Affordability of current, and healthy, more equitable, sustainable diets by area of socioeconomic disadvantage and remoteness in Queensland: insights into food choice

Background

Poor diet is the leading preventable risk factor contributing to the burden of disease globally and in Australia, and is inequitably distributed. As the price of healthy foods is a perceived barrier to improved diets, evidence on the cost and affordability of current (unhealthy) and recommended (healthy, more equitable and sustainable) diets is required to support policy action.

Methods

This study applied the Healthy Diets ASAP (Australian Standardised Affordability and Pricing) methods protocol to measure the cost, cost differential and affordability of current and recommended diets for a reference household in Queensland, Australia. Food prices were collected in 18 randomly selected locations stratified by area of socioeconomic disadvantage and remoteness. Diet affordability was calculated for three income categories.

Results

Surprisingly, recommended diets would cost 20% less than the current diet in Queensland as a whole. Households spent around 60% of their food budget on discretionary choices (that is, those not required for health that are high in saturated fat, added sugar, salt and/or alcohol). Queensland families would need to spend around 23% of their income on recommended diets. However, recommended diets would not be affordable in low socioeconomic or very remote areas, costing 30 and 35% of median household income respectively. The government supplements due to the SARS-CoV-2 pandemic would improve affordability of recommended diets by 29%.

Conclusions

Study findings highlight that while price is one factor affecting consumer food choice, other drivers such as taste, convenience, advertising and availability are important. Nevertheless, the study found that recommended diets would be unaffordable in very remote areas, and that low-income families are likely experiencing food stress, irrespective of where they live in Queensland. Policy actions, such as increasing to 20% the current 10% tax differential between basic healthy, and unhealthy foods in Australia, and supplementing incomes of vulnerable households, especially in remote areas, are recommended to help improve diet equity and sustainability, and health and wellbeing for all.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12939-021-01481-8.

Small decreases in SBPase cause a linear decline in the apparent RuBP regeneration rate, but do not affect Rubisco carboxylation capacity

The response of net photosynthetic CO(2) uptake (A) to increasing leaf intercellular CO(2) concentration (c(i)) was determined in antisense Nicotiana tabacum plants, derived from six independent transformation lines, displaying a range of sedoheptulose-1, 7-bisphosphatase (SBPase) activities. The maximum in vivo ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) carboxylation (V(c,max)) and RuBP regeneration (J(max)) rates were calculated from the steady-state measurements of the A to c(i) response curves. In plants with reductions in SBPase activity of between 9% and 60%, maximum RuBP regeneration capacity declined linearly (r(2)=0.79) and no significant change in apparent in vivo Rubisco activity (V(c,max)) was observed in these plants. No correlation between V(c,max) and a decrease in capacity for RuBP regeneration was observed (r(2)=0.14) in the SBPase antisense plants. These data demonstrate that small decreases in SBPase activity limit photosynthetic carbon assimilation by reducing the capacity for RuBP regeneration.

Expression of six expansin genes in relation to extension activity in developing strawberry fruit

Expansins are proteins which have been demonstrated to induce cell wall extension in vitro. The identification and characterization of six expansin cDNAs from strawberry fruit, termed FaExp3 to FaExp7, as well as the previously identified FaExp2 is reported here. Analysis of expansin mRNAs during fruit development and in leaves, roots and stolons revealed a unique pattern of expression for each cDNA. FaExp3 mRNA was present at much lower levels than the other expansin mRNAs and was expressed in small green fruit and in ripe fruit. FaExp4 mRNA was present throughout fruit development, but was more strongly expressed during ripening. FaExp5 was the only clone to show fruit specific expression which was up-regulated at the onset of ripening. FaExp6 and FaExp7 mRNAs were present at low levels in the fruit with highest expression in stolon tissue. During fruit development FaExp6 had the highest expression at the white, turning and orange stages whereas expression of FaExp7 was highest in white fruit. The expression profiles of FaExp2 and FaExp5 in developing fruit were similar except that FaExp2 was induced at an earlier stage. Analysis of expansin protein by Western blotting using an antibody raised against CsExp1 from cucumber hypocotyls identified two bands of 29 and 31 kDa from developing fruit. Protein extracts from developing fruit were assayed for extension activity. Considerable rates of extension were observed with extracts from ripening fruit, but no extension was observed with protein from unripe green fruit. These results demonstrate the presence of at least six expansin genes in strawberry fruit and that during ripening the fruit acquires the ability to cause extension in vitro, characteristic of expansin action.