women with a zinc intake below the EAR was 78%, much higher than 25% suggested by IZiNCG indicating that the whole population are at increased risk of zinc deficiency.

Mean (SD) serum zinc concentration was 10.8 (1.6) µmol/L after adjustment for infection and OCA use. Similarly, 52% of women had low serum zinc concentration, higher than the level suggested by the IZiNCG (> 20%) for the whole population to be at increased risk of zinc deficiency. No difference was seen between in rural and tribal women in Ramtek Block for any of the socio-demographic, dietary or serum zinc variables examined. Using multivariate regression analysis, only energy intake (p=0.012) and current lactation (p=0.001) were significantly associated with serum zinc concentration. Breastfeeding decreased serum zinc concentration by 7% (95% Confidence Interval: 2 to 12%) compared to those women who do not breastfeed and for every one MJ increase in energy, serum zinc concentration decreased by 2% (95% Confidence Interval: 1 to 3%).

This study is the first of its kind to examine and compare zinc intake and zinc status of rural and tribal women living in central India. The low energy intakes and poor bioavailability of zinc in the diets of these women was likely to be the primary cause for their elevated risk of zinc deficiency. In light of these results, it is suggested that current supplementation programmes include zinc and that this supplementation programme be extended to include all women in rural and tribal areas in Ramtek Block, particularly to those women who are currently lactating.