Fruit and vegetable (F&V) consumption has long been shown to be associated with a decrease in all-cause mortality, incidence of CVD, stroke and certain types of cancer(Reference Key1–Reference Agudo, Cabrera and Amiano4). Although not universally accepted, increased F&V intake has also been suggested to be associated with a lower incidence of diabetes and obesity(Reference Bazzano, Li and Joshipura5, Reference Alinia, Hels and Tetens6).
According to the WHO panel on diet, nutrition and prevention recommendations, an intake of five or more servings of F&V per d (400 g or more with 80 g servings) is considered adequate consumption(7). This value has served as a criterion for adequate F&V intake in a number of studies(Reference Liu, Manson and Lee8). Despite the great impact of F&V consumption on public health, the pattern of F&V intake has not been evaluated by a nation-wide survey in the Iranian adult population. In the present study, we aimed to investigate the pattern of F&V consumption in the Iranian adult population.
Subjects and methods
Study population
The present study uses the data collected in the Third National Surveillance of Risk Factors of Non-communicable Diseases in Iran (SuRFNCD-2007). Details of the survey can be found elsewhere(9). In brief, a cluster sampling scheme was applied to randomly select a representative sample of the Iranian adult population across the country. Trained health care professionals conducted household interviews and physical examinations. All interviews were in Persian. The data were recorded in standardised questionnaires and were rechecked based on a predetermined schedule. The study was conducted according to the guidelines laid down in the Declaration of Helsinki and the study protocol was approved by the Iran Center for Disease Control Ethics Committee. Informed consent was obtained from all subjects before the interview and was witnessed and formally recorded by the interviewer.
Fruit and vegetable data
Participants were asked to answer the following four questions regarding their consumption of F&V:
(1) In a typical week, on how many days do you eat fruit?
(2) How many servings of fruit do you eat on one of those days?
(3) In a typical week, on how many days do you eat vegetables?
(4) How many servings of vegetables do you eat on one of those days?
A serving size was defined as 80 g of fruit or vegetables. In detail, one serving of vegetables was defined as one cup of raw green leafy vegetables, one-half cup if cooked or chopped or one-half cup of vegetable juice. Similarly, one medium-sized fruit (such as banana, apple, orange, etc.), one-half cup if cooked, chopped or canned, or one-half cup of fruit juice (any type) was defined as one serving of fruit. Tubers including potato, sweet potato and beet were not included. To guide the respondents through answering, cups with different serving sizes and show cards (containing pictures of various servings of F&V) were prepared beforehand and were shown while answering questions. Average daily serving size of fruit/vegetables was calculated according to the STEPS guidelines as follows(10): number of days fruit (or vegetables) being eaten in a typical week multiplied by number of servings eaten in a day divided by 7.
Statistical analysis
Complex sample survey analysis was performed using SPSS 17.0 for Windows (2008; Chicago, IL, USA). For extrapolation of the results to the Iranian adult population, data were weighted for age (10-year strata), sex and residence area (rural/urban) using Iran's 2006 national census estimates (according to the census estimates, there were 31 409 737 adults aged 25–64 years residing in Iran(11)). Based on the age, sex and residential area strata, clusters of the sampling protocol, and the determined weights, an analysis plan was established. Continuous variables were compared across sex, residential area and age groups using general linear models, and categorical variables were compared using design-based χ2 analysis. P values for linear trend were calculated when comparing across age groups. National estimates are expressed as means with their standard errors for continuous variables. In all analyses, a P value < 0·05 was considered statistically significant.
Results
A total of 4231 adults aged 25–64 years were enrolled in the present study. However, some data for fruit (n 193), vegetable (n 215) and F&V (n 121) consumption were not available. After excluding participants with missing data (n 529; complete response rate 87·5 %), patterns of F&V consumption were investigated in 3702 subjects. Characteristics of the survey's participants have been described elsewhere(Reference Esteghamati, Meysamie and Khalilzadeh12). Average age of the study participants was 43·5 years, of which 50 % were women and 68·4 % resided in urban areas. Table 1 summarises the patterns of F&V consumption. Iranian adults consumed fruit, on average, in 4·33 d/week, with younger age categories and urban dwellers consuming more often (P = 0·024 and < 0·001, respectively). No sex predilection was observed in this regard (P = 0·091). Iranian adults reported consuming on average 1·26 daily servings of fruit, with younger and urban dwellers consuming more (P < 0·001 for both). The number of fruit servings did not differ significantly between the two sexes (P = 0·415). About 31·6 % of the subjects responded that they eat fruit every day, for vegetable intake this estimate was 38·1 %.
(Mean values with their standard errors)
Iranian adults had vegetables on their daily diet on average 4·68 d/week. Women tended to eat vegetables more frequently compared with men (4·49 d/week for men and 4·87 d/week for women, P < 0·001). Although subjects in the 55–64 years age category consumed vegetables less frequently than the 45–54 years age group, there was an overall incremental trend in vegetable consumption across age categories (P for trend = 0·008). Frequency of vegetable consumption was not significantly different in urban v. rural areas (P = 0·917). The mean number of servings of vegetables eaten per d was 1·32 and did not differ significantly among age and urban/rural categories (P = 0·070 and 0·075, respectively). On average, women consumed more servings of vegetables per d compared with men (1·40 for women and 1·24 for men, P = 0·002).
Taken together, Iranian adults ate on average 2·58 servings of F&V daily. F&V consumption significantly decreased with increasing age (P = 0·004), albeit the 35–44 years age category did not follow this general trend. Women consumed more amounts of F&V (P = 0·040); no significant difference was observed between urban and rural residents (Table 2).
(Percentage of prevalence, 95 % confidence intervals, mean values with their standard errors)
* Rounded to the nearest million.
Based on the WHO definition on low F&V consumption, about 87·5 % (95 % CI 85·8, 89·1) of the subjects consumed less than five servings of F&V per d. Low fruit consumption tended to be higher in older age categories (P = 0·004). The prevalence of low fruit consumption was not significantly different among men and women or rural and urban dwellers (P = 0·274 and P = 0·741, respectively).
Discussion
The present study demonstrated that average daily F&V consumption was 2·58 servings (206 g) per d among the Iranian adult population. Recently, two regional observations in Iran have reported daily F&V intakes of 1·76 (mean age 64 years) and 5·6 (mean age 37·2 years)(Reference Mirmiran, Noori and Zavareh13, Reference Salehi, Eftekhar and Mohammad14). Since these studies are not conducted on a national scale, and the age categories of the studied populations are different from the present study, a direct comparison with the present results is not possible.
About 87·5 % of Iranian adults consumed less than the WHO-recommended daily intake (88·4 % of men and 86·6 % of women). In the Middle East region, Iran stands somewhere in the middle; with a lower consumption than Turkey (80·7 for men and 81·3 for women) and the United Arab Emirates (77·8 for men and 74·5 for women), and higher than its eastern neighbour Pakistan (99·2 for men and 99·3 for women)(Reference Hall, Moore and Harper15). Comparing with developed nations, Iran has a lower F&V consumption. For instance, reports from the USA indicate a low consumption rate of 77 % (1991) and 75·3 % (2003)(Reference Subar, Heimendinger and Patterson16, Reference Blanck, Gillespie and Kimmons17). Observed estimates for the UK (78 % for men and 74 % for women) and Spain (78 % for men and 75·1 % for women) are also in the same range(Reference Hall, Moore and Harper15, Reference Blake, Chaudhury and Deverill18). On the other hand, only 46 % of men and 47 % of women in France consume less than five units of F&V daily(Reference Estaquio, Druesne-Pecollo and Latino-Martel19). Due to different sampling methods applied in each of these studies, direct comparisons should be done with caution.
In the present study, we showed that there is a linear trend towards low F&V consumption in advanced age groups, an observation made by other research groups in both developed and developing countries(Reference Hall, Moore and Harper15, Reference Tamers, Agurs-Collins and Dodd20). A multi-site study (INDEPTH), conducted in largely rural areas of south and south-eastern Asia, using the WHO STEPwise approach, showed that the increase in age is linked to low F&V consumption, with the oldest group having the lowest intake(Reference Kanungsukkasem, Ng and Van Minh21). Some studies, however, have pointed to a reverse correlation between age and low F&V consumption(Reference Jaime and Monteiro22, Reference Jaime, Figueiredo and Moura23).
Similar to the present results, previous studies have also reported inconsistent results regarding sex differencecs in F&V consumption. For example, a nationally representative study in the USA reported that in four out of the six centres studied, there were little differences with respect to sex(Reference Thompson, Demark-Wahnefried and Taylor24). The results of the INDEPTH study indicated that the rate of low F&V consumption is higher in women(Reference Kanungsukkasem, Ng and Van Minh21), while some other reports have observed that the rates are higher in men(Reference Thompson, Demark-Wahnefried and Taylor24, Reference Roos, Johansson and Kasmel25). In the World Health Survey, among the fifty-two studied countries, only in fifteen countries were there sex differences in the pattern of F&V intake, of which in five countries, women were consuming less and in ten, consuming more(Reference Hall, Moore and Harper15). We should also note that according to the World Health Survey, in forty-one countries, F&V consumption did not differ between urban and rural areas; similar observations were replicated in the present study(Reference Hall, Moore and Harper15).
Potential limitations in the present study should be acknowledged. We used a questionnaire-based method for quantification of F&V consumption, relying solely on the respondents' memory. This could cause measurement error and skew the results towards over- or underestimation. Nevertheless, it should be noted that the questionnaire used in this survey was approved by the WHO and covered questions only about the past few days before the interview. Moreover, interviewers provided respondents with images and examples of F&V servings, adding to the accuracy of quantifying F&V intake.
In summary, the present study gives insight about the magnitude of low F&V consumption problem. Iranian's F&V intake is remarkably low, lower than some of the developing and most of the developed nations. Of every eight adults living in Iran, seven have inadequate F&V intake with respect to the WHO guidelines, and this is a pivotal – yet preventable – source of morbidity and mortality. Plans have to emerge to promote adequate F&V consumption; policy makers, public health personnel, mass media and the educational system are key players in this regard.
Acknowledgements
This study received no specific grant from any funding agency in the public, commercial or non-profit sectors. A. E. provided clinical expertise throughout the project. S. N. and A. N. performed the statistical analysis and drafted the manuscript. O. K. supervised the analysis and manuscript preparation. M. K. contributed to the literature review and helped with the revised manuscript. M. N. provided clinical expertise and also helped with the revised manuscript. All authors read and approved the final manuscript draft. The authors declare that they have no conflict of interest.
