The new study is not a new conclusion - one of the "Lancet articles" in the nutrition world.

recent days, a message from a circle of friends went crazy: "Eat more staples and die fast?" The Lancet's latest study hits doctors and dietitians in the face." In the same veer, "What's wrong with a firmly believed meal?" Lancet PURE Research Impact Dietary Guidelines! "Shock! Eat more staples and die early, low-fat diet is the killer? The latest findings in the Lancet's authoritative medical journal have caused a stir.news, many experts in China's nutrition sector have called out that such a "title", such a one-sided interpretation not only contrary to scientific thinking, but also may affect the diet of thousands of people and behavior, social consequences are very serious. Chairman of the Chinese Nutrition Society Yang Yuexin, Ding Gangqiang, Vice Chairman of Sun Changxuan, Cheng Yiyong, Kong Lingzhi, Li Wei, Lin Xu, Yu Kang, Fan Zhihong and other well-known scholars have expressed their views on different occasions. Cloud heartless, intellectuals and other scientific and technological micro-signals also expressed views. "China Nutrition Industry" interviewed experts and scholars in nutrition related research, listened to the voices from China, the United States, Australia, New Zealand. Let's hear from nutrition experts on this matter.. First, as a nutrition expert, what do you think of the conclusions of the PURE study?. Prof. Frank Hu:Professor of Nutrition Epidemiology, Director of the Department of Nutrition at Harvard University,
Fellow of the American College of Medicine First, the study was one of the mistakes of mixing all carbohydrates together.
PURE study found a positive correlation between high carbohydrate intake and overall mortality. Carbohydrate-rich foods include rice, corn, wheat, potatoes, a variety of beans, vegetables, fruits and sugars. Eating too many low-fiber, finely processed carbohydrates, such as white rice, white noodles, and added sugars, can be harmful to your health. However, healthy carbohydrates such as high-fiber whole grain foods, legumes, vegetables and fruits can reduce mortality. Current U.S. dietary guidelines emphasize the use of healthy carbohydrates instead of fine carbohydrates., the study found that high fat intake reduced mortality, and this conclusion is misleading. Dietary fatty acids are healthy and unhealthy. Healthy fatty acids include monounsaturated fatty acids and polyunsaturated fatty acids, mainly from vegetable oils, tree nuts, seeds, peanuts, and sea products. Unhealthy fatty acids include saturated fatty acids and trans fatty acids. Saturated fatty acids come mainly from red meat, processed meats, high-fat dairy products and tropical oils such as palm oil. The main source of trans fatty acids is partially hydrogenated vegetable oil, which is commonly used in processed and fast food and other foods. . One limitation of pure research is that it ignores the role of trans fatty acids. The study found a negative correlation between high saturated fatty acid intake and overall mortality. However, the nutrients compared to saturated fatty acids are fine carbohydrates. Many studies have found that saturated fat and fine carbohydrates also increase the risk of coronary heart disease. When compared with polyunsaturated fatty acids, saturated fatty acids significantly increased the risk of coronary heart disease.
, U.S. dietary guidelines recommend replacing saturated fatty acids with polyunsaturated fatty acids to avoid trans fatty acids.. Prof. Li Wei: Professor of Nutrition , Vice Dean of The Institute of Nutritional Health, Qingdao University, Editor-in-Chief of the Asia-Pacific Journal of Clinical NutritionThe advantage of this document is that the sample size is large, but the accuracy of the data from China needs further examination, of which the fat energy ratio is 17.7% of the total energy, carbohydrate accounts for 67%, this should not be the current Chinese groups of data, should be 30 years ago data. Second, the carbohydrate analysis in the study of the article did not indicate what kind of carbohydrate, for example, is added sugar, refined rice white noodles, whole grains, because different types of carbohydrate and health relationship is not the same, there will be completely different outcomes. Third, the health status of the group in the study was also questionable. In general, people with cardiovascular disease or risk factors for cardiovascular disease tend to have lower fat intake, and accordingly, these populations have higher carbohydrate intake, and this group of people themselves may have a high mortality rate, which is a significant shift from the results of the study. , the key issue in this document is the scientific nature of the conclusions. The authors put together data from the cohort study in 18 countries for statistical analysis, and the results of the cohort study should write that A is significantly positive or negatively related to B. The study concluded that the relationship between fat, carbohydrate and disease can only be related, not causal, and that the authors' conclusions are causation, which misleads the reader.
recommendations that research methods and indicators are key to results or conclusions?
. Prof. Ding Gangqiang:Nutrition Expert, Director of the Nutrition and Health Institute of the CDC, Vice President of the Chinese Nutrition SocietyAccording to the results of the "2010-2013 Monitoring of Nutrition and Health status of Chinese Residents" (survey method 3 days 24-hour dietary review), the proportion of energy provided by carbohydrates in urban and rural areas in China is 5 5.0%, of which 51.0% are urban, 59.1% are rural and 62.1% are poor rural areas, while the energy ratio of urban and rural residents in China is 32.9%, of which 36.1% are urban residents, 29.7% are rural residents and 27.3% are poor rural areas.the results of the 2002 survey on nutrition and health of Chinese residents (survey method 3 days, 24-hour dietary review), the proportion of energy provided by carbohydrates provided by urban and rural residents in China in 2002 was 58.6%, of which 51.9% were in urban areas and 61 in rural areas. .2%, 61.6% in four rural areas, 29.6% of the energy provided by urban and rural residents in China, of which 35.0% are urban residents, 27.5% are rural residents and 27.4% are in four rural areas.And in the PURE study, the survey method used the food frequency method, the baseline survey time in China was September 2005, the survey site is not nationally representative (see the appendix to the PURE article), PURE research china baseline survey data show that the Chinese groups in the study carbohydrate and fat energy ratio of 67.0% and 17.7%, respectively. Therefore, the results of this paper do not represent the true situation of dietary intake in China in 2002 and 2010-2013, even compared with poor areas, there are significant differences.PanAn: Professor of nutrition epidemiology at , Professor of Public Health, Tongji Medical College, Hua zhong University of Science and Technology, and expert in the Youth 1,000 People Program in a multi-center study of , the control of mixed factors is very important, otherwise it is easy to get false positive results. In pure research, China's research data are likely to be extremely wrong. The authors report that Chinese, protein and carbohydrates in these groups were 17.7 percent, 15.3 percent and 67.0 percent, respectively. . The energy supply of fat in the PURE study was nearly half that of the national nutrition survey data, and the reliability of the data was very questionable. According to the authors, "the PURE study used the same food frequency questionnaire from the 2002 National Nutrition Survey." It is understood that the national survey did not use this method, methods and data make people doubt the reliability of their research. second, the article notes that the Chinese sources of fat in this group are pork, eggs, sunflower seeds, whole milk and flour. As anyone with a little common sense knows, cooking oil is the Chinese food source for fat in this group, and even more than 40% of fat comes from cooking oil. We strongly hope that the PURE study will Chinese group dietary data and make the nutrition community aware of its data collection and analysis process. , another problem in this study is the control and strated analysis of mixed factors. In epidemiological studies, especially in this multi-centre study, due to the huge differences in socio-economic conditions, customs and cultures, eating habits, lifestyles, disease burdens and so on, statistical analysis is generally layered analysis, taking into account the situation in each country separately, if the heterogeneity is not large enough to combine the data. For example, if a country's population has a high carbohydrate intake and the country's mortality rate is high, it is easy to get the illusion that carbohydrate intake increases the risk of death by simply putting together data from many countries. Therefore, in multi-center studies, the control of confuse factors is very important, otherwise it is very easy to get false positive results.
(Frank Hu): That's . I don
think there are serious methodological problems with the design of pure research. The study included data from 18 countries, a third of which came from China. Although the sample size is large, the follow-up period is short (about 7 years). The study combined Data from China with data from India, Pakistan, Bangladesh, etc. Because of the large differences in economic development levels and eating habits in these countries, a simple combination of data can lead to ecological fallacies and mixed biases. For example, people in the low-fat and high-carbohydrate intake group may have higher mortality rates due to poverty and poor medical conditions. Authors should analyze data from each country individually to minimize the bias caused by the mixing factors in data analysis. , the reliability of dietary data from China is in doubt. In the study, total fat intake accounted for 17.7% of total energy and carbohydrate 67.0%. However, according to the 2015 Survey of Nutrition and Chronic Diseases in China, the average fat intake of Chinese now accounts for 32.9% of total energy and carbohydrates account for 55.4% of total energy. Therefore, the PURE study does not correctly reflect china's nutritional intake status quo. Compared with china's nutrient intake data for nearly 50 years, the dietary data provided in this paper are similar to China's nutritional intake in 1980 or earlier. Dietary data in this study are far from those in other Chinese studies, and the reasons for this are yet to be further clarified by the authors.
, how should we study and view the relationship between diet and disease? Does the new study influence the views of the scientific community? Do national dietary guidelines for public guidance need to be revised?
. Professor SALLY Poppitt: Professor of Nutrition and Head of the Department of Human Nutrition at the University of Auckland In New Zealand and Australia, the relationship between fat and carbohydrate intake and cardiovascular disease is a matter of great concern to the nutrition community. Many researchers believe more relevant research is needed to confirm this. Dietary guidelines for each country, including the Dietary Guidelines for Chinese Residents, should not be based on an epidemiological queue study (such as this PURE study). The PURE findings are surprising, but, more importantly, the data have some problems: 1. In the countries covered in this study, many of the dietary habits were based on high-carbohydrate diets; and 2. The composition of carbohydrates was not analyzed in the study. Are these carbohydrates refined carbohydrates or sugars? This affects the results. Of course, it's also important to note that this study is not a randomized controlled trial, and although it's a forward-looking cohort study, there are still some questions about the reliability of data collection methods and epidemiological dietary data. . 3. For patients with cardiovascular disease, the greater impact on the disease is the type and composition of fat and carbohydrates in the diet, rather than a single fat or single carbohydrate diet.
, carbohydrates include sugar, dietary fiber, etc. For cardiovascular disease, it is important to consume the quality of carbohydrates and fats rather than the total amount. Carbohydrate diets rich in dietary fiber and complex carbohydrates may have more benefits than animal saturated fat intake.
4. When analyzing the risk of cardiovascular disease, it should be considered in the same regard as weight or obesity. To control your weight, you should eat foods with lower energy densities, such as high dietary fiber, grains that contain a lot of complex carbohydrates, and a low sugar index, instead of fat. Some studies have suggested that reducing saturated fatty acid intake and replacing complex carbohydrates with monounsaturated fatty acids, polyunsaturated fatty acids, or high fiber are beneficial to cardiovascular health. There is also research evidence that plant proteins may replace saturated fat to improve metabolism. For the public, these views will also need to be kept aware in the future.
(Frank Hu): That's . Now
s nutritional epidemiology has changed from a single nutrient-based study to one that emphasizes healthy dietary patterns. The U.S. Dietary Guidelines recommend a variety of healthy dietary patterns, including Healthy Eating Plate, Mediterranean Diet, And Lower Blood Diet (DASH). These healthy dietary patterns emphasize increasing the intake of whole grains, fruits, vegetables, nuts, low- or skimmed milk, legumes and fish, reducing the intake of processed meats, red meats, sugary drinks and highly refined cereals, and properly controlling salt intake. Because healthy eating patterns promote plant-based food intake, on the one hand, it is conducive to the health of individuals, on the other hand, it can also contribute to the sustainable development of the environment.
Panan: . It is highly irrational to change your eating habits, even as the authors suggest, by changing the formulation of dietary guidelines around the world, based on the publication of an article in pure research alone. The increase in mortality among the population is mainly due to mortality from non-cardiovascular diseases. Non-cardiovascular diseases include cancer, respiratory diseases and some infectious diseases. Many of these diseases (except cancer) are caused by factors such as poverty, unsothy living habits and the environment, and lack of medical services, which are the problems faced by many developing countries in the PURE study, especially in rural areas. work.