Literature search results and study characteristics
A total of 10,685 papers were searched from three databases after removing duplicates. Studies identified were screened based on titles and abstracts, and finally full texts of 375 papers including the 54 papers which were identified from the reference lists were assessed according to the inclusion and exclusion criteria. Ultimately, 47 papers were included in the present study. Full details of the search are outlined in Fig. 1.
![figure 1](https://i0.wp.com/media.springernature.com/lw685/springer-static/image/art%3A10.1186%2Fs40795-023-00781-2/MediaObjects/40795_2023_781_Fig1_HTML.png?resize=685%2C412&ssl=1)
Full characteristics of the papers and CASP scores from quality assessment are shown in Table 1. Within the included papers, 24 papers reported findings on total dairy consumption. 16 papers investigated milk only. The remaining 7 papers investigated sub-groups of dairy products. Dairy intake data from 21 papers were draw from several national surveys conducted in China [46, 47, 54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72]. Within papers that reported the number of participants, sample sizes ranged from 117 to over 90,000. With respect to reported dietary intake assessment methodology, 24-hour dietary recalls [46, 47, 54,55,56,57,58,59,60,61,62,63,64,65, 67,68,69,70, 73,74,75,76], Food Frequency Questionnaires [71, 72, 77,78,79,80,81,82,83,84,85,86,87,88], Questionnaires or in-person interview [38, 45, 72, 89,90,91,92], and Internet-based dietary questionnaire for Chinese (IDQC) [93,94,95] were used in the data collection in reported studies to assess overall diet.
Dairy consumption in different age groups
Of the 47 studies included in the final review, 12 reported dairy consumption across different age groups [45,46,47, 55, 62,63,64,65, 69, 73, 79, 89] (Table 2). In three studies, dairy consumption in those aged or average age over 60 were compared with other age cohorts [45, 46, 73]. Four studies focused on older cohorts aged over 50, with one reporting the differences in dairy intakes in those aged 50–70 [79], one that compared individuals aged 60–79 and 80 over [62], and three that compared ages 60–69 and 70 over [55, 65, 69]. One didn’t compare intakes between age groups but reported and compare the median age at low, high and non-consumer groups [64]. The other remaining studies included dairy consumption of working-age adults (20–59 years) [47], (18–59 years) [63], while one study used just 3 age groups to cover all ages (< 30, 30–50 and > 50) [89].
Of the three studies that compared dairy consumption in population groups aged under and over 60 years, two of these studies showed that people aged over 60 years reported consuming higher amounts [45], while had lower frequency of milk intake [46], compared to other age groups. Ba et al. [73] found that older adults had higher intakes of milk than younger adults with daily intakes reported in older adults (≥ 60 years) of 163.4 g/d, which was significantly greater than intakes reported in those aged 18–44 years and 45–59 years, with reported milk intakes of 75.8 and 96.6 g/d, respectively.
Focusing on people aged over 50 years, dairy consumption was reported in four studies. Xu et al. [55] reported that the median dairy intakes in males aged 60–69 years who consumed dairy in 2009 was 200 g/d, while the number in males aged 70 years and over was only 162 g/d. Likewise, Zong et al. [79] found that, within the age group 50–70 years, participants with higher intakes of dairy products were more likely to be of a younger age. In addition, Liu et al. [69] and Wang et al. [65] both found that people aged 70 years and over had significantly higher dairy intakes than those aged 60–69 years (P < 0.001 and P < 0.05 separately), with average intakes in these two age groups of 39.57 and 28.49 g/d, respectively. Similarly, Huang et al. [62] compared differences in dairy consumption between the age groups 60–79 years and 80 years and over, reporting that people aged over 80 years consumed significantly more dairy. One of the largest studies, Tian et al. [47] assessed dietary intake in residents from 12 cities and provinces in 2004, 2006, 2009 and 2011, and analysed intakes across two age groups (20–39 years, 40–59 years). Within this study, those aged 40–59 years reported higher mean daily dairy intakes than those aged 20–39 years, with intakes of 14.2 ± 55.8 g/d and 13.0 ± 47.1 g/d in each age group, respectively. However, this difference was not significant (P > 0.05). Similarly, results from the survey of Bai et al. [89], conducted in Qingdao city in 2005, showed that the people aged over 50 years consumed more milk than other age groups. However, these differences were not statistically tested, and only reported descriptively. Additionally, Wang et al. [63] analysed the national dairy consumption data from 1989 to 2011, finding that dairy consumers aged 40–59 years had higher average dairy intakes than adults aged 18–39 years in most of the years except in 1989, 1997 and 2011. Although, this difference was not significant (P > 0.05).
Dairy consumption in different geographical location groups
Of the 13 studies reporting on dairy consumption across location-specific cohorts comparing people living in different cities or provinces, two papers focused on dairy consumption in individual cities [38, 45], and eleven papers reported on dairy consumption in different regions of China classified by urban, rural; North, South, costal, inland; East, West, central; the size of city or economic status of rural area [46, 47, 56, 63,64,65, 67, 68, 71, 72, 79]. Table 3 summarises the characteristics and key findings of these papers.
Nine of the 11 papers examined dairy consumption between urban and rural areas, and reported higher intakes of dairy products in urban populations compared to those living in rural areas [47, 56, 63,64,65, 67, 68, 72, 79]. For example, Tian et al. [47] examined milk intakes from 12 cities or provinces in 2004, 2006, 2009, 2011 in China, and reported a greater mean intake of 30.9 g/d in urban populations, compared to only 5.1 g/d in rural residents. Zhang et al. [68] reported lower mean daily dairy intakes in a rural area in 2002 of 11.4 g/d, compared to 65.8 g/d in urban residents in the same study.
Wang et al. examined differences in reported dairy intakes from urban and rural areas from 1989 to 2011 using data from CHNS. The authors reported that urban residents had a significantly higher consumption than people living in rural areas across these years (P < 0.0001) [63]. Most recently, He et al. reported a significant difference in high milk consumption in urban and rural areas among 31 provinces in China, with a high percentage of consumers (74.17%) are living in urban areas. The high milk consumption in this study was classified as ≥ 200 ml/day and ≥ 5 day/week [72]. In addition, one paper analyzed dietary intake data from national survey CHNS in 1991, 2000 and 2015, reporting a significant difference of mean daily intake between urban and rural residents with 40.4 g in urban areas and 10.6 g in rural areas (P < 0.05) [65].
Of the papers that examining dairy consumption in other geographical location groups, Li et al. [67] compared milk intakes between coastal and inland areas, reporting that people living in coastal areas had higher milk intakes than those living in inland, reporting mean intakes of 32.65 and 25.62 g/d, respectively. Research also found that those living in Northern China reported higher milk intakes than those living in Southern China in three separate studies [38, 67, 79]. For example, Li et al. [67] found that, at a national level in 2002, those in northern regions consumed more milk than people living in southern regions, with reported intakes of 33.38 g/d and 22.24 g/d, respectively. A difference in dairy consumption was also found among people living in Eastern, Central and Western areas, where it was reported that people living in Eastern cities had significant higher intakes than people living in the other two areas [64, 71]. Furthermore, only one study compared milk consumption according to the size of the city and type of rural area, demonstrating that people living in big cities consumed much more milk than those living in smaller sized cities and normal rural areas, with 64.3 g/d in big cities, 24.2 and 9.1 g/d in other areas respectively [46].
Dairy consumption in different sex groups
Table 4 summarises the results from 16 papers that considered differences in dairy consumption across reported sex groups (male and female). All but four of these papers reported higher dairy consumption in females than males [47, 54, 55, 60, 61, 63,64,65, 69, 72, 78, 79, 84, 86, 92, 95]. Within those papers, eleven studies analysed data at the national level. Specifically, 8 papers analysed data from the national survey CHNS, while focusing on the different age groups and/or different collection years [47, 54, 55, 60, 61, 63,64,65]. One used data from the CNHS study in 2010–2012 [69]. One study analyzed the data from CNSSPP [72]. In addition, one study conducted across different regions in China [92]. The other five studies were conducted in individual cities (Beijing, Shanghai or Guangzhou) [78, 79, 86], Tibet [84] or regional locations (northern China) [95].
At the national level, papers that studied the survey data in different years from 1989 to 2011 reported higher dairy intakes among females, with significant differences found by Wang et al. [63] and Tian et al. [47], whilst the difference between sexes was either not significant or not statistically tested in other papers [54, 60, 61, 64].
Mirroring the findings from these national studies, Zong et al. [79] examined dairy consumption in males and females aged 50–70 years in Beijing and Shanghai in 2005, and found that females in this age group consumed higher amounts of dairy than males, with only 25.8% of those who consumed more than one serving of dairy foods per day being male. Sun et al. [78] collected information on milk consumption in older Chinese (aged over 50 years) in Guangzhou across two time periods ((Phase 1 (2003–2004) and Phase 2 (2005–2006)), and reported a slight difference between males and females, with 27% females and 25% males consuming over 250 ml whole cow’s milk per week, however, the results were not statistically analysed, and thus are observational. Guo et al. [95] examined the proportion of sexes across quartiles of reported dairy consumption in people living in northern China, finding that females had higher dairy intakes than males, with 47.23% males in Q1 (mean intake 6.42 ml/d), compared to 35.02% males in Q4 (mean intake 227.89 ml/d).
Four of the 16 papers examining differences in reported dairy intake across sex groups found that, for those who consumed dairy products, males had higher dairy intake compared to females with only one study reported significant difference [55, 65, 84, 92]. Xu et al., who examined reported intakes using data from CHNS 2009 [55] reported that more males met the recommended intakes for dairy than females in older adults, with median intakes in males and females aged 60–69 years 200 g/d and 167 g/d respectively. However, the differences were not statistically tested, and only provided as descriptive figures. Another study, which collected data during the COVID-19 lockdown period from March to April 2020, which examined dietary behavior across China showed that males consumed milk more frequently (P < 0.001) and more dairy in general compared to females [92]. Finally, another study examining intakes in the Tibetan plateau, showed greater consumption of dairy foods in males compared to females, however the amount of intake was not reported and statistically tested [84].
Consumption of different types of dairy products
Differences in the consumption of the different types of dairy products were reported in six papers [38, 62, 90, 91, 95, 96] (Table 5). Two of the six studies reported the mean amount consumed or the range on intakes for milk, yogurt, milk powder and ice cream [38, 90]. One reported the percentage of consumers of each product among people aged 60 years and over with a focus on milk, yogurt, milk powder and other dairy products [62]. The other three focused on specific products, namely; milk, yogurt and milk powder [95], milk and yogurt [91] and only milk and butter [96].
All six papers showed that participants had highest intake of milk among these types of dairy products in China. Fuller et al. [38], examining intakes in Beijing, Shanghai and Guangzhou in 2001, reported that of the annual dairy products consumed, milk consumption was highest in these three cities, with yogurt consumption ranked second, followed by ice cream and milk powder. They also reported that younger, more educated participants consumed more yogurt, whilst elderly participants tended to consume more milk powder. Similarly, the other three studies also reported much higher milk consumption than other types of dairy products (yogurt, milk powder, butter) [91, 95, 96]. Silanikove et al. [96] reported remarkably lower annual intakes of butter than milk in 2011 with 0.1 kg/y of butter and 9.1 L/y of milk. More recently, Huang et al. [62] investigated the dairy consumption in 4921 participants aged 60 years and over, and reported the percentage of consumers of each type of dairy product, finding that milk and yogurt were the main dairy products consumed in this group. Yang et al. [91] who examined the dairy consumption among adults in China during the COVID-19 lockdown, reported that the median intakes of milk and yogurt were 71.5 ml/d and 17.8 ml/d separately.
Changes in dairy consumption over time
Seven papers report analysis of dairy consumption over time at a national level using data from CHNS [47, 56, 58, 63, 65], CNNHS [68] and NBS [66]. Of the five papers that analysed data from CHNS, one examined dairy intakes in adults aged 18–45 across 6 survey years (1989, 1991, 1993, 1997, 2000, 2004) [56], and one studied dairy intakes across four survey years (2004, 2006, 2009, 2011) among people aged 20–59 years [47]. Batis et al. [58] reported the percentage of consumers of animal-based milk during survey years 1991–2009. The other reported the dairy consumption data of adults aged 18–59 years, covering all of nine survey years (1989–2011) [63]. In addition, Wang et al. [65] examined dietary intake data in 1991, 2000 and 2015 among people aged ≥ 60 years in China. Data from these studies showed an increase in dairy intakes. For example, during the period 1989–2004, consumption of dairy products was reported to increase six-fold from 2 g/d to 12 g/d [56]. From 2004 to 2009, consumption of milk and its products then appeared to experience a decreasing trend, reaching its lowest consumption in 2009, of 25 g/d. However, from 2009 to 2011, reported intakes increased to 35 g/d, which was higher than that of the previous year [47]. Additionally, from 1991 to 2015, the average intake of dairy foods among elders had significant increase, with 8.0 g/d in 1991, 14.1 g/d in 2000 and 20.3 g/d in 2015 (P < 0.001) [65].Of the other two papers, Fu et al. [66] reported increasing consumption of dairy products from NBS for both urban and rural areas from 1990 to 2010, with reported dairy intakes from 0.64 kg/y to 3.55 kg/y in rural area, 4.60 kg/y to 18.10 kg/y in urban area, whereas the dairy intakes in urban residents experienced a significant decline from 22.54 to 18.10 kg/y from 2006 to 2010. The remaining paper using the data from CNNHS reported a similar increase in reported intakes of dairy products from 1982, to 1992 and 2002, reporting intakes of 8.1, 14.9, and 26.5 g/d separately [68]. It also further reported the specific changes in urban and rural areas. Compared to rural areas, urban residents reported a significantly greater increase in dairy consumption during this period, with 9.9 and 65.8 g/d reported in 1992 and 2002 in urban groups, compared to 7.3 and 11.4 g/d in rural groups. When considering differences within individual provinces, one paper reported changes in dietary intakes from 1982 to 2012 in the Hunan province, reporting that dairy intakes experienced a rapid increase from 1982 (5.9 g/d) to 2002 (95.5 g/d), but this then decreased to 16.6 g/d in 2012 [75].
In addition, researchers examined the changes of eating habits in elderly residents during COVID-19 lockdown in March 2020 in Wuhan city in China, finding that dairy consumption was reduced during this period [85]. Specifically, a 24.5% reduction was observed among males, and 45.3% among females. Considering age groups, dairy consumption reduced by 38.8% in 60–69 year old, 40.0% in 70–79 year old and 25% in those aged 80 and over.
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