Failure to study climate change impact on wild foods can show on global health indicators

Increasing levels of atmospheric carbon dioxide can affect the ability of plants to absorb minerals such as nitrogen, phosphorus and iron from the soil, researchers from Institute for Plant Science in Montpellier, France have concluded.

The conclusion after their analysis of available research, published in the journal Trends in Plant Science November 3, doesn’t surprise. 

Way back in 1997, a study published in the British Food Journal compared the nutritional values of 20 fruits and 20 vegetables grown between the 1930s and 1980s. It found that the levels of calcium, magnesium, copper and sodium went down in vegetables and the levels of magnesium, iron, copper and potassium decreased in fruits.

In a 2014 study published in Nature, researchers compared the nutrient levels in wheat grown in present-day conditions with those grown in an atmosphere with elevated CO2 levels, as expected by 2050.

They found that wheat grown in high CO2 levels had 9.3 per cent less zinc, 5.1 per cent less iron and 6.3 per cent less protein. Rice grown in such a condition had 5.2 per cent less iron, 3.3 per cent less zinc and 7.8 per cent less protein.

Declining nutritive values are seen in India too. In the report, Indian Food Composition Tables 2017, researchers at the National Institute of Nutrition measured the values of 151 nutrients in 528 food items collected from markets across six geographical regions.

Down To Earth compared the values with NIN’s previous estimation done in 1989 (Nutritive Value of Indian Foods) and decline was visible in almost everything. 

The researchers of the study published in Trends in Plant Science point out the need to understand the mechanisms. 

But there is a problem. The understanding of the impact of climate change on nutrition is based on  studies carried out on cultivated plants and foraged and wild plants are nowhere in the picture. 

According to the latest assessment by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services released in July 2022, one in every five persons rely on wild species for food and income and more than 10,000 wild species are harvested regularly for food. 

There is little data on the impact of climate change on these wild plants. In fact, while the 1989 NIN report included a category “less familiar foods”, this is missing in the 2017 report. This lack of data makes it difficult to figure out whether or not, nutrition is declining in wild food too. 

There are a few indicators though. Bathua (Chenopodium album) generally is not cultivated and grows as a weed. The plant is foraged out of farms and a comparison between the two reports shows that proteins went down from 3.7g to 2.50 g per 100 g while iron went down from 4.2 mg to 2.66 mg.

However, it is difficult to put this down as a trend, In phalsa fruit (Grewia asiatica), the level of proteins increased but the level of iron decreased. In wild yam, the level of protein increased while that of iron remained more or less the same. 

Considering the importance of these plants in diets, especially that of the poor, it is important that wild plants too are included in studies on the impact of climate change on nutritive value of food species.