Concerns over rising carbon dioxide levels around the world are not unwarranted as a new study reveals that vital nutrients in crops, that form an integral part of our diet, have decreased significantly.

According to the study conducted by the Harvard University School of Public Health, iron and zinc levels in key produce like soybean, wheat, rice and pea reduced were considerably low when they were grown under conditions of elevated CO2 that is expected by 2050. The research was published on Wednesday, May 7, in the journal Nature.

Using the Free Air Concentration Enrichment (FACE) system, the researchers grew soybeans, wheat, rice and pea along with sorghum and corn in seven different fields in three different countries - Australia, U.S. and Japan. The advantage of using FACE is that it enables scientists to grow crops in open fields instead of a contained environment like a laboratory or greenhouse, as well as simulate required conditions.

The scientists cultivated the crops by deploying an atmosphere that contained 550 parts of CO2 per million, which is forecasted as the level of CO2 in Earth's atmosphere in the next 36 years.

"Across a diverse set of environments in a number of countries, we see this decrease in crop quality," reveals Andrew Leakey, a professor of plant biology at the University of Illinois and co-author of the study, to CBC News

Close to 2 billion of the world's population receives 70 percent or more of their iron and zinc intake from the above-mentioned crops. The experiments conducted by the scientists reveal that the levels of iron, zinc and protein are likely reduced by nearly 10 percent in both wheat and rice, which is quite alarming as the crops form an inimical part of diets. A deficiency in the necessary nutrients can be detrimental for the human body and has severe repercussions, including heart ailments and hypertension.

"Zinc deficiency can cause child mortality from infectious diseases because the immune system is not functioning properly, and iron deficiency can cause maternal mortality and reductions in IQ and work productivity, and increased mortality from infectious diseases," says Samuel Myers, the study's first author and a researcher at the Harvard School of Public Health in Boston.

While the study found "significant reductions" in iron and zinc levels in rice, wheat, peas and soybeans, the elevated level of CO2 did not really affect the nutrients in sorghum and corn.