Published 14 December 2017
In our present-day food system, our priorities for food have shifted away from taste, quality and nutrition, and we now prioritise the production of large quantities at a faster rate in the pursuit of profit.
The prioritisation of quantity and profit over quality fails to acknowledge that the nutritional value of produce is declining and a significant proportion of this decline can be attributed to rising atmospheric carbon dioxide (CO2) levels (Conroy, 1992). The concentration of carbon in our atmosphere is increasing and altering the composition of food, for the worse.
Despite scientific evidence highlight the effects of CO2 on nutrition in produce, it has been argued that more carbon does not translate to better produce under the claim that higher concentrations of CO2 promote plant growth. While there are correlations in some plants that elevated CO2 can accelerate photosynthesis making them grow faster and bigger in quantity, this enables the plants to synthesise more carbohydrates at the expense of other beneficial nutrients, which in turn affects plant quality (Leakey, et al., 2009).
An interesting study investigating the effect of rising CO2 levels on nutrients found an 8% decrease in calcium, magnesium, potassium, zinc and iron content within 130 plant varieties. Similarly, a 2014 Harvard study found that increased CO2 reduced protein, zinc and iron content in rice, wheat, potatoes and barley, while carbohydrates (starch, sugar and/or fibre) increased by 95%! With over two billion people relying on these crops for their zinc and iron requirements, the rise of nutrient deficiencies in plants is a growing global health problem that needs to be addressed if we are to meet the nutritional needs of our expanding global population.
Often overlooked is the strong correlation between flavour concentration and water content in farmed crops (Jarrell & Beverly, 1981). Cultivar selection for yield has resulted in a “dilution effect”, enhancing carbohydrate and water fractions without a proportional increase in mineral content (Jarrell & Beverly, 1981). Simply put, the larger the produce, bigger the cell size, greater the water content and more dilution of flavones. The more a tomato weighs for instance, the lower its concentration of lycopene, vitamin C and beta-carotene (Zuo & Zhang, 2010). Unfortunately, taste becomes a trade-off. Thus, bigger is smaller in taste terms. Furthermore, the return of heritage varieties to farmer’s markets can be attributed to their higher pulp concentrations and flavourful taste profiles.
The chief culprit in this disconcerting nutritional trend, however, is soil depletion. Using yield potential as the dominant criterion, intensive cropping methods and selective breeding have engineered plants to grow faster and larger with little regard for nutrient value or taste (Ahmad & Mukhtar, 2017). Big transnational agrochemical corporations thrive (figuratively and literally) on this idea. Take the humble broccoli plant for instance. According to USDA data, in 1950 broccoli had 130 mg of calcium, while today that number has plummeted to a meagre 48 mg (Davis, et al., 2004). Why has this happened? Unwittingly, we have stripped phytonutrients from our diet with the very things that speed growth. Selective breeding and synthetic fertilisers hamper plant’s ability to absorb and synthesise nutrients from the soil. We may be able to produce more with less, but the trade-off is a hit to nutritional quality. In fact, produce is now anywhere from 5 to 40% lower in minerals than 50 years ago (Davis, et al., 2004; Mayer, 1997). Sadly, each successive fast-growing, pest-resistant generation is less nutritious than the previous. Another study concluded that we would need to eat eight oranges today for the same amount of Vitamin A as our grandparents would have received from one! We are literally breeding the nutrition out of our food.
The growing need to address climate disruption and feeding humanity are interrelated. With a burgeoning global population, many argue that intensive farming is the solution to feeding everyone. However, studies show that lack of proper distribution, not a lack of food, is contributing to world hunger. Thus, we need to start taking notice of the problems within our current food system. A recent study revealed that Australians wastes nearly 20% of the food they purchase. We are biting off more than we can chew, so to speak.
Overcoming these challenges requires integration of knowledge, and revision of our health directive, as well as advances in soil management practices and crop breeding. The science is clear, as the produce we eat gets larger, its beneficial nutrients significantly diminish, and so does taste. Logically, if the nutritional quality of staple crops can be improved by integrated soil and crop management approaches, these practices would benefit human nutrition. It’s time to reassess our priorities and strive for nutritional quality and taste over quantity!
Leakey, A., Ainsworth, E., Bernacchi, C., Rogers, A., Long, S. and Ort, D. (2009). Elevated CO2 effects on plant carbon, nitrogen, and water relations: six important lessons from FACE. Journal of Experimental Botany, 60(10), 2859-2876.
Jarrell, W. and Beverly, R. (1981). The Dilution Effect in Plant Nutrition Studies, Advances in Agronomy, 34 (1),197-224.
Zuo, Y. and Zhang, F. (2010). Soil and crop management strategies to prevent iron deficiency in crops. Plant and Soil, 339(2), 83-95.
Ahmad, N. and Mukhtar, Z. (2017). Genetic manipulations in crops: challenges and opportunities. Genomics, 3 (1), 102-107.
Davis, D., Epp, M. and Riordan, H. (2004). Changes in USDA Food Composition Data for 43Garden Crops, 1950 to 1999. Journal of the American College of Nutrition, 23(6), 669-682.
Mayer, A. (1997). Historical changes in the mineral content of fruits and vegetables. British Food Journal, 99(6), 207-211.
Conroy, P. (1992). Influence of Elevated Atmospheric CO2 Concentrations on Plant Nutrition. Australian Journal of Botany, 40(5), 445-456.
Nicola Fernandes is a Master of Sustainability Candidate at The University of Sydney. Nicola is a connector of dots and people – a creative thinker with a passion for all things sustainability. With a background in nutrition, her interests dabble in the spheres of food, public health and environmental science. She firmly believes sustainability should be addressed from the bottom up, top down, from left to right, and right to left. She strives to be a more conscious, curious and educated consumer.