The latest research in the United States once again proves that the nutrition of modern fruits and vegetables is diluted

People always complain that vegetables are not as good as they used to be Can anyone think that the nutrition of vegetables is also decreasing now? Recently, studies have shown that with the growing size of fruits and vegetables, the nutrients in them are gradually decreasing Donald Davis, Professor of the College of Biochemistry, Texas State University, led the research team to study the nutritional data of 43 kinds of vegetables and fruits recorded by the U.S Department of agriculture from 1950 to 1999 It was found that the contents of protein, calcium, phosphorus, iron, vitamin B2 and vitamin C in these vegetables and fruits were reduced by 5% to 40% on average, and other trace elements, including magnesium, were reduced The contents of zinc, vitamin B6 and so on also decreased in different degrees For example, the average protein content of vegetables and fruits produced in 1999 was 6% lower than that of the same kind in 1950, and the riboflavin was 38% lower Among them, celery, green pepper and tomato were the most protein reduced, while the vitamin C in Eggplant and tomato was not the same as 50 years ago Similarly, the study of 12 kinds of fresh vegetables from 1975 to 1997 conducted by the justaff Institute in the United States showed that their average calcium content decreased by 27%, iron by 37%, vitamin A by 21%, and vitamin C by 30% A British study of the nutrition data of 20 kinds of fruits and vegetables from 1930 to 1980 showed that the calcium content of these fruits and vegetables decreased by an average of 19%, iron by 22%, and potassium by 14% Fan Zhihong, associate professor of the school of food, China Agricultural University, told the life times that the content of vitamin C and antioxidant substances in vegetables and fruits with low degree of artificial cultivation was several times or even dozens of times higher than that in cultivated vegetables Generally, the content of antioxidants in fruits and vegetables with long cultivation time and high yield will decrease In the 2010 version of China's food composition table, the nutritional data of many kinds of fruits and vegetables are lower than the data measured in the 1990s What is the reason for the decreasing nutrition of fruits and vegetables? Professor Davis said that the reduction of modern fruit and vegetable nutrition is actually "nutrient dilution" He called the external factors "environmental dilution effect", including the deterioration of soil nutrition, improper irrigation and excessive application of chemical fertilizers and pesticides; the internal factors "gene dilution effect", including the shortening of the growth cycle of fruits and vegetables and the weakening of their disease resistance Most of the new agricultural technologies focus on increasing the unit yield of crops, shortening the growth cycle and strengthening the disease and insect resistance, but pay little attention to nutrition More and more people use chemical fertilizers and pesticides to help crops resist diseases, pests and bad weather, which also leads to crops do not need so many nutrients to resist external adverse factors, just like human beings use antibiotic drugs to reduce their disease resistance Fan Zhihong explained that variety change is the most important reason Breeding and extension in agricultural production are usually based on the criteria of sweeter, bigger, higher yield and more storage tolerance, without considering the nutritional value Because the varieties with high antioxidant content usually have some acid, astringency and bitterness, which consumers don't like, they will be eliminated first Secondly, the way of cultivation has changed Because of the change of production environment, the nutritive value of the fruits and vegetables planted in the greenhouse decreased Thirdly, different soil conditions lead to the decrease of nutrition of fruits and vegetables Finally, freshness and maturity are not as good as before Fruits and vegetables transported from afar are picked before they are mature, which not only leads to insufficient nutrition due to insufficient maturity, but also leads to decreased freshness and nutrient loss due to long-term transportation So, in the face of the overall decline of fruit and vegetable nutrition, how should consumers deal with it? "Quality is not enough, quantity is enough," Fan said The most effective way is that we should try to eat more fresh fruits and vegetables than before, so as to make up for the reduction of nutrients Secondly, we should choose more nutritious fruits and vegetables "Even if the fruits and vegetables in the past were high in nutrition and the nutrition in the present is low, the nutrition in the cucumber in the past will certainly not catch up with the amaranth in the present." So try to eat more vegetables with high nutrient content, such as dark vegetables, fan said Finally, don't just pursue fresh and sweet fruits and vegetables Many healthy antioxidants taste sour Learn to accept the natural sour taste of fruits and vegetables.