Table 2.

Overview of studies reviewed. Results

Author Year Journal	Results	Confounders	Conclusion	Additional comments (e.g., details of intervention)
Sugar
Divaris 2012 Acta Odontol Scand	Although a positive trend emerged, the frequency of the children’s sweet consumption was not found significantly associated with the caregivers’ level of oral HL (only a bivariate distribution was performed).	Age Education level Race	OHL was not significantly associated with child’s oral health-related quality of life
Irwan 2016 International Journal of Nursing Sciences	No association was found between HL level and sugar limitation	Gender Occupation Education level Health status	Sugar limitation correlated with salt limitation (0·15, P < 0·05) and MHC – Monthly Health Check-ups (0·10)
Joulaei 2018 Progress in Nutrition	Among boys, an increasing FNL (component of total nutrition literacy) was associated with higher sugar score quartile, which showed lower intake of sugar (OR 1·071, 95 % CI 1·002, 1·146, P < 0·05)	Gender BMI Parents’ education level Physical activity	A higher FNL was associated with lower sugar intake and a better energy balance in boys
Persoskie 2017 Prev Chronic Dis	In unadjusted models, NFP label understanding was negatively associated with sugar-sweetened soda consumption: participants with a better understanding of the NFP reported consuming sugar-sweetened soda fewer days a week (OR 0·88; 95 % CI 0·81, 0·94; P = 0·001). After adjusting for demographic characteristics, the association between NFP label understanding and sugar-sweetened soda consumption remained significant (OR 0·90; 95 % CI 0·81, 0·99; P = 0·03)	Age Gender Education level Income Race/ethnicity	Many consumers have difficulty interpreting nutrition labels and label understanding correlates with self-reported dietary behaviours (those with better label understanding tended to drink less sugar-sweetened soda) Higher scores for label understanding were associated with consuming less sugar-sweetened soda, even after adjusting for demographic factors
Sistani 2017 Eur J Dent	High OHL scores 12–17 correlated significantly with a lower consumption of sugary snacks or beverages (<1/d between meals) (OR = 1·56, 95 % CI 1·13, 2·15, P = 0·007)	Age Gender Education level Economic status	Age and OHL scores predict individuals’ consumption of sugary drinks and snacks (<1/day between meals). This result indicates that all adults, and especially youngsters and those with limited literacy skills, should have access to easily understood messages about a diet for oral health.
Zoellner 2011 J Am Diet Assoc.	HL significantly predicted SSB beverage consumption (R 2 = 0·15; F = 6·3; P < 0·01), while accounting for demographic variables. For SSB, participants in the lowest HL category consumed about 119 kcal/d more than those with an adequate HL Every 1 point in HL scores was associated with 34 fewer SSB kcal/d	Age Gender Education level Household income Race SNAP participation	An important relationship exists between HL and SSB consumption and illustrates how understanding the causes and consequences of limited HL is an important factor in promoting compliance with the Dietary Guidelines for Americans
Zoellner 2016 Int J Behav Nutr Phys Act	HL status did not significantly influence 6-month retention rates (low HL = 79 ± 41 %, high HL = 72 ± 45 %; P = 0·56) or class engagement rates (low HL = 2·14 ± 1·03, high HL = 1·97 ± 1·15; P = 0·20) The 6-month SSB kcal reduction between participants in the SipSmarter condition with low HL v. high HL was not statistically significant (P = 0·21).	Age Gender Education level Income Race/ethnicity Employment status Number of children Smoking status BMI HL	Baseline HL status did not moderate any of the primary or secondary outcomes. Between the low HL and high HL groups, the relative effect of the treatment was not statistically significant (P = 0·31).	SipSmarter targeted decreasing SSB consumption, with the primary goal of achieving the SSB recommendation of <8 fluid ounces a day. To sufficiently target SSB reduction, participants were educated on recommendations for all beverage categories (including water, unsweetened beverages, milk). The comparison condition, MoveMore targeted PA promotion, with the primary goal of achieving 150 min of moderate-intensity aerobic activity and doing muscle-strengthening activities on two or more days a week. The final 6-month intervention structure, informed by the preliminary work, included three small-group classes, one live teach-back call and eleven Interactive Voice Response calls. SipSmarter and MoveMore conditions were matched in duration and contact. Each of the small-group classes was 90–120 min in duration and delivered in weeks 1, 6 and 17
Salt
Irwan 2016 International Journal of Nursing Sciences	No association was found between HL level and salt limitation	Gender Occupation Education level Health status	The number of respondents who never limited their sugar and salt intake was especially surprising. An intervention programme should be developed to limit salt and sugar intake by the Indonesian elderly
Luta 2018 Nutr Metab Cardiovasc Dis	In multiple regression analysis, neither HL nor FL was significantly associated with salt intake	Age Gender	There was no significant association between the HL index or FL scores and salt intake. The only variable significantly associated with salt intake (P = 0·005) was how salt content impacts food/menu choice. The analysis strongly emphasises the need to raise health-related knowledge, abilities and skills regarding Na/salt and K in the working population of Switzerland and, in particular, to bridge the gap between knowledge and salt-related dietary practices
Fat
Guntzviller 2017 J Immigr Minor Health	HL and avoiding fatty foods were not significantly associated	Age Gender Race Education level	Self-efficacy interacted with HL in avoiding fatty foods although the interaction was only marginally significant. As participants’ HL increased, the positive relationship between self-efficacy and avoiding fatty foods became stronger

HL, health literacy; OHL, oral health literacy; FNL, functional nutrition literacy; NFP, Nutrition Facts panel; SSB, sugar-sweetened beverage; FL, food literacy; SNAP, Supplemental Nutrition Assistance Program.