Abstract
There was growing concern in New Zealand in the 1990's that Food Security: access by all people at all times to enough food for an active healthy life, was not being achieved, despite an abundant food supply. A study of a convenience sample of 40 families with children (58 adults and 92 children) whose sole income was a government welfare benefit was undertaken. Two-thirds of these households regularly relied on a limited variety of food; one-half did not have a sufficient amount of food because of lack of money and outstanding debts. Over the previous year two thirds had sourced food from a food bank and one-third had been gifted food from friends or relatives. Women's intakes were compromised regularly but not children's. All of the women experienced worry about feeding their household. One-fifth were overweight and over 40% obese despite low reported daily energy intakes (median (SE) 5.7 (0.5) MJ) compared to national data. Six repeated 24-hour diet recalls collected randomly over a two-week period enabled calculation of usual daily intake and the prevalence of inadequate intake for eight micronutrients which were disturbingly high. The children's growth patterns compared favourably with US population percentiles.
The National Nutrition Survey (NNS97) allowed the adaption of eight questions developed by Reid using qualitative methods-to eight indicator statements about food security to be addressed by each participant on behalf of them or their household. Prevalence was significantly higher (p<0.05) for females compared to males for the majority of indicator statements among New Zealand European and Others (NZEO) and Maori. NZEO reported the most food security; Pacific people reported the least and Maori fell between the two. There was a significant increasing linear trend of food security with age (p<0.001) after adjusting for gender.
Rasch analysis was performed on 1868 households where participants reported some food insecurity. The responses were ranked according to the proportion and ordering of their positive responses to eight indices of food security, achieving reliability (Cronbach's Alpha) close to the conventionally accepted level of 0.7. The eight indices were ranked on the same scale; the minimum score -1.66 was achieved by the index 'use special food grants/banks' (the index least reported and most severe) and the maximum score 1.86 was achieved by the index 'variety of foods eaten limited' (the index most reported and least severe).
Categories of food security were assigned using scale cut points: 'fully/almost fully food secure'; 'moderate food security'; 'low food security'. Category status was associated with consumption of recommended number of daily serves of fruit, vegetables, fruits and vegetables, consumption of leaner meats, fatty meats and daily serves of bread. By ANOV A and controlling for sex, ethnicity, Index of Deprivation, urban/rural location, age, level of education, income, and household size, category of household food security was associated with the level of daily intake of total fat, saturated, monounsaturated and polyunsaturated fat, cholesterol, glucose, fructose, lactose, vitamin B6, vitamin B 12, and vitamin C. Dietary data were from the primary 24-hour diet recall of respondents. Participants in the fully/almost fully food secure category of households had a mean BMI of 28. 7 compared to those moderately secure (29.2) and of low food security (29.5) (p=0.015 for difference among categories).
In the Children's Nutrition Survey 2002 (CNS02) data set, the same eight indices were used and food insecurity was experienced significantly more often by children in the largest households, those in the most deprived areas of residence (NZDepO 1 Quintile) and those of Pacific and Maori ethnicity compared to NZEO children. Rasch analysis was performed on responses for 1561 households with children which reported some food insecurity. Subject reliability was close to 0.7 (the conventionally acceptable level). The distribution of the eight indices on the Rasch scale was similar to that observed among the NNS97 households and almost identical to the sub-set of households with children, from that dataset. Categories of food security status were assigned as in the NNS97 and they predicted daily nutrient intake levels of children: total sugars, lactose, vitamin A, ~-carotene, vitamin B 12 and calcium. A more rigorous assigning of categories at the low/moderate scale cut-off, resulted in a further association with level of intake of glucose, fructose and folate. Mean BMI across categories of food security did not differ.
Collectively these data provide unequivocal evidence that food insecurity exists in New Zealand, that it can be quantified and associated with nutrition outcomes. It has a negative impact on the nutrient intakes of both adults and children and a negative impact on the body weight status of adults. These data have implications for nutrition and health professionals and policy makers in New Zealand. They also add to the world-wide body of knowledge of the experience of, and the measurement and predictive potential of food security in populations where the food supply appears plentiful.