Awareness and practice of dietary recommendations for cancer prevention among participants of the 2023 Korean National Cancer Prevention for Dietary Awareness and Practice Survey

doi:10.21203/rs.3.rs-4203091/v1

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Awareness and practice of dietary recommendations for cancer prevention among participants of the 2023 Korean National Cancer Prevention for Dietary Awareness and Practice Survey

https://doi.org/10.21203/rs.3.rs-4203091/v1

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Background

Most cancers are preventable, especially by improving dietary habits, which account for a large proportion of cancer causes. However, several factors influence a person’s dietary behaviors, and it can be challenging to implement healthy behaviors. Individuals with poor dietary behaviors should be encouraged to improve them and those making efforts should be encouraged to adopt more active steps to prevent cancer. Therefore, to identify the proportion of Korean adults who followed the recommended guidelines for dietary factors to prevent cancer risk and those with less practice, we surveyed Korean adults using an Internet-based questionnaire.

Methods

The 2023 Korean National Cancer Prevention for Dietary Awareness and Practice Survey was a cross-sectional online survey conducted during September 4–25, 2023, and included adults aged 20–69 years. The survey included questions on sociodemographic and lifestyle factors to assess the practice of five dietary recommendations: “consume sufficient amounts of fruits and vegetables,” “balance your diet with a wide range of healthy foods,” “limit your salt intake from all sources,” “avoid burnt or charred foods,” and “avoid alcohol consumption.”

Results

Among the 4,000 participants, 82.6% were aware that unbalanced diet is a risk factor for cancer. Being physically active and having nutritional education were associated with a higher odds ratio (OR) for always practicing the five dietary recommendations. Participants with a history of chronic disease had a lower OR for consuming a balanced diet (OR: 0.822) and limited salt intake (OR: 0.771). Compared with those who did not have a chronic disease, participants with hypertension, dyslipidemia, or type 2 diabetes had a lower OR of always limiting salt intake (0.654, 0.657, and 0.595, respectively). Participants with hypertension or dyslipidemia had ORs of 29% and 27% of always avoiding alcohol consumption, respectively. Those with dyslipidemia had ORs of 32% and 31% for always consuming a balanced diet and avoiding burnt or charred food, respectively.

Conclusions

Despite high awareness of dietary cancer prevention, individuals with chronic diseases, especially dyslipidemia, showed poor adherence to cancer-preventive dietary practices. Our findings highlight the need for targeted interventions to improve the dietary habits of this atrisk population.

practice

awareness

cancer prevention

dietary recommendation

Globally, 10 million deaths are attributed to cancer and 19.3 million new cases are diagnosed annually [1]. The burden of cancer was expected to increase by 47% by 2020, reaching 28.4 million cases by 2040, and may be exacerbated by an increase in risk factors [1]. According to the World Health Organization (WHO), 30–50% of cancers are preventable, especially by improving dietary habits, which account for a large proportion of cancer causes [2–4]. Therefore, the WHO, World Cancer Research Fund (WCRF), and American Institute for Cancer Research (AICR) have developed cancer prevention guidelines that recommend adopting a healthy diet to prevent cancer [5, 6].

South Korea has also established a recommendation for cancer prevention comprising 10 items agreed upon with the participation of many experts from the National Cancer Center and Ministry of Health and Welfare in 2009; the recommendation was revised in 2016 and has been maintained so far. Of these 10 items, the following 5 correspond to diet [7]: consume sufficient amounts of fruits and vegetables, balance your diet with a wide range of healthy foods, limit your salt intake from all sources, avoid burnt or charred foods, and avoid alcohol consumption.

These are major recommendations from the WHO, WCRF, and AICR [5, 8] and have been related to cancer prevention or the risk of cancer in many studies. Various nutritional components present in vegetables and fruits, such as antioxidants, phytochemicals, and fiber, play a role in cancer prevention by inhibiting the process through which normal cells develop into cancerous cells [9–11]. Consuming a balanced diet means that a variety of foods are needed to fully meet the nutritional requirements [5]. A balanced and healthy diet contributes to the proper supply of nutrients throughout the body [2, 12]. Salty foods can damage the gastric mucosa, creating an environment in which cancer cells can readily propagate [13–15]. When red meat or fish is grilled at high temperatures, powerful carcinogens are generated on their surfaces. Their consumption can increase the risk of stomach, colon, pancreatic, and breast cancers [16, 17]. Alcohol is classified as a Group 1 carcinogen by the International Agency for Research on Cancer and has been associated with an increased risk of various cancers, including breast, oral, pharyngeal, and laryngeal cancers [18, 19]. Therefore, the National Cancer Center recommends that the public not specialize in any one food but rather consume six food groups during each meal: grains, vegetables, legumes, fruits, dairy, and sugars—eat plenty of vegetables and fruits, reduce salty and fatty foods, and consume small portions [7].

These recommendations can play an important role not only in cancer prevention but also in the prevention and modification of chronic diseases such as obesity, hypertension, diabetes, and dyslipidemia, as they share these “dietary” risk factors [20, 21]. For those with chronic diseases, lifestyle modification is more important because they are at an increased risk of developing various cancers, including oral, esophageal, gastric, colorectal, gallbladder, liver, breast, and endometrial cancers [22–24]. Hence, governments are attempting to raise awareness by publishing prevention recommendations and promoting cancer prevention practices [25–28].

Several factors influence a person’s dietary behaviors, and it can be challenging to implement healthy behaviors because the food environment has changed dramatically in recent years, such as the proliferation of ultra-processed foods and the increased accessibility to fast food restaurants and convenience stores [29–32]. Especially since COVID-19, a significant increase has been observed in the consumption of high-sodium and ultra-processed foods [33–38]. Individuals with poor dietary behaviors should be encouraged to improve their behaviors and those making efforts should be encouraged to adopt more active steps to prevent cancer [39]. Therefore, this study aimed to explore the awareness and practice rates of dietary recommendations for cancer prevention among the general population in South Korea and identify those with particularly low practice rates.

Study participants and data collection

In this cross-sectional study, Korean adults aged 20–69 years were recruited to obtain nationwide information on the awareness and practice of dietary recommendations for cancer prevention. The survey was facilitated through online forms available during September 4–25, 2023. Participants were selected using proportional quota sampling with respect to age, sex, and population distribution of the provinces. Among 5,642 participants, 907 who were not eligible and 735 who did not complete the survey were excluded. Therefore, 4,000 participants (2,036 male and 1,964 female) were included in the final analysis. This study was approved by the Institutional Review Board of the National Cancer Center of Korea (Approval Number: NCC2023-0251), and all participants provided informed consent.

Questionnaires

Factors such as sex, age, region, educational level, marital status, monthly household income, physical activity, nutritional education, obesity, history of cancer or chronic disease, type of chronic disease, and awareness of dietary recommendations for cancer prevention were assessed using self-administered structured questionnaires. Participants were divided into three age groups: 20–39, 40–59, and 60–69 years. Region was categorized as metropolitan cities, small and mediumsized cities, and counties. Educational level was categorized as middle school or less, high school, or college or more. Marital status was categorized as married, single, or other (widow/divorced/separated). Monthly household income level was classified as < 3 (approximately 2,300 dollars), 3–5.99, and ≥ 6 million won. Physical activity was defined as 150 min/week of moderateto-vigorous-intensity activity and was categorized as active or inactive. We recorded responses on whether participants had received nutritional education as yes and no. Obesity was defined by body mass index (BMI) calculated as weight divided by height in meters squared (kg/m²) and categorized as follows: underweight (< 18.5), normal (18.5 ≤ BMI < 25.0), and obese (≥ 25) [40]. History of cancer (yes or no) and chronic disease (yes or no) and type of chronic disease (hypertension, dyslipidemia, or type 2 diabetes) were self-identified and selfreported. Awareness of dietary recommendations for cancer prevention was determined as the percentage of participants who responded “Yes” to the question “Have you ever heard that you can prevent cancer through diet?”

Practice ascertainment

The survey included information regarding the degree of practice of the five dietary recommendations for cancer prevention. During the survey, participants were asked to answer the following five questions: “Do you consume sufficient amounts of fruits and vegetables?”; “Do you balance your diet with a wide range of healthy foods?”; “Do you limit your salt intake from all sources?”; “Do you avoid burnt of charred foods?”; “Do you avoid alcohol consumption?” Participants were asked to indicate the number of times they practiced each recommendation, and five response options were available (do not practice, less practice, sometimes practice, always practice, and do not know). We defined practice of dietary recommendations using self-reported answers and divided participants into no-to-less, sometimes, and always practice groups. We grouped “do not practice” and “less practice” because the proportion of “do not practice” group participants was very low.

Statistical analysis

Descriptive statistics for potentially related categorical variables are presented as number and percentage and mean or standard deviation. The chi-square test was used to explore correlations between dietary recommendation practices and sociodemographic, lifestyle, and other potentially related factors. Multivariate logistic regression analysis was used to calculate whether sex, age, region, educational level, marital status, monthly household income level, physical activity, nutritional education, history of cancer or chronic disease, and obesity were associated with the practice of each dietary recommendation. The reference odds ratio (OR) is the no-to-less practice group, and ORs were adjusted for each aforementioned factor. A two-sided p value < 0.05 indicated statistical significance. Data were analyzed using SAS version 9.4 (SAS Institute, Cary, NC).

Participant characteristics

Sociodemographic characteristics are presented in Table 1. The mean age of the 4,000 participants (2,036 male and 1,964 female) was 45.4 ± 13.3 years (median, 46 years). Of the participants, 50.9% were male, 44.8% were aged 40–59 years, 49.5% lived in small and medium-sized cities, 78.3% had attended college or higher, and 56.8% were married. Most had a monthly household income level of 3–6 million won (45.7%), were physically inactive (86.5%), had no nutritional education (80.7%), and had a normal weight (46.1%); 6.3% and 34.0% had a history of cancer and chronic disease, respectively. The prevalence of a history of hypertension was 15.4%; dyslipidemia, 6.9%; and type 2 diabetes, 5.8%. Most participants (82.6%) were aware of the importance of diet in cancer prevention.

Table 1

Sociodemographic characteristics
Variable	Total (n = 4,000)
Sex
Male	2,036 (50.9)
Female	1,964 (49.1)
Age (years)	45.4 ± 13.3
20–39	1,392 (34.8)
40–59	1,792 (44.8)
60–69	816 (20.4)
Region
Metropolitan cities	1,749 (43.7)
Small and medium-sized cities	1,980 (49.5)
Counties	271 (6.8)
Educational level
Middle school or less	44 (1.1)
High school	823 (20.6)
College or more	3,133 (78.3)
Marital status
Married	2,270 (56.8)
Single	1,431 (35.8)
Widow/Divorced/Separated	299 (7.5)
Monthly household income (million Korean won)
< 3	976 (24.4)
3–6	1,827 (45.7)
≥ 6	1,197 (29.9)
Physical activity
Inactive	3,459 (86.5)
Active	541 (13.5)
Nutritional education
No	3,226 (80.7)
Yes	774 (19.4)
Obesity
Underweight	281 (7.0)
Normal	1,845 (46.1)
Overweight	869 (21.7)
Obese	1,005 (25.1)
History of cancer
No	3747 (93.7)
Yes	253 (6.3)
History of chronic disease
No	2,642 (66.1)
Yes	1,358 (34.0)
Type of chronic disease
Hypertension	616 (15.4)
Dyslipidemia	277 (6.9)
Type 2 diabetes	232 (5.8)
No	698 (17.5)
Yes	3,302 (82.6)
Data are presented as n (%) or mean ± standard deviation. Physical activity was defined as moderate-to-vigorous intensity activity for 150 min/week.

Practice of each dietary recommendation for cancer prevention

More than half of the participants always practiced the dietary recommendations “avoid burnt or charred foods” and “avoid alcohol consumption.” The “always practice” rate for the other three dietary recommendations was 30–40%; the “always practice” rate for “balance your diet with a wide range of healthy foods” was 31.9%, which was lower than the “sometimes practice” rate of 37.1% [Table 2].

Table 2

Practice rate of each dietary recommendation for cancer prevention
	Practice group
	No-to-less	Sometimes	Always	Do not know
Consume sufficient amounts of fruits and vegetables	1,046 (26.2)	1,458 (36.5)	1,470 (36.8)	26 (0.7)
Balance your diet with a wide range of healthy foods	1,205 (30.1)	1,485 (37.1)	1,275 (31.9)	35 (0.9)
Limit your salt intake from all sources	1,012 (25.3)	1,386 (34.7)	1,575 (39.4)	27 (0.7)
Avoid burnt or charred foods	686 (17.2)	1,013 (25.3)	2,267 (56.7)	34 (0.9)
Avoid alcohol consumption	950 (23.8)	938 (23.5)	2080 (52.0)	32 (0.8)
Data are presented as n (%).

Practice of “consume sufficient amounts of fruits and vegetables”

The frequencies of these practices are shown in Additional file 1. Participants who were older, married, physically active, had a normal weight, higher educational level, higher income level, nutritional education, and history of cancer practiced this recommendation more than their counterparts (all p < 0.05). The OR of practices for the five dietary recommendations is shown in Tables 3 and 4. After adjusting for sex, age, region, educational level, marital status, monthly household income level, physical activity, nutritional education, history of chronic disease and cancer, and obesity, compared with those who answered “no,” those who had nutritional education and a history of cancer had a higher “sometimes practice” rate for “consume sufficient amounts of fruits and vegetables” (OR: 1.383, 95% confidence interval [CI]: 1.096–1.747 and OR: 1.772, 95% CI: 1.194–2.629, respectively); this rate was higher than the “always practice” rate for this recommendation (OR: 2.465, 95% CI: 1.973–3.080 and OR: 2.269, 95% CI: 1.548–3.326, respectively). Participants with a BMI ≥ 25 kg/m² had a lower OR of “sometimes practice” (OR: 0.804, 95% CI: 0.656–0.984) and “always practice” rates (OR: 0.690, 95% CI: 0.560–0.850). Participants with a monthly household income level > 6 million won (OR: 1.348, 95% CI: 1.060–1.716) and who were physically active (OR: 2.264, 95% CI: 1.756–2.918) had a higher OR of the “sometimes practice” rate for “consume sufficient amounts of fruits and vegetables.” However, no significant differences were observed in practice rates between participants with a higher monthly household income level and who were either physically active or not.

Table 3

Odds ratio of “sometimes practice” for each dietary recommendation for cancer prevention according to covariates
	Consume sufficient amounts of fruits and vegetables	Balance your diet with a wide range of healthy foods	Limit your salt intake from all sources	Avoid burnt or charred foods	Avoid alcohol consumption
Sex
Male	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)
Female	1.176 (1.000–1.383)	0.929 (0.795–1.085)	1.216 (1.030–1.435)	1.103 (0.906–1.345)	1.134 (0.940–1.367)
Age (years)
20–39	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)
40–59	0.868 (0.613–1.228)	1.091 (0.781–1.523)	1.153 (0.810–1.641)	1.154 (0.759–1.755)	0.794 (0.535–1.179)
60–69	0.937 (0.529–1.662)	1.407 (0.812–2.435)	1.046 (0.581–1.882)	1.125 (0.560–2.260)	0.825 (0.431–1.578)
Region
Metropolitan cities	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)
Small and medium-sized cities	1.082 (0.915–1.278)	0.904 (0.770–1.061)	0.981 (0.827–1.165)	0.959 (0.782–1.177)	0.825 (0.683–0.997)
Counties	1.059 (0.759–1.478)	0.851 (0.616–1.174)	0.800 (0.570–1.123)	0.837 (0.570–1.228)	0.793 (0.538–1.168)
Educational level
Middle school or less	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)
High school	0.859 (0.388–1.901)	0.872 (0.373–2.040)	0.941 (0.403–2.199)	1.365 (0.527–3.539)	0.859 (0.313–2.360)
College or more	1.055 (0.480–2.316)	0.884 (0.381–2.055)	0.936 (0.404–2.167)	1.581 (0.615–4.061)	1.092 (0.401–2.968)
Marital status
Married	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)
Single	0.989 (0.792–1.235)	0.749 (0.605–0.927)	1.127 (0.899–1.413)	0.859 (0.656–1.124)	1.047 (0.811–1.352)
Widow/Divorced/Separated	0.764 (0.554–1.053)	0.624 (0.459–0.850)	1.105 (0.780–1.564)	1.008 (0.681–1.493)	1.006 (0.687–1.472)
Monthly household income (million Korean won)
< 3	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)
3–6	1.197 (0.972–1.473)	1.076 (0.881–1.315)	0.970 (0.781–1.204)	0.950 (0.739–1.221)	1.148 (0.898–1.467)
≥ 6	1.194 (0.941–1.516)	1.110 (0.884–1.394)	1.128 (0.881–1.443)	1.052 (0.787–1.405)	0.959 (0.729–1.261)
Physical activity
Inactive	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)
Active	1.182 (0.899–1.554)	1.351 (1.037–1.760)	1.631 (1.227–2.167)	0.969 (0.707–1.329)	1.089 (0.815–1.454)
Nutritional education
No	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)
Yes	1.383 (1.096–1.747)	1.475 (1.182–1.841)	1.139 (0.908–1.429)	1.401 (1.068–1.839)	1.226 (0.947–1.587)
History of cancer
No	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)
Yes	1.772 (1.194–2.629)	1.477 (1.027–2.124)	1.590 (1.050–2.408)	0.878 (0.555–1.389)	2.859 (1.753–4.664)
History of chronic disease
No	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)
Yes	0.950 (0.795–1.136)	0.877 (0.740–1.041)	0.788 (0.656–0.946)	1.058 (0.851–1.316)	0.661 (0.539–0.810)
Obesity
Underweight	1.054 (0.754–1.474)	1.03 (0.752–1.412)	1.045 (0.739–1.476)	1.18 (0.771–1.806)	1.047 (0.690–1.590)
Normal	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)
Overweight	0.753 (0.607–0.935)	0.972 (0.790–1.197)	1.012 (0.809–1.266)	0.998 (0.766–1.299)	1.141 (0.899–1.448)
Obese	0.804 (0.656–0.984)	0.752 (0.619–0.915)	0.688 (0.560–0.845)	1.020 (0.801–1.300)	0.874 (0.694–1.101)
Odds ratios represent the prevalence in the “sometimes practice” group. The reference group was the “no-to-less practice” group.
Odds ratios were adjusted for age, sex, region, educational level, marital status, monthly household income level, physical activity, nutritional education, history of chronic disease and cancer, and obesity.

Table 4

Odds ratio of “always practice” for each dietary recommendation for cancer prevention according to covariates
	Consume sufficient amounts of fruits and vegetables	Balance your diet with a wide range of healthy foods	Limit your salt intake from all sources	Avoid burnt or charred foods	Avoid alcohol consumption
Sex
Male	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)
Female	1.004 (0.852–1.183)	0.696 (0.590–0.821)	1.204 (1.021–1.419)	1.384 (1.161–1.650)	2.062 (1.756–2.421)
Age (years)
20–39	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)
40–59	0.797 (0.557–1.140)	0.760 (0.529–1.093)	1.042 (0.731–1.484)	0.895 (0.615–1.304)	0.803 (0.568–1.135)
60–69	1.228 (0.684–2.204)	1.405 (0.780–2.530)	1.135 (0.634–2.035)	1.458 (0.784–2.711)	1.125 (0.640–1.978)
Region
Metropolitan cities	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)
Small and medium-sized cities	0.995 (0.840–1.179)	0.837 (0.706–0.993)	0.881 (0.743–1.045)	0.975 (0.814–1.169)	0.925 (0.785–1.091)
Counties	0.986 (0.704–1.382)	0.915 (0.656–1.277)	0.797 (0.573–1.111)	0.722 (0.512–1.016)	0.973 (0.704–1.346)
Educational level
Middle school or less	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)
High school	0.982 (0.435–2.217)	0.500 (0.223–1.120)	1.042 (0.444–2.448)	1.291 (0.577–2.889)	0.843 (0.369–1.927)
College or more	1.010 (0.451–2.265)	0.458 (0.206–1.018)	1.186 (0.509–2.762)	1.547 (0.697–3.434)	0.902 (0.397–2.047)
Marital status
Married	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)
Single	1.047 (0.835–1.314)	0.871 (0.694–1.094)	0.996 (0.795–1.249)	0.993 (0.782–1.262)	1.306 (1.047–1.630)
Widow/Divorced/Separated	0.814 (0.591–1.121)	0.715 (0.520–0.983)	0.955 (0.678–1.345)	0.860 (0.605–1.222)	1.026 (0.743–1.415)
Monthly household income (million Korean won)
< 3	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)
3–6	1.178 (0.953–1.455)	1.205 (0.973–1.492)	0.823 (0.664–1.020)	1.061 (0.848–1.326)	1.014 (0.823–1.249)
≥ 6	1.348 (1.060–1.716)	1.237 (0.969–1.578)	0.904 (0.708–1.155)	1.159 (0.895–1.501)	0.821 (0.650–1.038)
Physical activity
Inactive	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)
Active	2.264 (1.756–2.918)	2.698 (2.098–3.470)	2.468 (1.884–3.232)	1.465 (1.117–1.922)	1.494 (1.17–1.907)
Nutritional education
No	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)
Yes	2.465 (1.973–3.08)	2.792 (2.245–3.471)	1.789 (1.442–2.221)	1.625 (1.274–2.073)	1.760 (1.415–2.188)
History of cancer
No	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)
Yes	2.269 (1.548–3.326)	2.167 (1.521–3.087)	2.474 (1.677–3.649)	1.403 (0.954–2.064)	3.546 (2.280–5.514)
History of chronic disease
No	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)
Yes	0.918 (0.766–1.100)	0.822 (0.686–0.986)	0.771 (0.643–0.924)	0.964 (0.794–1.171)	0.848 (0.714–1.008)
Obesity
Underweight	1.131 (0.807–1.586)	1.150 (0.825–1.604)	1.226 (0.873–1.721)	1.295 (0.889–1.888)	1.28 (0.907–1.806)
Normal	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)	1.000 (reference)
Overweight	0.847 (0.683–1.050)	0.920 (0.738–1.145)	1.060 (0.848–1.323)	1.049 (0.832–1.323)	0.889 (0.719–1.098)
Obese	0.690 (0.560–0.850)	0.678 (0.550–0.835)	0.714 (0.581–0.877)	0.848 (0.682–1.054)	0.848 (0.696–1.033)
Odds ratios represent the prevalence in the “always practice” group. The reference group was the “no-to-less practice” group.
Odds ratios were adjusted for age, sex, region, educational level, marital status, monthly household income level, physical activity, nutritional education, history of chronic disease and cancer, and obesity.

Practice of “balance your diet with a wide range of healthy foods”

Participants who were male, older, married, physically active, had a normal weight, higher income level, nutritional education, and history of cancer practiced this recommendation more than their counterparts (all p < 0.01) [see Additional file 2]. Participants who were physically active (OR: 1.351, 95% CI: 1.037–1.760 and OR: 2.698, 95% CI: 2.098–3.471), had nutritional education (OR: 1.475, 95% CI: 1.182–1.841 and OR: 2.792, 95% CI: 2.245–3.471), or had a history of cancer (OR: 1.477, 95% CI: 1.027–2.124 and OR: 2.167, 95% CI: 1.521–3.087) had higher “sometimes practice” and “always practice” rates. Participants who were single (OR: 0.749, 95% CI: 0.605–0.927 for “sometimes practice”) or widow/divorced/separated (OR: 0.624, 95% CI: 0.459–0.850 for “sometimes practice” and OR: 0.715, 95% CI: 0.520–0.983 for “always practice”), had a history of chronic disease (OR: 0.822, 95% CI: 0.686–0.986 for “always practice”), or were obese (OR: 0.752, 95% CI: 0.619–0.915 for “sometimes practice” and OR: 0.678, 95% CI: 0.550–0.835 for “always practice”) had lower practice rates after adjusting potential variables.

Practice of “limit your salt intake from all sources”

Participants who were older, not single, physically active, had nutritional education, a normal weight, and a history of cancer or chronic disease practiced this recommendation more than their counterparts (all p < 0.05) [see Additional file 3]. The “sometimes practice” rate was significantly higher among participants who were female (OR: 1.216, 95% CI: 1.030–1.435), physically active (OR: 1.631, 95% CI: 1.227–2.167), and had a history of cancer (OR: 1.590, 95% CI: 1.050–2.408). Participants who were physically active (OR: 2.468, 95% CI: 1.884–3.232) and had a history of cancer (OR: 2.474, 95% CI: 1.677–3.649) had higher “always practice” than “sometimes practice” rates (Tables 3 and 4). Participants who had nutritional education had a higher “always practice” rate than those who did not have it (OR: 1.789, 95% CI: 1.442–2.221).

Practice of “avoid burnt or charred foods”

Participants who were of the male sex, older, married, physically active, had a normal weight, higher educational level, higher income level, nutritional education, history of cancer or chronic disease practiced this recommendation more than their counterparts (all p < 0.05) [see Additional file 4]. Nutritional education was associated with a higher practice of this recommendation (OR: 1.401, 95% CI: 1.068–1.839 for “sometimes practice” and OR: 1.625, 95% CI: 1.274–2.073 for “always practice”; Tables 3 and 4). Female sex (OR: 1.384, 95% CI: 1.161–1.650) and being physically active (OR: 1.465, 95% CI: 1.117–1.922) were associated with the “always practice” rate for this recommendation.

Practice of “avoid alcohol consumption”

Participants who were female, older, not married, physically active, had a normal weight, higher educational level, lower monthly household income level, nutritional education, and history of cancer or chronic disease practiced this recommendation more than their counterparts (all p < 0.05) [see Additional file 5]. Compared with the “no-to-less practice” group, the “sometimes practice” group possibly had a history of cancer (OR: 2.859, 95% CI: 1.753–4.664). The “sometimes practice” group was inversely associated with a history of chronic disease (OR: 0.661, 95% CI: 0.539–0.810). Participants who were single (OR: 1.306, 95% CI: 1.047–1.630), physically active (OR: 1.494, 95% CI: 1.170–1.907), had nutritional education (OR: 1.760, 95% CI: 1.415–2.188), or a history of cancer (OR: 3.546, 95% CI: 2.280–5.514) had a higher “always practice” rate for this recommendation.

History of disease and practice of each dietary recommendation

For the recommendation “avoid alcohol consumption,” participants with a history of hypertension and dyslipidemia tended to practice it less compared with those with a history of type 2 diabetes. However, no differences were observed in other recommendations [see Additional files 1–5]. Figure 1 presents the ORs and 95% CI for practice of each dietary recommendation and for cancer prevention and history of hypertension, dyslipidemia, and type 2 diabetes. A history of hypertension in the “sometimes practice” than in the “no-to-less practice” group was associated with a lower OR for “balance your diet with a wide range of healthy foods” (OR: 0.776, 95% CI: 0.614–0.981), “limit your salt intake from all sources” (OR: 0.691, 95% CI: 0.539–0.885), and “avoid alcohol consumption” (OR: 0.598, 95% CI: 0.457–0.781). It was also associated in the “always practice” group with a lower OR for “limit your salt intake from all sources” (OR: 0.654, 95% CI: 0.513–0.834) and “avoid alcohol consumption” (OR: 0.711, 95% CI: 0.566–0.893). A lower practice frequency of the five dietary recommendations was observed in participants with a history of dyslipidemia. The OR (95% CI) in the “always practice” group was 0.697 (0.487–0.946) for “consume sufficient amounts of fruits and vegetables,” 0.603 (0.428–0.849) for “balance your diet with a wide range of healthy foods,” 0.657 (0.469–0.921) for “limit your salt intake from all sources,” 0.691 (0.493–0.969) for “avoid burnt or charred foods,” and 0.716 (0.525–0.975) for “avoid alcohol consumption.” However, no differences were observed in practices between participants with a history of type 2 diabetes and without any chronic disease except for the recommendation “limit your salt intake from all sources.” Participants with a history of type 2 diabetes had lower “sometimes practice” (OR: 0.651, 95% CI: 0.451–0.939) and “always practice” (OR: 0.595, 95% CI: 0.416–0.851) rates for “limit your salt intake from all sources” than those without a history of any chronic disease.

In this cross-sectional study of South Korean adults, we explored the awareness and practice rates of dietary recommendations for cancer prevention and identified participants with particularly low practice rates. Participants were highly aware (82.6%) of the importance of dietary factors for cancer prevention. However, only 31.9–56.7% always practiced each dietary recommendation. Being physically active and having nutritional education were associated with a higher practice rate of the five dietary recommendations. Participants with a history of cancer practiced more dietary recommendations. For some dietary recommendations, the practice rate was lower among participants with a history of chronic disease than among those without. Participants with a history of hypertension or dyslipidemia had a low OR for practicing two or more of the five dietary recommendations. No significant difference was observed between participants with a history of type 2 diabetes and those without a history of any chronic disease except for the recommendation “limit your salt intake from all sources.” Participants with a history of type 2 diabetes tended to less practice “limit your salt intake from all sources.”

Diet is a major risk factor for cancer, and many people are aware of the need for healthy dietary habits. However, for various reasons, few people implemented them. The study that analyzed the intensity of adherence (sometimes versus always) to the five cancer-prevention dietary recommendations of South Korea’s National Cancer Center found that those who practiced the dietary recommendations were more likely to be physically active, have nutritional education, and a history of cancer diagnosis. Individuals who engage in more physical activity are more likely to be health conscious—this supports the existing research that they are also more motivated to be diet conscious [41, 42]. Those with nutritional education are more likely to follow dietary recommendations than those without [43]. Individuals with a history of cancer are more likely to seek healthcare and follow dietary recommendations to reduce the risk of recurrence [44].

A concerning finding was that participants with obesity and chronic diseases were less likely than the general population to follow dietary recommendations for cancer prevention. In particular, they were less likely to consume a balanced diet and limit their salt intake. Even considering “sometimes” behaviors, they were less likely to consume a balanced diet, limit salt intake, and avoid alcohol consumption. Participants who were obese were less likely to practice all these behaviors. This is in contrast to those with a history of cancer, who had higher rates of both “sometimes practice” and “always practice” except for “avoid burnt or charred foods.”

Obesity and chronic diseases such as hypertension, diabetes, and dyslipidemia, which share “dietary” risk factors with cancer, are themselves major risk factors for cancer incidence. Obesity is associated with increased rates of endometrial, colon, gallbladder, prostate, and kidney cancers [45]. Patients with hypertension, diabetes, and dyslipidemia have a significantly higher risk of cancer than those without [22–24, 45–48]. Therefore, patients with these chronic diseases are a high-risk group for whom lifestyle changes, including healthy eating behaviors, are important. However, our results revealed that dietary behaviors were poor, suggesting interventions are needed.

Even if they are already obese and have chronic diseases, their poor dietary behavior may be owing to a lack of adequate nutritional education or awareness that obesity and chronic diseases are major risk factors for cancer. Although they may want to correct their behaviors, factors such as a dietary culture that favors salty and sugary foods, easy access to a wide variety of foods, and availability of ultra-processed foods cheaper than healthy vegetables and fruits make it difficult. Cancer and chronic diseases start long before symptoms appear, even if they do not appear until later. Therefore, people who have not been diagnosed with cancer but have chronic diseases need to make substantial effort to improve their dietary behaviors not only for cancer prevention but also for chronic disease control, and the government needs to support them.

A combination of low vegetable and fruit consumption and high-risk dietary behaviors is associated with 11 million deaths per year and approximately 255 million disability-adjusted lifeyears [49]. Therefore, a healthy diet is important, and without improvement in dietary habits, this figure is likely to increase with significant negative consequences. However, diet is a modifiable cancer risk factor [3]. The government should encourage individuals to practice healthy dietary behaviors to prevent cancer.

Our study has some limitations. First, because this study has a cross-sectional design and a small sample size, it may prevent us from establishing causality. Second, an online survey could reduce participants’ concentration and cause them to mindlessly respond, which could lead to inaccurate responses. Third, because only interested individuals in the survey and those who could use the Internet participated in the online survey, this survey could not include individual who were not interested in the survey, or who were not proficient in the internet use.

Despite these limitations, our study has several strengths. First, the study population was selected by considering sex, age, and region, and the survey period was short at 3 weeks. Therefore, the results of this study reflected the overall current practice rate of dietary recommendations for cancer prevention in the Korean population. However, to generalize the results nationwide, we need to study a larger population with nationwide sampling and face-to-face surveys. Second, to our knowledge, this study is the first to investigate both the awareness and practice of dietary recommendation behaviors for cancer prevention. Moreover, we categorized the practice groups as no-to-less, sometimes, and always according to the practice rate of each dietary recommendation, owing to which we could determine which recommendation had the lowest practice. Third, we considered the impact of potential confounders; thus, we adjusted for age, sex, region, educational level, marital status, monthly household income level, physical activity, nutritional education, history of chronic disease and cancer, and obesity to analyze the independent effects of each covariate and dietary recommendation for cancer prevention.

This study showed the level of awareness and practice of dietary recommendations for cancer prevention among Korean adults. Most were aware of the importance of dietary factors in cancer prevention. The OR for practicing dietary recommendations was generally high among participants who were physically active, had nutritional education, and had a history of cancer. However, dietary recommendations for cancer prevention were not sufficiently practiced among those with a history of hypertension and dyslipidemia. To increase the practice of dietary recommendations, it is important to identify individuals with low practice rates and conduct appropriate educational interventions. Our findings provide insights into policy efforts that should be made to actively improve poor dietary behaviors, which account for a large proportion of cancer cases.

AICR, American Institute for Cancer Research; BMI, body mass index; CI, confidence interval; OR, odds ratio; WCRF, World Cancer Research Fund; WHO, World Health Organization.

Ethics approval and consent to participate

The survey protocol and secondary data were approved by the Institutional Review Board of the National Cancer Center, Republic of Korea [No. NCC2023-0251].

All participants provided written informed consent.

Consent for publication

Not applicable.

Availability of data and materials

The datasets used in this study available from the corresponding author on reasonable request.

Competing interests

The authors declare that they have no competing interests.

Funding

This research was supported by the National Cancer Center Research Grant [NCC-2311440-2].

Authors’ contributions

Yoonjoo Choi, Hyein Jung, and Byungmi Kim: Conceptualization, Methodology. Hyein Jung: Formal Analysis. Yoonjoo Choi and Hyein Jung: Writing-Original draft, review and editing. Yoonjoo Choi and Byungmi Kim: Writing-Review and editing. All authors read and approved the final manuscript.

Acknowledgements

Not applicable.

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No competing interests reported.

AdditionalFile1.docx
Title of data: Frequency of practice of the dietary recommendation “consume sufficient amounts of fruits and vegetables” Description of data: Table
AdditionalFile2.docx
Title of data: Frequency of practice of the dietary recommendation “balance your diet with a wide range of healthy foods” Description of data: Table
AdditionalFile3.docx
Title of data: Frequency of practice of the dietary recommendation “limit your salt intake from all sources” Description of data: Table
AdditionalFile4.docx
Title of data: Frequency of practice of the dietary recommendation “avoid burnt or charred foods” Description of data: Table
AdditionalFile5.docx
Title of data: Frequency of practice of the dietary recommendation “avoid alcohol consumption” Description of data: Table

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Awareness and practice of dietary recommendations for cancer prevention among participants of the 2023 Korean National Cancer Prevention for Dietary Awareness and Practice Survey

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Abstract

Background

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Background

Methods

Study participants and data collection

Questionnaires

Practice ascertainment

Statistical analysis

Results

Participant characteristics

Practice of each dietary recommendation for cancer prevention

Practice of “consume sufficient amounts of fruits and vegetables”

Practice of “balance your diet with a wide range of healthy foods”

Practice of “limit your salt intake from all sources”

Practice of “avoid burnt or charred foods”

Practice of “avoid alcohol consumption”

History of disease and practice of each dietary recommendation

Discussion

Conclusions

List of abbreviations

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References

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