Espacios públicos asociados a la vida y obra de Vallejo como elementos

experiment

A method for studying the impact of food on human health is model experiments with animals. Such experiments can be designed so the food is completely controlled and the risk of confounding by extraneous factors is minimised. In the project, rats were fed through several generations with feed produced from plants grown in model systems with three different combinations of organic and conventional methods for fertilisation and plant protection. As in other investigations, there were no substantial differences in the rat’s fertility, mineral uptake or feed utilisation. Conversely, the experiment showed that feed from plants grown with organic fertilisation and organic plant protection resulted in the highest anti- body levels, least adipose tissue and longest sleep periods. These characteristics have not been measured in previous investigations.

Many consumers expect that organic foods are better for health and more nutritious than foods produced with conventional methods, but scientific studies clearly sup- porting this perception are missing. There are many reasons why it is difficult to study the influence of diet on human health, among others that a long list of factors other than food influence health, that individuals react differently to food components and last, but not least, that diet affects health throughout life, so our long lifespan makes it particularly difficult to study the effect of food on humans. For comparison of organic and conventional food is it an additional complication that there is a large variation in the production methods used within each of these categories. Due to this, the project used rats as a model instead of humans. And instead of a complete human diet with both plant and animal products, the feed for the rats was produced from vegetables, fruit and rapeseed oil. It is known that the digestion and metabolism of rats is somewhat dif- ferent from that of humans, so the results are not directly transferable to humans, in particular not to non-vegetarians.

Investigation of physiological differences

The objective of the project was therefore to investigate, if the difference between conventional and organic food can cause physiological differences in animals, which indicate differences in effects on humans. If differences in diet cause differences in the health of the rats, is it likely humans will experience a difference as well, and that the same aspects of

III.4 Or ganic f o o d and he alth – a multigener atio n animal exp er imen t (O R GAN IC H EAL TH )

health will be affected. This knowledge will then allow the design of future investigations to become more targeted and thus with a better chance of reaching a definitive conclusion. The experiment was carried out with rats that were fed with a mixture of potatoes, carrots, peas, rapeseed oil, kale and apples. The ingredients were processed as for human food and then freeze dried, and were mixed in proportions that ensured sufficient content of energy and protein. These ingredients were grown in 001 and 00 in model systems, which represent different methods for plant production: 1. Low input without pesticides: low input of fertiliser; no

pesticides (model of organic production)

. Low input with pesticides: low input of fertiliser; with pesticides (model of production with reduced intensity of fertilisation)

3. High input with pesticides: high input of fertiliser; with pesticides (model of conventional production)

The model systems were chosen to ensure well-controlled growing conditions and to represent extremes in existing cultivation methods. Due to this the feed ingredients do not necessarily correspond to typical organic or conventional products on the market. Those vitamins, minerals and amino acids that can be deficient in a purely plant based diet were added to all three feed mixtures in order to cover the rat’s needs for these compounds.

The plant material was investigated for differences in picture forming properties (biocrystallization), in the content of characteristic secondary metabolites and the most important nutrients and minerals, as well as for the biological value of the most important protein sources in the feed.

For the picture forming properties, protein and minerals were only small differences detected in the feed, and dif- ferences between the cultivation years were greater than between the cultivation treatments. Some of the secondary metabolites showed the highest and lowest content in the same cultivation treatments in both years, but only few of these systematic differences were significant, and even the significant differences were not very large in % of the average contents.

Minor effect on classic measures of health

The rats were fed with the three feed mixtures; each rat and its offspring received the same diet for the entire life, through three generations. Fertility and growth was recorded for every litter. Female rats from the second generation were selected for more detailed health assessments, which started at the age of 19 weeks, after each had bred one litter. Their health was investigated through physiological response measurements, which comprised nutrient utilisation, organ function and physical activity. After being sacrificed at the age of 44 weeks, samples of blood and tissue were collected for analysis of biomarkers of health, including immunity, antioxidant status and nutrient status.

Fat 8

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lgG Vitamin E Organic Minimally fertilized Conventional

The rats grew well on all three diets, with only small differences in growth rate and breeding outcome, no

significant trends were replicated across the generations. Even though the rats where genetically susceptible to development of diabetes, no symptoms were observed of this disease. The selected rats also only showed insignificant differences regarding the utilisation of nutrients and energy, or uptake and excretion of minerals. These negative results correspond to the conclusions from previous investigations comparing the effect of organic and conventional diets on health of animals or humans, which only showed small or contradictory differences in the effects of these “classic” measures of health.

Differences in antibody, obesity and sleep patterns However, the new aspects were that we had also included several health measures that had not been used in other investigations.

Even though short-term measurements of energy expenditure did not show any difference related to the feed treatments, there was a trend for rats on feed type 1 (organically grown) had lower weight and lower amount of adipose tissue (Figure 1) than rats from the other treatments. Additionally, rats fed with feed from treatment 1 (organically grown) and (low fertiliser input) had a higher content of immunoglobulin G, which participated in the immune defence against infectious diseases, than rats raised on feed from treatment 3 (conventio- nally grown) (Figure 1). In contrast there were no differences for the contents of immunoglobulin A and M.

Concomitantly with the measurement of energy expenditure the physical activity was monitored using infrared sensors. Rats are night active animals, and there was no difference between the diet types for the activity during the night. However, during the day, when rats are expected to rest, the data indicated that rats fed the diet produced with organic methods were quieter than rats fed with the other diet types (Figure ).

All in all the project showed that exactly those measures of health and well-being, which have not been included in previous studies, showed differences between rats fed with

Figure 1. Content of adipose fat in the body (%), and plasma content og

immunoglobulin G (IgG, mg/ml) and vitamin E (mg/l) in rats fed organic, minimally fertilized or conventional diets

III.4 Or ganic f o o d and he alth – a multigener atio n animal exp er imen t (O R GAN IC H EAL TH ) Project leader

Kirsten Brandt, senior lecturer, School of Agriculture, Food and Rural Development, University of Newcastle upon Tyne, UK (previously DIAS).

E-mail: [email protected]

Project participants

Charlotte Lauridsen, Henry Jørgensen, Rikke Nørbæk, Ulla Kidmose, Hanne Lindhard Pedersen, Kristian Thorup-Kristensen, Jens Peter Mølgaard, Uffe Jørgensen, Ulrich Halekoh, Danish Institute of Agricultural Sciences; Susanne Højbjerg Bügel, Jens-Otto Andersen, The Royal Veterinary and Agricultural University; Lars Frøsig, Research Centre Risø; Merel Ritskes- Hoitinga, Ingrid Marie Jegstrup, University of Southern Denmark; Helle W. Ravn, National Institute of Environ- mental Research

Publications and further information

See the project website:

www.darcof.dk/research/darcofii/iii4.html and the internet-archive: www.orgprints.org plant materials grown with different methods. In other

words, we would not have found any difference if we had only measured the same aspects as in previous investigations, where also no differences were found.

The project has thus shown a clear direction for future research: more emphasis must be placed on the importance of diet for the immune system, lipid metabolism and brain func- tions, while the production methods for plant foods have less influence on growth, reproduction and nutrient utilisation.

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Minimally fertilized Conventional

Organic Day Night R ela tive activity

Figure 2. Relative activity of rats at day and night. The rats were fed organic, minimally fertilized or conventional diets