Is the link between nutrients and foods understood? The case of fibre and folate

Objectives: To assess and contrast awareness of the link between dietary fibre and folate and their major food sources (fruit, vegetables, bread and cereals).

Design and setting: Mailed questionnaire investigating changes made to dietary intake of fibre, folate, fruit, vegetables, bread and cereals in the previous six months.

Setting: The survey was conducted between June and November 1998 in the Australian Capital Territory.

Subjects: One thousand one hundred and twenty-six adults randomly selected from the electoral roll.

Results: More women than men in both older (50 + years) and younger (18–49 years) age groups reported increasing their consumption of folate, fibre, fruit and vegetables in the prior six months. In contrast, more men than women reported increased consumption of bread, cereals, rice and pasta in the previous six months. For food categories and fibre, less than 4% of respondents were unsure about changes in these food habits. However, 26% of men and women were ‘not sure’ about changes to folate intake. Similar proportions of men and women (about 33%) reported consuming more fruit, vegetables or cereal-based foods over the prior six months, yet only 6% of these men and 14% of these women reported consuming more folate. In contrast, 44% of men and 51% of women who reported consuming more plant foods also reported consuming more dietary fibre.

Conclusions: The results suggested that subjects, particularly the younger age group, had a poor understanding of the relationship between folate intake and its major food sources. The understanding of the relationship between fibre intake and its food sources appeared substantial, but confusion about specific food sources was still evident. These outcomes question the effectiveness of nutrition education used to date, particularly for the current priority of increasing folate intake in younger women in the new, ‘health claims’ environment.

The use of artificial biofilms to strip nutrients from an industrial smelters waste water under conditions of low temperature and high pH

The Victorian Environment Protection Authority (EPA) has identified Alcoa’s Point Henry aluminium smelter as being a major source of recognized pollutant input due to its disposal of effluent into Corio Bay. Historically, the water quality parameters that have most often exceeded Point Henry’s EPA limits have been pH and suspended solids from the smelter’s discharge points. These waste water discharges also experience high nitrogen and phosphorus concentrations which result in algal blooms that occur at the onset of warm weather. The main hypothesis of this study was that “prevention of algal blooming with the onset of warm weather by removal of nutrients during the cooler months, and continued removal thereafter, is better than curing the problems chemically”. Biofilms have been used to remove nutrients from waste waters, but not under the conditions experienced at Point Henry. The aim of this study, therefore, was to determine if significant biofilm growth would be observed on floating structures suspended in the Point Henry waste water stream during the cooler, winter months of the year. Statistically significant biofilm growth occurred on all suspended structures in all discharge ponds during the winter and early spring of 2000. The use of suspended structures, such as AquaMatTM, as an artificial substrate to attract and support periphyton and bacterial communities (biofilms), which are then able to out-compete phytoplankton communities for available nutrients, is therefore a viable option for the Point Henry smelter. However, further research on the competitive performance of biofilms in the Point Henry ponds during the summer months is required before adequate biofilm management strategies can be developed.

Nutrients in Pirron Yallock Creek, southwestern Victoria : paleolimnological and management considerations

The concentrations of various forms of nitrogen and phosphorus in the main stream and selected tributaries of Pirron Yallock Creek, southwestern Victoria were examined over a two-year period. Exceedingly high levels of both nutrients were found within a particular tributary, while generally high nutrient levels were observed throughout the catchment. The speciation results indicated that dairy effluent was the primary source of nutrients to Pirron Yallock Creek. A palaeolimnological study was undertaken to determine the impact of European settlement upon waterway nutrient concentrations within the region. The palaeolimnological study focused primarily on the diatom flora preserved within the sediments of nearby Lakes Corangamite and Bullen Merri. Lack of preservation of diatoms within the sediments of Lake Corangamite resulted in no water quality inferences for this lake. The preserved diatoms within Lake Bullen Merri suggested an increase in trophic status of this lake during the last 500 years. While a change in the diatom flora of Lake Bullen Merri was evident, it was not possible to differentiate the impact of European settlement upon nutrient status of this waterway from long-term trophic status change. In light of the particularly high nutrient concentrations observed in Pirron Yallock Creek, improved nutrient management strategies are proposed for the catchment. These strategies, which consider current nutrient management activities, are predominantly focussed on the dairy industry, which occupies the majority of the catchment.

Hydrodynamics, nutrients and algae of Fitzroy and Merri River estuaries

Various physical, biological and chemical attributes were investigated for the Fitzroy and Merri River estuaries. This research found algal communities were most influenced by high nitrogen concentrations at times of low flow. Mangement of nutrients within each catchment is therefore of high importance to reduce the possibility of future blooms.

Nutrients, palaeolimnology and cyanobacterial blooms in Lake Wallace, Western Victoria

The basic limnology, nutrient and hydraulic budgets and recent history (using fossil remains in the sediments) of Lake Wallace have been studies to determine factors that predispose the lake to the development of potentially toxic algal blooms.

Land use change and nutrients simulation for the Siah Darvishan basin of the Anzali wetland region, Iran

The Anzali Ramsar Convention wetland is located in an ecologically and economically important region in Iran. The wetland is largely surrounded by agriculture, natural forests and rangelands (approximately 36% and 63%, respectively). Urban areas consist of less than 1% of the total area. Urban land use produces the highest rates of nutrient transfer into the lake as TN, TP and BOD5 equal to 24, 2.4 and 79 Kg/ha/year, respectively, whilst, natural land use produces the lowest rate as 10, 1.3 and 27 kg/ha/year. These results will inform the future sustainable management of this important wetland in this ever increasingly water stressed region in Iran.

Modeling bacterial growth in drinking water : effect of nutrients

This article presents a model of growth of naturally occurring heterotrophic bacteria in the bulk water phase in the absence of disinfectant. The model considers growth with carbon, phosphorus, and nitrogen balance, death and lysis of bacteria, and conversion of less biodegradable organic carbon to assimilable organic carbon. Experimental data from two raw and two treated waters were used to test the model. The model describes the increase of live and dead bacterial cells in the water phase, and its output closely matches the experimental data. Such a model has the ability to characterize water nutrient status as well as to predict behavior of indigenous heterotrophic bacteria. The ability to predict bacterial population dynamics with respect to nutrients is beneficial for water treatment optimization. The model, based on microbiological measurements, helps to characterize treated water quality and project performance in terms of water quality into a distribution system.

Food fortification : the evidence, ethics and politics of adding nutrients to food

This research book presents a critical analysis of mandatory food fortification as a technology for protecting and promoting public health. Increasing numbers of foods fortified with novel amounts and combinations of nutrients are being introduced into the food supplies of countries around the world to raise populations’ nutrient intakes. Three topical food fortification case studies representing the different public health rationales for adding nutrients to food were assessed for their public health benefits, risks and ethical considerations: Universal salt iodisation (USI) to help prevent iodine deficiency disorders; mandatory flour fortification with folic acid (MFFFA) to help prevent neural tube defects; and mandatory milk fortification with vitamin D (MMFVD) to help prevent vitamin D deficiency. These assessments found that whereas USI performs strongly as a public health intervention, MFFFA and MMFVD are associated with more risks and less ethical justification than an alternative policy option. Food fortification can be a blunt policy response to complex policy problems. The findings highlight that the primary predictor of a mandatory food fortification policy’s benefits, risks and ethics is its ability to address the underlying cause of the policy problem. The analysis of the policy-making processes for each case study found that certain powerful actors use their influence to determine what counts as evidence in policy processes to privilege food fortification activities over alternative policy options. Policy-making frequently was notable for the low prominence it afforded ethical considerations and its lack of public engagement. Priority activities to help strengthen policy processes and outcomes are suggested.

Surviving on cached foods - the energetics of egg-caching by arctic foxes

Food-caching by arctic foxes (Vulpes lagopus (L., 1758)) is a behavioural adaptation thought to increase winter survival, especially in bird colonies where a large number of eggs can be cached during a short nesting season. In this paper, we measured the energy content of greater snow goose (Chen caerulescens atlantica Kennard, 1927) eggs and evaluated their perishability when cached in tundra soil for a whole summer. We estimated that eggs lost only ~8% of their dry mass over 60 days of storage in the ground. We used published estimates on digestibility of nutrients by arctic foxes to estimate that fresh and stored goose eggs contained 816 and 730 kJ of metabolizable energy, respectively, a difference of 11%. Using information on arctic fox energetics, we evaluated that 145 stored eggs were required to sustain the growth of one pup from the age of 1 to 3 months (nutritional independence). Moreover, 23 stored eggs were energetically equivalent to the average fat deposit of an arctic fox during winter. Finally, we calculated that an adult arctic fox would need to recover 160-220 stored eggs to survive 6 months in resting conditions during cold winter temperatures. This value increased to 480 when considering activity cost. Based on egg acquisition and caching rates observed in many goose colonies, we conclude that cached eggs represent an important source of energy relative to the needs of an arctic fox during winter, and have thus a high fitness value.

Nutrients, not caloric restriction, extend lifespan in Queensland fruit flies (Bactrocera tryoni)

Caloric restriction (CR) has been widely accepted as a mechanism explaining increased lifespan (LS) in organisms subjected to dietary restriction (DR), but recent studies investigating the role of nutrients have challenged the role of CR in extending longevity. Fuelling this debate is the difficulty in experimentally disentangling CR and nutrient effects due to compensatory feeding (CF) behaviour. We quantified CF by measuring the volume of solution imbibed and determined how calories and nutrients influenced LS and fecundity in unmated females of the Queensland fruit fly, Bactocera tryoni (Diptera: Tephritidae). We restricted flies to one of 28 diets varying in carbohydrate:protein (C:P) ratios and concentrations. On imbalanced diets, flies overcame dietary dilutions, consuming similar caloric intakes for most dilutions. The response surface for LS revealed that increasing C:P ratio while keeping calories constant extended LS, with the maximum LS along C:P ratio of 21:1. In general, LS was reduced as caloric intake decreased. Lifetime egg production was maximized at a C:P ratio of 3:1. When given a choice of separate sucrose and yeast solutions, each at one of five concentrations (yielding 25 choice treatments), flies regulated their nutrient intake to match C:P ratio of 3:1. Our results (i) demonstrate that CF can overcome dietary dilutions; (ii) reveal difficulties with methods presenting fixed amounts of liquid diet; (iii) illustrate the need to measure intake to account for CF in DR studies and (iv) highlight nutrients rather than CR as a dominant influence on LS.