Climate change reduces the nutritional value of food crops

Increasing atmospheric CO₂ concentrations and increasing temperatures are causing physiological responses in crops, which lead to them having reduced protein and micronutrient contents. This research aims to quantify these nutritional changes and directly investigate the consequences to human health.

Climate change is well established as a major threat to global food security. Worldwide temperatures are expected to continue increasing, along with an increase in CO₂, within the next 30 years. Heat stress, particularly heat shock and high night-time temperatures are already a major cause of global crop yield reduction. The effects of elevated temperatures on crop growth and yield in current atmospheric levels of CO₂ are well known. What is less well understood is what happens to crop yield and especially nutritional quality during heat stress and with the higher CO₂ levels predicted for 20-30 years' time. Elevated CO₂ (eCO₂) increases yields in many crop plants, but it also changes their phytochemical and nutritional content by changing how plants photosynthesise. Although this seems like a positive consequence in a world with an ever-growing population, eCO₂ can have a counterproductive action. eCO₂ leads to increased carbon assimilation and carbohydrate storage in the plant structures. This results in a lower nitrogen-to-carbon (N:C) ratio affecting crop nutritional quality through altered synthesis of different nutrients (e.g., amino acids, vitamins), phytochemicals (e.g., polyphenols) or matrix components (e.g., non-digestible components – aka dietary fibre) required for adequate nutrition in humans and animals. Additionally, variations in food composition can have a direct impact on nutrient bioavailability and utilization within the body and as a result, we may need to consume higher amounts of vegetables to maintain the required nutrient and phytochemical intakes.

This research will incorporate a novel cross disciplinary approach that combines plant physiology, biochemistry, and human nutrition to investigate the nutritional quality of these stressed plants from quantification of the changes to the quality of the leaves, yield, and photosynthetic performance, to how these components can be digested by the human body, using a novel artificial digestion system. We will also investigate how climate induced changes to plant nutritional quality affect our cells using an animal free, cell culture model. We will develop a system to model climate change-derived stress conditions for vegetable crops widely grown in the UK (e.g., spinach, rocket, kale), coupled with in vitro model of mammalian digestion, absorption, and metabolic function. Plants will be grown under combined eCO₂ and temperature stress conditions at levels predicted to occur in the UK in the next 20-30 years. Phytochemicals, macronutrients, micronutrients, along with the bioavailability and absorption rates of biomolecules of interest present will be analysed in the enzymatically digested crops, using intestinal cells in vitro, co-cultured with preadipocytes, adipocytes, and immune cells, to study the metabolic and physiological impact of the crops. Developing a system to model the physiological impact of crop composition in response to different environmental conditions will help to determine the best conditions and mitigations for optimising crop yields qualitatively and quantitatively.

The PhD student will join our flourishing School of Biological & Environmental Sciences, at Liverpool John Moores University and work under the supervisory team of Dr Rachael Symonds, Dr Fatima Perez De Heredia Benedicte and Dr Richard Webster (BES) and Dr Katie Lane and Fadel Abdulmannan (SES). The PhD research will involve a cross disciplinary approach to identifying the effects of climate change on our diet.

In addition to holding a masters or strong first degree in Biological or Nutritional Sciences or equivalent field, the ideal applicant will be able to demonstrate significant interest in and prior experience of biology, plant sciences, human physiology /nutrition. A good working knowledge of statistical analysis, strong organisational skills and the ability to work both independently and collaboratively with a team would be advantageous. Full training in plant growth analysis, enzymatic digestion, cell culture techniques, advanced statistical analysis and appropriate research methodologies will be provided by the supervisory team and through our Doctoral Academy.