Human Nutrition

As a precondition for growth, health and the production of nutritious food, plants require 14 essential mineral nutrients in sufficient quantities.

Fertilizer programs implemented in the past mainly focused on improving soil fertility and crop yields to increase farm incomes, with the main emphasis given to nitrogen (N), phosphorus (P), potassium (K) and sulfur (S) fertilizers (i.e. macronutrients found in plants at levels of about 2 to 50 g/kg of dry matter). Less attention has been paid to nutritional outcomes for human health, despite the important links between plant nutrition, health and dietary intakes of nutrients which recent studies have highlighted. In the United States, for example, a constant decline in ratios of K fertilizer and removals in crops has led to a decline in dietary K intake in the US population and a rise of hypokalemia, a human illness caused by low levels of potassium in the blood serum. in 2011, 3.5 and 1.1 billion people were at risk of calcium (Ca) and zinc (Zn) deficiency respectively, due to inadequate dietary supply, mostly in Africa and Asia.

A handful of micronutrient-poor crops dominate the global food and feed chains and have often decreased crop diversity or displaced traditional crops such as pulses Owing to often insufficient micronutrient (i.e. nutrients that concentrate in plants at a range of 0.1 to 100 μg/kg) fertilization, the steady growth of crop yields in recent decades has compounded the problem by depleting micronutrient concentrations in grains and soils, although, thus far the benefits of increased yields to supply food for a growing population appear to outweigh such nutrient dilution effects. However, in sub-Saharan Africa, for example, significant relationships can be found between soil nutrients and child mortality, stunting, wasting and underweight.

Micronutrient deficiencies affect an estimated 2 billion people in the world. Iron (Fe), zinc (Zn), selenium (Se) and iodine (I) deficiencies are well-documented problems, affecting both human and animal health, and also impacting agricultural productivity. Yields can be affected by deficiencies that impair the physiological processes related to seed formation, synthesis and the distribution of carbohydrates, biological nitrogen fixation and plant resistance to biotic and abiotic diseases. Zinc deficiency is common in up to 50% of wheat-cultivated soils worldwide and large areas of agricultural soils are also deficient in iron. Most of the earth’s surface is iodine deficient. Soil selenium concentrations are dominated by climate–soil interactions, and climate change is likely to further increase the risk of Se-deficiencies. Livestock health, productivity and product quality directly depend on a balanced supply of micronutrients from crops fed to animals and pastures used for grazing.

Food systems have become increasingly globalized and interdependent, and diets around the world can be expected to keep changing.

Nutrition-sensitive agriculture is a food-based approach to agricultural development that puts nutritionally rich foods, dietary diversity, and food fortification at the heart of overcoming malnutrition and micronutrient deficiencies. Making agriculture more nutritionsensitive requires a new way of thinking, planning, implementing, and partnering. Nutrition and health outcomes need to be systematically embedded in agricultural and other policies, including integration of education and extension programs targeting farmers and consumers. Promoting the diversification of production in the field, improved food processing, healthier diets, or other interventions along the supply chain requires good collaboration among the concerned sectors and actors.

Critical entry points where nutrition goals can be best incorporated into agri-food systems must be clearly identified. Nutrition-sensitive agricultural programs and policies will not be successful if the targeted nutrients are missing in soils and/or in the edible plant parts at desirable levels for animal and human nutrition. In Africa, for example, statistically significant relations can be found between soil nutrients and child mortality, stunting, wasting and underweight. Therefore, fertilizers – both mineral and organic fertilizers – play a key role in helping to sustainably diversify and intensify agricultural production and through that achieve better nutritional and health outcomes. At the same time, it is also vital that impurities in fertilizers do not adversely affect soil or food quality, with cadmium being the element requiring most careful management in mineral fertilizers.