This review provided a comprehensive overview of the evidence regarding the influence of nutrition claims relating to fat, sugar, and energy content on food choices and energy intake. Results showed that nutrition claims relating to fat, sugar, or energy content can shape the knowledge of consumers with respect to perceived healthfulness of products, as well as expected and experienced tastiness of food products – making food products with nutrition claims generally seem healthier and less tasty. Nutrition claims can also make the appropriate portion size appear to be larger and lead to an underestimation of the energy content of food products. Nutrition claims can influence food purchase intentions, moderated by the perceived healthfulness of the relevant food products and the health consciousness of individuals. Nutrition claims were also found to have an influence on food purchases and on ‘consumption guilt’ associated with eating a food product, and to increase consumption, moderated by the weight status of individuals. These influences were shown to vary depending on the type of claim and food carrying the claim.
These results align with the findings of previous reviews that have shown that nutrition and health claims can have ‘health halo’ effects where consumers perceive products carrying such claims as lower in calories and healthier than they are [23, 24]. Williams found that ‘health halos’ may discourage consumers from reading more comprehensive nutrition information on labels [23]. Chandon concluded that nutrition and health claims can influence consumers’ perceptions, increasing consumption and lowering perceived energy intake [24]. Further, a recent meta-analysis on the influence of nutrition and health claims on food choices showed that foods carrying claims are 75% more likely to be chosen than identical products without a claim [26]. However, the meta-analysis showed that nutrition and health claims had a larger influence on food products categorised as ‘beans, pulse, fish, eggs, meat and other proteins’ or ‘fruits and vegetables’ as compared to ‘foods high in fat and/or sugar’ or other categories of food products [26].
The results of the review have been summarised into a conceptual model regarding the potential influence of nutrition claims on food choices. The model is presented in Fig. 2.
As the proposed conceptual model (Fig. 2) suggests, nutrition claims may influence expected and experienced tastiness of food products, perceived nutrition characteristics of food products as well as perceived appropriate portion size of food products [32, 33, 35,36,37, 39, 40]. Perceived nutrition characteristics of food products include perceived healthfulness of food products [33, 37, 39]. Both weight status and nutrition knowledge may moderate how nutrition claims influence nutrition characteristics perceptions of food products and the perceptions of appropriate portion size [41]. Subsequently, expected tastiness, perceived nutrition characteristics, and perceived appropriate portion size may potentially influence food choices [31, 34, 35, 38,39,40]. Motivation to adopt a healthy diet as well as emotions might further moderate how both nutrition characteristics perceptions of food products and the perceptions of appropriate portion size may influence food choices [33, 41]. Previous studies on cognitive and emotional influences have also shown that feelings can affect decision-making [42,43,44]. Guilt was found to guide and influence decisions [45, 46]. Burnett and Lunsford pointed out that health guilt or the absence of it can influence purchase as well as consumption decisions [45]. They explained that health guilt occurs when consumers believe that their decisions are not beneficial to their health [45]. Besides, other emotions such as sadness and happiness, can affect decision-making [44]. Comparably, the conceptual model suggests that food choices may vary depending on the moderating influence of emotions such as ‘consumption guilt’. Food choices can encompass purchase intentions, purchases, and consumption [31,32,33,34, 38, 40]. Consumption is understood as the foods consumed and the portion size of the foods consumed [31, 34, 38, 40]. Food choices (type and portion size of foods consumed) may further influence experienced tastiness and energy intake. Energy intake, in turn, predicts weight status [47, 48]. This model should be interpreted cautiously. While the proposed model suggests the potential influence of nutrition claims on food choices, the strength of each influence requires confirmation and quantification through further research.
This is the first systematic review focusing on specific nutrition claims. Methodological strengths of this review were its systematic nature and the use of the EPHPP tool to assess the methodological quality of the studies [28, 29]. However, there were several limitations with the nature of the evidence included in this review. Firstly, the methodological quality of most studies included in the review was low. This was mostly due to potential selection bias and relevant information (for quality assessment) not being reported. Information on validity and reliability of data collection tools was missing in many studies [34,35,36, 38,39,40]. Five studies had a relatively small sample size (n < 150) which may limit the generalizability of their findings [31, 34, 36, 38, 40]. Secondly, all studies besides one [40] were conducted in a laboratory setting that may not represent how consumers respond in ‘real-world’ situations [49]. Thirdly, all of the included studies focused on nutrition claims relating to fat, with only a small number also looking at nutrition claims relating to sugar (n = 2) and energy content (n = 1). This may limit the generalizability of the results relating to the influence of nutrition claims (not related to fat) on food choices. Generalizability of the results may be further limited because the majority of food categories assessed in the included studies were snack foods, i.e. chocolate, chips, cookies, M&M's., granola bars, and milkshakes. Only three studies focused on ‘healthier’ food products such as yogurt, coleslaw, and cereals [32, 33, 35]. More studies are needed in different food categories to draw general conclusions about the influence of nutrition claims. A fourth limitation is that only a few studies measured energy intake and studies typically only looked at the impact on selected aspects of diet. For example, several studies looked at single purchase or consumption decisions but did not assess energy in a meal, overall daily energy intake or diet quality. Thus, the overall impact of nutrition claims on daily energy intake is largely unknown. Further research needs to look at the impact on daily intake and identify potential compensatory behaviours.
There were also a number of limitations associated with the review methods themselves. The review only included articles written in English, and therefore relevant studies in other languages may have been excluded. Furthermore, as the review focused on the isolated influence of nutrition claims, conclusions regarding the influence of nutrition claims should be drawn cautiously as many other factors such as availability, affordability, and cultural differences may influence food consumption [50,51,52]. In addition, this review did not examine the impact on consumers’ beverages choices as it focused on nutrition claims on food products. Further, this review did not look at the potential impact on supply-side factors such as product development and reformulation. The way nutrition claims are displayed (e.g. size and colour) and their interaction with other components of the package (e.g. front-of-pack (FOP) labelling systems, warning labels) needs to be investigated. Moreover, the way in which nutrition claims interact with other factors within the food environment such as food advertising and food formulation need to be considered and further investigated to better understand how the food environment influences overweight and obesity.
Implications for policy makers
Policy approaches contributing to the prevention of overweight and obesity through the food selection environment have focused on providing nutrition information to promote healthier eating behaviours. Results of this review indicate that nutrition claims relating to fat, sugar, and energy content are likely to increase purchase intentions when food products are perceived as healthier. However, there are indications that they may also have the unintended consequence of leading to energy overconsumption.
Although the quality of the evidence included in this review is low, and the results are indicative at best, the current evidence suggests that policy makers may need to exercise caution regarding nutrition claims relating to fat, sugar and energy content due to their potential negative influences on the healthiness of food choices and, consequently, population weight outcomes. In Australia, before any health claim can be made, the food product must meet a certain level of healthiness determined by a detailed set of nutrient profiling criteria. However, the same criteria do not apply to nutrition claims [16]. In the EU, the use of nutrition and health claims is permitted, subject to regulations regarding the specific claims that can be made [17]. The regulations planned to incorporate specific nutrient profiles for the use of nutrition and health claims. The regulations planned for the level of certain nutrients contained in a food product as well as the role and importance of that product in a healthy diet to be eligibility criteria for permitting nutrition and health claims. However, the criteria have not yet been proposed and have thus not yet been applied [17, 53]. Given the potential negative influence of nutrition claims and that such claims are in principle regulated to prevent any practices that may mislead consumers in their food purchases, governments could consider options to limit potential negative influences of nutrition claims, such as by preventing their use or only allowing their use on food products that meet specific measures of healthiness. Moreover, if nutrition claims are used, policy makers could consider making it mandatory to have interpretive FOP labels (e.g., Health Star Rating or warning labels) that can give an overall impression of the product’s healthfulness. This will help to ensure consumers have, for every food product, concise and useful nutrition information at their disposal to make healthier food choices [8, 15, 54].
A recent meta-analysis assessing the impact of nutrition labelling on food choices showed that nutrition labelling may be an effective approach in steering consumers’ food choices towards healthier products [20]. Although nutrition claims are one aspect of nutrition labelling, policy makers need to consider all aspects of labelling, including FOP symbols and interpretive labelling, warning labels, back-of-pack nutrition information panels, and claims. A potential alternative to nutrition claims may be Chile’s warning labels that flag food products with high content of key nutrients to discourage consumption of unhealthy food products [55], although their impact needs to be evaluated. Importantly, all forms of nutrition labelling are likely to be only a minor influence on diets overall. Accordingly, policies on nutrition claims need to be only one part of a comprehensive strategy to improve population diets and address obesity [56,57,58,59].