Does diet intervention in line with nutrition recommendations affect dietary carbon footprint? Results from a weight loss trial among lactating women.

BACKGROUND/OBJECTIVES: Results from studies evaluating the sustainability of diets combining environmental and nutritional aspects have been diverse; thus, greenhouse gas emissions (that is, carbon footprint (CF)) of diets in line with dietary recommendations in free-living individuals warrants further examination. Here, changes in dietary CF related to changes in food choice during a weight loss trial among lactating women who received a 12-week diet intervention based on the Nordic Nutrition Recommendations (NNR) 2004 were analyzed. The objective of this study was to examine if a diet intervention based on NNR 2004 results in reduced dietary CF. SUBJECTS/METHODS: Changes in dietary CF were analyzed among 61 lactating women participating in a weight loss trial. Food intake data from 4-day weighed diet records and results from life cycle analyses were used to examine changes in dietary CF across eight food groups during the intervention, specified in the unit carbon dioxide equivalent (CO2eq/day). Differences in changes in dietary CF between women receiving diet treatment (D-group) and women not receiving it (ND-group) were compared. RESULTS: There was no difference in change in dietary CF of the overall diet between D- and ND-group (P>0.05). As for the eight food groups, D-group increased their dietary CF from fruit and vegetables (+0.06±0.13 kg CO2eq/day) compared with a decrease in ND-group (-0.01±0.01 kg CO2eq/day) during the intervention, P=0.01. CONCLUSIONS: A diet intervention in line with NNR 2004 produced clinically relevant weight loss, but did not reduce dietary CF among lactating women with overweight and obesity. Dietary interventions especially designed to decrease dietary CF and their coherence with dietary recommendations need further exploration.

Upgrading plant amino acids through cattle to improve the nutritional value for humans: effects of different production systems.

Efficiency in animal protein production can be defined in different ways, for example the amount of human-digestible essential amino acids (HDEAA) in the feed ration relative to the amount of HDEAA in the animal products. Cattle production systems are characterised by great diversity and a wide variety of feeds and feed ration compositions, due to ruminants' ability to digest fibrous materials inedible to humans such as roughage and by-products from the food and biofuel industries. This study examined the upgrading of protein quality through cattle by determining the quantity of HDEAA in feeds and animal products and comparing different milk and beef production systems. Four different systems for milk and beef production were designed, a reference production system for milk and beef representing typical Swedish production systems today and three alternative improved systems: (i) intensive cattle production based on maize silage, (ii) intensive systems based on food industry by-products for dairy cows and high-quality forage for beef cattle, and (iii) extensive systems based on forage with only small amounts of concentrate. In all four production systems, the quantity of HDEAA in the products (milk and meat) generally exceeded the quantity of HDEAA in the feeds. The intensive production models for beef calves generally resulted in output of the same magnitude as input for most HDEAA. However, in beef production based on calves from dairy cows, the intensive rearing systems resulted in lower output than input of HDEAA. For the extensive models, the amounts of HDEAA in meat were of the same magnitude as the amounts in the feeds. The extensive models with beef calves from suckler cows resulted in higher output in meat than input in feeds for all HDEAA. It was concluded that feeding cattle plants for production of milk and meat, instead of using the plants directly as human food, generally results in an upgrading of both the quantity and quality of protein, especially when extensive, forage-based production models are used. The results imply that the key to efficiency is the utilisation of human-inedible protein by cattle and justifies their contribution to food production, especially in regions where grasslands and/or forage production has comparative benefits over plant food production. By fine-tuning estimation of the efficiency of conversion from human-edible protein to HDEAA, comparisons of different sources of protein production may be more complete and the magnitude of amino acid upgrading in plants through cattle more obvious.

Trends in greenhouse gas emissions from consumption and production of animal food products - implications for long-term climate targets.

To analyse trends in greenhouse gas (GHG) emissions from production and consumption of animal products in Sweden, life cycle emissions were calculated for the average production of pork, chicken meat, beef, dairy and eggs in 1990 and 2005. The calculated average emissions were used together with food consumption statistics and literature data on imported products to estimate trends in per capita emissions from animal food consumption. Total life cycle emissions from the Swedish livestock production were around 8.5 Mt carbon dioxide equivalents (CO2e) in 1990 and emissions decreased to 7.3 Mt CO2e in 2005 (14% reduction). Around two-thirds of the emission cut was explained by more efficient production (less GHG emission per product unit) and one-third was due to a reduced animal production. The average GHG emissions per product unit until the farm-gate were reduced by 20% for dairy, 15% for pork and 23% for chicken meat, unchanged for eggs and increased by 10% for beef. A larger share of the average beef was produced from suckler cows in cow-calf systems in 2005 due to the decreasing dairy cow herd, which explains the increased emissions for the average beef in 2005. The overall emission cuts from the livestock sector were a result of several measures taken in farm production, for example increased milk yield per cow, lowered use of synthetic nitrogen fertilisers in grasslands, reduced losses of ammonia from manure and a switch to biofuels for heating in chicken houses. In contrast to production, total GHG emissions from the Swedish consumption of animal products increased by around 22% between 1990 and 2005. This was explained by strong growth in meat consumption based mainly on imports, where growth in beef consumption especially was responsible for most emission increase over the 15-year period. Swedish GHG emissions caused by consumption of animal products reached around 1.1 t CO2e per capita in 2005. The emission cuts necessary for meeting a global temperature-increase target of 2° might imply a severe constraint on the long-term global consumption of animal food. Due to the relatively limited potential for reducing food-related emissions by higher productivity and technological means, structural changes in food consumption towards less emission-intensive food might be required for meeting the 2° target.