China has made substantial progress in improving nutrition. The diet quality was improved remarkably from 1982 to 2012 in China. The trends of energy intake was constantly going down in the survey rounds due to the fast pace of modernization and urbanization. The percentage of fat contributed to energy spiked, that of carbohydrates fell all the way, and that of protein stabilized within a small range. The macronutrient composition was going through poor to ideal and far away from ideal again. Though the composition was not satisfying at the beginning round of CNNS in1982 which featured full of carbohydrates and lack of fat, it turned to more ideal in the 1992 survey round. The macronutrient composition was within the national recommendations among most subpopulations around that period. But in the recent two surveys, the macronutrient composition had dropped out of the ideal ranges which led health condition to the other part of malnutrition, overnutrition, potentially contributing the prevalence of nutrition-related NCDs national wide. We considered different fat composition at the same level of energy intake could have diverse impacts in the development of obesity. It seemed a paradox in China that overweight and obesity were dramatically increasing since 1980s despite of energy intake constantly decreasing.[1, 11] Reduced physical activity could explain the uprising prevalence of obesity, but most developed countries, like America, Korea, also experienced both obesity prevalent and energy intake uprising.[12–15] Indeed, very less countries, like Japan, had the similar situation with ours that obesity rate went up along with energy intake decreasing. New studies suggested that the percentage of fat contributed to energy could be the cause of adiposity but not carbohydrates or protein. In fact, the proportion of fat in diet kept going up worldwide as well as the prevalence of obesity.[13, 16, 18, 19] The current findings were based on massive samples and from observation in a long term which might provide new thoughts to the causality of obesity.
The great achievements from social and economic shifts after 1979 had tremendous impact on the diet of Chinese population. It took no more than one decade for Chinese people from lack of various food to plenty of every food. There was a big leap in nutrition improvement and the diet patterns changed most in 1980s and 1990s. The macronutrient composition rapidly reached the ideal ranges at that time. The pace of the change in the macronutrient composition got slow down but it was off satisfying in recent years. The promoter of the diet has shifted. Economy and food supply were still continuing improved but it had yet added little credit on the diet improvement recently in China. Other things like nutrition policy retargeting or availabilities of nutrition education and knowledge might be the key to promote the current diet quality in China.
The disparities persistently existed in different subpopulations across China, but the gaps were narrowed in the recent years. The Chinese government has put huge efforts on poverty reduction, transportation system construction, and agricultural yield raising which all potentially increased equity of access to various food by people with different background. Especially in the most recent survey round, the percentages of fat and carbohydrates contributed to energy were getting closer between the two ends within subpopulations in the aspects of area, education level, and economic background. It was obvious that the subpopulations with better social profile (living in urban, well-educated, and wealthy economic background) were leading the diet trends and the rest followed in next one decade or two. Nevertheless, the macronutrient composition of those with better social profile had been going toward the overnutrition pattern since years around 2002 which was probably a major cause of nutrition-related NCDs prevailing in China.[3, 10, 21] If people with low social profile continues following the diet trend, there might be another surge of nutrition-related NCDs in China. Moreover, inequalities of health resources had existed for some time in China. It would deepen the social contradictions if those who suffered from diseases could not be able to access necessary health resources. More governmental interventions should be launched on the subpopulation with low social profile in order to slow down or even curb their following paces to overnutrition.
One promising trend was discovered in the well-educated subpopulation. In the survey round of 2012, the macronutrient composition distinctively retuned to the recommended ranges among these people. “Eat well” was linked to “live well” in Chinese culture but people always confused “eat well” with “eat whatever one wants”. Actually, “eat well” means “eat properly” in the modern nutritional theory and it leads to “live well”. It is convinced some risks of nutrition-related NCDs can be modified though education improvement. Well-educated people have more wills and abilities to acquire health information which might help them regulate dietary behaviors rather than follow the instinct appetite or preference. Health education would probably be a useful tool to help China get through the possible dilemma of further potential surge of NCDs in the subpopulations with low social profile.
This study has several limitations. First, 3-day 24-h dietary recalls were used to obtain food consumption information, the accuracy of dietary intake was mostly dependent on the participants’ recall and estimation. Second, for the individual income information varied in different survey rounds, the classification of GNP level was applied. It was based on each province’s GNP in the survey year which might not classify the each participant meticulously. Third, a recent study mentioned the quality or food sources of macronutrients might lead to different health outcomes . The diet quality in the current study was determined based on the macronutrient composition which might cause bias without taking food composition into consideration. Fourth, the inference of macronutrient composition and later health outcome in the discussion was only derived from reports on the national level in ecological way rather than the relationship among CNNS participants.