A synergistic combination of micronutrients comprised of various vitamins and minerals is essential for survival and maintaining optimal health. Vitamins are organic substances produced by plants or animals, while minerals are inorganic elements present in the soil and water and are absorbed by plants. The main source of minerals for humans is through the plants we eat. However, a study published in 2004 in the Journal of the American College of Nutrition concluded that in the past fifty years there has been significant decline in the nutritional content of vegetables and fruits with regards to the amount of vitamins C and B2, protein, calcium, iron, and phosphorus. Based on their results, the authors estimated that there would likely have been similar declines in other nutrients as well, such as magnesium, zinc, and vitamins B6 and E. Aggressive farming practices, and the abundant use of chemical fertilizers, pesticides, and other harmful chemicals are the main reason for the nutritional decline. It is claimed that today one would have to eat eight oranges to derive the same amount of Vitamin A as our grandparents would have obtained from one.