Compared to those in Western cultures, Chinese people used to be reluctant to consume dietary supplements (Liu et al., 2021), believing instead in the beneficial effects of traditional Chinese medicine for health preservation, such as drinking herbal decoctions, practicing tai chi, and meditating (Li et al., 2017; Yang et al., 2021). However, in the last 20 years interest in taking dietary supplements has increased greatly among Chinese people (Djaoudene et al., 2023; Liu et al., 2021). This interest may result from various factors, such as globalization, economic development, environmental pollution, and food safety issues (Liu et al., 2021). In particular, the outbreak of COVID-19 dramatically increased people’s motivation in regard to dietary supplement consumption (Liu et al., 2021). Given that the severity of symptoms of COVID-19 varies depending on the immune system, people have begun paying much more attention to measures to improve immunity, including taking dietary supplements (Hamulka et al., 2021; Mehta et al., 2023). For example, medical research has demonstrated that certain micronutrients, such as vitamins and zinc, have prophylactic and therapeutic potentials (Gorton & Jarvis, 1999; Mehta et al., 2023). Despite the surge in sales, few studies have examined purchase intention for dietary supplements in China (e.g., Chung et al., 2012; Liu et al., 2021; Sun & Li, 2023). For example, Liu et al. (2021) investigated consumer behavior in the purchase of dietary supplements during the COVID-19 pandemic and found that attitudes, subjective norms, and perceived behavioral control mediated the relationship of the fear of COVID-19 and purchase intention for dietary supplements. Thus, an examination of strategies influencing purchase intention for dietary supplements is particularly necessary for informing marketing practices at the present time. 

 

Another important gap in research on consumption of health products is the lack of attention to young people (Barnes et al., 2016; Gahche et al., 2017; Pokarowski et al., 2023; Wathanakom, 2023; Yeo et al., 2023). Most prior studies of health product consumption and purchase intention have been conducted with older adults (e.g., Gahche et al., 2017; Qato et al., 2016; Tse et al., 2014). This is not surprising because older adults have higher needs for health products than do young people. However, particularly since the outbreak of COVID-19, young people have shown a stronger interest in purchasing health products such as dietary supplements (Pokarowski et al., 2023). Young people’s decision making in the purchase of dietary supplements may differ from that of older adults (Yeo et al., 2023). The current lack of research on young people’s decision making regarding purchasing dietary supplements hampers the development of effective marketing strategies targeting this emerging market in China.

Celebrity endorsement plays an important role in consumer decision making (Bahl et al., 2023; Calvo-Porral et al., 2021; Danniswara et al., 2020; Lee et al., 2008; Shukre & Dugar, 2013; Yen & Teng, 2015). The positive impact of celebrity endorsement on purchase intention and behavior has been documented in research on various types of products, such as fast-moving consumer goods (Shukre & Dugar, 2013), food (Calvo-Porral et al., 2021), and tourism destination selection (Lee et al., 2008; Yen & Teng, 2015). Celebrity involvement is an important mechanism explaining the effect of celebrity endorsement. The concept of celebrity involvement originates from leisure involvement, which refers to “an unobservable state of motivation, arousal, or interest toward a recreational activity or associated activity” (Yen & Teng, 2015, p. 3). The involvement consists of both cognitive and emotional elements and has been conceptualized as having three dimensions: attraction, centrality, and self-expression (Kim & Ko, 2012; McIntyre & Pigram, 1992). Attraction reflects an individual’s level of interest in, enjoyment, or liking of the subject of involvement. Centrality relates to the significance or importance of the involved object, topic, or activity in an individual’s life, indicating how central or integral the subject of involvement is to the individual’s identity (Kim, 2012). Self-expression pertains to the extent to which the involved object, topic, or activity allows individuals to express or communicate their identity, values, or emotions (McIntyre & Pigram, 1992), reflecting how individuals use the subject of involvement as a means of self-expression and personal reflection (Kim & Ko, 2012). Fans with a high (vs. low) level of involvement identify with a celebrity, show higher levels of attachment to and trust in the celebrity, and are more active in celebrity activities (Kim & Ko, 2012). It is not surprising that consumers develop a positive attitude toward a product if they are involved with or attached to the celebrity endorsing the product (Ilicic & Webster, 2011).

 

Empirical studies conducted in various cultural contexts have demonstrated that celebrity involvement is positively associated with consumers’ perceived value of and purchase intention for the endorsed product (Aldlaigan & Buttle, 2005; Ilicic & Webster, 2011; Kim & Ko, 2012; Lajnef, 2023; Yen & Teng, 2015). For instance, Calvo-Porral et al. (2021) collected data from 316 consumers in Spain and found that celebrity involvement was associated with a stronger food purchase intention and greater willingness to pay premium prices. Therefore, celebrity involvement may increase perceived value and purchase intention for health products in China. However, as the importance of celebrity involvement has rarely been examined in China, particularly in regard to its impact on purchase intention for dietary supplements, it is not clear whether the expected effect of celebrity involvement manifests in this emerging market. Thus, we proposed the following hypothesis:

Hypothesis 1: Celebrity involvement on social media sites will be positively associated with purchase intention for dietary supplements among Chinese people.

Consumers’ perceived value is a key concept in marketing that has attracted considerable research attention (see, for a review, Vieira et al., 2018). A consumer’s perceived value of a product is influenced by a range of factors such as the perception of the product’s price, quality, and social value (Vieira et al., 2018). For instance, consumers perceive the product’s value based on the difference between the amount of money paid and the perceived quality of the product (Konuk, 2019). In addition, the value may be perceived as high if the goods carry particular social meaning, for example, as an indicator of socioeconomic status. Researchers agree that perceived value is a multidimensional concept, but they have conceptualized it as having different values (e.g., Baars et al., 2019; Kunkel et al., 2017; Vieira et al., 2018; Zietsman et al., 2020). For food and health products, perceived health value is a particularly important element (Baars et al., 2019). Rahnama (2017) examined the effect of consumption values, including perceived health value, on consumers’ purchase behavior toward organic food. The results showed that health value exerted a positive effect on purchase decision making, whereas the effect of social value was not significant. Dietary supplements are among the most common health products people consume on a daily basis. It is thus reasonable to expect that perceived health value will play a role in Chinese consumers’ decision making when purchasing dietary supplements.

 

In marketing research in general, scholars have repeatedly documented the positive effects of celebrity involvement on consumers’ perceived value of a product or service (Osei-Frimpong et al., 2019; Parayitam et al., 2020). For instance, Osei-Frimpong et al. (2019) conducted a survey with 500 university students in Ghana and found that when there was a celebrity recommendation for the product, the students’ perception of the quality of that product became more positive. At the same time, perceived value is a robust predictor of consumer purchase intention and behavior (Alberto de Morais Watanabe et al., 2020; Kung et al., 2021). Obviously, consumers hope to buy the products that bring them most value. It is reasonable to expect that perceived value will act as a mediator of the relationship of celebrity involvement and purchase intention for dietary supplements. However, the mediating effect of perceived value in the relationship of celebrity involvement with purchase intention for health products such as dietary supplements has not been well studied. In particular, the perceived health value of products such as dietary supplements has not been closely examined in prior studies (e.g., Kung et al., 2021). Therefore, we proposed the following hypothesis:

Hypothesis 2: Chinese consumers’ perceived health value of dietary supplements will mediate the relationship of celebrity involvement on social media sites and consumers’ purchase intention.

One explanation for Chinese people’s recent interest in purchasing health products may be a perception of heightened vulnerability to disease (Liu et al., 2021; Mohsen et al., 2021). For example, similar to other infectious diseases, an important feature of COVID-19 is the elicitation of fear (Liu et al., 2021), which may be more pronounced among Chinese people. China enforced a strict policy to control COVID-19 for 3 years, which means that lockdowns occurred even when there was only one positive case (Liu et al., 2021). The geographic scope of the intermittent lockdowns ranged from a building to an entire city. Chinese people’s fear of diseases has increased significantly during the COVID-19 pandemic (Liu et al., 2021). At the same time, it has been found that Chinese people’s perceived vulnerability to disease has heightened in recent years for diverse reasons, such as air pollution, concerns about food safety, and the increasing rate of cancer (Chen et al., 2017). To reduce their fear, people may resort to a range of precautions, such as taking micronutrients to enhance immunity (Liu et al., 2021; Mohsen et al., 2021; Santisi et al., 2021).

 

Although the effect of perceived vulnerability to disease on health-product consumption has been documented (e.g., Liu et al., 2021; Mohsen et al., 2021; Santisi et al., 2021), there have been fewer studies of the moderating effect of perceived vulnerability to disease. We reasoned that the effect of predictors of dietary supplement consumption, such as celebrity involvement and perceived value, may vary according to the consumer’s perception of their level of vulnerability to disease. For instance, consumers may show a stronger intention to buy a dietary supplement if they feel involved with the celebrity endorsing the products (e.g., Calvo-Porral et al., 2021). This relationship may be stronger if these consumers perceive a greater probability of getting sick, because their motivation for staying healthy is heightened and the effect of celebrity involvement is amplified. In the same vein, perceived vulnerability to disease may also moderate the effect of perceived health value on purchase intention for dietary supplements. However, this moderating effect of perceived vulnerability to disease has received little research attention. Therefore, we proposed the following hypotheses:

Hypothesis 3: Perceived vulnerability to disease will moderate the direct effects of celebrity involvement on social media sites and of perceived health value on consumers’ purchase intention for dietary supplements.

Hypothesis 4: Perceived vulnerability to disease will moderate the indirect effect of celebrity involvement on consumers’ purchase intention for dietary supplements on social media sites.

 

The conceptual model of this study is depicted in Figure 1.

 

The data analyzed in this study were collected from undergraduate students at Ningbo University of Finance and Economics and Ningbo University of Technology. We used convenience sampling to randomly select 15 classes at each of the two universities and invited all students in these classes to participate in the survey. Wenjuanxing was used to administer the survey electronically. During class meeting time, the researchers sent a link for students to access the survey. Participants were informed that the purpose of the study was to understand the influences of marketing on social media platforms and informed that they had the right to quit at any stage. We made it clear that this study focused solely on social media platforms and gave a few popular websites/applications as examples in our instructions. No incentive or gift was offered to participants. Anonymity was ensured. The study was reviewed by the Research Ethics Committee of Ningbo University of Finance and Economics as well as the two participating universities.

 

We received responses from 1,100 students. After excluding surveys in which responses were invalid (e.g., not fully answered), the final number of valid responses used for data analysis was 1,059 (valid response rate = 96.27%).

 

 

Following a prior study (Liu et al., 2021), we used three items to assess the behavioral intention toward the purchase of dietary supplements: “I am willing to purchase dietary supplements for maintaining a healthy condition,” “I have suggested others buy dietary supplements,” and “I am willing to pay more for dietary supplements than for ordinary food products.” Participants rated each item on a 5-point Likert scale ranging from 1 (strongly disagree) to 5 (strongly agree), with higher scores indicating a stronger purchase intention. Cronbach’s alpha in this study was .82.

 

To capture perceived health value, three items were adapted from Rahnama’s (2017) study: “Dietary supplements keep me healthy,” “Dietary supplements are nutritious,” and “Dietary supplements are good for my skin/teeth/hair/bones.” Participants were asked to rate each item on a 5-point Likert scale ranging from 1 (strongly disagree) to 5 (strongly agree), where higher scores indicate higher levels of perceived health value. Cronbach’s alpha in this study was .90.

 

Following prior studies (Lee et al., 2008; Wiley et al., 2000), this study captured three dimensions of celebrity involvement: attraction, centrality, and self-expression, with each dimension measured with four items. Respondents were asked to report how much they agreed with 12 statements such as “The celebrity activity is very important to me” (attraction), “I find a lot of my life is organized around the celebrity” (centrality), and “You can tell a lot about a person by seeing them participating in celebrity activity” (self-expression). Responses are rated on a 5-point Likert scale ranging from 1 (strongly disagree) to 5 (strongly agree), with higher scores indicating greater celebrity involvement. Cronbach’s alpha in this study was .79.

 

Perceived vulnerability to disease was assessed with a 15-item self-report scale (Duncan et al., 2009) designed to measure perceived infectability and germ aversion. Respondents report how much they agree with statements such as “In general, I am very susceptible to colds, flu, and other infectious diseases” and “It does not make me anxious to be around sick people.” Responses are rated on a 5-point Likert scale ranging from 1 (strongly disagree) to 5 (strongly agree). Some responses are reverse coded so that a higher score indicates higher levels of perceived vulnerability to disease. Cronbach’s alpha in this study was .80.

 

We controlled for the demographic variables of gender (0 = male, 1 = female), year of study (1 = 1st, 2 = 2nd, 3 = 3rd, 4 = 4th), family income (1 = much lower than average, 2 = lower than average, 3 = average, 4 = higher than average, 5 = much higher than average), and the university at which the participant was studying. 

We used SPSS 21.0 to perform descriptive analyses for each variable. Then, Model 15 of the PROCESS macro (Hayes, 2017) was used to evaluate the moderated mediation model. The bootstrapping method with 3,000 iterations was used because this method has been found to generate more robust results than do normal-theory tests regarding moderated mediation effects (Preacher et al., 2007).

There may be a risk of common method bias in collecting data through a survey. Therefore, we followed the method recommended by prior researchers to control common method bias (anonymity of respondents and reverse scoring of some items), and used Harman’s single-factor test to test for common method bias (Podsakoff et al., 2003). The first factor explained 29.01% of the total variance, which is much smaller than the recommended threshold of 50%. Thus, there was no serious common method deviation in this study.

The descriptive statistics are shown in Table 1.

The results regarding direct and moderating effects are shown in Table 2. Celebrity involvement was significantly associated with the perceived health value of dietary supplements. Specifically, an increase in celebrity involvement was associated with a higher perceived health value of the dietary supplements. Year of study was positively associated with perceived health value, that is, senior students reported greater perceived health value of the dietary supplements than did those in the other years. Gender was significantly associated with the perceived health value of the supplements. Women reported higher perceived value of dietary supplements than men did. Level of parental income did not have a significant effect on students’ perception of the health value of supplements. There was no significant difference between the students at the two universities in their perception of the health value of dietary supplements.

 

Celebrity involvement was positively associated with purchase intention. Specifically, the greater the celebrity involvement, the stronger the intention to purchase dietary supplements. Perceived health value of dietary supplements and perceived vulnerability to disease were significantly and positively associated with purchase intention. The control variables (year of study, gender, parental income, and university) were not significantly related to purchase intention. Perceived vulnerability to disease did not significantly moderate the direct effect of celebrity involvement on purchase intention, but it did moderate the relationship of perceived health value of dietary supplements and purchase intention. That is, celebrity involvement exerted a constant effect on the purchase intention for dietary supplements among students at any level of perceived vulnerability to disease. However, the higher the level of perceived vulnerability to disease, the stronger the effect of perceived health value of dietary supplements on the intention to purchase.

The moderated mediation effect is presented in Table 3. The path of celebrity involvement → perceived health value of dietary supplements → purchase intention existed only among respondents who reported medium or high levels of perceived vulnerability to disease. The indirect effect increased alongside increases in the respondents’ perceived vulnerability to disease, suggesting the existence of a moderated mediation effect (Hayes, 2017).

The sale of dietary supplements in China has experienced a significant increase in the last 20 years, and this upward trend is expected to continue (e.g., Chung et al., 2012; Liu et al., 2021; Sun & Li, 2023). However, there is a lack of research on marketing of dietary supplements in this emerging market. In particular, in the era of digital media, research on purchasing behavior on new media platforms is necessary for informing marketing practices. We found that celebrity involvement on social media sites was positively associated with Chinese university students’ purchase intention for dietary supplements, and that this positive association was mediated by students’ perception of the health value of the celebrity-endorsed dietary supplements. Perceived vulnerability to disease moderated the effect of the perceived health value of the supplements on students’ purchase intention. Further, the indirect effect of celebrity involvement on purchase intention was moderated by perceived vulnerability to disease. To sum up, our four hypotheses were supported.

 

This study contributes to scholarship by extending prior research on purchase intention of health products among young adults. In existing studies on purchase intention for health products, including dietary supplements, primarily older adults had been surveyed (e.g., Gahche et al., 2017; Qato et al., 2016; Tse et al., 2014). Previous studies collectively showed that factors such as perceived vulnerability to disease and the perceived value of products were positively related to participants’ purchase intention and behavior (e.g., Liu et al., 2021). Consistent with these studies, we found that the perceived health value of dietary supplements and perceived vulnerability to disease were associated with purchase intention among young adults in China. The findings add to previous empirical findings on the factors influencing Chinese people’s purchase intention for dietary supplements (Chung et al., 2012; Liu et al., 2021; Sun & Li, 2023). One of the reasons explaining older adults’ stronger intention to purchase health products may be their heightened perceived vulnerability to disease compared with younger adults. Since the outbreak of COVID-19, people have shown a much stronger perception of vulnerability to disease in general (Liu et al., 2021). Young people are also alert to the importance of strengthening their immune system. The influence of COVID-19 on people’s mentality may linger long after the pandemic (Mehta et al., 2023). The heightened interest in purchasing dietary supplements among people of all ages may continue in the next decade. Therefore, our examination of the effectiveness of marketing strategies for dietary supplements on social media sites offer important implications for marketing of dietary supplement brands targeting younger generations.

 

This study also contributes to research on digital marketing. Specifically, this study examined the relationships of celebrity involvement on social media sites with the perceived health value of dietary supplements, perceived vulnerability to disease, and purchase intention. It is not surprising to see that celebrity involvement was positively related to the perceived health value of the supplements and to purchase intention. These results are consistent with prior findings regarding traditional media such as television and magazines (e.g., Lee et al., 2008). New media of all kinds have emerged and evolved fast, with platforms such as TikTok and Xiaohongshu having obtained billions of users in less than 10 years. The dissemination of information has become more decentralized as everyone can post and gain popularity in a very short period of time (see, e.g., Meese & Hurcombe, 2021). These new platforms may result in a challenge to prior findings regarding the effectiveness of marketing, such as celebrity endorsement. It is reassuring for companies marketing products to see that in our research celebrity involvement exerted strong and positive effects on students’ perception of the health value of dietary supplements and on their purchase intention. Social media sites allow celebrities to interact and bond with fans more easily and effectively, which is more effective for marketing purposes.

 

Further, we found that perceived vulnerability to disease moderated both the direct effect of the perceived health value of supplements and the indirect effect of celebrity involvement on purchase intention. This moderating effect has not been well examined in prior research (e.g., Liu et al., 2021), despite being very reasonable. Our results showed that when university students perceived higher vulnerability to disease, their perception of the health value of dietary supplements exerted a strong impact on their purchase intention for the supplements. We did not find this surprising because when people anticipate that they may get sick and they believe in the health value of a dietary supplement, they will have a stronger motivation to make a purchase. At the same time, the path from celebrity involvement to perceived health value and then to purchase intention was moderated by perceived vulnerability to disease. We note that this moderation path did not apply among students with low levels of perceived vulnerability to disease. This may be because young people who perceive a very low likelihood of getting sick may have no interest in purchasing dietary supplements, making celebrity endorsement or involvement irrelevant. As the perception of vulnerability to disease becomes stronger, the indirect effect of celebrity involvement on purchase intention becomes stronger. This finding has important implications for precision targeting of marketing for dietary supplement brands on new media platforms.

Our findings have important implications for marketing practice. Makers of brands of dietary supplements need to find ways to enhance Chinese consumers’ perception about the value of dietary supplements. This is particularly important because, until recently, Chinese people had low intention in regard to purchase of dietary supplements. The lack of interest may result from a perception of little value of dietary supplements. Many Chinese people perceive traditional Chinese medicines to be effective in maintaining physical health (Li et al., 2017; Yang et al., 2021); thus, they may doubt the effectiveness of Western dietary supplements. COVID-19 pushed Chinese people to seek all possible measures to strengthen their immunity. Makers of dietary supplements should seize the opportunity to instill in Chinese consumers the value of their products. This could be achieved through social media marketing. As has been repeatedly emphasized by researchers and practitioners alike, social media marketing has multiple advantages with which traditional media cannot compete, such as interactivity and an instant quality (see, for a review, Alves et al., 2016). Through marketing efforts, such as celebrity endorsement on social media platforms, makers of dietary supplement brands may well enhance Chinese consumers’ perception of the health and emotional value of their products.

 

In addition, our findings on the factors influencing purchase decision for dietary supplements are in general consistent with those reported in prior research conducted among older adults. This has implications for marketing strategies for dietary supplements. In particular, we found that among students who perceived that they had low vulnerability to disease, celebrity involvement did not influence their perception of the health value of the dietary supplements and, thus, did not influence their purchase intention. This highlights the importance of customer segmentation and precision marketing of dietary supplements in China. When makers of brands of dietary supplements aim to expand their market share among young people, our advice is that they invite those celebrities who are loved by the target population to endorse their products and to target those young people who perceive that they have high vulnerability to disease.

Our findings need to be interpreted in the light of some caveats. Analysis of cross-sectional data cannot produce causal relationships. Although findings from prior studies justify our hypothesized causality (e.g., Qato et al., 2016; Tse et al., 2014), longitudinal research is preferable to our cross-sectional research design. In addition, we used nonprobability sampling for this study, which limits the generalizability of our findings. Compared with other groups, university students may be more susceptible to influence by celebrities (Apejoye, 2013). Therefore, future studies should replicate our research using more diverse samples. Furthermore, we included only the perceived health value of dietary supplements as a mediating variable. Given that perceived value is a multidimensional concept, it is necessary to examine other dimensions of the perceived value of these supplements. At the same time, the actual benefits of dietary supplements, especially to young people, should be further investigated. Given that the beneficial effects of dietary supplements may be difficult to perceive, future studies on purchase intention of such health products could be conducted to differentiate between perceived effects and actual effects.

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