The Impact of Environmental Changes on Yields and Nutritional Quality of Fruit, Nuts & Seeds

Many scientific studies now demonstrate that the planet’s environment is changing rapidly, and that this poses a growing risk to human health. An indirect effect on human health will arise from the impact of environmental changes on the food supply. Changes such as agricultural land degradation, water shortages, rising temperatures and changing rainfall patterns can affect yields and nutrient levels of crops which are important for human health, such as fruit, nuts and seeds. Fruits are a particularly vital source of micronutrients, which are important in maintaining a balanced diet and preventing diseases of deficiency. Nuts and seeds provide an energy-dense and long shelf-life alternative to animal products as a source of protein and other nutrients. Consumption of fruit, nuts and seeds along with other nutritionally important food groups such as vegetables and legumes, is known to decrease the risk of noncommunicable diseases such as heart disease. Micronutrient deficiencies and non-communicable diseases are currently major public health concerns worldwide, and a climate-induced decrease in consumption of these food groups will likely result in a greater burden of disease.

Fruit, nuts and seeds, like many other crops, are sensitive to changes in environmental factors throughout the year. The number of hot days, changes in minimum and maximum daily temperatures, and reductions in winter chill, for example, can affect cultivation and fruit development.
 
Researchers from The London School of Hygiene and Tropical Medicine1 set out to further explore the effect of environmental changes on yields and nutritional quality of fruit, vegetables, legumes, nuts and seeds by reviewing and synthesising the currently available scientific evidence published on this topic, in order to provide an overview of what the combination of evidence is showing. A systematic search of published scientific literature found studies that had examined the effect of a change in one or more environmental stressors (namely water availability, carbon dioxide concentration, tropospheric ozone, water salinity, and ambient temperature) on yield or nutritional quality of crops contained within these food groups. Two separate reviews were conducted –one focusing on vegetables and legumes, and the other on fruit, nuts and seeds. Although technically classified as legumes, peanuts were included within the second review because they are commonly eaten as nuts. Where possible, the results of the different studies included in the reviews were synthesised to produce mean changes in yields and nutrient concentrations.
 
The review on fruit, nuts and seeds found that the yield of the fruit, nut and peanut groups studied decreased in response to reduced water availability and increased water salinity (Figure 1 & 2). An increase in ozone concentration also resulted in decreased fruit, peanut and linseed yields, and a reduction in ambient temperature decreased fruit and peanut yields, but no studies were performed on (other) nuts and seeds. Interestingly, increased carbon dioxide concentrations actually showed a positive effect on berries and peanut yields, but when combined with other environmental stressors such as increased ozone concentration or ambient temperature, this positive effect was lost. Although not many studies looked at the effect on nutritional quality, synthesising the evidence from the small number that looked at the impact of a combination of environmental stressors on fruit crops demonstrated a negative effect.

As all the studies included in the review were experiments, they represent the hypothetical situation of a certain level of environmental change, but with no new agricultural techniques in place that would help adapt to the new environmental circumstances, for example, drought or heat-resistant crop varieties. As there is a lot of ongoing research in the agricultural field, this is obviously not very realistic as it is likely that new techniques and technologies will be employed. However, these findings present a picture of what would happen if we do not succeed in attenuating current trends in environmental change, and reinforce the need for adaptation and mitigation strategies, which will depend on an integrated strategy effort across multiple sectors including agriculture, trade and public health.

 
In conclusion, this review suggests that in the absence of appropriate adaptation strategies, changes to the environment are likely to have a substantial negative effect on yields of fruit, nuts and seeds. This will have far-reaching implications not only for food security due to decreased availability but also for non-communicable disease risk and suboptimal intake of essential nutrients. With the implementation of successful adaptation strategies, and efforts to attenuate changes to the environment, it is hoped that our food systems will be able to deliver diverse and healthy foods for generations to come.

References
1. Alae-Carew C, Nicoleau S, Bird FA, Hawkins P, Tuomisto HL, Haines A, Dangour AD, Scheelbeek PFD. The impact of environmental changes on the yield and nutritional quality of fruits, nuts and seeds: a systematic review. Environ Res Lett. 2020 Feb;15(2):023002