Women of childbearing age: dietary patterns and vitamin B12 status

Abstract

From conception the dynamic balance between nutritional and activity factors play a role in the accumulation of risk for future disease. Maternal nutrient balance and the subsequent dietary pattern of the family set the path for the growth and development of the individual and therefore also for their offspring. There is strong evidence from studies in India that mothers who have a low vitamin B12 status, but high folate, will have children with higher adiposity and more cardiovascular risk factors than those with adequate B12. The B12 status is closely linked to the dietary pattern particularly the consumption of red meat which has a high B12 content. In New Zealand there are an increasing number of Indian migrants. Vegetarianism is also practiced by an increasing number including young women. In addition, there is a high rate (up to 60%) of unplanned pregnancies in New Zealand. In the 1997 New Zealand National Nutrition Survey (NNS97) report, vitamin B12 intake appeared adequate for the New Zealand population and breakfast cereals were reported as one major dietary source of B12. Cereals in New Zealand however, were not fortified with B12 and there was an error in the FOODfile™ data entries for B12 in some cereals. The raw data of reported B12 intakes in the 24-hour diet recall (24HDR) of NNS97 was reanalysed at the individual level by subtracting the B12 derived from breakfast cereals and applying the 2005 revised estimated average requirement (EAR) value. The possible prevalence of B12 insufficiency was 2.4 times that originally reported by the NNS97, translating into a prevalence of up to 27% of the population sampled. This analysis was limited as it was not adjusted for day-to-day variance or to the New Zealand population. This apparently high prevalence of risk for inadequate B12 intake in the surveyed individuals required confirmation that the B12 intake from 24HDR and also a 7-day diet diary (7DDD) was a valid assessment of B12 status. The group of particular interest is women of childbearing age (18-50y) with a range of eating patterns. Thirty eight women aged 19-48y; 12 non-red-meat-eaters (5 Indians vs. 7 non-Indians) and 26 red-meat-eaters (1 Indian vs. 25 non-Indians) participated in this validation study. Anthropometry and hand-to-foot bioelectrical impedance (BIA) were measured on the same day as a 24HDR was recorded. Fasting serum lipids, glucose, haematological parameters, and serum B12, holotranscobalamin II (holo-TC II, a specific B12 biomarker), and folate concentrations were measured. Foods eaten and time spent in physical activity during the following 7 days were extracted from 7DDD and 7-day physical activity diary (7DPAD). There was no significant correlation between dietary intake (24HDR or 7DDD) and biomarkers for B12 status. Indians reported lower mean daily B12 intakes in 7DDD than non-Indians (1.6 vs. 4.5 μg/day, p<0.001) and this was confirmed by Indians’ significantly low serum B12 (203 vs. 383 pmol/L, p=0.04) and holo-TC II (35 vs. 72 pmol/L, p=0.02) concentrations compared to non-Indians. A similar pattern was found between non-red-meat-eaters and red-meat-eaters in daily B12 intake in 7DDD (2.3 vs. 4.8 μg/day, p<0.001) and in B12 biomarkers (serum B12, 263 vs. 397 pmol/L, p=0.01; holo-TC II, 43 vs. 77 pmol/L, p<0.005). Non-red-meat-eaters reported significantly higher daily folate intake in 7DDD (359 vs. 260 μg/day, p=0.01) than red-meat-eaters but no significant difference was found in serum folate concentration between these groups (29 vs. 24 pmol/L, p=0.10). Indians/non-red-meat-eaters also reported lower daily protein intake and higher percentage of total energy from carbohydrate in 7DDD compared to non-Indians/red-meat-eaters but total reported energy intake tended to be under-reported and physical activity over-reported when assessed against estimated basal metabolic rate (BMR). Body composition varied by dietary pattern. Indians/non-red-meat-eaters had higher body fat percentage (BF %) and weaker grip strength than non-Indians/red-meat-eaters. In addition, Indians had a significantly higher waist-to-hip ratio (WHR) than non-Indians. Overall, the whole group reported that they were inactive. The median time spent in moderate, high and maximal intensity activities was only 19 minutes a day, which did not meet the NZ guideline for adults of 30 minutes a day. In this small study nutrient analysis of diet by 24HDR or 7DDD, was not a reliable or accurate way to assess B12 insufficiency. Questions about dietary patterns such as “do you eat red meat”, and taking ethnicity into account could more easily identify the at risk population. Supplementation and/or fortification of B12 should be considered before pregnancy.