What serious consequences can vitamin A deficiency lead to?
Vitamin A deficiency (VAD) is a chronic disease, ranging from dry eyes to blindness and even death. When I was young, my eyes blurred when I read at night. The old man said it was "corns", which meant that the chicken was going home and into the cage, and children could not read at this time. In fact, this is a manifestation of night blindness caused by vitamin deficiency. VAD is a global problem. According to the WHO survey, 78 countries in the world have been proved to have a public health problem of vitamin A deficiency. About a quarter of school-age children (65.438+27 billion) in the world have vitamin A deficiency, and more than 250,000 children are blind every year (65.438+0). The results of the investigation on the nutrition and health status of China residents in 2002 show that the deficiency of micronutrients such as vitamin A and iron is a common problem among urban and rural residents in China. The vitamin A deficiency rate of children aged 3- 12 is 9.3%, including 3.0% in urban areas and1.2% in rural areas. In poor areas such as Southwest China, the proportion is as high as 50%(2). This kind of malnutrition, also known as "hidden hunger", not only affects the health of people in poor areas, but also causes huge economic losses. According to the estimation of Professor Chen Chunming from China Center for Disease Control and Prevention, in 200 1 year, iron deficiency in children alone accounted for 2.9% of GDP. However, if measures are taken to reduce the anemia rate in China by 30%, the economic benefits brought by the improvement of labor productivity of adults and children will be 455.3 billion yuan (2). The economic losses caused by VAD are similar.
The solution to VAD
At present, there are several ways to solve micronutrient deficiency (including VAD) in the world: 1) Dietary diversity. If you eat rice, vegetables, fruits and meat every day, there is generally no VAD problem. 2) food fortification is added to the food that must be eaten. The successful cases of food addition in China are as follows: first, iodized salt almost completely eliminated the big neck disease in China; One is that iron fortified soy sauce has also made remarkable progress, but because soy sauce is not a necessity for everyone, there is still a long way to go to eliminate iron deficiency. 3) Pill supplements, such as a large number of various vitamin tablets sold in the market. Although these methods can partially solve some problems, they also have obvious limitations: 1) Most people who need to improve nutritional deficiency are poor, and they often have no effective means to obtain fortified food or ensure dietary diversity; 2) As we all know, the poor have many kinds of micronutrient deficiencies, not all of which can be prevented by fortified food; 3) As far as the content, stability and physical characteristics of nutrients are concerned, the strengthening technology of various foods has not been fully formed, and the knowledge about nutrient interaction is insufficient, which complicates the technology of adding nutrients to a certain food; 4) The cost of pill tonic is relatively high. Therefore, on the basis of these means, a more promising method-biological enhancement is put forward. The plan is to improve the content of trace elements in major food crops through breeding and biotechnology, so as to solve the nutritional deficiency problem of poor people who take these food crops as their staple food, that is, the lack of most poor people. This method will not increase the additional cost and does not depend on the distribution channel.
The Past Life of "Golden Rice"
Rice is the staple food of more than half of the people in the world, especially the poor. If the content of vitamin A in rice can be increased, the problem of vitamin A deficiency among poor people in the world will be solved. Based on this idea, Professor Ingo Potrykus of Zurich Institute of Technology bravely undertook the task of turning ordinary rice into rice rich in vitamin A at a meeting held in the Philippines in 1984. After eight years of hard work, he finally launched a concept product. In fact, ordinary rice itself can't synthesize vitamin A, so you can't get a variety with high vitamin A content through traditional hybridization. Professor Potrykus came up with a brilliant idea. Four genes of the production line for synthesizing vitamin A from bacteria and daffodils were introduced into rice, so that the content of vitamin A in rice was increased from zero to a few micrograms per gram, which was also the first generation of "golden rice". However, this content is far from meeting the human body's demand for vitamin A. Theoretically, if the content of vitamin A reaches 1.5μg/g, everyone can basically meet the human body's demand for vitamin A. According to this content, it is obviously impossible for everyone to eat several kilograms of rice every day.
After the first generation of products came out, some opponents ridiculed that it was just a pie to satisfy everyone's hunger. Later, researchers from Syngenta, a famous biotechnology company, took over the baton. They found genes with stronger efficacy from corn, reorganized the production line, and cultivated the second generation of "golden rice", which increased the content of vitamin A by dozens of times, so that everyone could meet the needs of the whole day as long as they didn't eat 2 liang of rice every day, and made this product practical at once.
Because of the company's participation, Greenpeace questioned that this was a big conspiracy by international companies for their ulterior commercial purposes. Once promoted, the company will seek huge commercial benefits. So Syngenta and other companies with relevant patents announced that they would give up all patents related to "golden rice" and provide them to farmers in developing countries free of charge. Let "golden rice" truly become a humanitarian project. And formulated relevant regulations, including: all developing countries, including China, can use this technology for free; This technology can also be used for other major food crops free of charge; Companies selling this crop can't raise the price because of using this technology; Farmers can also cultivate their own seeds for the next generation.
Greenpeace's objection is:
Why does Greenpeace oppose golden rice? My simple understanding is that this is their job, and their important job is to oppose genetic modification. Not long ago, I heard a famous scientist say that Greenpeace does not intend to oppose "golden rice" because they also know that this is a humanitarian project, and the result of opposition is to make the poor who need help most and have no voice endure more disasters. I had a slight affection for Greenpeace at that time, but their recent hype brought my opinion back to the original point. Generally speaking, most people who speak out against it here will not be vitamin A deficiency patients. For them, "golden rice" is dispensable, because all the supplementary ways mentioned above can be easily obtained.
What does Greenpeace object to? The first thing that attracts people's attention is that this is a "human experiment", and it is also a human experiment of children in China. The fact is: this test is not a safety test at all (the safety test of golden rice has long been completed), but a test of the transformation effect of vitamin A in the human body. In fact, what I said above about vitamin A is not accurate. Strictly speaking, it should be the source of vitamin A. This biotechnologically modified rice can not directly produce vitamin A, but β-carotene, which can be converted into vitamin A in human body. This experiment conducted jointly by China and the United States gives the perfect answer (3). Children who eat 2-3 grains of rice (about one or two grains of dry rice) can meet 60% of their daily vitamin A requirements, which is the same as taking vitamin A tablets. The author also made it clear in the article that the experiment was approved by the China-US Ethics Committee. So it's not a secret experiment at all.
Others questioned why this experiment should not be done on American children, but on China children and mountain children. The answer is that the American experiment has already been done. Not the "safety experiment" mentioned above. There is no safety problem at all, just a "transformation effect" experiment, that is, how effective it is after eating it. Nearly half of the children in China, especially those in poor areas, have vitamin A deficiency, and they are the people who need the most care, while this problem basically does not exist in the United States. More experiments will be carried out in other poor areas in Asia and Africa.
Can "golden rice" solve the problem of global vitamin A deficiency? Greenpeace also questioned that the popularization of "golden rice" would aggravate the world food security crisis. They think that diversification of diet is a good solution to this problem, and I agree that diversification of diet is a good solution, but the fact is, how many organizations or individuals are making sincere efforts to make poor people all over the world have all kinds of vegetables and meat besides food? Golden rice is not everything, but we need to be familiar with and respect the fact that more than 3 billion people in the world live on rice, and many of them have little food to eat every day except rice. Poverty is the root cause of vitamin A deficiency, and the elimination of poverty requires the joint efforts of governments all over the world. Golden rice can not replace the current efforts to solve these problems, but there is no doubt that it can be used as a powerful auxiliary means to promote the process of solving nutritional problems, especially in remote rural areas.
Twenty-eight years have passed since the concept of golden rice was put forward, from the research and development of the first generation of products to the perfection of products, and then to the difficult promotion process today, and countless scientists and enthusiasts have paid their lives for it. Such a great product should have entered the market long ago to save countless poor people suffering from illness. However, due to some organizations and individuals, or because of their special purposes and interests, or because of lack of corresponding knowledge, or because of "kindness", the promotion and application of this product have been hindered. Most of these opponents are not vitamin A deficiency patients. For them, "golden rice" is dispensable, but what about the poor? Someone once summed up the triple obstacles to the promotion of golden rice, namely, technology, patents and competitors. Now technology and patents are not a problem, only one opponent is left. As Professor Ingo Potrykus, one of the inventors of golden rice, said, "We need to discuss the problem of golden rice more rationally, not emotionally."